Initial import with skill sheet working

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# Changelog
## [1.4.1] - 2024-01-20
### Fixed
- Fix race condition in tests ([#90](https://github.com/Level/classic-level/issues/90)) ([`9ff2e82`](https://github.com/Level/classic-level/commit/9ff2e82)) (Matthew Keil).
## [1.4.0] - 2023-11-26
_Not released to npm because of a race issue, which was fixed in 1.4.1._
### Added
- Add opt-in multithreading ([#85](https://github.com/Level/classic-level/issues/85)) ([`7d497a5`](https://github.com/Level/classic-level/commit/7d497a5)) (Matthew Keil).
## [1.3.0] - 2023-04-07
### Changed
- Refactor some pointer usage ([#25](https://github.com/Level/classic-level/issues/25)) ([`d6437b4`](https://github.com/Level/classic-level/commit/d6437b4)) (Robert Nagy)
- Refactor: handle view encoding (Uint8Array) natively ([#43](https://github.com/Level/classic-level/issues/43)) ([`b9fd5e9`](https://github.com/Level/classic-level/commit/b9fd5e9)) (Vincent Weevers)
- Bump and unlock `napi-macros` from 2.0.0 to 2.2.2 ([#58](https://github.com/Level/classic-level/issues/58)) ([`8a4717b`](https://github.com/Level/classic-level/commit/8a4717b)) (Vincent Weevers).
### Fixed
- Swap linux-arm build to use `linux-arm64-lts` ([#71](https://github.com/Level/classic-level/issues/71)) ([`5ea74ab`](https://github.com/Level/classic-level/commit/5ea74ab)) (Cody Swendrowski)
- Add `openssl_fips` variable to gyp bindings ([#72](https://github.com/Level/classic-level/issues/72)) ([`b3f8517`](https://github.com/Level/classic-level/commit/b3f8517)) (Cody Swendrowski).
## [1.2.0] - 2022-03-25
### Added
- Yield `LEVEL_LOCKED` error when lock is held ([#8](https://github.com/Level/classic-level/issues/8)) ([`aa975de`](https://github.com/Level/classic-level/commit/aa975de)) (Vincent Weevers)
### Fixed
- Fix `getMany()` memory leak ([#9](https://github.com/Level/classic-level/issues/9)) ([`00364c7`](https://github.com/Level/classic-level/commit/00364c7)) (Vincent Weevers).
## [1.1.0] - 2022-03-06
### Added
- Create location directory recursively ([#6](https://github.com/Level/classic-level/issues/6)) ([`1ba0b69`](https://github.com/Level/classic-level/commit/1ba0b69)) (Vincent Weevers)
### Fixed
- Fix TypeScript type declarations ([`a79fe82`](https://github.com/Level/classic-level/commit/a79fe82)) (Vincent Weevers)
- Document the return type of `db.batch()` and add example ([`a909ea6`](https://github.com/Level/classic-level/commit/a909ea6)) (Vincent Weevers).
## [1.0.0] - 2022-03-04
_:seedling: Initial release. If you are upgrading from `leveldown` please see [`UPGRADING.md`](UPGRADING.md)._
[1.4.1]: https://github.com/Level/classic-level/releases/tag/v1.4.1
[1.4.0]: https://github.com/Level/classic-level/releases/tag/v1.4.0
[1.3.0]: https://github.com/Level/classic-level/releases/tag/v1.3.0
[1.2.0]: https://github.com/Level/classic-level/releases/tag/v1.2.0
[1.1.0]: https://github.com/Level/classic-level/releases/tag/v1.1.0
[1.0.0]: https://github.com/Level/classic-level/releases/tag/v1.0.0

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MIT License
Copyright (c) 2012 Rod Vagg and the contributors to classic-level and leveldown.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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# classic-level
**An [`abstract-level`](https://github.com/Level/abstract-level) database backed by [LevelDB](https://github.com/google/leveldb).** The successor to [`leveldown`](https://github.com/Level/leveldown) with builtin encodings, sublevels, events, promises and support of Uint8Array. If you are upgrading please see [`UPGRADING.md`](UPGRADING.md).
> :pushpin: Which module should I use? What is `abstract-level`? Head over to the [FAQ](https://github.com/Level/community#faq).
[![level badge][level-badge]](https://github.com/Level/awesome)
[![npm](https://img.shields.io/npm/v/classic-level.svg)](https://www.npmjs.com/package/classic-level)
[![Node version](https://img.shields.io/node/v/classic-level.svg)](https://www.npmjs.com/package/classic-level)
[![Test](https://img.shields.io/github/workflow/status/Level/classic-level/Test?label=test)](https://github.com/Level/classic-level/actions/workflows/test.yml)
[![Coverage](https://img.shields.io/codecov/c/github/Level/classic-level?label=\&logo=codecov\&logoColor=fff)](https://codecov.io/gh/Level/classic-level)
[![Standard](https://img.shields.io/badge/standard-informational?logo=javascript\&logoColor=fff)](https://standardjs.com)
[![Common Changelog](https://common-changelog.org/badge.svg)](https://common-changelog.org)
[![Donate](https://img.shields.io/badge/donate-orange?logo=open-collective\&logoColor=fff)](https://opencollective.com/level)
## Table of Contents
<details><summary>Click to expand</summary>
- [Usage](#usage)
- [Supported Platforms](#supported-platforms)
- [API](#api)
- [`db = new ClassicLevel(location[, options])`](#db--new-classiclevellocation-options)
- [`db.location`](#dblocation)
- [`db.status`](#dbstatus)
- [`db.open([options][, callback])`](#dbopenoptions-callback)
- [`db.close([callback])`](#dbclosecallback)
- [`db.supports`](#dbsupports)
- [`db.get(key[, options][, callback])`](#dbgetkey-options-callback)
- [`db.getMany(keys[, options][, callback])`](#dbgetmanykeys-options-callback)
- [`db.put(key, value[, options][, callback])`](#dbputkey-value-options-callback)
- [`db.del(key[, options][, callback])`](#dbdelkey-options-callback)
- [`db.batch(operations[, options][, callback])`](#dbbatchoperations-options-callback)
- [`chainedBatch = db.batch()`](#chainedbatch--dbbatch)
- [`iterator = db.iterator([options])`](#iterator--dbiteratoroptions)
- [About high water](#about-high-water)
- [`keyIterator = db.keys([options])`](#keyiterator--dbkeysoptions)
- [`valueIterator = db.values([options])`](#valueiterator--dbvaluesoptions)
- [`db.clear([options][, callback])`](#dbclearoptions-callback)
- [`sublevel = db.sublevel(name[, options])`](#sublevel--dbsublevelname-options)
- [`db.approximateSize(start, end[, options][, callback])`](#dbapproximatesizestart-end-options-callback)
- [`db.compactRange(start, end[, options][, callback])`](#dbcompactrangestart-end-options-callback)
- [`db.getProperty(property)`](#dbgetpropertyproperty)
- [`chainedBatch`](#chainedbatch)
- [`chainedBatch.put(key, value[, options])`](#chainedbatchputkey-value-options)
- [`chainedBatch.del(key[, options])`](#chainedbatchdelkey-options)
- [`chainedBatch.clear()`](#chainedbatchclear)
- [`chainedBatch.write([options][, callback])`](#chainedbatchwriteoptions-callback)
- [`chainedBatch.close([callback])`](#chainedbatchclosecallback)
- [`chainedBatch.length`](#chainedbatchlength)
- [`chainedBatch.db`](#chainedbatchdb)
- [`iterator`](#iterator)
- [`for await...of iterator`](#for-awaitof-iterator)
- [`iterator.next([callback])`](#iteratornextcallback)
- [`iterator.nextv(size[, options][, callback])`](#iteratornextvsize-options-callback)
- [`iterator.all([options][, callback])`](#iteratoralloptions-callback)
- [`iterator.seek(target[, options])`](#iteratorseektarget-options)
- [`iterator.close([callback])`](#iteratorclosecallback)
- [`iterator.db`](#iteratordb)
- [`iterator.count`](#iteratorcount)
- [`iterator.limit`](#iteratorlimit)
- [`keyIterator`](#keyiterator)
- [`valueIterator`](#valueiterator)
- [`sublevel`](#sublevel)
- [`sublevel.prefix`](#sublevelprefix)
- [`sublevel.db`](#subleveldb)
- [`ClassicLevel.destroy(location[, callback])`](#classicleveldestroylocation-callback)
- [`ClassicLevel.repair(location[, callback])`](#classiclevelrepairlocation-callback)
- [Development](#development)
- [Getting Started](#getting-started)
- [Contributing](#contributing)
- [Publishing](#publishing)
- [Donate](#donate)
- [License](#license)
</details>
## Usage
```js
const { ClassicLevel } = require('classic-level')
// Create a database
const db = new ClassicLevel('./db', { valueEncoding: 'json' })
// Add an entry with key 'a' and value 1
await db.put('a', 1)
// Add multiple entries
await db.batch([{ type: 'put', key: 'b', value: 2 }])
// Get value of key 'a': 1
const value = await db.get('a')
// Iterate entries with keys that are greater than 'a'
for await (const [key, value] of db.iterator({ gt: 'a' })) {
console.log(value) // 2
}
```
All asynchronous methods also support callbacks.
<details><summary>Callback example</summary>
```js
db.put('example', { hello: 'world' }, (err) => {
if (err) throw err
db.get('example', (err, value) => {
if (err) throw err
console.log(value) // { hello: 'world' }
})
})
```
</details>
Usage from TypeScript requires generic type parameters.
<details><summary>TypeScript example</summary>
```ts
// Specify types of keys and values (any, in the case of json).
// The generic type parameters default to ClassicLevel<string, string>.
const db = new ClassicLevel<string, any>('./db', { valueEncoding: 'json' })
// All relevant methods then use those types
await db.put('a', { x: 123 })
// Specify different types when overriding encoding per operation
await db.get<string, string>('a', { valueEncoding: 'utf8' })
// Though in some cases TypeScript can infer them
await db.get('a', { valueEncoding: db.valueEncoding('utf8') })
// It works the same for sublevels
const abc = db.sublevel('abc')
const xyz = db.sublevel<string, any>('xyz', { valueEncoding: 'json' })
```
</details>
## Supported Platforms
We aim to support _at least_ Active LTS and Current Node.js releases, Electron 5.0.0, as well as any future Node.js and Electron releases thanks to [Node-API](https://nodejs.org/api/n-api.html).
The `classic-level` npm package ships with prebuilt binaries for popular 64-bit platforms as well as ARM, M1, Android, Alpine (musl), Windows 32-bit, Linux flavors with an old glibc (Debian 8, Ubuntu 14.04, RHEL 7, CentOS 7) and is known to work on:
- **Linux**, including ARM platforms such as Raspberry Pi and Kindle
- **Mac OS** (10.7 and later)
- **Windows**
- **FreeBSD**
When installing `classic-level`, [`node-gyp-build`](https://github.com/prebuild/node-gyp-build) will check if a compatible binary exists and fallback to compiling from source if it doesn't. In that case you'll need a [valid `node-gyp` installation](https://github.com/nodejs/node-gyp#installation).
If you don't want to use the prebuilt binary for the platform you are installing on, specify the `--build-from-source` flag when you install. One of:
```
npm install --build-from-source
npm install classic-level --build-from-source
```
If you are working on `classic-level` itself and want to recompile the C++ code, run `npm run rebuild`.
Note: the Android prebuilds are made for and built against Node.js core rather than the [`nodejs-mobile`](https://github.com/JaneaSystems/nodejs-mobile) fork.
## API
The API of `classic-level` follows that of [`abstract-level`](https://github.com/Level/abstract-level) with a few additional options and methods specific to LevelDB. The documentation below covers it all except for [Encodings](https://github.com/Level/abstract-level#encodings), [Events](https://github.com/Level/abstract-level#events) and [Errors](https://github.com/Level/abstract-level#errors) which are exclusively documented in `abstract-level`.
An `abstract-level` and thus `classic-level` database is at its core a [key-value database](https://en.wikipedia.org/wiki/Key%E2%80%93value_database). A key-value pair is referred to as an _entry_ here and typically returned as an array, comparable to [`Object.entries()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/entries).
### `db = new ClassicLevel(location[, options])`
Create a database or open an existing database. The `location` argument must be a directory path (relative or absolute) where LevelDB will store its files. If the directory does not yet exist (and `options.createIfMissing` is true) it will be created recursively. The optional `options` object may contain:
- `keyEncoding` (string or object, default `'utf8'`): encoding to use for keys
- `valueEncoding` (string or object, default `'utf8'`): encoding to use for values.
See [Encodings](https://github.com/Level/abstract-level#encodings) for a full description of these options. Other `options` (except `passive`) are forwarded to `db.open()` which is automatically called in a next tick after the constructor returns. Any read & write operations are queued internally until the database has finished opening. If opening fails, those queued operations will yield errors.
### `db.location`
Read-only getter that returns the `location` string that was passed to the constructor (as-is).
### `db.status`
Read-only getter that returns a string reflecting the current state of the database:
- `'opening'` - waiting for the database to be opened
- `'open'` - successfully opened the database
- `'closing'` - waiting for the database to be closed
- `'closed'` - successfully closed the database.
### `db.open([options][, callback])`
Open the database. The `callback` function will be called with no arguments when successfully opened, or with a single error argument if opening failed. The database has an exclusive lock (on disk): if another process or instance has already opened the underlying LevelDB store at the given `location` then opening will fail with error code [`LEVEL_LOCKED`](https://github.com/Level/abstract-level#errors). If no callback is provided, a promise is returned. Options passed to `open()` take precedence over options passed to the database constructor.
The optional `options` object may contain:
- `createIfMissing` (boolean, default: `true`): If `true`, create an empty database if one doesn't already exist. If `false` and the database doesn't exist, opening will fail.
- `errorIfExists` (boolean, default: `false`): If `true` and the database already exists, opening will fail.
- `passive` (boolean, default: `false`): Wait for, but do not initiate, opening of the database.
- `multithreading` (boolean, default: `false`): Allow multiple threads to access the database. This is only relevant when using [worker threads](https://nodejs.org/api/worker_threads.html)
For advanced performance tuning, the `options` object may also contain the following. Modify these options only if you can prove actual benefit for your particular application.
<details>
<summary>Click to expand</summary>
- `compression` (boolean, default: `true`): Unless set to `false`, all _compressible_ data will be run through the Snappy compression algorithm before being stored. Snappy is very fast so leave this on unless you have good reason to turn it off.
- `cacheSize` (number, default: `8 * 1024 * 1024`): The size (in bytes) of the in-memory [LRU](http://en.wikipedia.org/wiki/Least_Recently_Used) cache with frequently used uncompressed block contents.
- `writeBufferSize` (number, default: `4 * 1024 * 1024`): The maximum size (in bytes) of the log (in memory and stored in the `.log` file on disk). Beyond this size, LevelDB will convert the log data to the first level of sorted table files. From LevelDB documentation:
> Larger values increase performance, especially during bulk loads. Up to two write buffers may be held in memory at the same time, so you may wish to adjust this parameter to control memory usage. Also, a larger write buffer will result in a longer recovery time the next time the database is opened.
- `blockSize` (number, default: `4096`): The _approximate_ size of the blocks that make up the table files. The size relates to uncompressed data (hence "approximate"). Blocks are indexed in the table file and entry-lookups involve reading an entire block and parsing to discover the required entry.
- `maxOpenFiles` (number, default: `1000`): The maximum number of files that LevelDB is allowed to have open at a time. If your database is likely to have a large working set, you may increase this value to prevent file descriptor churn. To calculate the number of files required for your working set, divide your total data size by `maxFileSize`.
- `blockRestartInterval` (number, default: `16`): The number of entries before restarting the "delta encoding" of keys within blocks. Each "restart" point stores the full key for the entry, between restarts, the common prefix of the keys for those entries is omitted. Restarts are similar to the concept of keyframes in video encoding and are used to minimise the amount of space required to store keys. This is particularly helpful when using deep namespacing / prefixing in your keys.
- `maxFileSize` (number, default: `2 * 1024 * 1024`): The maximum amount of bytes to write to a file before switching to a new one. From LevelDB documentation:
> If your filesystem is more efficient with larger files, you could consider increasing the value. The downside will be longer compactions and hence longer latency / performance hiccups. Another reason to increase this parameter might be when you are initially populating a large database.
</details>
It's generally not necessary to call `open()` because it's automatically called by the database constructor. It may however be useful to capture an error from failure to open, that would otherwise not surface until another method like `db.get()` is called. It's also possible to reopen the database after it has been closed with [`close()`](#dbclosecallback). Once `open()` has then been called, any read & write operations will again be queued internally until opening has finished.
The `open()` and `close()` methods are idempotent. If the database is already open, the `callback` will be called in a next tick. If opening is already in progress, the `callback` will be called when that has finished. If closing is in progress, the database will be reopened once closing has finished. Likewise, if `close()` is called after `open()`, the database will be closed once opening has finished and the prior `open()` call will receive an error.
### `db.close([callback])`
Close the database. The `callback` function will be called with no arguments if closing succeeded or with a single `error` argument if closing failed. If no callback is provided, a promise is returned.
A database has associated resources like file handles and locks. When the database is no longer needed (for the remainder of a program) it's recommended to call `db.close()` to free up resources. The underlying LevelDB store cannot be opened by multiple `classic-level` instances or processes simultaneously.
After `db.close()` has been called, no further read & write operations are allowed unless and until `db.open()` is called again. For example, `db.get(key)` will yield an error with code [`LEVEL_DATABASE_NOT_OPEN`](https://github.com/Level/abstract-level#errors). Any unclosed iterators or chained batches will be closed by `db.close()` and can then no longer be used even when `db.open()` is called again.
A `classic-level` database waits for any pending operations to finish before closing. For example:
```js
db.put('key', 'value', function (err) {
// This happens first
})
db.close(function (err) {
// This happens second
})
```
### `db.supports`
A [manifest](https://github.com/Level/supports) describing the features supported by this database. Might be used like so:
```js
if (!db.supports.permanence) {
throw new Error('Persistent storage is required')
}
```
### `db.get(key[, options][, callback])`
Get a value from the database by `key`. The optional `options` object may contain:
- `keyEncoding`: custom key encoding for this operation, used to encode the `key`.
- `valueEncoding`: custom value encoding for this operation, used to decode the value.
- `fillCache` (boolean, default: `true`): Unless set to `false`, LevelDB will fill its in-memory [LRU](http://en.wikipedia.org/wiki/Least_Recently_Used) cache with data that was read.
The `callback` function will be called with an error if the operation failed. If the key was not found, the error will have code [`LEVEL_NOT_FOUND`](https://github.com/Level/abstract-level#errors). If successful the first argument will be `null` and the second argument will be the value. If no callback is provided, a promise is returned.
A `classic-level` database supports snapshots (as indicated by `db.supports.snapshots`) which means `db.get()` _should_ read from a snapshot of the database, created at the time `db.get()` was called. This means it should not see the data of simultaneous write operations. However, there's currently a small delay before the snapshot is created.
### `db.getMany(keys[, options][, callback])`
Get multiple values from the database by an array of `keys`. The optional `options` object may contain:
- `keyEncoding`: custom key encoding for this operation, used to encode the `keys`.
- `valueEncoding`: custom value encoding for this operation, used to decode values.
- `fillCache`: same as described for [`db.get()`](#dbgetkey-options-callback).
The `callback` function will be called with an error if the operation failed. If successful the first argument will be `null` and the second argument will be an array of values with the same order as `keys`. If a key was not found, the relevant value will be `undefined`. If no callback is provided, a promise is returned.
A `classic-level` database supports snapshots (as indicated by `db.supports.snapshots`) which means `db.getMany()` _should_ read from a snapshot of the database, created at the time `db.getMany()` was called. This means it should not see the data of simultaneous write operations. However, there's currently a small delay before the snapshot is created.
### `db.put(key, value[, options][, callback])`
Add a new entry or overwrite an existing entry. The optional `options` object may contain:
- `keyEncoding`: custom key encoding for this operation, used to encode the `key`.
- `valueEncoding`: custom value encoding for this operation, used to encode the `value`.
- `sync` (boolean, default: `false`): if set to `true`, LevelDB will perform a synchronous write of the data although the operation will be asynchronous as far as Node.js or Electron is concerned. Normally, LevelDB passes the data to the operating system for writing and returns immediately. In contrast, a synchronous write will use [`fsync()`](https://man7.org/linux/man-pages/man2/fsync.2.html) or equivalent, so the `put()` call will not complete until the data is actually on disk. Synchronous writes are significantly slower than asynchronous writes.
The `callback` function will be called with no arguments if the operation was successful or with an error if it failed. If no callback is provided, a promise is returned.
### `db.del(key[, options][, callback])`
Delete an entry by `key`. The optional `options` object may contain:
- `keyEncoding`: custom key encoding for this operation, used to encode the `key`.
- `sync` (boolean, default: `false`): same as described for [`db.put()`](#dbputkey-value-options-callback)
The `callback` function will be called with no arguments if the operation was successful or with an error if it failed. If no callback is provided, a promise is returned.
### `db.batch(operations[, options][, callback])`
Perform multiple _put_ and/or _del_ operations in bulk. The `operations` argument must be an array containing a list of operations to be executed sequentially, although as a whole they are performed as an atomic operation.
Each operation must be an object with at least a `type` property set to either `'put'` or `'del'`. If the `type` is `'put'`, the operation must have `key` and `value` properties. It may optionally have `keyEncoding` and / or `valueEncoding` properties to encode keys or values with a custom encoding for just that operation. If the `type` is `'del'`, the operation must have a `key` property and may optionally have a `keyEncoding` property.
An operation of either type may also have a `sublevel` property, to prefix the key of the operation with the prefix of that sublevel. This allows atomically committing data to multiple sublevels. Keys and values will be encoded by the sublevel, to the same effect as a `sublevel.batch(..)` call. In the following example, the first `value` will be encoded with `'json'` rather than the default encoding of `db`:
```js
const people = db.sublevel('people', { valueEncoding: 'json' })
const nameIndex = db.sublevel('names')
await db.batch([{
type: 'put',
sublevel: people,
key: '123',
value: {
name: 'Alice'
}
}, {
type: 'put',
sublevel: nameIndex,
key: 'Alice',
value: '123'
}])
```
The optional `options` object may contain:
- `keyEncoding`: custom key encoding for this batch, used to encode keys.
- `valueEncoding`: custom value encoding for this batch, used to encode values.
- `sync` (boolean, default: `false`): same as described for [`db.put()`](#dbputkey-value-options-callback).
Encoding properties on individual operations take precedence. In the following example, the first value will be encoded with the `'utf8'` encoding and the second with `'json'`.
```js
await db.batch([
{ type: 'put', key: 'a', value: 'foo' },
{ type: 'put', key: 'b', value: 123, valueEncoding: 'json' }
], { valueEncoding: 'utf8' })
```
The `callback` function will be called with no arguments if the batch was successful or with an error if it failed. If no callback is provided, a promise is returned.
### `chainedBatch = db.batch()`
Create a [`chained batch`](#chainedbatch), when `batch()` is called with zero arguments. A chained batch can be used to build and eventually commit an atomic batch of operations. Depending on how it's used, it is possible to obtain greater performance with this form of `batch()`.
```js
await db.batch()
.del('bob')
.put('alice', 361)
.put('kim', 220)
.write()
```
### `iterator = db.iterator([options])`
Create an [`iterator`](#iterator). The optional `options` object may contain the following _range options_ to control the range of entries to be iterated:
- `gt` (greater than) or `gte` (greater than or equal): define the lower bound of the range to be iterated. Only entries where the key is greater than (or equal to) this option will be included in the range. When `reverse` is true the order will be reversed, but the entries iterated will be the same.
- `lt` (less than) or `lte` (less than or equal): define the higher bound of the range to be iterated. Only entries where the key is less than (or equal to) this option will be included in the range. When `reverse` is true the order will be reversed, but the entries iterated will be the same.
- `reverse` (boolean, default: `false`): iterate entries in reverse order. Beware that a reverse seek can be slower than a forward seek.
- `limit` (number, default: `Infinity`): limit the number of entries yielded. This number represents a _maximum_ number of entries and will not be reached if the end of the range is reached first. A value of `Infinity` or `-1` means there is no limit. When `reverse` is true the entries with the highest keys will be returned instead of the lowest keys.
The `gte` and `lte` range options take precedence over `gt` and `lt` respectively. If no range options are provided, the iterator will visit all entries of the database, starting at the lowest key and ending at the highest key (unless `reverse` is true). In addition to range options, the `options` object may contain:
- `keys` (boolean, default: `true`): whether to return the key of each entry. If set to `false`, the iterator will yield keys that are `undefined`. Prefer to use `db.keys()` instead.
- `values` (boolean, default: `true`): whether to return the value of each entry. If set to `false`, the iterator will yield values that are `undefined`. Prefer to use `db.values()` instead.
- `keyEncoding`: custom key encoding for this iterator, used to encode range options, to encode `seek()` targets and to decode keys.
- `valueEncoding`: custom value encoding for this iterator, used to decode values.
- `fillCache` (boolean, default: `false`): if set to `true`, LevelDB will fill its in-memory [LRU](http://en.wikipedia.org/wiki/Least_Recently_Used) cache with data that was read.
- `highWaterMarkBytes` (number, default: `16 * 1024`): limit the amount of data that the iterator will hold in memory. Explained below.
#### About high water
While [`iterator.nextv(size)`](#iteratornextvsize-options-callback) is reading entries from LevelDB into memory, it sums up the byte length of those entries. If and when that sum has exceeded `highWaterMarkBytes`, reading will stop. If `nextv(2)` would normally yield two entries but the first entry is too large, then only one entry will be yielded. More `nextv(size)` calls must then be made to get the remaining entries.
If memory usage is less of a concern, increasing `highWaterMarkBytes` can increase the throughput of `nextv(size)`. If set to `0` then `nextv(size)` will never yield more than one entry, as `highWaterMarkBytes` will be exceeded on each call. It can not be set to `Infinity`. On key- and value iterators (see below) it applies to the byte length of keys or values respectively, rather than the combined byte length of keys _and_ values.
Optimal performance can be achieved by setting `highWaterMarkBytes` to at least `size` multiplied by the expected byte length of an entry, ensuring that `size` is always met. In other words, that `nextv(size)` will not stop reading before `size` amount of entries have been read into memory. If the iterator is wrapped in a [Node.js stream](https://github.com/Level/read-stream) or [Web Stream](https://github.com/Level/web-stream) then the `size` parameter is dictated by the stream's `highWaterMark` option. For example:
```js
const { EntryStream } = require('level-read-stream')
// If an entry is 50 bytes on average
const stream = new EntryStream(db, {
highWaterMark: 1000,
highWaterMarkBytes: 1000 * 50
})
```
Side note: the "watermark" analogy makes more sense in Node.js streams because its internal `highWaterMark` can grow, indicating the highest that the "water" has been. In a `classic-level` iterator however, `highWaterMarkBytes` is fixed once set. Getting exceeded does not change it.
The `highWaterMarkBytes` option is also applied to an internal cache that `classic-level` employs for [`next()`](#iteratornextcallback) and [`for await...of`](#for-awaitof-iterator). When `next()` is called, that cache is populated with at most 1000 entries, or less than that if `highWaterMarkBytes` is exceeded by the total byte length of entries. To avoid reading too eagerly, the cache is not populated on the first `next()` call, or the first `next()` call after a `seek()`. Only on subsequent `next()` calls.
### `keyIterator = db.keys([options])`
Create a [key iterator](#keyiterator), having the same interface as `db.iterator()` except that it yields keys instead of entries. If only keys are needed, using `db.keys()` may increase performance because values won't have to fetched, copied or decoded. Options are the same as for `db.iterator()` except that `db.keys()` does not take `keys`, `values` and `valueEncoding` options.
```js
// Iterate lazily
for await (const key of db.keys({ gt: 'a' })) {
console.log(key)
}
// Get all at once. Setting a limit is recommended.
const keys = await db.keys({ gt: 'a', limit: 10 }).all()
```
### `valueIterator = db.values([options])`
Create a [value iterator](#valueiterator), having the same interface as `db.iterator()` except that it yields values instead of entries. If only values are needed, using `db.values()` may increase performance because keys won't have to fetched, copied or decoded. Options are the same as for `db.iterator()` except that `db.values()` does not take `keys` and `values` options. Note that it _does_ take a `keyEncoding` option, relevant for the encoding of range options.
```js
// Iterate lazily
for await (const value of db.values({ gt: 'a' })) {
console.log(value)
}
// Get all at once. Setting a limit is recommended.
const values = await db.values({ gt: 'a', limit: 10 }).all()
```
### `db.clear([options][, callback])`
Delete all entries or a range. Not guaranteed to be atomic. Accepts the following options (with the same rules as on iterators):
- `gt` (greater than) or `gte` (greater than or equal): define the lower bound of the range to be deleted. Only entries where the key is greater than (or equal to) this option will be included in the range. When `reverse` is true the order will be reversed, but the entries deleted will be the same.
- `lt` (less than) or `lte` (less than or equal): define the higher bound of the range to be deleted. Only entries where the key is less than (or equal to) this option will be included in the range. When `reverse` is true the order will be reversed, but the entries deleted will be the same.
- `reverse` (boolean, default: `false`): delete entries in reverse order. Only effective in combination with `limit`, to delete the last N entries.
- `limit` (number, default: `Infinity`): limit the number of entries to be deleted. This number represents a _maximum_ number of entries and will not be reached if the end of the range is reached first. A value of `Infinity` or `-1` means there is no limit. When `reverse` is true the entries with the highest keys will be deleted instead of the lowest keys.
- `keyEncoding`: custom key encoding for this operation, used to encode range options.
The `gte` and `lte` range options take precedence over `gt` and `lt` respectively. If no options are provided, all entries will be deleted. The `callback` function will be called with no arguments if the operation was successful or with an error if it failed. If no callback is provided, a promise is returned.
### `sublevel = db.sublevel(name[, options])`
Create a [sublevel](#sublevel) that has the same interface as `db` (except for additional `classic-level` methods like `db.approximateSize()`) and prefixes the keys of operations before passing them on to `db`. The `name` argument is required and must be a string.
```js
const example = db.sublevel('example')
await example.put('hello', 'world')
await db.put('a', '1')
// Prints ['hello', 'world']
for await (const [key, value] of example.iterator()) {
console.log([key, value])
}
```
Sublevels effectively separate a database into sections. Think SQL tables, but evented, ranged and realtime! Each sublevel is an `AbstractLevel` instance with its own keyspace, [events](https://github.com/Level/abstract-level#events) and [encodings](https://github.com/Level/abstract-level#encodings). For example, it's possible to have one sublevel with `'buffer'` keys and another with `'utf8'` keys. The same goes for values. Like so:
```js
db.sublevel('one', { valueEncoding: 'json' })
db.sublevel('two', { keyEncoding: 'buffer' })
```
An own keyspace means that `sublevel.iterator()` only includes entries of that sublevel, `sublevel.clear()` will only delete entries of that sublevel, and so forth. Range options get prefixed too.
Fully qualified keys (as seen from the parent database) take the form of `prefix + key` where `prefix` is `separator + name + separator`. If `name` is empty, the effective prefix is two separators. Sublevels can be nested: if `db` is itself a sublevel then the effective prefix is a combined prefix, e.g. `'!one!!two!'`. Note that a parent database will see its own keys as well as keys of any nested sublevels:
```js
// Prints ['!example!hello', 'world'] and ['a', '1']
for await (const [key, value] of db.iterator()) {
console.log([key, value])
}
```
> :pushpin: The key structure is equal to that of [`subleveldown`](https://github.com/Level/subleveldown) which offered sublevels before they were built-in to `abstract-level` and thus `classic-level`. This means that an `classic-level` sublevel can read sublevels previously created with (and populated by) `subleveldown`.
Internally, sublevels operate on keys that are either a string, Buffer or Uint8Array, depending on choice of encoding. Which is to say: binary keys are fully supported. The `name` must however always be a string and can only contain ASCII characters.
The optional `options` object may contain:
- `separator` (string, default: `'!'`): Character for separating sublevel names from user keys and each other. Must sort before characters used in `name`. An error will be thrown if that's not the case.
- `keyEncoding` (string or object, default `'utf8'`): encoding to use for keys
- `valueEncoding` (string or object, default `'utf8'`): encoding to use for values.
The `keyEncoding` and `valueEncoding` options are forwarded to the `AbstractLevel` constructor and work the same, as if a new, separate database was created. They default to `'utf8'` regardless of the encodings configured on `db`. Other options are forwarded too but `classic-level` has no relevant options at the time of writing. For example, setting the `createIfMissing` option will have no effect. Why is that?
Like regular databases, sublevels open themselves but they do not affect the state of the parent database. This means a sublevel can be individually closed and (re)opened. If the sublevel is created while the parent database is opening, it will wait for that to finish. If the parent database is closed, then opening the sublevel will fail and subsequent operations on the sublevel will yield errors with code [`LEVEL_DATABASE_NOT_OPEN`](https://github.com/Level/abstract-level#errors).
### `db.approximateSize(start, end[, options][, callback])`
Get the approximate number of bytes of file system space used by the range `[start..end)`. The result might not include recently written data. The optional `options` object may contain:
- `keyEncoding`: custom key encoding for this operation, used to encode `start` and `end`.
The `callback` function will be called with a single error argument if the operation failed. If successful the first argument will be `null` and the second argument will be the approximate size as a number. If no callback is provided, a promise is returned. This method is an additional method that is not part of the [`abstract-level`](https://github.com/Level/abstract-level) interface.
### `db.compactRange(start, end[, options][, callback])`
Manually trigger a database compaction in the range `[start..end]`. The optional `options` object may contain:
- `keyEncoding`: custom key encoding for this operation, used to encode `start` and `end`.
The `callback` function will be called with no arguments if the operation was successful or with an error if it failed. If no callback is provided, a promise is returned. This method is an additional method that is not part of the [`abstract-level`](https://github.com/Level/abstract-level) interface.
### `db.getProperty(property)`
Get internal details from LevelDB. When issued with a valid `property` string, a string value is returned synchronously. Valid properties are:
- `leveldb.num-files-at-levelN`: return the number of files at level _N_, where N is an integer representing a valid level (e.g. "0").
- `leveldb.stats`: returns a multi-line string describing statistics about LevelDB's internal operation.
- `leveldb.sstables`: returns a multi-line string describing all of the _sstables_ that make up contents of the current database.
This method is an additional method that is not part of the [`abstract-level`](https://github.com/Level/abstract-level) interface.
### `chainedBatch`
#### `chainedBatch.put(key, value[, options])`
Queue a `put` operation on this batch, not committed until `write()` is called. This will throw a [`LEVEL_INVALID_KEY`](https://github.com/Level/abstract-level#errors) or [`LEVEL_INVALID_VALUE`](https://github.com/Level/abstract-level#errors) error if `key` or `value` is invalid. The optional `options` object may contain:
- `keyEncoding`: custom key encoding for this operation, used to encode the `key`.
- `valueEncoding`: custom value encoding for this operation, used to encode the `value`.
- `sublevel` (sublevel instance): act as though the `put` operation is performed on the given sublevel, to similar effect as `sublevel.batch().put(key, value)`. This allows atomically committing data to multiple sublevels. The `key` will be prefixed with the `prefix` of the sublevel, and the `key` and `value` will be encoded by the sublevel (using the default encodings of the sublevel unless `keyEncoding` and / or `valueEncoding` are provided).
#### `chainedBatch.del(key[, options])`
Queue a `del` operation on this batch, not committed until `write()` is called. This will throw a [`LEVEL_INVALID_KEY`](https://github.com/Level/abstract-level#errors) error if `key` is invalid. The optional `options` object may contain:
- `keyEncoding`: custom key encoding for this operation, used to encode the `key`.
- `sublevel` (sublevel instance): act as though the `del` operation is performed on the given sublevel, to similar effect as `sublevel.batch().del(key)`. This allows atomically committing data to multiple sublevels. The `key` will be prefixed with the `prefix` of the sublevel, and the `key` will be encoded by the sublevel (using the default key encoding of the sublevel unless `keyEncoding` is provided).
#### `chainedBatch.clear()`
Clear all queued operations on this batch.
#### `chainedBatch.write([options][, callback])`
Commit the queued operations for this batch. All operations will be written atomically, that is, they will either all succeed or fail with no partial commits.
The optional `options` object may contain:
- `sync` (boolean, default: `false`): same as described for [`db.put()`](#dbputkey-value-options-callback).
Note that `write()` does not take encoding options. Those can only be set on `put()` and `del()` because `classic-level` synchronously forwards such calls to LevelDB and thus need keys and values to be encoded at that point.
The `callback` function will be called with no arguments if the batch was successful or with an error if it failed. If no callback is provided, a promise is returned.
After `write()` or `close()` has been called, no further operations are allowed.
#### `chainedBatch.close([callback])`
Free up underlying resources. This should be done even if the chained batch has zero queued operations. Automatically called by `write()` so normally not necessary to call, unless the intent is to discard a chained batch without committing it. The `callback` function will be called with no arguments. If no callback is provided, a promise is returned. Closing the batch is an idempotent operation, such that calling `close()` more than once is allowed and makes no difference.
#### `chainedBatch.length`
The number of queued operations on the current batch.
#### `chainedBatch.db`
A reference to the database that created this chained batch.
### `iterator`
An iterator allows one to lazily read a range of entries stored in the database. The entries will be sorted by keys in [lexicographic order](https://en.wikipedia.org/wiki/Lexicographic_order) (in other words: byte order) which in short means key `'a'` comes before `'b'` and key `'10'` comes before `'2'`.
An iterator reads from a snapshot of the database, created at the time `db.iterator()` was called. This means the iterator will not see the data of simultaneous write operations.
Iterators can be consumed with [`for await...of`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for-await...of) and `iterator.all()`, or by manually calling `iterator.next()` or `nextv()` in succession. In the latter case, `iterator.close()` must always be called. In contrast, finishing, throwing, breaking or returning from a `for await...of` loop automatically calls `iterator.close()`, as does `iterator.all()`.
An iterator reaches its natural end in the following situations:
- The end of the database has been reached
- The end of the range has been reached
- The last `iterator.seek()` was out of range.
An iterator keeps track of calls that are in progress. It doesn't allow concurrent `next()`, `nextv()` or `all()` calls (including a combination thereof) and will throw an error with code [`LEVEL_ITERATOR_BUSY`](https://github.com/Level/abstract-level#errors) if that happens:
```js
// Not awaited and no callback provided
iterator.next()
try {
// Which means next() is still in progress here
iterator.all()
} catch (err) {
console.log(err.code) // 'LEVEL_ITERATOR_BUSY'
}
```
#### `for await...of iterator`
Yields entries, which are arrays containing a `key` and `value`. The type of `key` and `value` depends on the options passed to `db.iterator()`.
```js
try {
for await (const [key, value] of db.iterator()) {
console.log(key)
}
} catch (err) {
console.error(err)
}
```
#### `iterator.next([callback])`
Advance to the next entry and yield that entry. If an error occurs, the `callback` function will be called with an error. Otherwise, the `callback` receives `null`, a `key` and a `value`. The type of `key` and `value` depends on the options passed to `db.iterator()`. If the iterator has reached its natural end, both `key` and `value` will be `undefined`.
If no callback is provided, a promise is returned for either an array (containing a `key` and `value`) or `undefined` if the iterator reached its natural end.
**Note:** `iterator.close()` must always be called once there's no intention to call `next()` or `nextv()` again. Even if such calls yielded an error and even if the iterator reached its natural end. Not closing the iterator will result in memory leaks and may also affect performance of other operations if many iterators are unclosed and each is holding a snapshot of the database.
#### `iterator.nextv(size[, options][, callback])`
Advance repeatedly and get at most `size` amount of entries in a single call. Can be faster than repeated `next()` calls. The `size` argument must be an integer and has a soft minimum of 1. There are no `options` currently.
If an error occurs, the `callback` function will be called with an error. Otherwise, the `callback` receives `null` and an array of entries, where each entry is an array containing a key and value. The natural end of the iterator will be signaled by yielding an empty array. If no callback is provided, a promise is returned.
```js
const iterator = db.iterator()
while (true) {
const entries = await iterator.nextv(100)
if (entries.length === 0) {
break
}
for (const [key, value] of entries) {
// ..
}
}
await iterator.close()
```
#### `iterator.all([options][, callback])`
Advance repeatedly and get all (remaining) entries as an array, automatically closing the iterator. Assumes that those entries fit in memory. If that's not the case, instead use `next()`, `nextv()` or `for await...of`. There are no `options` currently. If an error occurs, the `callback` function will be called with an error. Otherwise, the `callback` receives `null` and an array of entries, where each entry is an array containing a key and value. If no callback is provided, a promise is returned.
```js
const entries = await db.iterator({ limit: 100 }).all()
for (const [key, value] of entries) {
// ..
}
```
#### `iterator.seek(target[, options])`
Seek to the key closest to `target`. Subsequent calls to `iterator.next()`, `nextv()` or `all()` (including implicit calls in a `for await...of` loop) will yield entries with keys equal to or larger than `target`, or equal to or smaller than `target` if the `reverse` option passed to `db.iterator()` was true.
The optional `options` object may contain:
- `keyEncoding`: custom key encoding, used to encode the `target`. By default the `keyEncoding` option of the iterator is used or (if that wasn't set) the `keyEncoding` of the database.
If range options like `gt` were passed to `db.iterator()` and `target` does not fall within that range, the iterator will reach its natural end.
#### `iterator.close([callback])`
Free up underlying resources. The `callback` function will be called with no arguments. If no callback is provided, a promise is returned. Closing the iterator is an idempotent operation, such that calling `close()` more than once is allowed and makes no difference.
If a `next()` ,`nextv()` or `all()` call is in progress, closing will wait for that to finish. After `close()` has been called, further calls to `next()` ,`nextv()` or `all()` will yield an error with code [`LEVEL_ITERATOR_NOT_OPEN`](https://github.com/Level/abstract-level#errors).
#### `iterator.db`
A reference to the database that created this iterator.
#### `iterator.count`
Read-only getter that indicates how many keys have been yielded so far (by any method) excluding calls that errored or yielded `undefined`.
#### `iterator.limit`
Read-only getter that reflects the `limit` that was set in options. Greater than or equal to zero. Equals `Infinity` if no limit, which allows for easy math:
```js
const hasMore = iterator.count < iterator.limit
const remaining = iterator.limit - iterator.count
```
### `keyIterator`
A key iterator has the same interface as `iterator` except that its methods yield keys instead of entries. For the `keyIterator.next(callback)` method, this means that the `callback` will receive two arguments (an error and key) instead of three. Usage is otherwise the same.
### `valueIterator`
A value iterator has the same interface as `iterator` except that its methods yield values instead of entries. For the `valueIterator.next(callback)` method, this means that the `callback` will receive two arguments (an error and value) instead of three. Usage is otherwise the same.
### `sublevel`
A sublevel is an instance of the `AbstractSublevel` class (as found in [`abstract-level`](https://github.com/Level/abstract-level)) which extends `AbstractLevel` and thus has the same API as documented above, except for additional `classic-level` methods like `db.approximateSize()`. Sublevels have a few additional properties.
#### `sublevel.prefix`
Prefix of the sublevel. A read-only string property.
```js
const example = db.sublevel('example')
const nested = example.sublevel('nested')
console.log(example.prefix) // '!example!'
console.log(nested.prefix) // '!example!!nested!'
```
#### `sublevel.db`
Parent database. A read-only property.
```js
const example = db.sublevel('example')
const nested = example.sublevel('nested')
console.log(example.db === db) // true
console.log(nested.db === db) // true
```
### `ClassicLevel.destroy(location[, callback])`
Completely remove an existing LevelDB database directory. You can use this method in place of a full directory removal if you want to be sure to only remove LevelDB-related files. If the directory only contains LevelDB files, the directory itself will be removed as well. If there are additional, non-LevelDB files in the directory, those files and the directory will be left alone.
The `callback` function will be called when the destroy operation is complete, with a possible error argument. If no callback is provided, a promise is returned. This method is an additional method that is not part of the [`abstract-level`](https://github.com/Level/abstract-level) interface.
Before calling `destroy()`, close a database if it's using the same `location`:
```js
const db = new ClassicLevel('./db')
await db.close()
await ClassicLevel.destroy('./db')
```
### `ClassicLevel.repair(location[, callback])`
Attempt a restoration of a damaged database. It can also be used to perform a compaction of the LevelDB log into table files. From LevelDB documentation:
> If a DB cannot be opened, you may attempt to call this method to resurrect as much of the contents of the database as possible. Some data may be lost, so be careful when calling this function on a database that contains important information.
The `callback` function will be called when the repair operation is complete, with a possible error argument. If no callback is provided, a promise is returned. This method is an additional method that is not part of the [`abstract-level`](https://github.com/Level/abstract-level) interface.
You will find information on the repair operation in the `LOG` file inside the database directory.
Before calling `repair()`, close a database if it's using the same `location`.
## Development
### Getting Started
This repository uses git submodules. Clone it recursively:
```bash
git clone --recurse-submodules https://github.com/Level/classic-level.git
```
Alternatively, initialize submodules inside the working tree:
```bash
cd classic-level
git submodule update --init --recursive
```
### Contributing
[`Level/classic-level`](https://github.com/Level/classic-level) is an **OPEN Open Source Project**. This means that:
> Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.
See the [Contribution Guide](https://github.com/Level/community/blob/master/CONTRIBUTING.md) for more details.
### Publishing
1. Increment the version: `npm version ..`
2. Push to GitHub: `git push --follow-tags`
3. Wait for CI to complete
4. Download prebuilds into `./prebuilds`: `npm run download-prebuilds`
5. Optionally verify loading a prebuild: `npm run test-prebuild`
6. Optionally verify which files npm will include: `canadian-pub`
7. Finally: `npm publish`
## Donate
Support us with a monthly donation on [Open Collective](https://opencollective.com/level) and help us continue our work.
## License
[MIT](LICENSE)
[level-badge]: https://leveljs.org/img/badge.svg

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# Upgrade Guide
This document describes breaking changes and how to upgrade. For a complete list of changes including minor and patch releases, please refer to the [changelog](CHANGELOG.md).
## 1.0.0
**Introducing `classic-level`: a fork of [`leveldown`](https://github.com/Level/leveldown) that implements the [`abstract-level`](https://github.com/Level/abstract-level) interface instead of [`abstract-leveldown`](https://github.com/Level/abstract-leveldown). It thus has the same API as `level` and `levelup` including encodings, promises and events. In addition, you can now choose to use Uint8Array instead of Buffer. Sublevels are builtin.**
We've put together several upgrade guides for different modules. See the [FAQ](https://github.com/Level/community#faq) to find the best upgrade guide for you. This one describes how to replace `leveldown` with `classic-level`. There will be a separate guide for upgrading `level`.
Support of Node.js 10 has been dropped.
### What is not covered here
If you are using any of the following, please also read the upgrade guide of [`abstract-level@1`](https://github.com/Level/abstract-level/blob/main/UPGRADING.md#100) which goes into more detail about these:
- Specific error messages (replaced with error codes)
- The `db.iterator().end()` method (renamed to `close()`, with `end()` as an alias)
- Zero-length keys and range options (now valid)
- The `db.supports.bufferKeys` property.
### Changes to initialization
We started using classes, which means using `new` is now required. If you previously did:
```js
const leveldown = require('leveldown')
const db = leveldown('./db')
```
You must now do:
```js
const { ClassicLevel } = require('classic-level')
const db = new ClassicLevel('./db')
```
Because `abstract-level` does not require calling `db.open()` before other methods (a feature known as deferred open) it is now preferred to pass options to the constructor. For example:
```js
const db = new ClassicLevel('./db', {
createIfMissing: false,
compression: false
})
```
If `db.open(options)` is called manually those options will be shallowly merged with options from the constructor:
```js
// Results in { createIfMissing: false, compression: true }
await db.open({ compression: true })
```
This means that if you were using this `db.open(options)` pattern, it works as before, except if you were _also_ wrapping `leveldown` with `levelup` _and_ passing options to the `levelup` constructor. Because `levelup` would overwrite rather than merge options.
### There is only encodings
The `asBuffer`, `valueAsBuffer` and `keyAsBuffer` options have been replaced with encoding options. The default encoding is `'utf8'` which means operations return strings rather than Buffers by default. If you previously did:
```js
db.get('example', { asBuffer: false }, callback)
db.get('example', callback)
```
You must now do:
```js
db.get('example', callback)
db.get('example', { valueEncoding: 'buffer' }, callback)
```
Or using promises (new):
```js
const str = await db.get('example')
const buf = await db.get('example', { valueEncoding: 'buffer' })
```
Or using Uint8Array (new):
```js
const arr = await db.get('example', { valueEncoding: 'view' })
```
### Unwrapping the onion
If you were wrapping `leveldown` with `levelup`, `encoding-down` and / or `subleveldown`, remove those modules. If you previously did:
```js
const leveldown = require('leveldown')
const levelup = require('levelup')
const enc = require('encoding-down')
const subleveldown = require('subleveldown')
const db = levelup(enc(leveldown('./db')))
const sublevel = subleveldown(db, 'foo')
```
You must now do:
```js
const { ClassicLevel } = require('classic-level')
const db = new ClassicLevel('./db')
const sublevel = db.sublevel('foo')
```
### Changes to iterators
- The `highWaterMark` option has been renamed to `highWaterMarkBytes` to remove a conflict with streams. Please see the README for details on this (previously undocumented) option.
- On iterators with `{ keys: false }` or `{ values: false }` options, the key or value is now `undefined` rather than an empty string (this was only the case in `leveldown`).
- The `iterator.cache` and `iterator.finished` properties are no longer accessible. If you were using these then you'll want to checkout the new `nextv()` method in the README.
### Sugar on additional methods
The additional methods `db.approximateSize()` and `db.compactRange()` now support the same patterns as other methods:
- Support of encoding options
- Deferred open (no need to call `db.open()` before these methods)
- Returning a promise if no callback is provided.
---
_For earlier releases, before `classic-level` was forked from `leveldown` (v6.1.0), please see [the upgrade guide of `leveldown`](https://github.com/Level/leveldown/blob/HEAD/UPGRADING.md)._

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{
"variables": {
'openssl_fips': ''
},
"targets": [{
"target_name": "classic_level",
"conditions": [
["OS == 'win'", {
"defines": [
"_HAS_EXCEPTIONS=0"
],
"msvs_settings": {
"VCCLCompilerTool": {
"RuntimeTypeInfo": "false",
"EnableFunctionLevelLinking": "true",
"ExceptionHandling": "2",
"DisableSpecificWarnings": [ "4355", "4530" ,"4267", "4244", "4506" ]
}
}
}],
["OS == 'linux'", {
"cflags": [],
"cflags!": [ "-fno-tree-vrp"]
}],
["OS == 'mac'", {
"cflags+": ["-fvisibility=hidden"],
"xcode_settings": {
# -fvisibility=hidden
"GCC_SYMBOLS_PRIVATE_EXTERN": "YES",
# Set minimum target version because we're building on newer
# Same as https://github.com/nodejs/node/blob/v10.0.0/common.gypi#L416
"MACOSX_DEPLOYMENT_TARGET": "10.7",
# Build universal binary to support M1 (Apple silicon)
"OTHER_CFLAGS": [
"-arch x86_64",
"-arch arm64"
],
"OTHER_LDFLAGS": [
"-arch x86_64",
"-arch arm64"
]
}
}],
["OS == 'android'", {
"cflags": [ "-fPIC" ],
"ldflags": [ "-fPIC" ],
"cflags!": [
"-fno-tree-vrp",
"-mfloat-abi=hard",
"-fPIE"
],
"ldflags!": [ "-fPIE" ]
}],
["target_arch == 'arm'", {
"cflags": [ "-mfloat-abi=hard" ]
}]
],
"dependencies": [
"<(module_root_dir)/deps/leveldb/leveldb.gyp:leveldb"
],
"include_dirs" : [
"<!(node -e \"require('napi-macros')\")"
],
"sources": [
"binding.cc"
]
}]
}

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module.exports = require('node-gyp-build')(__dirname)

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'use strict'
const { AbstractChainedBatch } = require('abstract-level')
const binding = require('./binding')
const kContext = Symbol('context')
class ChainedBatch extends AbstractChainedBatch {
constructor (db, context) {
super(db)
this[kContext] = binding.batch_init(context)
}
_put (key, value) {
binding.batch_put(this[kContext], key, value)
}
_del (key) {
binding.batch_del(this[kContext], key)
}
_clear () {
binding.batch_clear(this[kContext])
}
_write (options, callback) {
binding.batch_write(this[kContext], options, callback)
}
_close (callback) {
// TODO: close native batch (currently done on GC)
process.nextTick(callback)
}
}
exports.ChainedBatch = ChainedBatch

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Copyright (c) 2011 The LevelDB Authors. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
* Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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@ -0,0 +1,424 @@
# Copyright (c) 2011 The LevelDB Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file. See the AUTHORS file for names of contributors.
#-----------------------------------------------
# Uncomment exactly one of the lines labelled (A), (B), and (C) below
# to switch between compilation modes.
# (A) Production use (optimized mode)
OPT ?= -O2 -DNDEBUG
# (B) Debug mode, w/ full line-level debugging symbols
# OPT ?= -g2
# (C) Profiling mode: opt, but w/debugging symbols
# OPT ?= -O2 -g2 -DNDEBUG
#-----------------------------------------------
# detect what platform we're building on
$(shell CC="$(CC)" CXX="$(CXX)" TARGET_OS="$(TARGET_OS)" \
./build_detect_platform build_config.mk ./)
# this file is generated by the previous line to set build flags and sources
include build_config.mk
TESTS = \
db/autocompact_test \
db/c_test \
db/corruption_test \
db/db_test \
db/dbformat_test \
db/fault_injection_test \
db/filename_test \
db/log_test \
db/recovery_test \
db/skiplist_test \
db/version_edit_test \
db/version_set_test \
db/write_batch_test \
helpers/memenv/memenv_test \
issues/issue178_test \
issues/issue200_test \
table/filter_block_test \
table/table_test \
util/arena_test \
util/bloom_test \
util/cache_test \
util/coding_test \
util/crc32c_test \
util/env_posix_test \
util/env_test \
util/hash_test
UTILS = \
db/db_bench \
db/leveldbutil
# Put the object files in a subdirectory, but the application at the top of the object dir.
PROGNAMES := $(notdir $(TESTS) $(UTILS))
# On Linux may need libkyotocabinet-dev for dependency.
BENCHMARKS = \
doc/bench/db_bench_sqlite3 \
doc/bench/db_bench_tree_db
CFLAGS += -I. -I./include $(PLATFORM_CCFLAGS) $(OPT)
CXXFLAGS += -I. -I./include $(PLATFORM_CXXFLAGS) $(OPT)
LDFLAGS += $(PLATFORM_LDFLAGS)
LIBS += $(PLATFORM_LIBS)
SIMULATOR_OUTDIR=out-ios-x86
DEVICE_OUTDIR=out-ios-arm
ifeq ($(PLATFORM), IOS)
# Note: iOS should probably be using libtool, not ar.
AR=xcrun ar
SIMULATORSDK=$(shell xcrun -sdk iphonesimulator --show-sdk-path)
DEVICESDK=$(shell xcrun -sdk iphoneos --show-sdk-path)
DEVICE_CFLAGS = -isysroot "$(DEVICESDK)" -arch armv6 -arch armv7 -arch armv7s -arch arm64
SIMULATOR_CFLAGS = -isysroot "$(SIMULATORSDK)" -arch i686 -arch x86_64
STATIC_OUTDIR=out-ios-universal
else
STATIC_OUTDIR=out-static
SHARED_OUTDIR=out-shared
STATIC_PROGRAMS := $(addprefix $(STATIC_OUTDIR)/, $(PROGNAMES))
SHARED_PROGRAMS := $(addprefix $(SHARED_OUTDIR)/, db_bench)
endif
STATIC_LIBOBJECTS := $(addprefix $(STATIC_OUTDIR)/, $(SOURCES:.cc=.o))
STATIC_MEMENVOBJECTS := $(addprefix $(STATIC_OUTDIR)/, $(MEMENV_SOURCES:.cc=.o))
DEVICE_LIBOBJECTS := $(addprefix $(DEVICE_OUTDIR)/, $(SOURCES:.cc=.o))
DEVICE_MEMENVOBJECTS := $(addprefix $(DEVICE_OUTDIR)/, $(MEMENV_SOURCES:.cc=.o))
SIMULATOR_LIBOBJECTS := $(addprefix $(SIMULATOR_OUTDIR)/, $(SOURCES:.cc=.o))
SIMULATOR_MEMENVOBJECTS := $(addprefix $(SIMULATOR_OUTDIR)/, $(MEMENV_SOURCES:.cc=.o))
SHARED_LIBOBJECTS := $(addprefix $(SHARED_OUTDIR)/, $(SOURCES:.cc=.o))
SHARED_MEMENVOBJECTS := $(addprefix $(SHARED_OUTDIR)/, $(MEMENV_SOURCES:.cc=.o))
TESTUTIL := $(STATIC_OUTDIR)/util/testutil.o
TESTHARNESS := $(STATIC_OUTDIR)/util/testharness.o $(TESTUTIL)
STATIC_TESTOBJS := $(addprefix $(STATIC_OUTDIR)/, $(addsuffix .o, $(TESTS)))
STATIC_UTILOBJS := $(addprefix $(STATIC_OUTDIR)/, $(addsuffix .o, $(UTILS)))
STATIC_ALLOBJS := $(STATIC_LIBOBJECTS) $(STATIC_MEMENVOBJECTS) $(STATIC_TESTOBJS) $(STATIC_UTILOBJS) $(TESTHARNESS)
DEVICE_ALLOBJS := $(DEVICE_LIBOBJECTS) $(DEVICE_MEMENVOBJECTS)
SIMULATOR_ALLOBJS := $(SIMULATOR_LIBOBJECTS) $(SIMULATOR_MEMENVOBJECTS)
default: all
# Should we build shared libraries?
ifneq ($(PLATFORM_SHARED_EXT),)
# Many leveldb test apps use non-exported API's. Only build a subset for testing.
SHARED_ALLOBJS := $(SHARED_LIBOBJECTS) $(SHARED_MEMENVOBJECTS) $(TESTHARNESS)
ifneq ($(PLATFORM_SHARED_VERSIONED),true)
SHARED_LIB1 = libleveldb.$(PLATFORM_SHARED_EXT)
SHARED_LIB2 = $(SHARED_LIB1)
SHARED_LIB3 = $(SHARED_LIB1)
SHARED_LIBS = $(SHARED_LIB1)
SHARED_MEMENVLIB = $(SHARED_OUTDIR)/libmemenv.a
else
# Update db.h if you change these.
SHARED_VERSION_MAJOR = 1
SHARED_VERSION_MINOR = 20
SHARED_LIB1 = libleveldb.$(PLATFORM_SHARED_EXT)
SHARED_LIB2 = $(SHARED_LIB1).$(SHARED_VERSION_MAJOR)
SHARED_LIB3 = $(SHARED_LIB1).$(SHARED_VERSION_MAJOR).$(SHARED_VERSION_MINOR)
SHARED_LIBS = $(SHARED_OUTDIR)/$(SHARED_LIB1) $(SHARED_OUTDIR)/$(SHARED_LIB2) $(SHARED_OUTDIR)/$(SHARED_LIB3)
$(SHARED_OUTDIR)/$(SHARED_LIB1): $(SHARED_OUTDIR)/$(SHARED_LIB3)
ln -fs $(SHARED_LIB3) $(SHARED_OUTDIR)/$(SHARED_LIB1)
$(SHARED_OUTDIR)/$(SHARED_LIB2): $(SHARED_OUTDIR)/$(SHARED_LIB3)
ln -fs $(SHARED_LIB3) $(SHARED_OUTDIR)/$(SHARED_LIB2)
SHARED_MEMENVLIB = $(SHARED_OUTDIR)/libmemenv.a
endif
$(SHARED_OUTDIR)/$(SHARED_LIB3): $(SHARED_LIBOBJECTS)
$(CXX) $(LDFLAGS) $(PLATFORM_SHARED_LDFLAGS)$(SHARED_LIB2) $(SHARED_LIBOBJECTS) -o $(SHARED_OUTDIR)/$(SHARED_LIB3) $(LIBS)
endif # PLATFORM_SHARED_EXT
all: $(SHARED_LIBS) $(SHARED_PROGRAMS) $(STATIC_OUTDIR)/libleveldb.a $(STATIC_OUTDIR)/libmemenv.a $(STATIC_PROGRAMS)
check: $(STATIC_PROGRAMS)
for t in $(notdir $(TESTS)); do echo "***** Running $$t"; $(STATIC_OUTDIR)/$$t || exit 1; done
clean:
-rm -rf out-static out-shared out-ios-x86 out-ios-arm out-ios-universal
-rm -f build_config.mk
-rm -rf ios-x86 ios-arm
$(STATIC_OUTDIR):
mkdir $@
$(STATIC_OUTDIR)/db: | $(STATIC_OUTDIR)
mkdir $@
$(STATIC_OUTDIR)/helpers/memenv: | $(STATIC_OUTDIR)
mkdir -p $@
$(STATIC_OUTDIR)/port: | $(STATIC_OUTDIR)
mkdir $@
$(STATIC_OUTDIR)/table: | $(STATIC_OUTDIR)
mkdir $@
$(STATIC_OUTDIR)/util: | $(STATIC_OUTDIR)
mkdir $@
.PHONY: STATIC_OBJDIRS
STATIC_OBJDIRS: \
$(STATIC_OUTDIR)/db \
$(STATIC_OUTDIR)/port \
$(STATIC_OUTDIR)/table \
$(STATIC_OUTDIR)/util \
$(STATIC_OUTDIR)/helpers/memenv
$(SHARED_OUTDIR):
mkdir $@
$(SHARED_OUTDIR)/db: | $(SHARED_OUTDIR)
mkdir $@
$(SHARED_OUTDIR)/helpers/memenv: | $(SHARED_OUTDIR)
mkdir -p $@
$(SHARED_OUTDIR)/port: | $(SHARED_OUTDIR)
mkdir $@
$(SHARED_OUTDIR)/table: | $(SHARED_OUTDIR)
mkdir $@
$(SHARED_OUTDIR)/util: | $(SHARED_OUTDIR)
mkdir $@
.PHONY: SHARED_OBJDIRS
SHARED_OBJDIRS: \
$(SHARED_OUTDIR)/db \
$(SHARED_OUTDIR)/port \
$(SHARED_OUTDIR)/table \
$(SHARED_OUTDIR)/util \
$(SHARED_OUTDIR)/helpers/memenv
$(DEVICE_OUTDIR):
mkdir $@
$(DEVICE_OUTDIR)/db: | $(DEVICE_OUTDIR)
mkdir $@
$(DEVICE_OUTDIR)/helpers/memenv: | $(DEVICE_OUTDIR)
mkdir -p $@
$(DEVICE_OUTDIR)/port: | $(DEVICE_OUTDIR)
mkdir $@
$(DEVICE_OUTDIR)/table: | $(DEVICE_OUTDIR)
mkdir $@
$(DEVICE_OUTDIR)/util: | $(DEVICE_OUTDIR)
mkdir $@
.PHONY: DEVICE_OBJDIRS
DEVICE_OBJDIRS: \
$(DEVICE_OUTDIR)/db \
$(DEVICE_OUTDIR)/port \
$(DEVICE_OUTDIR)/table \
$(DEVICE_OUTDIR)/util \
$(DEVICE_OUTDIR)/helpers/memenv
$(SIMULATOR_OUTDIR):
mkdir $@
$(SIMULATOR_OUTDIR)/db: | $(SIMULATOR_OUTDIR)
mkdir $@
$(SIMULATOR_OUTDIR)/helpers/memenv: | $(SIMULATOR_OUTDIR)
mkdir -p $@
$(SIMULATOR_OUTDIR)/port: | $(SIMULATOR_OUTDIR)
mkdir $@
$(SIMULATOR_OUTDIR)/table: | $(SIMULATOR_OUTDIR)
mkdir $@
$(SIMULATOR_OUTDIR)/util: | $(SIMULATOR_OUTDIR)
mkdir $@
.PHONY: SIMULATOR_OBJDIRS
SIMULATOR_OBJDIRS: \
$(SIMULATOR_OUTDIR)/db \
$(SIMULATOR_OUTDIR)/port \
$(SIMULATOR_OUTDIR)/table \
$(SIMULATOR_OUTDIR)/util \
$(SIMULATOR_OUTDIR)/helpers/memenv
$(STATIC_ALLOBJS): | STATIC_OBJDIRS
$(DEVICE_ALLOBJS): | DEVICE_OBJDIRS
$(SIMULATOR_ALLOBJS): | SIMULATOR_OBJDIRS
$(SHARED_ALLOBJS): | SHARED_OBJDIRS
ifeq ($(PLATFORM), IOS)
$(DEVICE_OUTDIR)/libleveldb.a: $(DEVICE_LIBOBJECTS)
rm -f $@
$(AR) -rs $@ $(DEVICE_LIBOBJECTS)
$(SIMULATOR_OUTDIR)/libleveldb.a: $(SIMULATOR_LIBOBJECTS)
rm -f $@
$(AR) -rs $@ $(SIMULATOR_LIBOBJECTS)
$(DEVICE_OUTDIR)/libmemenv.a: $(DEVICE_MEMENVOBJECTS)
rm -f $@
$(AR) -rs $@ $(DEVICE_MEMENVOBJECTS)
$(SIMULATOR_OUTDIR)/libmemenv.a: $(SIMULATOR_MEMENVOBJECTS)
rm -f $@
$(AR) -rs $@ $(SIMULATOR_MEMENVOBJECTS)
# For iOS, create universal object libraries to be used on both the simulator and
# a device.
$(STATIC_OUTDIR)/libleveldb.a: $(STATIC_OUTDIR) $(DEVICE_OUTDIR)/libleveldb.a $(SIMULATOR_OUTDIR)/libleveldb.a
lipo -create $(DEVICE_OUTDIR)/libleveldb.a $(SIMULATOR_OUTDIR)/libleveldb.a -output $@
$(STATIC_OUTDIR)/libmemenv.a: $(STATIC_OUTDIR) $(DEVICE_OUTDIR)/libmemenv.a $(SIMULATOR_OUTDIR)/libmemenv.a
lipo -create $(DEVICE_OUTDIR)/libmemenv.a $(SIMULATOR_OUTDIR)/libmemenv.a -output $@
else
$(STATIC_OUTDIR)/libleveldb.a:$(STATIC_LIBOBJECTS)
rm -f $@
$(AR) -rs $@ $(STATIC_LIBOBJECTS)
$(STATIC_OUTDIR)/libmemenv.a:$(STATIC_MEMENVOBJECTS)
rm -f $@
$(AR) -rs $@ $(STATIC_MEMENVOBJECTS)
endif
$(SHARED_MEMENVLIB):$(SHARED_MEMENVOBJECTS)
rm -f $@
$(AR) -rs $@ $(SHARED_MEMENVOBJECTS)
$(STATIC_OUTDIR)/db_bench:db/db_bench.cc $(STATIC_LIBOBJECTS) $(TESTUTIL)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/db_bench.cc $(STATIC_LIBOBJECTS) $(TESTUTIL) -o $@ $(LIBS)
$(STATIC_OUTDIR)/db_bench_sqlite3:doc/bench/db_bench_sqlite3.cc $(STATIC_LIBOBJECTS) $(TESTUTIL)
$(CXX) $(LDFLAGS) $(CXXFLAGS) doc/bench/db_bench_sqlite3.cc $(STATIC_LIBOBJECTS) $(TESTUTIL) -o $@ -lsqlite3 $(LIBS)
$(STATIC_OUTDIR)/db_bench_tree_db:doc/bench/db_bench_tree_db.cc $(STATIC_LIBOBJECTS) $(TESTUTIL)
$(CXX) $(LDFLAGS) $(CXXFLAGS) doc/bench/db_bench_tree_db.cc $(STATIC_LIBOBJECTS) $(TESTUTIL) -o $@ -lkyotocabinet $(LIBS)
$(STATIC_OUTDIR)/leveldbutil:db/leveldbutil.cc $(STATIC_LIBOBJECTS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/leveldbutil.cc $(STATIC_LIBOBJECTS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/arena_test:util/arena_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) util/arena_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/autocompact_test:db/autocompact_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/autocompact_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/bloom_test:util/bloom_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) util/bloom_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/c_test:$(STATIC_OUTDIR)/db/c_test.o $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(STATIC_OUTDIR)/db/c_test.o $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/cache_test:util/cache_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) util/cache_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/coding_test:util/coding_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) util/coding_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/corruption_test:db/corruption_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/corruption_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/crc32c_test:util/crc32c_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) util/crc32c_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/db_test:db/db_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/db_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/dbformat_test:db/dbformat_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/dbformat_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/env_posix_test:util/env_posix_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) util/env_posix_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/env_test:util/env_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) util/env_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/fault_injection_test:db/fault_injection_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/fault_injection_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/filename_test:db/filename_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/filename_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/filter_block_test:table/filter_block_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) table/filter_block_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/hash_test:util/hash_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) util/hash_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/issue178_test:issues/issue178_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) issues/issue178_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/issue200_test:issues/issue200_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) issues/issue200_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/log_test:db/log_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/log_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/recovery_test:db/recovery_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/recovery_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/table_test:table/table_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) table/table_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/skiplist_test:db/skiplist_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/skiplist_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/version_edit_test:db/version_edit_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/version_edit_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/version_set_test:db/version_set_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/version_set_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/write_batch_test:db/write_batch_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS)
$(CXX) $(LDFLAGS) $(CXXFLAGS) db/write_batch_test.cc $(STATIC_LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
$(STATIC_OUTDIR)/memenv_test:$(STATIC_OUTDIR)/helpers/memenv/memenv_test.o $(STATIC_OUTDIR)/libmemenv.a $(STATIC_OUTDIR)/libleveldb.a $(TESTHARNESS)
$(XCRUN) $(CXX) $(LDFLAGS) $(STATIC_OUTDIR)/helpers/memenv/memenv_test.o $(STATIC_OUTDIR)/libmemenv.a $(STATIC_OUTDIR)/libleveldb.a $(TESTHARNESS) -o $@ $(LIBS)
$(SHARED_OUTDIR)/db_bench:$(SHARED_OUTDIR)/db/db_bench.o $(SHARED_LIBS) $(TESTUTIL)
$(XCRUN) $(CXX) $(LDFLAGS) $(CXXFLAGS) $(PLATFORM_SHARED_CFLAGS) $(SHARED_OUTDIR)/db/db_bench.o $(TESTUTIL) $(SHARED_OUTDIR)/$(SHARED_LIB3) -o $@ $(LIBS)
.PHONY: run-shared
run-shared: $(SHARED_OUTDIR)/db_bench
LD_LIBRARY_PATH=$(SHARED_OUTDIR) $(SHARED_OUTDIR)/db_bench
$(SIMULATOR_OUTDIR)/%.o: %.cc
xcrun -sdk iphonesimulator $(CXX) $(CXXFLAGS) $(SIMULATOR_CFLAGS) -c $< -o $@
$(DEVICE_OUTDIR)/%.o: %.cc
xcrun -sdk iphoneos $(CXX) $(CXXFLAGS) $(DEVICE_CFLAGS) -c $< -o $@
$(SIMULATOR_OUTDIR)/%.o: %.c
xcrun -sdk iphonesimulator $(CC) $(CFLAGS) $(SIMULATOR_CFLAGS) -c $< -o $@
$(DEVICE_OUTDIR)/%.o: %.c
xcrun -sdk iphoneos $(CC) $(CFLAGS) $(DEVICE_CFLAGS) -c $< -o $@
$(STATIC_OUTDIR)/%.o: %.cc
$(CXX) $(CXXFLAGS) -c $< -o $@
$(STATIC_OUTDIR)/%.o: %.c
$(CC) $(CFLAGS) -c $< -o $@
$(SHARED_OUTDIR)/%.o: %.cc
$(CXX) $(CXXFLAGS) $(PLATFORM_SHARED_CFLAGS) -c $< -o $@
$(SHARED_OUTDIR)/%.o: %.c
$(CC) $(CFLAGS) $(PLATFORM_SHARED_CFLAGS) -c $< -o $@
$(STATIC_OUTDIR)/port/port_posix_sse.o: port/port_posix_sse.cc
$(CXX) $(CXXFLAGS) $(PLATFORM_SSEFLAGS) -c $< -o $@
$(SHARED_OUTDIR)/port/port_posix_sse.o: port/port_posix_sse.cc
$(CXX) $(CXXFLAGS) $(PLATFORM_SHARED_CFLAGS) $(PLATFORM_SSEFLAGS) -c $< -o $@

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**LevelDB is a fast key-value storage library written at Google that provides an ordered mapping from string keys to string values.**
[![Build Status](https://travis-ci.org/google/leveldb.svg?branch=master)](https://travis-ci.org/google/leveldb)
Authors: Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)
# Features
* Keys and values are arbitrary byte arrays.
* Data is stored sorted by key.
* Callers can provide a custom comparison function to override the sort order.
* The basic operations are `Put(key,value)`, `Get(key)`, `Delete(key)`.
* Multiple changes can be made in one atomic batch.
* Users can create a transient snapshot to get a consistent view of data.
* Forward and backward iteration is supported over the data.
* Data is automatically compressed using the [Snappy compression library](http://google.github.io/snappy/).
* External activity (file system operations etc.) is relayed through a virtual interface so users can customize the operating system interactions.
# Documentation
[LevelDB library documentation](https://github.com/google/leveldb/blob/master/doc/index.md) is online and bundled with the source code.
# Limitations
* This is not a SQL database. It does not have a relational data model, it does not support SQL queries, and it has no support for indexes.
* Only a single process (possibly multi-threaded) can access a particular database at a time.
* There is no client-server support builtin to the library. An application that needs such support will have to wrap their own server around the library.
# Contributing to the leveldb Project
The leveldb project welcomes contributions. leveldb's primary goal is to be
a reliable and fast key/value store. Changes that are in line with the
features/limitations outlined above, and meet the requirements below,
will be considered.
Contribution requirements:
1. **POSIX only**. We _generally_ will only accept changes that are both
compiled, and tested on a POSIX platform - usually Linux. Very small
changes will sometimes be accepted, but consider that more of an
exception than the rule.
2. **Stable API**. We strive very hard to maintain a stable API. Changes that
require changes for projects using leveldb _might_ be rejected without
sufficient benefit to the project.
3. **Tests**: All changes must be accompanied by a new (or changed) test, or
a sufficient explanation as to why a new (or changed) test is not required.
## Submitting a Pull Request
Before any pull request will be accepted the author must first sign a
Contributor License Agreement (CLA) at https://cla.developers.google.com/.
In order to keep the commit timeline linear
[squash](https://git-scm.com/book/en/v2/Git-Tools-Rewriting-History#Squashing-Commits)
your changes down to a single commit and [rebase](https://git-scm.com/docs/git-rebase)
on google/leveldb/master. This keeps the commit timeline linear and more easily sync'ed
with the internal repository at Google. More information at GitHub's
[About Git rebase](https://help.github.com/articles/about-git-rebase/) page.
# Performance
Here is a performance report (with explanations) from the run of the
included db_bench program. The results are somewhat noisy, but should
be enough to get a ballpark performance estimate.
## Setup
We use a database with a million entries. Each entry has a 16 byte
key, and a 100 byte value. Values used by the benchmark compress to
about half their original size.
LevelDB: version 1.1
Date: Sun May 1 12:11:26 2011
CPU: 4 x Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz
CPUCache: 4096 KB
Keys: 16 bytes each
Values: 100 bytes each (50 bytes after compression)
Entries: 1000000
Raw Size: 110.6 MB (estimated)
File Size: 62.9 MB (estimated)
## Write performance
The "fill" benchmarks create a brand new database, in either
sequential, or random order. The "fillsync" benchmark flushes data
from the operating system to the disk after every operation; the other
write operations leave the data sitting in the operating system buffer
cache for a while. The "overwrite" benchmark does random writes that
update existing keys in the database.
fillseq : 1.765 micros/op; 62.7 MB/s
fillsync : 268.409 micros/op; 0.4 MB/s (10000 ops)
fillrandom : 2.460 micros/op; 45.0 MB/s
overwrite : 2.380 micros/op; 46.5 MB/s
Each "op" above corresponds to a write of a single key/value pair.
I.e., a random write benchmark goes at approximately 400,000 writes per second.
Each "fillsync" operation costs much less (0.3 millisecond)
than a disk seek (typically 10 milliseconds). We suspect that this is
because the hard disk itself is buffering the update in its memory and
responding before the data has been written to the platter. This may
or may not be safe based on whether or not the hard disk has enough
power to save its memory in the event of a power failure.
## Read performance
We list the performance of reading sequentially in both the forward
and reverse direction, and also the performance of a random lookup.
Note that the database created by the benchmark is quite small.
Therefore the report characterizes the performance of leveldb when the
working set fits in memory. The cost of reading a piece of data that
is not present in the operating system buffer cache will be dominated
by the one or two disk seeks needed to fetch the data from disk.
Write performance will be mostly unaffected by whether or not the
working set fits in memory.
readrandom : 16.677 micros/op; (approximately 60,000 reads per second)
readseq : 0.476 micros/op; 232.3 MB/s
readreverse : 0.724 micros/op; 152.9 MB/s
LevelDB compacts its underlying storage data in the background to
improve read performance. The results listed above were done
immediately after a lot of random writes. The results after
compactions (which are usually triggered automatically) are better.
readrandom : 11.602 micros/op; (approximately 85,000 reads per second)
readseq : 0.423 micros/op; 261.8 MB/s
readreverse : 0.663 micros/op; 166.9 MB/s
Some of the high cost of reads comes from repeated decompression of blocks
read from disk. If we supply enough cache to the leveldb so it can hold the
uncompressed blocks in memory, the read performance improves again:
readrandom : 9.775 micros/op; (approximately 100,000 reads per second before compaction)
readrandom : 5.215 micros/op; (approximately 190,000 reads per second after compaction)
## Repository contents
See [doc/index.md](doc/index.md) for more explanation. See
[doc/impl.md](doc/impl.md) for a brief overview of the implementation.
The public interface is in include/*.h. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Guide to header files:
* **include/db.h**: Main interface to the DB: Start here
* **include/options.h**: Control over the behavior of an entire database,
and also control over the behavior of individual reads and writes.
* **include/comparator.h**: Abstraction for user-specified comparison function.
If you want just bytewise comparison of keys, you can use the default
comparator, but clients can write their own comparator implementations if they
want custom ordering (e.g. to handle different character encodings, etc.)
* **include/iterator.h**: Interface for iterating over data. You can get
an iterator from a DB object.
* **include/write_batch.h**: Interface for atomically applying multiple
updates to a database.
* **include/slice.h**: A simple module for maintaining a pointer and a
length into some other byte array.
* **include/status.h**: Status is returned from many of the public interfaces
and is used to report success and various kinds of errors.
* **include/env.h**:
Abstraction of the OS environment. A posix implementation of this interface is
in util/env_posix.cc
* **include/table.h, include/table_builder.h**: Lower-level modules that most
clients probably won't use directly

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#!/bin/sh
#
# Detects OS we're compiling on and outputs a file specified by the first
# argument, which in turn gets read while processing Makefile.
#
# The output will set the following variables:
# CC C Compiler path
# CXX C++ Compiler path
# PLATFORM_LDFLAGS Linker flags
# PLATFORM_LIBS Libraries flags
# PLATFORM_SHARED_EXT Extension for shared libraries
# PLATFORM_SHARED_LDFLAGS Flags for building shared library
# This flag is embedded just before the name
# of the shared library without intervening spaces
# PLATFORM_SHARED_CFLAGS Flags for compiling objects for shared library
# PLATFORM_CCFLAGS C compiler flags
# PLATFORM_CXXFLAGS C++ compiler flags. Will contain:
# PLATFORM_SHARED_VERSIONED Set to 'true' if platform supports versioned
# shared libraries, empty otherwise.
#
# The PLATFORM_CCFLAGS and PLATFORM_CXXFLAGS might include the following:
#
# -DLEVELDB_ATOMIC_PRESENT if <atomic> is present
# -DLEVELDB_PLATFORM_POSIX for Posix-based platforms
# -DSNAPPY if the Snappy library is present
#
OUTPUT=$1
PREFIX=$2
if test -z "$OUTPUT" || test -z "$PREFIX"; then
echo "usage: $0 <output-filename> <directory_prefix>" >&2
exit 1
fi
# Delete existing output, if it exists
rm -f $OUTPUT
touch $OUTPUT
if test -z "$CC"; then
CC=cc
fi
if test -z "$CXX"; then
CXX=g++
fi
if test -z "$TMPDIR"; then
TMPDIR=/tmp
fi
# Detect OS
if test -z "$TARGET_OS"; then
TARGET_OS=`uname -s`
fi
COMMON_FLAGS=
CROSS_COMPILE=
PLATFORM_CCFLAGS=
PLATFORM_CXXFLAGS=
PLATFORM_LDFLAGS=
PLATFORM_LIBS=
PLATFORM_SHARED_EXT="so"
PLATFORM_SHARED_LDFLAGS="-shared -Wl,-soname -Wl,"
PLATFORM_SHARED_CFLAGS="-fPIC"
PLATFORM_SHARED_VERSIONED=true
PLATFORM_SSEFLAGS=
MEMCMP_FLAG=
if [ "$CXX" = "g++" ]; then
# Use libc's memcmp instead of GCC's memcmp. This results in ~40%
# performance improvement on readrandom under gcc 4.4.3 on Linux/x86.
MEMCMP_FLAG="-fno-builtin-memcmp"
fi
case "$TARGET_OS" in
CYGWIN_*)
PLATFORM=OS_LINUX
COMMON_FLAGS="$MEMCMP_FLAG -lpthread -DOS_LINUX -DCYGWIN"
PLATFORM_LDFLAGS="-lpthread"
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
;;
Darwin)
PLATFORM=OS_MACOSX
COMMON_FLAGS="$MEMCMP_FLAG -DOS_MACOSX"
PLATFORM_SHARED_EXT=dylib
[ -z "$INSTALL_PATH" ] && INSTALL_PATH=`pwd`
PLATFORM_SHARED_LDFLAGS="-dynamiclib -install_name $INSTALL_PATH/"
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
;;
Linux)
PLATFORM=OS_LINUX
COMMON_FLAGS="$MEMCMP_FLAG -pthread -DOS_LINUX"
PLATFORM_LDFLAGS="-pthread"
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
;;
SunOS)
PLATFORM=OS_SOLARIS
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_SOLARIS"
PLATFORM_LIBS="-lpthread -lrt"
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
;;
FreeBSD)
PLATFORM=OS_FREEBSD
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_FREEBSD"
PLATFORM_LIBS="-lpthread"
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
;;
NetBSD)
PLATFORM=OS_NETBSD
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_NETBSD"
PLATFORM_LIBS="-lpthread -lgcc_s"
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
;;
OpenBSD)
PLATFORM=OS_OPENBSD
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_OPENBSD"
PLATFORM_LDFLAGS="-pthread"
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
;;
DragonFly)
PLATFORM=OS_DRAGONFLYBSD
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_DRAGONFLYBSD"
PLATFORM_LIBS="-lpthread"
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
;;
OS_ANDROID_CROSSCOMPILE)
PLATFORM=OS_ANDROID
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_ANDROID -DLEVELDB_PLATFORM_POSIX"
PLATFORM_LDFLAGS="" # All pthread features are in the Android C library
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
CROSS_COMPILE=true
;;
HP-UX)
PLATFORM=OS_HPUX
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_HPUX"
PLATFORM_LDFLAGS="-pthread"
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
# man ld: +h internal_name
PLATFORM_SHARED_LDFLAGS="-shared -Wl,+h -Wl,"
;;
IOS)
PLATFORM=IOS
COMMON_FLAGS="$MEMCMP_FLAG -DOS_MACOSX"
[ -z "$INSTALL_PATH" ] && INSTALL_PATH=`pwd`
PORT_FILE=port/port_posix.cc
PORT_SSE_FILE=port/port_posix_sse.cc
PLATFORM_SHARED_EXT=
PLATFORM_SHARED_LDFLAGS=
PLATFORM_SHARED_CFLAGS=
PLATFORM_SHARED_VERSIONED=
;;
*)
echo "Unknown platform!" >&2
exit 1
esac
# We want to make a list of all cc files within util, db, table, and helpers
# except for the test and benchmark files. By default, find will output a list
# of all files matching either rule, so we need to append -print to make the
# prune take effect.
DIRS="$PREFIX/db $PREFIX/util $PREFIX/table"
set -f # temporarily disable globbing so that our patterns aren't expanded
PRUNE_TEST="-name *test*.cc -prune"
PRUNE_BENCH="-name *_bench.cc -prune"
PRUNE_TOOL="-name leveldbutil.cc -prune"
PORTABLE_FILES=`find $DIRS $PRUNE_TEST -o $PRUNE_BENCH -o $PRUNE_TOOL -o -name '*.cc' -print | sort | sed "s,^$PREFIX/,," | tr "\n" " "`
set +f # re-enable globbing
# The sources consist of the portable files, plus the platform-specific port
# file.
echo "SOURCES=$PORTABLE_FILES $PORT_FILE $PORT_SSE_FILE" >> $OUTPUT
echo "MEMENV_SOURCES=helpers/memenv/memenv.cc" >> $OUTPUT
if [ "$CROSS_COMPILE" = "true" ]; then
# Cross-compiling; do not try any compilation tests.
true
else
CXXOUTPUT="${TMPDIR}/leveldb_build_detect_platform-cxx.$$"
# If -std=c++0x works, use <atomic> as fallback for when memory barriers
# are not available.
$CXX $CXXFLAGS -std=c++0x -x c++ - -o $CXXOUTPUT 2>/dev/null <<EOF
#include <atomic>
int main() {}
EOF
if [ "$?" = 0 ]; then
COMMON_FLAGS="$COMMON_FLAGS -DLEVELDB_PLATFORM_POSIX -DLEVELDB_ATOMIC_PRESENT"
PLATFORM_CXXFLAGS="-std=c++0x"
else
COMMON_FLAGS="$COMMON_FLAGS -DLEVELDB_PLATFORM_POSIX"
fi
# Test whether Snappy library is installed
# http://code.google.com/p/snappy/
$CXX $CXXFLAGS -x c++ - -o $CXXOUTPUT 2>/dev/null <<EOF
#include <snappy.h>
int main() {}
EOF
if [ "$?" = 0 ]; then
COMMON_FLAGS="$COMMON_FLAGS -DSNAPPY"
PLATFORM_LIBS="$PLATFORM_LIBS -lsnappy"
fi
# Test whether tcmalloc is available
$CXX $CXXFLAGS -x c++ - -o $CXXOUTPUT -ltcmalloc 2>/dev/null <<EOF
int main() {}
EOF
if [ "$?" = 0 ]; then
PLATFORM_LIBS="$PLATFORM_LIBS -ltcmalloc"
fi
rm -f $CXXOUTPUT 2>/dev/null
# Test if gcc SSE 4.2 is supported
$CXX $CXXFLAGS -x c++ - -o $CXXOUTPUT -msse4.2 2>/dev/null <<EOF
int main() {}
EOF
if [ "$?" = 0 ]; then
PLATFORM_SSEFLAGS="-msse4.2"
fi
rm -f $CXXOUTPUT 2>/dev/null
fi
# Use the SSE 4.2 CRC32C intrinsics iff runtime checks indicate compiler supports them.
if [ -n "$PLATFORM_SSEFLAGS" ]; then
PLATFORM_SSEFLAGS="$PLATFORM_SSEFLAGS -DLEVELDB_PLATFORM_POSIX_SSE"
fi
PLATFORM_CCFLAGS="$PLATFORM_CCFLAGS $COMMON_FLAGS"
PLATFORM_CXXFLAGS="$PLATFORM_CXXFLAGS $COMMON_FLAGS"
echo "CC=$CC" >> $OUTPUT
echo "CXX=$CXX" >> $OUTPUT
echo "PLATFORM=$PLATFORM" >> $OUTPUT
echo "PLATFORM_LDFLAGS=$PLATFORM_LDFLAGS" >> $OUTPUT
echo "PLATFORM_LIBS=$PLATFORM_LIBS" >> $OUTPUT
echo "PLATFORM_CCFLAGS=$PLATFORM_CCFLAGS" >> $OUTPUT
echo "PLATFORM_CXXFLAGS=$PLATFORM_CXXFLAGS" >> $OUTPUT
echo "PLATFORM_SSEFLAGS=$PLATFORM_SSEFLAGS" >> $OUTPUT
echo "PLATFORM_SHARED_CFLAGS=$PLATFORM_SHARED_CFLAGS" >> $OUTPUT
echo "PLATFORM_SHARED_EXT=$PLATFORM_SHARED_EXT" >> $OUTPUT
echo "PLATFORM_SHARED_LDFLAGS=$PLATFORM_SHARED_LDFLAGS" >> $OUTPUT
echo "PLATFORM_SHARED_VERSIONED=$PLATFORM_SHARED_VERSIONED" >> $OUTPUT

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// Copyright (c) 2013 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "leveldb/db.h"
#include "db/db_impl.h"
#include "leveldb/cache.h"
#include "util/testharness.h"
#include "util/testutil.h"
namespace leveldb {
class AutoCompactTest {
public:
std::string dbname_;
Cache* tiny_cache_;
Options options_;
DB* db_;
AutoCompactTest() {
dbname_ = test::TmpDir() + "/autocompact_test";
tiny_cache_ = NewLRUCache(100);
options_.block_cache = tiny_cache_;
DestroyDB(dbname_, options_);
options_.create_if_missing = true;
options_.compression = kNoCompression;
ASSERT_OK(DB::Open(options_, dbname_, &db_));
}
~AutoCompactTest() {
delete db_;
DestroyDB(dbname_, Options());
delete tiny_cache_;
}
std::string Key(int i) {
char buf[100];
snprintf(buf, sizeof(buf), "key%06d", i);
return std::string(buf);
}
uint64_t Size(const Slice& start, const Slice& limit) {
Range r(start, limit);
uint64_t size;
db_->GetApproximateSizes(&r, 1, &size);
return size;
}
void DoReads(int n);
};
static const int kValueSize = 200 * 1024;
static const int kTotalSize = 100 * 1024 * 1024;
static const int kCount = kTotalSize / kValueSize;
// Read through the first n keys repeatedly and check that they get
// compacted (verified by checking the size of the key space).
void AutoCompactTest::DoReads(int n) {
std::string value(kValueSize, 'x');
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
// Fill database
for (int i = 0; i < kCount; i++) {
ASSERT_OK(db_->Put(WriteOptions(), Key(i), value));
}
ASSERT_OK(dbi->TEST_CompactMemTable());
// Delete everything
for (int i = 0; i < kCount; i++) {
ASSERT_OK(db_->Delete(WriteOptions(), Key(i)));
}
ASSERT_OK(dbi->TEST_CompactMemTable());
// Get initial measurement of the space we will be reading.
const int64_t initial_size = Size(Key(0), Key(n));
const int64_t initial_other_size = Size(Key(n), Key(kCount));
// Read until size drops significantly.
std::string limit_key = Key(n);
for (int read = 0; true; read++) {
ASSERT_LT(read, 100) << "Taking too long to compact";
Iterator* iter = db_->NewIterator(ReadOptions());
for (iter->SeekToFirst();
iter->Valid() && iter->key().ToString() < limit_key;
iter->Next()) {
// Drop data
}
delete iter;
// Wait a little bit to allow any triggered compactions to complete.
Env::Default()->SleepForMicroseconds(1000000);
uint64_t size = Size(Key(0), Key(n));
fprintf(stderr, "iter %3d => %7.3f MB [other %7.3f MB]\n",
read+1, size/1048576.0, Size(Key(n), Key(kCount))/1048576.0);
if (size <= initial_size/10) {
break;
}
}
// Verify that the size of the key space not touched by the reads
// is pretty much unchanged.
const int64_t final_other_size = Size(Key(n), Key(kCount));
ASSERT_LE(final_other_size, initial_other_size + 1048576);
ASSERT_GE(final_other_size, initial_other_size/5 - 1048576);
}
TEST(AutoCompactTest, ReadAll) {
DoReads(kCount);
}
TEST(AutoCompactTest, ReadHalf) {
DoReads(kCount/2);
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/builder.h"
#include "db/filename.h"
#include "db/dbformat.h"
#include "db/table_cache.h"
#include "db/version_edit.h"
#include "leveldb/db.h"
#include "leveldb/env.h"
#include "leveldb/iterator.h"
namespace leveldb {
Status BuildTable(const std::string& dbname,
Env* env,
const Options& options,
TableCache* table_cache,
Iterator* iter,
FileMetaData* meta) {
Status s;
meta->file_size = 0;
iter->SeekToFirst();
std::string fname = TableFileName(dbname, meta->number);
if (iter->Valid()) {
WritableFile* file;
s = env->NewWritableFile(fname, &file);
if (!s.ok()) {
return s;
}
TableBuilder* builder = new TableBuilder(options, file);
meta->smallest.DecodeFrom(iter->key());
for (; iter->Valid(); iter->Next()) {
Slice key = iter->key();
meta->largest.DecodeFrom(key);
builder->Add(key, iter->value());
}
// Finish and check for builder errors
if (s.ok()) {
s = builder->Finish();
if (s.ok()) {
meta->file_size = builder->FileSize();
assert(meta->file_size > 0);
}
} else {
builder->Abandon();
}
delete builder;
// Finish and check for file errors
if (s.ok()) {
s = file->Sync();
}
if (s.ok()) {
s = file->Close();
}
delete file;
file = NULL;
if (s.ok()) {
// Verify that the table is usable
Iterator* it = table_cache->NewIterator(ReadOptions(),
meta->number,
meta->file_size);
s = it->status();
delete it;
}
}
// Check for input iterator errors
if (!iter->status().ok()) {
s = iter->status();
}
if (s.ok() && meta->file_size > 0) {
// Keep it
} else {
env->DeleteFile(fname);
}
return s;
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_BUILDER_H_
#define STORAGE_LEVELDB_DB_BUILDER_H_
#include "leveldb/status.h"
namespace leveldb {
struct Options;
struct FileMetaData;
class Env;
class Iterator;
class TableCache;
class VersionEdit;
// Build a Table file from the contents of *iter. The generated file
// will be named according to meta->number. On success, the rest of
// *meta will be filled with metadata about the generated table.
// If no data is present in *iter, meta->file_size will be set to
// zero, and no Table file will be produced.
extern Status BuildTable(const std::string& dbname,
Env* env,
const Options& options,
TableCache* table_cache,
Iterator* iter,
FileMetaData* meta);
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_BUILDER_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "leveldb/c.h"
#include <stdlib.h>
#include <unistd.h>
#include "leveldb/cache.h"
#include "leveldb/comparator.h"
#include "leveldb/db.h"
#include "leveldb/env.h"
#include "leveldb/filter_policy.h"
#include "leveldb/iterator.h"
#include "leveldb/options.h"
#include "leveldb/status.h"
#include "leveldb/write_batch.h"
using leveldb::Cache;
using leveldb::Comparator;
using leveldb::CompressionType;
using leveldb::DB;
using leveldb::Env;
using leveldb::FileLock;
using leveldb::FilterPolicy;
using leveldb::Iterator;
using leveldb::kMajorVersion;
using leveldb::kMinorVersion;
using leveldb::Logger;
using leveldb::NewBloomFilterPolicy;
using leveldb::NewLRUCache;
using leveldb::Options;
using leveldb::RandomAccessFile;
using leveldb::Range;
using leveldb::ReadOptions;
using leveldb::SequentialFile;
using leveldb::Slice;
using leveldb::Snapshot;
using leveldb::Status;
using leveldb::WritableFile;
using leveldb::WriteBatch;
using leveldb::WriteOptions;
extern "C" {
struct leveldb_t { DB* rep; };
struct leveldb_iterator_t { Iterator* rep; };
struct leveldb_writebatch_t { WriteBatch rep; };
struct leveldb_snapshot_t { const Snapshot* rep; };
struct leveldb_readoptions_t { ReadOptions rep; };
struct leveldb_writeoptions_t { WriteOptions rep; };
struct leveldb_options_t { Options rep; };
struct leveldb_cache_t { Cache* rep; };
struct leveldb_seqfile_t { SequentialFile* rep; };
struct leveldb_randomfile_t { RandomAccessFile* rep; };
struct leveldb_writablefile_t { WritableFile* rep; };
struct leveldb_logger_t { Logger* rep; };
struct leveldb_filelock_t { FileLock* rep; };
struct leveldb_comparator_t : public Comparator {
void* state_;
void (*destructor_)(void*);
int (*compare_)(
void*,
const char* a, size_t alen,
const char* b, size_t blen);
const char* (*name_)(void*);
virtual ~leveldb_comparator_t() {
(*destructor_)(state_);
}
virtual int Compare(const Slice& a, const Slice& b) const {
return (*compare_)(state_, a.data(), a.size(), b.data(), b.size());
}
virtual const char* Name() const {
return (*name_)(state_);
}
// No-ops since the C binding does not support key shortening methods.
virtual void FindShortestSeparator(std::string*, const Slice&) const { }
virtual void FindShortSuccessor(std::string* key) const { }
};
struct leveldb_filterpolicy_t : public FilterPolicy {
void* state_;
void (*destructor_)(void*);
const char* (*name_)(void*);
char* (*create_)(
void*,
const char* const* key_array, const size_t* key_length_array,
int num_keys,
size_t* filter_length);
unsigned char (*key_match_)(
void*,
const char* key, size_t length,
const char* filter, size_t filter_length);
virtual ~leveldb_filterpolicy_t() {
(*destructor_)(state_);
}
virtual const char* Name() const {
return (*name_)(state_);
}
virtual void CreateFilter(const Slice* keys, int n, std::string* dst) const {
std::vector<const char*> key_pointers(n);
std::vector<size_t> key_sizes(n);
for (int i = 0; i < n; i++) {
key_pointers[i] = keys[i].data();
key_sizes[i] = keys[i].size();
}
size_t len;
char* filter = (*create_)(state_, &key_pointers[0], &key_sizes[0], n, &len);
dst->append(filter, len);
free(filter);
}
virtual bool KeyMayMatch(const Slice& key, const Slice& filter) const {
return (*key_match_)(state_, key.data(), key.size(),
filter.data(), filter.size());
}
};
struct leveldb_env_t {
Env* rep;
bool is_default;
};
static bool SaveError(char** errptr, const Status& s) {
assert(errptr != NULL);
if (s.ok()) {
return false;
} else if (*errptr == NULL) {
*errptr = strdup(s.ToString().c_str());
} else {
// TODO(sanjay): Merge with existing error?
free(*errptr);
*errptr = strdup(s.ToString().c_str());
}
return true;
}
static char* CopyString(const std::string& str) {
char* result = reinterpret_cast<char*>(malloc(sizeof(char) * str.size()));
memcpy(result, str.data(), sizeof(char) * str.size());
return result;
}
leveldb_t* leveldb_open(
const leveldb_options_t* options,
const char* name,
char** errptr) {
DB* db;
if (SaveError(errptr, DB::Open(options->rep, std::string(name), &db))) {
return NULL;
}
leveldb_t* result = new leveldb_t;
result->rep = db;
return result;
}
void leveldb_close(leveldb_t* db) {
delete db->rep;
delete db;
}
void leveldb_put(
leveldb_t* db,
const leveldb_writeoptions_t* options,
const char* key, size_t keylen,
const char* val, size_t vallen,
char** errptr) {
SaveError(errptr,
db->rep->Put(options->rep, Slice(key, keylen), Slice(val, vallen)));
}
void leveldb_delete(
leveldb_t* db,
const leveldb_writeoptions_t* options,
const char* key, size_t keylen,
char** errptr) {
SaveError(errptr, db->rep->Delete(options->rep, Slice(key, keylen)));
}
void leveldb_write(
leveldb_t* db,
const leveldb_writeoptions_t* options,
leveldb_writebatch_t* batch,
char** errptr) {
SaveError(errptr, db->rep->Write(options->rep, &batch->rep));
}
char* leveldb_get(
leveldb_t* db,
const leveldb_readoptions_t* options,
const char* key, size_t keylen,
size_t* vallen,
char** errptr) {
char* result = NULL;
std::string tmp;
Status s = db->rep->Get(options->rep, Slice(key, keylen), &tmp);
if (s.ok()) {
*vallen = tmp.size();
result = CopyString(tmp);
} else {
*vallen = 0;
if (!s.IsNotFound()) {
SaveError(errptr, s);
}
}
return result;
}
leveldb_iterator_t* leveldb_create_iterator(
leveldb_t* db,
const leveldb_readoptions_t* options) {
leveldb_iterator_t* result = new leveldb_iterator_t;
result->rep = db->rep->NewIterator(options->rep);
return result;
}
const leveldb_snapshot_t* leveldb_create_snapshot(
leveldb_t* db) {
leveldb_snapshot_t* result = new leveldb_snapshot_t;
result->rep = db->rep->GetSnapshot();
return result;
}
void leveldb_release_snapshot(
leveldb_t* db,
const leveldb_snapshot_t* snapshot) {
db->rep->ReleaseSnapshot(snapshot->rep);
delete snapshot;
}
char* leveldb_property_value(
leveldb_t* db,
const char* propname) {
std::string tmp;
if (db->rep->GetProperty(Slice(propname), &tmp)) {
// We use strdup() since we expect human readable output.
return strdup(tmp.c_str());
} else {
return NULL;
}
}
void leveldb_approximate_sizes(
leveldb_t* db,
int num_ranges,
const char* const* range_start_key, const size_t* range_start_key_len,
const char* const* range_limit_key, const size_t* range_limit_key_len,
uint64_t* sizes) {
Range* ranges = new Range[num_ranges];
for (int i = 0; i < num_ranges; i++) {
ranges[i].start = Slice(range_start_key[i], range_start_key_len[i]);
ranges[i].limit = Slice(range_limit_key[i], range_limit_key_len[i]);
}
db->rep->GetApproximateSizes(ranges, num_ranges, sizes);
delete[] ranges;
}
void leveldb_compact_range(
leveldb_t* db,
const char* start_key, size_t start_key_len,
const char* limit_key, size_t limit_key_len) {
Slice a, b;
db->rep->CompactRange(
// Pass NULL Slice if corresponding "const char*" is NULL
(start_key ? (a = Slice(start_key, start_key_len), &a) : NULL),
(limit_key ? (b = Slice(limit_key, limit_key_len), &b) : NULL));
}
void leveldb_destroy_db(
const leveldb_options_t* options,
const char* name,
char** errptr) {
SaveError(errptr, DestroyDB(name, options->rep));
}
void leveldb_repair_db(
const leveldb_options_t* options,
const char* name,
char** errptr) {
SaveError(errptr, RepairDB(name, options->rep));
}
void leveldb_iter_destroy(leveldb_iterator_t* iter) {
delete iter->rep;
delete iter;
}
unsigned char leveldb_iter_valid(const leveldb_iterator_t* iter) {
return iter->rep->Valid();
}
void leveldb_iter_seek_to_first(leveldb_iterator_t* iter) {
iter->rep->SeekToFirst();
}
void leveldb_iter_seek_to_last(leveldb_iterator_t* iter) {
iter->rep->SeekToLast();
}
void leveldb_iter_seek(leveldb_iterator_t* iter, const char* k, size_t klen) {
iter->rep->Seek(Slice(k, klen));
}
void leveldb_iter_next(leveldb_iterator_t* iter) {
iter->rep->Next();
}
void leveldb_iter_prev(leveldb_iterator_t* iter) {
iter->rep->Prev();
}
const char* leveldb_iter_key(const leveldb_iterator_t* iter, size_t* klen) {
Slice s = iter->rep->key();
*klen = s.size();
return s.data();
}
const char* leveldb_iter_value(const leveldb_iterator_t* iter, size_t* vlen) {
Slice s = iter->rep->value();
*vlen = s.size();
return s.data();
}
void leveldb_iter_get_error(const leveldb_iterator_t* iter, char** errptr) {
SaveError(errptr, iter->rep->status());
}
leveldb_writebatch_t* leveldb_writebatch_create() {
return new leveldb_writebatch_t;
}
void leveldb_writebatch_destroy(leveldb_writebatch_t* b) {
delete b;
}
void leveldb_writebatch_clear(leveldb_writebatch_t* b) {
b->rep.Clear();
}
void leveldb_writebatch_put(
leveldb_writebatch_t* b,
const char* key, size_t klen,
const char* val, size_t vlen) {
b->rep.Put(Slice(key, klen), Slice(val, vlen));
}
void leveldb_writebatch_delete(
leveldb_writebatch_t* b,
const char* key, size_t klen) {
b->rep.Delete(Slice(key, klen));
}
void leveldb_writebatch_iterate(
leveldb_writebatch_t* b,
void* state,
void (*put)(void*, const char* k, size_t klen, const char* v, size_t vlen),
void (*deleted)(void*, const char* k, size_t klen)) {
class H : public WriteBatch::Handler {
public:
void* state_;
void (*put_)(void*, const char* k, size_t klen, const char* v, size_t vlen);
void (*deleted_)(void*, const char* k, size_t klen);
virtual void Put(const Slice& key, const Slice& value) {
(*put_)(state_, key.data(), key.size(), value.data(), value.size());
}
virtual void Delete(const Slice& key) {
(*deleted_)(state_, key.data(), key.size());
}
};
H handler;
handler.state_ = state;
handler.put_ = put;
handler.deleted_ = deleted;
b->rep.Iterate(&handler);
}
leveldb_options_t* leveldb_options_create() {
return new leveldb_options_t;
}
void leveldb_options_destroy(leveldb_options_t* options) {
delete options;
}
void leveldb_options_set_comparator(
leveldb_options_t* opt,
leveldb_comparator_t* cmp) {
opt->rep.comparator = cmp;
}
void leveldb_options_set_filter_policy(
leveldb_options_t* opt,
leveldb_filterpolicy_t* policy) {
opt->rep.filter_policy = policy;
}
void leveldb_options_set_create_if_missing(
leveldb_options_t* opt, unsigned char v) {
opt->rep.create_if_missing = v;
}
void leveldb_options_set_error_if_exists(
leveldb_options_t* opt, unsigned char v) {
opt->rep.error_if_exists = v;
}
void leveldb_options_set_paranoid_checks(
leveldb_options_t* opt, unsigned char v) {
opt->rep.paranoid_checks = v;
}
void leveldb_options_set_env(leveldb_options_t* opt, leveldb_env_t* env) {
opt->rep.env = (env ? env->rep : NULL);
}
void leveldb_options_set_info_log(leveldb_options_t* opt, leveldb_logger_t* l) {
opt->rep.info_log = (l ? l->rep : NULL);
}
void leveldb_options_set_write_buffer_size(leveldb_options_t* opt, size_t s) {
opt->rep.write_buffer_size = s;
}
void leveldb_options_set_max_open_files(leveldb_options_t* opt, int n) {
opt->rep.max_open_files = n;
}
void leveldb_options_set_cache(leveldb_options_t* opt, leveldb_cache_t* c) {
opt->rep.block_cache = c->rep;
}
void leveldb_options_set_block_size(leveldb_options_t* opt, size_t s) {
opt->rep.block_size = s;
}
void leveldb_options_set_block_restart_interval(leveldb_options_t* opt, int n) {
opt->rep.block_restart_interval = n;
}
void leveldb_options_set_compression(leveldb_options_t* opt, int t) {
opt->rep.compression = static_cast<CompressionType>(t);
}
leveldb_comparator_t* leveldb_comparator_create(
void* state,
void (*destructor)(void*),
int (*compare)(
void*,
const char* a, size_t alen,
const char* b, size_t blen),
const char* (*name)(void*)) {
leveldb_comparator_t* result = new leveldb_comparator_t;
result->state_ = state;
result->destructor_ = destructor;
result->compare_ = compare;
result->name_ = name;
return result;
}
void leveldb_comparator_destroy(leveldb_comparator_t* cmp) {
delete cmp;
}
leveldb_filterpolicy_t* leveldb_filterpolicy_create(
void* state,
void (*destructor)(void*),
char* (*create_filter)(
void*,
const char* const* key_array, const size_t* key_length_array,
int num_keys,
size_t* filter_length),
unsigned char (*key_may_match)(
void*,
const char* key, size_t length,
const char* filter, size_t filter_length),
const char* (*name)(void*)) {
leveldb_filterpolicy_t* result = new leveldb_filterpolicy_t;
result->state_ = state;
result->destructor_ = destructor;
result->create_ = create_filter;
result->key_match_ = key_may_match;
result->name_ = name;
return result;
}
void leveldb_filterpolicy_destroy(leveldb_filterpolicy_t* filter) {
delete filter;
}
leveldb_filterpolicy_t* leveldb_filterpolicy_create_bloom(int bits_per_key) {
// Make a leveldb_filterpolicy_t, but override all of its methods so
// they delegate to a NewBloomFilterPolicy() instead of user
// supplied C functions.
struct Wrapper : public leveldb_filterpolicy_t {
const FilterPolicy* rep_;
~Wrapper() { delete rep_; }
const char* Name() const { return rep_->Name(); }
void CreateFilter(const Slice* keys, int n, std::string* dst) const {
return rep_->CreateFilter(keys, n, dst);
}
bool KeyMayMatch(const Slice& key, const Slice& filter) const {
return rep_->KeyMayMatch(key, filter);
}
static void DoNothing(void*) { }
};
Wrapper* wrapper = new Wrapper;
wrapper->rep_ = NewBloomFilterPolicy(bits_per_key);
wrapper->state_ = NULL;
wrapper->destructor_ = &Wrapper::DoNothing;
return wrapper;
}
leveldb_readoptions_t* leveldb_readoptions_create() {
return new leveldb_readoptions_t;
}
void leveldb_readoptions_destroy(leveldb_readoptions_t* opt) {
delete opt;
}
void leveldb_readoptions_set_verify_checksums(
leveldb_readoptions_t* opt,
unsigned char v) {
opt->rep.verify_checksums = v;
}
void leveldb_readoptions_set_fill_cache(
leveldb_readoptions_t* opt, unsigned char v) {
opt->rep.fill_cache = v;
}
void leveldb_readoptions_set_snapshot(
leveldb_readoptions_t* opt,
const leveldb_snapshot_t* snap) {
opt->rep.snapshot = (snap ? snap->rep : NULL);
}
leveldb_writeoptions_t* leveldb_writeoptions_create() {
return new leveldb_writeoptions_t;
}
void leveldb_writeoptions_destroy(leveldb_writeoptions_t* opt) {
delete opt;
}
void leveldb_writeoptions_set_sync(
leveldb_writeoptions_t* opt, unsigned char v) {
opt->rep.sync = v;
}
leveldb_cache_t* leveldb_cache_create_lru(size_t capacity) {
leveldb_cache_t* c = new leveldb_cache_t;
c->rep = NewLRUCache(capacity);
return c;
}
void leveldb_cache_destroy(leveldb_cache_t* cache) {
delete cache->rep;
delete cache;
}
leveldb_env_t* leveldb_create_default_env() {
leveldb_env_t* result = new leveldb_env_t;
result->rep = Env::Default();
result->is_default = true;
return result;
}
void leveldb_env_destroy(leveldb_env_t* env) {
if (!env->is_default) delete env->rep;
delete env;
}
void leveldb_free(void* ptr) {
free(ptr);
}
int leveldb_major_version() {
return kMajorVersion;
}
int leveldb_minor_version() {
return kMinorVersion;
}
} // end extern "C"

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@ -0,0 +1,390 @@
/* Copyright (c) 2011 The LevelDB Authors. All rights reserved.
Use of this source code is governed by a BSD-style license that can be
found in the LICENSE file. See the AUTHORS file for names of contributors. */
#include "leveldb/c.h"
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
const char* phase = "";
static char dbname[200];
static void StartPhase(const char* name) {
fprintf(stderr, "=== Test %s\n", name);
phase = name;
}
static const char* GetTempDir(void) {
const char* ret = getenv("TEST_TMPDIR");
if (ret == NULL || ret[0] == '\0')
ret = "/tmp";
return ret;
}
#define CheckNoError(err) \
if ((err) != NULL) { \
fprintf(stderr, "%s:%d: %s: %s\n", __FILE__, __LINE__, phase, (err)); \
abort(); \
}
#define CheckCondition(cond) \
if (!(cond)) { \
fprintf(stderr, "%s:%d: %s: %s\n", __FILE__, __LINE__, phase, #cond); \
abort(); \
}
static void CheckEqual(const char* expected, const char* v, size_t n) {
if (expected == NULL && v == NULL) {
// ok
} else if (expected != NULL && v != NULL && n == strlen(expected) &&
memcmp(expected, v, n) == 0) {
// ok
return;
} else {
fprintf(stderr, "%s: expected '%s', got '%s'\n",
phase,
(expected ? expected : "(null)"),
(v ? v : "(null"));
abort();
}
}
static void Free(char** ptr) {
if (*ptr) {
free(*ptr);
*ptr = NULL;
}
}
static void CheckGet(
leveldb_t* db,
const leveldb_readoptions_t* options,
const char* key,
const char* expected) {
char* err = NULL;
size_t val_len;
char* val;
val = leveldb_get(db, options, key, strlen(key), &val_len, &err);
CheckNoError(err);
CheckEqual(expected, val, val_len);
Free(&val);
}
static void CheckIter(leveldb_iterator_t* iter,
const char* key, const char* val) {
size_t len;
const char* str;
str = leveldb_iter_key(iter, &len);
CheckEqual(key, str, len);
str = leveldb_iter_value(iter, &len);
CheckEqual(val, str, len);
}
// Callback from leveldb_writebatch_iterate()
static void CheckPut(void* ptr,
const char* k, size_t klen,
const char* v, size_t vlen) {
int* state = (int*) ptr;
CheckCondition(*state < 2);
switch (*state) {
case 0:
CheckEqual("bar", k, klen);
CheckEqual("b", v, vlen);
break;
case 1:
CheckEqual("box", k, klen);
CheckEqual("c", v, vlen);
break;
}
(*state)++;
}
// Callback from leveldb_writebatch_iterate()
static void CheckDel(void* ptr, const char* k, size_t klen) {
int* state = (int*) ptr;
CheckCondition(*state == 2);
CheckEqual("bar", k, klen);
(*state)++;
}
static void CmpDestroy(void* arg) { }
static int CmpCompare(void* arg, const char* a, size_t alen,
const char* b, size_t blen) {
int n = (alen < blen) ? alen : blen;
int r = memcmp(a, b, n);
if (r == 0) {
if (alen < blen) r = -1;
else if (alen > blen) r = +1;
}
return r;
}
static const char* CmpName(void* arg) {
return "foo";
}
// Custom filter policy
static unsigned char fake_filter_result = 1;
static void FilterDestroy(void* arg) { }
static const char* FilterName(void* arg) {
return "TestFilter";
}
static char* FilterCreate(
void* arg,
const char* const* key_array, const size_t* key_length_array,
int num_keys,
size_t* filter_length) {
*filter_length = 4;
char* result = malloc(4);
memcpy(result, "fake", 4);
return result;
}
unsigned char FilterKeyMatch(
void* arg,
const char* key, size_t length,
const char* filter, size_t filter_length) {
CheckCondition(filter_length == 4);
CheckCondition(memcmp(filter, "fake", 4) == 0);
return fake_filter_result;
}
int main(int argc, char** argv) {
leveldb_t* db;
leveldb_comparator_t* cmp;
leveldb_cache_t* cache;
leveldb_env_t* env;
leveldb_options_t* options;
leveldb_readoptions_t* roptions;
leveldb_writeoptions_t* woptions;
char* err = NULL;
int run = -1;
CheckCondition(leveldb_major_version() >= 1);
CheckCondition(leveldb_minor_version() >= 1);
snprintf(dbname, sizeof(dbname),
"%s/leveldb_c_test-%d",
GetTempDir(),
((int) geteuid()));
StartPhase("create_objects");
cmp = leveldb_comparator_create(NULL, CmpDestroy, CmpCompare, CmpName);
env = leveldb_create_default_env();
cache = leveldb_cache_create_lru(100000);
options = leveldb_options_create();
leveldb_options_set_comparator(options, cmp);
leveldb_options_set_error_if_exists(options, 1);
leveldb_options_set_cache(options, cache);
leveldb_options_set_env(options, env);
leveldb_options_set_info_log(options, NULL);
leveldb_options_set_write_buffer_size(options, 100000);
leveldb_options_set_paranoid_checks(options, 1);
leveldb_options_set_max_open_files(options, 10);
leveldb_options_set_block_size(options, 1024);
leveldb_options_set_block_restart_interval(options, 8);
leveldb_options_set_compression(options, leveldb_no_compression);
roptions = leveldb_readoptions_create();
leveldb_readoptions_set_verify_checksums(roptions, 1);
leveldb_readoptions_set_fill_cache(roptions, 0);
woptions = leveldb_writeoptions_create();
leveldb_writeoptions_set_sync(woptions, 1);
StartPhase("destroy");
leveldb_destroy_db(options, dbname, &err);
Free(&err);
StartPhase("open_error");
db = leveldb_open(options, dbname, &err);
CheckCondition(err != NULL);
Free(&err);
StartPhase("leveldb_free");
db = leveldb_open(options, dbname, &err);
CheckCondition(err != NULL);
leveldb_free(err);
err = NULL;
StartPhase("open");
leveldb_options_set_create_if_missing(options, 1);
db = leveldb_open(options, dbname, &err);
CheckNoError(err);
CheckGet(db, roptions, "foo", NULL);
StartPhase("put");
leveldb_put(db, woptions, "foo", 3, "hello", 5, &err);
CheckNoError(err);
CheckGet(db, roptions, "foo", "hello");
StartPhase("compactall");
leveldb_compact_range(db, NULL, 0, NULL, 0);
CheckGet(db, roptions, "foo", "hello");
StartPhase("compactrange");
leveldb_compact_range(db, "a", 1, "z", 1);
CheckGet(db, roptions, "foo", "hello");
StartPhase("writebatch");
{
leveldb_writebatch_t* wb = leveldb_writebatch_create();
leveldb_writebatch_put(wb, "foo", 3, "a", 1);
leveldb_writebatch_clear(wb);
leveldb_writebatch_put(wb, "bar", 3, "b", 1);
leveldb_writebatch_put(wb, "box", 3, "c", 1);
leveldb_writebatch_delete(wb, "bar", 3);
leveldb_write(db, woptions, wb, &err);
CheckNoError(err);
CheckGet(db, roptions, "foo", "hello");
CheckGet(db, roptions, "bar", NULL);
CheckGet(db, roptions, "box", "c");
int pos = 0;
leveldb_writebatch_iterate(wb, &pos, CheckPut, CheckDel);
CheckCondition(pos == 3);
leveldb_writebatch_destroy(wb);
}
StartPhase("iter");
{
leveldb_iterator_t* iter = leveldb_create_iterator(db, roptions);
CheckCondition(!leveldb_iter_valid(iter));
leveldb_iter_seek_to_first(iter);
CheckCondition(leveldb_iter_valid(iter));
CheckIter(iter, "box", "c");
leveldb_iter_next(iter);
CheckIter(iter, "foo", "hello");
leveldb_iter_prev(iter);
CheckIter(iter, "box", "c");
leveldb_iter_prev(iter);
CheckCondition(!leveldb_iter_valid(iter));
leveldb_iter_seek_to_last(iter);
CheckIter(iter, "foo", "hello");
leveldb_iter_seek(iter, "b", 1);
CheckIter(iter, "box", "c");
leveldb_iter_get_error(iter, &err);
CheckNoError(err);
leveldb_iter_destroy(iter);
}
StartPhase("approximate_sizes");
{
int i;
int n = 20000;
char keybuf[100];
char valbuf[100];
uint64_t sizes[2];
const char* start[2] = { "a", "k00000000000000010000" };
size_t start_len[2] = { 1, 21 };
const char* limit[2] = { "k00000000000000010000", "z" };
size_t limit_len[2] = { 21, 1 };
leveldb_writeoptions_set_sync(woptions, 0);
for (i = 0; i < n; i++) {
snprintf(keybuf, sizeof(keybuf), "k%020d", i);
snprintf(valbuf, sizeof(valbuf), "v%020d", i);
leveldb_put(db, woptions, keybuf, strlen(keybuf), valbuf, strlen(valbuf),
&err);
CheckNoError(err);
}
leveldb_approximate_sizes(db, 2, start, start_len, limit, limit_len, sizes);
CheckCondition(sizes[0] > 0);
CheckCondition(sizes[1] > 0);
}
StartPhase("property");
{
char* prop = leveldb_property_value(db, "nosuchprop");
CheckCondition(prop == NULL);
prop = leveldb_property_value(db, "leveldb.stats");
CheckCondition(prop != NULL);
Free(&prop);
}
StartPhase("snapshot");
{
const leveldb_snapshot_t* snap;
snap = leveldb_create_snapshot(db);
leveldb_delete(db, woptions, "foo", 3, &err);
CheckNoError(err);
leveldb_readoptions_set_snapshot(roptions, snap);
CheckGet(db, roptions, "foo", "hello");
leveldb_readoptions_set_snapshot(roptions, NULL);
CheckGet(db, roptions, "foo", NULL);
leveldb_release_snapshot(db, snap);
}
StartPhase("repair");
{
leveldb_close(db);
leveldb_options_set_create_if_missing(options, 0);
leveldb_options_set_error_if_exists(options, 0);
leveldb_repair_db(options, dbname, &err);
CheckNoError(err);
db = leveldb_open(options, dbname, &err);
CheckNoError(err);
CheckGet(db, roptions, "foo", NULL);
CheckGet(db, roptions, "bar", NULL);
CheckGet(db, roptions, "box", "c");
leveldb_options_set_create_if_missing(options, 1);
leveldb_options_set_error_if_exists(options, 1);
}
StartPhase("filter");
for (run = 0; run < 2; run++) {
// First run uses custom filter, second run uses bloom filter
CheckNoError(err);
leveldb_filterpolicy_t* policy;
if (run == 0) {
policy = leveldb_filterpolicy_create(
NULL, FilterDestroy, FilterCreate, FilterKeyMatch, FilterName);
} else {
policy = leveldb_filterpolicy_create_bloom(10);
}
// Create new database
leveldb_close(db);
leveldb_destroy_db(options, dbname, &err);
leveldb_options_set_filter_policy(options, policy);
db = leveldb_open(options, dbname, &err);
CheckNoError(err);
leveldb_put(db, woptions, "foo", 3, "foovalue", 8, &err);
CheckNoError(err);
leveldb_put(db, woptions, "bar", 3, "barvalue", 8, &err);
CheckNoError(err);
leveldb_compact_range(db, NULL, 0, NULL, 0);
fake_filter_result = 1;
CheckGet(db, roptions, "foo", "foovalue");
CheckGet(db, roptions, "bar", "barvalue");
if (phase == 0) {
// Must not find value when custom filter returns false
fake_filter_result = 0;
CheckGet(db, roptions, "foo", NULL);
CheckGet(db, roptions, "bar", NULL);
fake_filter_result = 1;
CheckGet(db, roptions, "foo", "foovalue");
CheckGet(db, roptions, "bar", "barvalue");
}
leveldb_options_set_filter_policy(options, NULL);
leveldb_filterpolicy_destroy(policy);
}
StartPhase("cleanup");
leveldb_close(db);
leveldb_options_destroy(options);
leveldb_readoptions_destroy(roptions);
leveldb_writeoptions_destroy(woptions);
leveldb_cache_destroy(cache);
leveldb_comparator_destroy(cmp);
leveldb_env_destroy(env);
fprintf(stderr, "PASS\n");
return 0;
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "leveldb/db.h"
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "leveldb/cache.h"
#include "leveldb/env.h"
#include "leveldb/table.h"
#include "leveldb/write_batch.h"
#include "db/db_impl.h"
#include "db/filename.h"
#include "db/log_format.h"
#include "db/version_set.h"
#include "util/logging.h"
#include "util/testharness.h"
#include "util/testutil.h"
namespace leveldb {
static const int kValueSize = 1000;
class CorruptionTest {
public:
test::ErrorEnv env_;
std::string dbname_;
Cache* tiny_cache_;
Options options_;
DB* db_;
CorruptionTest() {
tiny_cache_ = NewLRUCache(100);
options_.env = &env_;
options_.block_cache = tiny_cache_;
dbname_ = test::TmpDir() + "/corruption_test";
DestroyDB(dbname_, options_);
db_ = NULL;
options_.create_if_missing = true;
Reopen();
options_.create_if_missing = false;
}
~CorruptionTest() {
delete db_;
DestroyDB(dbname_, Options());
delete tiny_cache_;
}
Status TryReopen() {
delete db_;
db_ = NULL;
return DB::Open(options_, dbname_, &db_);
}
void Reopen() {
ASSERT_OK(TryReopen());
}
void RepairDB() {
delete db_;
db_ = NULL;
ASSERT_OK(::leveldb::RepairDB(dbname_, options_));
}
void Build(int n) {
std::string key_space, value_space;
WriteBatch batch;
for (int i = 0; i < n; i++) {
//if ((i % 100) == 0) fprintf(stderr, "@ %d of %d\n", i, n);
Slice key = Key(i, &key_space);
batch.Clear();
batch.Put(key, Value(i, &value_space));
WriteOptions options;
// Corrupt() doesn't work without this sync on windows; stat reports 0 for
// the file size.
if (i == n - 1) {
options.sync = true;
}
ASSERT_OK(db_->Write(options, &batch));
}
}
void Check(int min_expected, int max_expected) {
int next_expected = 0;
int missed = 0;
int bad_keys = 0;
int bad_values = 0;
int correct = 0;
std::string value_space;
Iterator* iter = db_->NewIterator(ReadOptions());
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
uint64_t key;
Slice in(iter->key());
if (in == "" || in == "~") {
// Ignore boundary keys.
continue;
}
if (!ConsumeDecimalNumber(&in, &key) ||
!in.empty() ||
key < next_expected) {
bad_keys++;
continue;
}
missed += (key - next_expected);
next_expected = key + 1;
if (iter->value() != Value(key, &value_space)) {
bad_values++;
} else {
correct++;
}
}
delete iter;
fprintf(stderr,
"expected=%d..%d; got=%d; bad_keys=%d; bad_values=%d; missed=%d\n",
min_expected, max_expected, correct, bad_keys, bad_values, missed);
ASSERT_LE(min_expected, correct);
ASSERT_GE(max_expected, correct);
}
void Corrupt(FileType filetype, int offset, int bytes_to_corrupt) {
// Pick file to corrupt
std::vector<std::string> filenames;
ASSERT_OK(env_.GetChildren(dbname_, &filenames));
uint64_t number;
FileType type;
std::string fname;
int picked_number = -1;
for (size_t i = 0; i < filenames.size(); i++) {
if (ParseFileName(filenames[i], &number, &type) &&
type == filetype &&
int(number) > picked_number) { // Pick latest file
fname = dbname_ + "/" + filenames[i];
picked_number = number;
}
}
ASSERT_TRUE(!fname.empty()) << filetype;
struct stat sbuf;
if (stat(fname.c_str(), &sbuf) != 0) {
const char* msg = strerror(errno);
ASSERT_TRUE(false) << fname << ": " << msg;
}
if (offset < 0) {
// Relative to end of file; make it absolute
if (-offset > sbuf.st_size) {
offset = 0;
} else {
offset = sbuf.st_size + offset;
}
}
if (offset > sbuf.st_size) {
offset = sbuf.st_size;
}
if (offset + bytes_to_corrupt > sbuf.st_size) {
bytes_to_corrupt = sbuf.st_size - offset;
}
// Do it
std::string contents;
Status s = ReadFileToString(Env::Default(), fname, &contents);
ASSERT_TRUE(s.ok()) << s.ToString();
for (int i = 0; i < bytes_to_corrupt; i++) {
contents[i + offset] ^= 0x80;
}
s = WriteStringToFile(Env::Default(), contents, fname);
ASSERT_TRUE(s.ok()) << s.ToString();
}
int Property(const std::string& name) {
std::string property;
int result;
if (db_->GetProperty(name, &property) &&
sscanf(property.c_str(), "%d", &result) == 1) {
return result;
} else {
return -1;
}
}
// Return the ith key
Slice Key(int i, std::string* storage) {
char buf[100];
snprintf(buf, sizeof(buf), "%016d", i);
storage->assign(buf, strlen(buf));
return Slice(*storage);
}
// Return the value to associate with the specified key
Slice Value(int k, std::string* storage) {
Random r(k);
return test::RandomString(&r, kValueSize, storage);
}
};
TEST(CorruptionTest, Recovery) {
Build(100);
Check(100, 100);
Corrupt(kLogFile, 19, 1); // WriteBatch tag for first record
Corrupt(kLogFile, log::kBlockSize + 1000, 1); // Somewhere in second block
Reopen();
// The 64 records in the first two log blocks are completely lost.
Check(36, 36);
}
TEST(CorruptionTest, RecoverWriteError) {
env_.writable_file_error_ = true;
Status s = TryReopen();
ASSERT_TRUE(!s.ok());
}
TEST(CorruptionTest, NewFileErrorDuringWrite) {
// Do enough writing to force minor compaction
env_.writable_file_error_ = true;
const int num = 3 + (Options().write_buffer_size / kValueSize);
std::string value_storage;
Status s;
for (int i = 0; s.ok() && i < num; i++) {
WriteBatch batch;
batch.Put("a", Value(100, &value_storage));
s = db_->Write(WriteOptions(), &batch);
}
ASSERT_TRUE(!s.ok());
ASSERT_GE(env_.num_writable_file_errors_, 1);
env_.writable_file_error_ = false;
Reopen();
}
TEST(CorruptionTest, TableFile) {
Build(100);
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
dbi->TEST_CompactMemTable();
dbi->TEST_CompactRange(0, NULL, NULL);
dbi->TEST_CompactRange(1, NULL, NULL);
Corrupt(kTableFile, 100, 1);
Check(90, 99);
}
TEST(CorruptionTest, TableFileRepair) {
options_.block_size = 2 * kValueSize; // Limit scope of corruption
options_.paranoid_checks = true;
Reopen();
Build(100);
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
dbi->TEST_CompactMemTable();
dbi->TEST_CompactRange(0, NULL, NULL);
dbi->TEST_CompactRange(1, NULL, NULL);
Corrupt(kTableFile, 100, 1);
RepairDB();
Reopen();
Check(95, 99);
}
TEST(CorruptionTest, TableFileIndexData) {
Build(10000); // Enough to build multiple Tables
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
dbi->TEST_CompactMemTable();
Corrupt(kTableFile, -2000, 500);
Reopen();
Check(5000, 9999);
}
TEST(CorruptionTest, MissingDescriptor) {
Build(1000);
RepairDB();
Reopen();
Check(1000, 1000);
}
TEST(CorruptionTest, SequenceNumberRecovery) {
ASSERT_OK(db_->Put(WriteOptions(), "foo", "v1"));
ASSERT_OK(db_->Put(WriteOptions(), "foo", "v2"));
ASSERT_OK(db_->Put(WriteOptions(), "foo", "v3"));
ASSERT_OK(db_->Put(WriteOptions(), "foo", "v4"));
ASSERT_OK(db_->Put(WriteOptions(), "foo", "v5"));
RepairDB();
Reopen();
std::string v;
ASSERT_OK(db_->Get(ReadOptions(), "foo", &v));
ASSERT_EQ("v5", v);
// Write something. If sequence number was not recovered properly,
// it will be hidden by an earlier write.
ASSERT_OK(db_->Put(WriteOptions(), "foo", "v6"));
ASSERT_OK(db_->Get(ReadOptions(), "foo", &v));
ASSERT_EQ("v6", v);
Reopen();
ASSERT_OK(db_->Get(ReadOptions(), "foo", &v));
ASSERT_EQ("v6", v);
}
TEST(CorruptionTest, CorruptedDescriptor) {
ASSERT_OK(db_->Put(WriteOptions(), "foo", "hello"));
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
dbi->TEST_CompactMemTable();
dbi->TEST_CompactRange(0, NULL, NULL);
Corrupt(kDescriptorFile, 0, 1000);
Status s = TryReopen();
ASSERT_TRUE(!s.ok());
RepairDB();
Reopen();
std::string v;
ASSERT_OK(db_->Get(ReadOptions(), "foo", &v));
ASSERT_EQ("hello", v);
}
TEST(CorruptionTest, CompactionInputError) {
Build(10);
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
dbi->TEST_CompactMemTable();
const int last = config::kMaxMemCompactLevel;
ASSERT_EQ(1, Property("leveldb.num-files-at-level" + NumberToString(last)));
Corrupt(kTableFile, 100, 1);
Check(5, 9);
// Force compactions by writing lots of values
Build(10000);
Check(10000, 10000);
}
TEST(CorruptionTest, CompactionInputErrorParanoid) {
options_.paranoid_checks = true;
options_.write_buffer_size = 512 << 10;
Reopen();
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
// Make multiple inputs so we need to compact.
for (int i = 0; i < 2; i++) {
Build(10);
dbi->TEST_CompactMemTable();
Corrupt(kTableFile, 100, 1);
env_.SleepForMicroseconds(100000);
}
dbi->CompactRange(NULL, NULL);
// Write must fail because of corrupted table
std::string tmp1, tmp2;
Status s = db_->Put(WriteOptions(), Key(5, &tmp1), Value(5, &tmp2));
ASSERT_TRUE(!s.ok()) << "write did not fail in corrupted paranoid db";
}
TEST(CorruptionTest, UnrelatedKeys) {
Build(10);
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
dbi->TEST_CompactMemTable();
Corrupt(kTableFile, 100, 1);
std::string tmp1, tmp2;
ASSERT_OK(db_->Put(WriteOptions(), Key(1000, &tmp1), Value(1000, &tmp2)));
std::string v;
ASSERT_OK(db_->Get(ReadOptions(), Key(1000, &tmp1), &v));
ASSERT_EQ(Value(1000, &tmp2).ToString(), v);
dbi->TEST_CompactMemTable();
ASSERT_OK(db_->Get(ReadOptions(), Key(1000, &tmp1), &v));
ASSERT_EQ(Value(1000, &tmp2).ToString(), v);
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_DB_IMPL_H_
#define STORAGE_LEVELDB_DB_DB_IMPL_H_
#include <deque>
#include <set>
#include "db/dbformat.h"
#include "db/log_writer.h"
#include "db/snapshot.h"
#include "leveldb/db.h"
#include "leveldb/env.h"
#include "port/port.h"
#include "port/thread_annotations.h"
namespace leveldb {
class MemTable;
class TableCache;
class Version;
class VersionEdit;
class VersionSet;
class DBImpl : public DB {
public:
DBImpl(const Options& options, const std::string& dbname);
virtual ~DBImpl();
// Implementations of the DB interface
virtual Status Put(const WriteOptions&, const Slice& key, const Slice& value);
virtual Status Delete(const WriteOptions&, const Slice& key);
virtual Status Write(const WriteOptions& options, WriteBatch* updates);
virtual Status Get(const ReadOptions& options,
const Slice& key,
std::string* value);
virtual Iterator* NewIterator(const ReadOptions&);
virtual const Snapshot* GetSnapshot();
virtual void ReleaseSnapshot(const Snapshot* snapshot);
virtual bool GetProperty(const Slice& property, std::string* value);
virtual void GetApproximateSizes(const Range* range, int n, uint64_t* sizes);
virtual void CompactRange(const Slice* begin, const Slice* end);
// Extra methods (for testing) that are not in the public DB interface
// Compact any files in the named level that overlap [*begin,*end]
void TEST_CompactRange(int level, const Slice* begin, const Slice* end);
// Force current memtable contents to be compacted.
Status TEST_CompactMemTable();
// Return an internal iterator over the current state of the database.
// The keys of this iterator are internal keys (see format.h).
// The returned iterator should be deleted when no longer needed.
Iterator* TEST_NewInternalIterator();
// Return the maximum overlapping data (in bytes) at next level for any
// file at a level >= 1.
int64_t TEST_MaxNextLevelOverlappingBytes();
// Record a sample of bytes read at the specified internal key.
// Samples are taken approximately once every config::kReadBytesPeriod
// bytes.
void RecordReadSample(Slice key);
private:
friend class DB;
struct CompactionState;
struct Writer;
Iterator* NewInternalIterator(const ReadOptions&,
SequenceNumber* latest_snapshot,
uint32_t* seed);
Status NewDB();
// Recover the descriptor from persistent storage. May do a significant
// amount of work to recover recently logged updates. Any changes to
// be made to the descriptor are added to *edit.
Status Recover(VersionEdit* edit, bool* save_manifest)
EXCLUSIVE_LOCKS_REQUIRED(mutex_);
void MaybeIgnoreError(Status* s) const;
// Delete any unneeded files and stale in-memory entries.
void DeleteObsoleteFiles();
// Compact the in-memory write buffer to disk. Switches to a new
// log-file/memtable and writes a new descriptor iff successful.
// Errors are recorded in bg_error_.
void CompactMemTable() EXCLUSIVE_LOCKS_REQUIRED(mutex_);
Status RecoverLogFile(uint64_t log_number, bool last_log, bool* save_manifest,
VersionEdit* edit, SequenceNumber* max_sequence)
EXCLUSIVE_LOCKS_REQUIRED(mutex_);
Status WriteLevel0Table(MemTable* mem, VersionEdit* edit, Version* base)
EXCLUSIVE_LOCKS_REQUIRED(mutex_);
Status MakeRoomForWrite(bool force /* compact even if there is room? */)
EXCLUSIVE_LOCKS_REQUIRED(mutex_);
WriteBatch* BuildBatchGroup(Writer** last_writer);
void RecordBackgroundError(const Status& s);
void MaybeScheduleCompaction() EXCLUSIVE_LOCKS_REQUIRED(mutex_);
static void BGWork(void* db);
void BackgroundCall();
void BackgroundCompaction() EXCLUSIVE_LOCKS_REQUIRED(mutex_);
void CleanupCompaction(CompactionState* compact)
EXCLUSIVE_LOCKS_REQUIRED(mutex_);
Status DoCompactionWork(CompactionState* compact)
EXCLUSIVE_LOCKS_REQUIRED(mutex_);
Status OpenCompactionOutputFile(CompactionState* compact);
Status FinishCompactionOutputFile(CompactionState* compact, Iterator* input);
Status InstallCompactionResults(CompactionState* compact)
EXCLUSIVE_LOCKS_REQUIRED(mutex_);
// Constant after construction
Env* const env_;
const InternalKeyComparator internal_comparator_;
const InternalFilterPolicy internal_filter_policy_;
const Options options_; // options_.comparator == &internal_comparator_
bool owns_info_log_;
bool owns_cache_;
const std::string dbname_;
// table_cache_ provides its own synchronization
TableCache* table_cache_;
// Lock over the persistent DB state. Non-NULL iff successfully acquired.
FileLock* db_lock_;
// State below is protected by mutex_
port::Mutex mutex_;
port::AtomicPointer shutting_down_;
port::CondVar bg_cv_; // Signalled when background work finishes
MemTable* mem_;
MemTable* imm_; // Memtable being compacted
port::AtomicPointer has_imm_; // So bg thread can detect non-NULL imm_
WritableFile* logfile_;
uint64_t logfile_number_;
log::Writer* log_;
uint32_t seed_; // For sampling.
// Queue of writers.
std::deque<Writer*> writers_;
WriteBatch* tmp_batch_;
SnapshotList snapshots_;
// Set of table files to protect from deletion because they are
// part of ongoing compactions.
std::set<uint64_t> pending_outputs_;
// Has a background compaction been scheduled or is running?
bool bg_compaction_scheduled_;
// Information for a manual compaction
struct ManualCompaction {
int level;
bool done;
const InternalKey* begin; // NULL means beginning of key range
const InternalKey* end; // NULL means end of key range
InternalKey tmp_storage; // Used to keep track of compaction progress
};
ManualCompaction* manual_compaction_;
VersionSet* versions_;
// Have we encountered a background error in paranoid mode?
Status bg_error_;
// Per level compaction stats. stats_[level] stores the stats for
// compactions that produced data for the specified "level".
struct CompactionStats {
int64_t micros;
int64_t bytes_read;
int64_t bytes_written;
CompactionStats() : micros(0), bytes_read(0), bytes_written(0) { }
void Add(const CompactionStats& c) {
this->micros += c.micros;
this->bytes_read += c.bytes_read;
this->bytes_written += c.bytes_written;
}
};
CompactionStats stats_[config::kNumLevels];
// No copying allowed
DBImpl(const DBImpl&);
void operator=(const DBImpl&);
const Comparator* user_comparator() const {
return internal_comparator_.user_comparator();
}
};
// Sanitize db options. The caller should delete result.info_log if
// it is not equal to src.info_log.
extern Options SanitizeOptions(const std::string& db,
const InternalKeyComparator* icmp,
const InternalFilterPolicy* ipolicy,
const Options& src);
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_DB_IMPL_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/db_iter.h"
#include "db/filename.h"
#include "db/db_impl.h"
#include "db/dbformat.h"
#include "leveldb/env.h"
#include "leveldb/iterator.h"
#include "port/port.h"
#include "util/logging.h"
#include "util/mutexlock.h"
#include "util/random.h"
namespace leveldb {
#if 0
static void DumpInternalIter(Iterator* iter) {
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
ParsedInternalKey k;
if (!ParseInternalKey(iter->key(), &k)) {
fprintf(stderr, "Corrupt '%s'\n", EscapeString(iter->key()).c_str());
} else {
fprintf(stderr, "@ '%s'\n", k.DebugString().c_str());
}
}
}
#endif
namespace {
// Memtables and sstables that make the DB representation contain
// (userkey,seq,type) => uservalue entries. DBIter
// combines multiple entries for the same userkey found in the DB
// representation into a single entry while accounting for sequence
// numbers, deletion markers, overwrites, etc.
class DBIter: public Iterator {
public:
// Which direction is the iterator currently moving?
// (1) When moving forward, the internal iterator is positioned at
// the exact entry that yields this->key(), this->value()
// (2) When moving backwards, the internal iterator is positioned
// just before all entries whose user key == this->key().
enum Direction {
kForward,
kReverse
};
DBIter(DBImpl* db, const Comparator* cmp, Iterator* iter, SequenceNumber s,
uint32_t seed)
: db_(db),
user_comparator_(cmp),
iter_(iter),
sequence_(s),
direction_(kForward),
valid_(false),
rnd_(seed),
bytes_counter_(RandomPeriod()) {
}
virtual ~DBIter() {
delete iter_;
}
virtual bool Valid() const { return valid_; }
virtual Slice key() const {
assert(valid_);
return (direction_ == kForward) ? ExtractUserKey(iter_->key()) : saved_key_;
}
virtual Slice value() const {
assert(valid_);
return (direction_ == kForward) ? iter_->value() : saved_value_;
}
virtual Status status() const {
if (status_.ok()) {
return iter_->status();
} else {
return status_;
}
}
virtual void Next();
virtual void Prev();
virtual void Seek(const Slice& target);
virtual void SeekToFirst();
virtual void SeekToLast();
private:
void FindNextUserEntry(bool skipping, std::string* skip);
void FindPrevUserEntry();
bool ParseKey(ParsedInternalKey* key);
inline void SaveKey(const Slice& k, std::string* dst) {
dst->assign(k.data(), k.size());
}
inline void ClearSavedValue() {
if (saved_value_.capacity() > 1048576) {
std::string empty;
swap(empty, saved_value_);
} else {
saved_value_.clear();
}
}
// Pick next gap with average value of config::kReadBytesPeriod.
ssize_t RandomPeriod() {
return rnd_.Uniform(2*config::kReadBytesPeriod);
}
DBImpl* db_;
const Comparator* const user_comparator_;
Iterator* const iter_;
SequenceNumber const sequence_;
Status status_;
std::string saved_key_; // == current key when direction_==kReverse
std::string saved_value_; // == current raw value when direction_==kReverse
Direction direction_;
bool valid_;
Random rnd_;
ssize_t bytes_counter_;
// No copying allowed
DBIter(const DBIter&);
void operator=(const DBIter&);
};
inline bool DBIter::ParseKey(ParsedInternalKey* ikey) {
Slice k = iter_->key();
ssize_t n = k.size() + iter_->value().size();
bytes_counter_ -= n;
while (bytes_counter_ < 0) {
bytes_counter_ += RandomPeriod();
db_->RecordReadSample(k);
}
if (!ParseInternalKey(k, ikey)) {
status_ = Status::Corruption("corrupted internal key in DBIter");
return false;
} else {
return true;
}
}
void DBIter::Next() {
assert(valid_);
if (direction_ == kReverse) { // Switch directions?
direction_ = kForward;
// iter_ is pointing just before the entries for this->key(),
// so advance into the range of entries for this->key() and then
// use the normal skipping code below.
if (!iter_->Valid()) {
iter_->SeekToFirst();
} else {
iter_->Next();
}
if (!iter_->Valid()) {
valid_ = false;
saved_key_.clear();
return;
}
// saved_key_ already contains the key to skip past.
} else {
// Store in saved_key_ the current key so we skip it below.
SaveKey(ExtractUserKey(iter_->key()), &saved_key_);
}
FindNextUserEntry(true, &saved_key_);
}
void DBIter::FindNextUserEntry(bool skipping, std::string* skip) {
// Loop until we hit an acceptable entry to yield
assert(iter_->Valid());
assert(direction_ == kForward);
do {
ParsedInternalKey ikey;
if (ParseKey(&ikey) && ikey.sequence <= sequence_) {
switch (ikey.type) {
case kTypeDeletion:
// Arrange to skip all upcoming entries for this key since
// they are hidden by this deletion.
SaveKey(ikey.user_key, skip);
skipping = true;
break;
case kTypeValue:
if (skipping &&
user_comparator_->Compare(ikey.user_key, *skip) <= 0) {
// Entry hidden
} else {
valid_ = true;
saved_key_.clear();
return;
}
break;
}
}
iter_->Next();
} while (iter_->Valid());
saved_key_.clear();
valid_ = false;
}
void DBIter::Prev() {
assert(valid_);
if (direction_ == kForward) { // Switch directions?
// iter_ is pointing at the current entry. Scan backwards until
// the key changes so we can use the normal reverse scanning code.
assert(iter_->Valid()); // Otherwise valid_ would have been false
SaveKey(ExtractUserKey(iter_->key()), &saved_key_);
while (true) {
iter_->Prev();
if (!iter_->Valid()) {
valid_ = false;
saved_key_.clear();
ClearSavedValue();
return;
}
if (user_comparator_->Compare(ExtractUserKey(iter_->key()),
saved_key_) < 0) {
break;
}
}
direction_ = kReverse;
}
FindPrevUserEntry();
}
void DBIter::FindPrevUserEntry() {
assert(direction_ == kReverse);
ValueType value_type = kTypeDeletion;
if (iter_->Valid()) {
do {
ParsedInternalKey ikey;
if (ParseKey(&ikey) && ikey.sequence <= sequence_) {
if ((value_type != kTypeDeletion) &&
user_comparator_->Compare(ikey.user_key, saved_key_) < 0) {
// We encountered a non-deleted value in entries for previous keys,
break;
}
value_type = ikey.type;
if (value_type == kTypeDeletion) {
saved_key_.clear();
ClearSavedValue();
} else {
Slice raw_value = iter_->value();
if (saved_value_.capacity() > raw_value.size() + 1048576) {
std::string empty;
swap(empty, saved_value_);
}
SaveKey(ExtractUserKey(iter_->key()), &saved_key_);
saved_value_.assign(raw_value.data(), raw_value.size());
}
}
iter_->Prev();
} while (iter_->Valid());
}
if (value_type == kTypeDeletion) {
// End
valid_ = false;
saved_key_.clear();
ClearSavedValue();
direction_ = kForward;
} else {
valid_ = true;
}
}
void DBIter::Seek(const Slice& target) {
direction_ = kForward;
ClearSavedValue();
saved_key_.clear();
AppendInternalKey(
&saved_key_, ParsedInternalKey(target, sequence_, kValueTypeForSeek));
iter_->Seek(saved_key_);
if (iter_->Valid()) {
FindNextUserEntry(false, &saved_key_ /* temporary storage */);
} else {
valid_ = false;
}
}
void DBIter::SeekToFirst() {
direction_ = kForward;
ClearSavedValue();
iter_->SeekToFirst();
if (iter_->Valid()) {
FindNextUserEntry(false, &saved_key_ /* temporary storage */);
} else {
valid_ = false;
}
}
void DBIter::SeekToLast() {
direction_ = kReverse;
ClearSavedValue();
iter_->SeekToLast();
FindPrevUserEntry();
}
} // anonymous namespace
Iterator* NewDBIterator(
DBImpl* db,
const Comparator* user_key_comparator,
Iterator* internal_iter,
SequenceNumber sequence,
uint32_t seed) {
return new DBIter(db, user_key_comparator, internal_iter, sequence, seed);
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_DB_ITER_H_
#define STORAGE_LEVELDB_DB_DB_ITER_H_
#include <stdint.h>
#include "leveldb/db.h"
#include "db/dbformat.h"
namespace leveldb {
class DBImpl;
// Return a new iterator that converts internal keys (yielded by
// "*internal_iter") that were live at the specified "sequence" number
// into appropriate user keys.
extern Iterator* NewDBIterator(
DBImpl* db,
const Comparator* user_key_comparator,
Iterator* internal_iter,
SequenceNumber sequence,
uint32_t seed);
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_DB_ITER_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include <stdio.h>
#include "db/dbformat.h"
#include "port/port.h"
#include "util/coding.h"
namespace leveldb {
static uint64_t PackSequenceAndType(uint64_t seq, ValueType t) {
assert(seq <= kMaxSequenceNumber);
assert(t <= kValueTypeForSeek);
return (seq << 8) | t;
}
void AppendInternalKey(std::string* result, const ParsedInternalKey& key) {
result->append(key.user_key.data(), key.user_key.size());
PutFixed64(result, PackSequenceAndType(key.sequence, key.type));
}
std::string ParsedInternalKey::DebugString() const {
char buf[50];
snprintf(buf, sizeof(buf), "' @ %llu : %d",
(unsigned long long) sequence,
int(type));
std::string result = "'";
result += EscapeString(user_key.ToString());
result += buf;
return result;
}
std::string InternalKey::DebugString() const {
std::string result;
ParsedInternalKey parsed;
if (ParseInternalKey(rep_, &parsed)) {
result = parsed.DebugString();
} else {
result = "(bad)";
result.append(EscapeString(rep_));
}
return result;
}
const char* InternalKeyComparator::Name() const {
return "leveldb.InternalKeyComparator";
}
int InternalKeyComparator::Compare(const Slice& akey, const Slice& bkey) const {
// Order by:
// increasing user key (according to user-supplied comparator)
// decreasing sequence number
// decreasing type (though sequence# should be enough to disambiguate)
int r = user_comparator_->Compare(ExtractUserKey(akey), ExtractUserKey(bkey));
if (r == 0) {
const uint64_t anum = DecodeFixed64(akey.data() + akey.size() - 8);
const uint64_t bnum = DecodeFixed64(bkey.data() + bkey.size() - 8);
if (anum > bnum) {
r = -1;
} else if (anum < bnum) {
r = +1;
}
}
return r;
}
void InternalKeyComparator::FindShortestSeparator(
std::string* start,
const Slice& limit) const {
// Attempt to shorten the user portion of the key
Slice user_start = ExtractUserKey(*start);
Slice user_limit = ExtractUserKey(limit);
std::string tmp(user_start.data(), user_start.size());
user_comparator_->FindShortestSeparator(&tmp, user_limit);
if (tmp.size() < user_start.size() &&
user_comparator_->Compare(user_start, tmp) < 0) {
// User key has become shorter physically, but larger logically.
// Tack on the earliest possible number to the shortened user key.
PutFixed64(&tmp, PackSequenceAndType(kMaxSequenceNumber,kValueTypeForSeek));
assert(this->Compare(*start, tmp) < 0);
assert(this->Compare(tmp, limit) < 0);
start->swap(tmp);
}
}
void InternalKeyComparator::FindShortSuccessor(std::string* key) const {
Slice user_key = ExtractUserKey(*key);
std::string tmp(user_key.data(), user_key.size());
user_comparator_->FindShortSuccessor(&tmp);
if (tmp.size() < user_key.size() &&
user_comparator_->Compare(user_key, tmp) < 0) {
// User key has become shorter physically, but larger logically.
// Tack on the earliest possible number to the shortened user key.
PutFixed64(&tmp, PackSequenceAndType(kMaxSequenceNumber,kValueTypeForSeek));
assert(this->Compare(*key, tmp) < 0);
key->swap(tmp);
}
}
const char* InternalFilterPolicy::Name() const {
return user_policy_->Name();
}
void InternalFilterPolicy::CreateFilter(const Slice* keys, int n,
std::string* dst) const {
// We rely on the fact that the code in table.cc does not mind us
// adjusting keys[].
Slice* mkey = const_cast<Slice*>(keys);
for (int i = 0; i < n; i++) {
mkey[i] = ExtractUserKey(keys[i]);
// TODO(sanjay): Suppress dups?
}
user_policy_->CreateFilter(keys, n, dst);
}
bool InternalFilterPolicy::KeyMayMatch(const Slice& key, const Slice& f) const {
return user_policy_->KeyMayMatch(ExtractUserKey(key), f);
}
LookupKey::LookupKey(const Slice& user_key, SequenceNumber s) {
size_t usize = user_key.size();
size_t needed = usize + 13; // A conservative estimate
char* dst;
if (needed <= sizeof(space_)) {
dst = space_;
} else {
dst = new char[needed];
}
start_ = dst;
dst = EncodeVarint32(dst, usize + 8);
kstart_ = dst;
memcpy(dst, user_key.data(), usize);
dst += usize;
EncodeFixed64(dst, PackSequenceAndType(s, kValueTypeForSeek));
dst += 8;
end_ = dst;
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_DBFORMAT_H_
#define STORAGE_LEVELDB_DB_DBFORMAT_H_
#include <stdio.h>
#include "leveldb/comparator.h"
#include "leveldb/db.h"
#include "leveldb/filter_policy.h"
#include "leveldb/slice.h"
#include "leveldb/table_builder.h"
#include "util/coding.h"
#include "util/logging.h"
namespace leveldb {
// Grouping of constants. We may want to make some of these
// parameters set via options.
namespace config {
static const int kNumLevels = 7;
// Level-0 compaction is started when we hit this many files.
static const int kL0_CompactionTrigger = 4;
// Soft limit on number of level-0 files. We slow down writes at this point.
static const int kL0_SlowdownWritesTrigger = 8;
// Maximum number of level-0 files. We stop writes at this point.
static const int kL0_StopWritesTrigger = 12;
// Maximum level to which a new compacted memtable is pushed if it
// does not create overlap. We try to push to level 2 to avoid the
// relatively expensive level 0=>1 compactions and to avoid some
// expensive manifest file operations. We do not push all the way to
// the largest level since that can generate a lot of wasted disk
// space if the same key space is being repeatedly overwritten.
static const int kMaxMemCompactLevel = 2;
// Approximate gap in bytes between samples of data read during iteration.
static const int kReadBytesPeriod = 1048576;
} // namespace config
class InternalKey;
// Value types encoded as the last component of internal keys.
// DO NOT CHANGE THESE ENUM VALUES: they are embedded in the on-disk
// data structures.
enum ValueType {
kTypeDeletion = 0x0,
kTypeValue = 0x1
};
// kValueTypeForSeek defines the ValueType that should be passed when
// constructing a ParsedInternalKey object for seeking to a particular
// sequence number (since we sort sequence numbers in decreasing order
// and the value type is embedded as the low 8 bits in the sequence
// number in internal keys, we need to use the highest-numbered
// ValueType, not the lowest).
static const ValueType kValueTypeForSeek = kTypeValue;
typedef uint64_t SequenceNumber;
// We leave eight bits empty at the bottom so a type and sequence#
// can be packed together into 64-bits.
static const SequenceNumber kMaxSequenceNumber =
((0x1ull << 56) - 1);
struct ParsedInternalKey {
Slice user_key;
SequenceNumber sequence;
ValueType type;
ParsedInternalKey() { } // Intentionally left uninitialized (for speed)
ParsedInternalKey(const Slice& u, const SequenceNumber& seq, ValueType t)
: user_key(u), sequence(seq), type(t) { }
std::string DebugString() const;
};
// Return the length of the encoding of "key".
inline size_t InternalKeyEncodingLength(const ParsedInternalKey& key) {
return key.user_key.size() + 8;
}
// Append the serialization of "key" to *result.
extern void AppendInternalKey(std::string* result,
const ParsedInternalKey& key);
// Attempt to parse an internal key from "internal_key". On success,
// stores the parsed data in "*result", and returns true.
//
// On error, returns false, leaves "*result" in an undefined state.
extern bool ParseInternalKey(const Slice& internal_key,
ParsedInternalKey* result);
// Returns the user key portion of an internal key.
inline Slice ExtractUserKey(const Slice& internal_key) {
assert(internal_key.size() >= 8);
return Slice(internal_key.data(), internal_key.size() - 8);
}
inline ValueType ExtractValueType(const Slice& internal_key) {
assert(internal_key.size() >= 8);
const size_t n = internal_key.size();
uint64_t num = DecodeFixed64(internal_key.data() + n - 8);
unsigned char c = num & 0xff;
return static_cast<ValueType>(c);
}
// A comparator for internal keys that uses a specified comparator for
// the user key portion and breaks ties by decreasing sequence number.
class InternalKeyComparator : public Comparator {
private:
const Comparator* user_comparator_;
public:
explicit InternalKeyComparator(const Comparator* c) : user_comparator_(c) { }
virtual const char* Name() const;
virtual int Compare(const Slice& a, const Slice& b) const;
virtual void FindShortestSeparator(
std::string* start,
const Slice& limit) const;
virtual void FindShortSuccessor(std::string* key) const;
const Comparator* user_comparator() const { return user_comparator_; }
int Compare(const InternalKey& a, const InternalKey& b) const;
};
// Filter policy wrapper that converts from internal keys to user keys
class InternalFilterPolicy : public FilterPolicy {
private:
const FilterPolicy* const user_policy_;
public:
explicit InternalFilterPolicy(const FilterPolicy* p) : user_policy_(p) { }
virtual const char* Name() const;
virtual void CreateFilter(const Slice* keys, int n, std::string* dst) const;
virtual bool KeyMayMatch(const Slice& key, const Slice& filter) const;
};
// Modules in this directory should keep internal keys wrapped inside
// the following class instead of plain strings so that we do not
// incorrectly use string comparisons instead of an InternalKeyComparator.
class InternalKey {
private:
std::string rep_;
public:
InternalKey() { } // Leave rep_ as empty to indicate it is invalid
InternalKey(const Slice& user_key, SequenceNumber s, ValueType t) {
AppendInternalKey(&rep_, ParsedInternalKey(user_key, s, t));
}
void DecodeFrom(const Slice& s) { rep_.assign(s.data(), s.size()); }
Slice Encode() const {
assert(!rep_.empty());
return rep_;
}
Slice user_key() const { return ExtractUserKey(rep_); }
void SetFrom(const ParsedInternalKey& p) {
rep_.clear();
AppendInternalKey(&rep_, p);
}
void Clear() { rep_.clear(); }
std::string DebugString() const;
};
inline int InternalKeyComparator::Compare(
const InternalKey& a, const InternalKey& b) const {
return Compare(a.Encode(), b.Encode());
}
inline bool ParseInternalKey(const Slice& internal_key,
ParsedInternalKey* result) {
const size_t n = internal_key.size();
if (n < 8) return false;
uint64_t num = DecodeFixed64(internal_key.data() + n - 8);
unsigned char c = num & 0xff;
result->sequence = num >> 8;
result->type = static_cast<ValueType>(c);
result->user_key = Slice(internal_key.data(), n - 8);
return (c <= static_cast<unsigned char>(kTypeValue));
}
// A helper class useful for DBImpl::Get()
class LookupKey {
public:
// Initialize *this for looking up user_key at a snapshot with
// the specified sequence number.
LookupKey(const Slice& user_key, SequenceNumber sequence);
~LookupKey();
// Return a key suitable for lookup in a MemTable.
Slice memtable_key() const { return Slice(start_, end_ - start_); }
// Return an internal key (suitable for passing to an internal iterator)
Slice internal_key() const { return Slice(kstart_, end_ - kstart_); }
// Return the user key
Slice user_key() const { return Slice(kstart_, end_ - kstart_ - 8); }
private:
// We construct a char array of the form:
// klength varint32 <-- start_
// userkey char[klength] <-- kstart_
// tag uint64
// <-- end_
// The array is a suitable MemTable key.
// The suffix starting with "userkey" can be used as an InternalKey.
const char* start_;
const char* kstart_;
const char* end_;
char space_[200]; // Avoid allocation for short keys
// No copying allowed
LookupKey(const LookupKey&);
void operator=(const LookupKey&);
};
inline LookupKey::~LookupKey() {
if (start_ != space_) delete[] start_;
}
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_DBFORMAT_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/dbformat.h"
#include "util/logging.h"
#include "util/testharness.h"
namespace leveldb {
static std::string IKey(const std::string& user_key,
uint64_t seq,
ValueType vt) {
std::string encoded;
AppendInternalKey(&encoded, ParsedInternalKey(user_key, seq, vt));
return encoded;
}
static std::string Shorten(const std::string& s, const std::string& l) {
std::string result = s;
InternalKeyComparator(BytewiseComparator()).FindShortestSeparator(&result, l);
return result;
}
static std::string ShortSuccessor(const std::string& s) {
std::string result = s;
InternalKeyComparator(BytewiseComparator()).FindShortSuccessor(&result);
return result;
}
static void TestKey(const std::string& key,
uint64_t seq,
ValueType vt) {
std::string encoded = IKey(key, seq, vt);
Slice in(encoded);
ParsedInternalKey decoded("", 0, kTypeValue);
ASSERT_TRUE(ParseInternalKey(in, &decoded));
ASSERT_EQ(key, decoded.user_key.ToString());
ASSERT_EQ(seq, decoded.sequence);
ASSERT_EQ(vt, decoded.type);
ASSERT_TRUE(!ParseInternalKey(Slice("bar"), &decoded));
}
class FormatTest { };
TEST(FormatTest, InternalKey_EncodeDecode) {
const char* keys[] = { "", "k", "hello", "longggggggggggggggggggggg" };
const uint64_t seq[] = {
1, 2, 3,
(1ull << 8) - 1, 1ull << 8, (1ull << 8) + 1,
(1ull << 16) - 1, 1ull << 16, (1ull << 16) + 1,
(1ull << 32) - 1, 1ull << 32, (1ull << 32) + 1
};
for (int k = 0; k < sizeof(keys) / sizeof(keys[0]); k++) {
for (int s = 0; s < sizeof(seq) / sizeof(seq[0]); s++) {
TestKey(keys[k], seq[s], kTypeValue);
TestKey("hello", 1, kTypeDeletion);
}
}
}
TEST(FormatTest, InternalKeyShortSeparator) {
// When user keys are same
ASSERT_EQ(IKey("foo", 100, kTypeValue),
Shorten(IKey("foo", 100, kTypeValue),
IKey("foo", 99, kTypeValue)));
ASSERT_EQ(IKey("foo", 100, kTypeValue),
Shorten(IKey("foo", 100, kTypeValue),
IKey("foo", 101, kTypeValue)));
ASSERT_EQ(IKey("foo", 100, kTypeValue),
Shorten(IKey("foo", 100, kTypeValue),
IKey("foo", 100, kTypeValue)));
ASSERT_EQ(IKey("foo", 100, kTypeValue),
Shorten(IKey("foo", 100, kTypeValue),
IKey("foo", 100, kTypeDeletion)));
// When user keys are misordered
ASSERT_EQ(IKey("foo", 100, kTypeValue),
Shorten(IKey("foo", 100, kTypeValue),
IKey("bar", 99, kTypeValue)));
// When user keys are different, but correctly ordered
ASSERT_EQ(IKey("g", kMaxSequenceNumber, kValueTypeForSeek),
Shorten(IKey("foo", 100, kTypeValue),
IKey("hello", 200, kTypeValue)));
// When start user key is prefix of limit user key
ASSERT_EQ(IKey("foo", 100, kTypeValue),
Shorten(IKey("foo", 100, kTypeValue),
IKey("foobar", 200, kTypeValue)));
// When limit user key is prefix of start user key
ASSERT_EQ(IKey("foobar", 100, kTypeValue),
Shorten(IKey("foobar", 100, kTypeValue),
IKey("foo", 200, kTypeValue)));
}
TEST(FormatTest, InternalKeyShortestSuccessor) {
ASSERT_EQ(IKey("g", kMaxSequenceNumber, kValueTypeForSeek),
ShortSuccessor(IKey("foo", 100, kTypeValue)));
ASSERT_EQ(IKey("\xff\xff", 100, kTypeValue),
ShortSuccessor(IKey("\xff\xff", 100, kTypeValue)));
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include <stdio.h>
#include "db/dbformat.h"
#include "db/filename.h"
#include "db/log_reader.h"
#include "db/version_edit.h"
#include "db/write_batch_internal.h"
#include "leveldb/env.h"
#include "leveldb/iterator.h"
#include "leveldb/options.h"
#include "leveldb/status.h"
#include "leveldb/table.h"
#include "leveldb/write_batch.h"
#include "util/logging.h"
namespace leveldb {
namespace {
bool GuessType(const std::string& fname, FileType* type) {
size_t pos = fname.rfind('/');
std::string basename;
if (pos == std::string::npos) {
basename = fname;
} else {
basename = std::string(fname.data() + pos + 1, fname.size() - pos - 1);
}
uint64_t ignored;
return ParseFileName(basename, &ignored, type);
}
// Notified when log reader encounters corruption.
class CorruptionReporter : public log::Reader::Reporter {
public:
WritableFile* dst_;
virtual void Corruption(size_t bytes, const Status& status) {
std::string r = "corruption: ";
AppendNumberTo(&r, bytes);
r += " bytes; ";
r += status.ToString();
r.push_back('\n');
dst_->Append(r);
}
};
// Print contents of a log file. (*func)() is called on every record.
Status PrintLogContents(Env* env, const std::string& fname,
void (*func)(uint64_t, Slice, WritableFile*),
WritableFile* dst) {
SequentialFile* file;
Status s = env->NewSequentialFile(fname, &file);
if (!s.ok()) {
return s;
}
CorruptionReporter reporter;
reporter.dst_ = dst;
log::Reader reader(file, &reporter, true, 0);
Slice record;
std::string scratch;
while (reader.ReadRecord(&record, &scratch)) {
(*func)(reader.LastRecordOffset(), record, dst);
}
delete file;
return Status::OK();
}
// Called on every item found in a WriteBatch.
class WriteBatchItemPrinter : public WriteBatch::Handler {
public:
WritableFile* dst_;
virtual void Put(const Slice& key, const Slice& value) {
std::string r = " put '";
AppendEscapedStringTo(&r, key);
r += "' '";
AppendEscapedStringTo(&r, value);
r += "'\n";
dst_->Append(r);
}
virtual void Delete(const Slice& key) {
std::string r = " del '";
AppendEscapedStringTo(&r, key);
r += "'\n";
dst_->Append(r);
}
};
// Called on every log record (each one of which is a WriteBatch)
// found in a kLogFile.
static void WriteBatchPrinter(uint64_t pos, Slice record, WritableFile* dst) {
std::string r = "--- offset ";
AppendNumberTo(&r, pos);
r += "; ";
if (record.size() < 12) {
r += "log record length ";
AppendNumberTo(&r, record.size());
r += " is too small\n";
dst->Append(r);
return;
}
WriteBatch batch;
WriteBatchInternal::SetContents(&batch, record);
r += "sequence ";
AppendNumberTo(&r, WriteBatchInternal::Sequence(&batch));
r.push_back('\n');
dst->Append(r);
WriteBatchItemPrinter batch_item_printer;
batch_item_printer.dst_ = dst;
Status s = batch.Iterate(&batch_item_printer);
if (!s.ok()) {
dst->Append(" error: " + s.ToString() + "\n");
}
}
Status DumpLog(Env* env, const std::string& fname, WritableFile* dst) {
return PrintLogContents(env, fname, WriteBatchPrinter, dst);
}
// Called on every log record (each one of which is a WriteBatch)
// found in a kDescriptorFile.
static void VersionEditPrinter(uint64_t pos, Slice record, WritableFile* dst) {
std::string r = "--- offset ";
AppendNumberTo(&r, pos);
r += "; ";
VersionEdit edit;
Status s = edit.DecodeFrom(record);
if (!s.ok()) {
r += s.ToString();
r.push_back('\n');
} else {
r += edit.DebugString();
}
dst->Append(r);
}
Status DumpDescriptor(Env* env, const std::string& fname, WritableFile* dst) {
return PrintLogContents(env, fname, VersionEditPrinter, dst);
}
Status DumpTable(Env* env, const std::string& fname, WritableFile* dst) {
uint64_t file_size;
RandomAccessFile* file = NULL;
Table* table = NULL;
Status s = env->GetFileSize(fname, &file_size);
if (s.ok()) {
s = env->NewRandomAccessFile(fname, &file);
}
if (s.ok()) {
// We use the default comparator, which may or may not match the
// comparator used in this database. However this should not cause
// problems since we only use Table operations that do not require
// any comparisons. In particular, we do not call Seek or Prev.
s = Table::Open(Options(), file, file_size, &table);
}
if (!s.ok()) {
delete table;
delete file;
return s;
}
ReadOptions ro;
ro.fill_cache = false;
Iterator* iter = table->NewIterator(ro);
std::string r;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
r.clear();
ParsedInternalKey key;
if (!ParseInternalKey(iter->key(), &key)) {
r = "badkey '";
AppendEscapedStringTo(&r, iter->key());
r += "' => '";
AppendEscapedStringTo(&r, iter->value());
r += "'\n";
dst->Append(r);
} else {
r = "'";
AppendEscapedStringTo(&r, key.user_key);
r += "' @ ";
AppendNumberTo(&r, key.sequence);
r += " : ";
if (key.type == kTypeDeletion) {
r += "del";
} else if (key.type == kTypeValue) {
r += "val";
} else {
AppendNumberTo(&r, key.type);
}
r += " => '";
AppendEscapedStringTo(&r, iter->value());
r += "'\n";
dst->Append(r);
}
}
s = iter->status();
if (!s.ok()) {
dst->Append("iterator error: " + s.ToString() + "\n");
}
delete iter;
delete table;
delete file;
return Status::OK();
}
} // namespace
Status DumpFile(Env* env, const std::string& fname, WritableFile* dst) {
FileType ftype;
if (!GuessType(fname, &ftype)) {
return Status::InvalidArgument(fname + ": unknown file type");
}
switch (ftype) {
case kLogFile: return DumpLog(env, fname, dst);
case kDescriptorFile: return DumpDescriptor(env, fname, dst);
case kTableFile: return DumpTable(env, fname, dst);
default:
break;
}
return Status::InvalidArgument(fname + ": not a dump-able file type");
}
} // namespace leveldb

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// Copyright 2014 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
// This test uses a custom Env to keep track of the state of a filesystem as of
// the last "sync". It then checks for data loss errors by purposely dropping
// file data (or entire files) not protected by a "sync".
#include "leveldb/db.h"
#include <map>
#include <set>
#include "db/db_impl.h"
#include "db/filename.h"
#include "db/log_format.h"
#include "db/version_set.h"
#include "leveldb/cache.h"
#include "leveldb/env.h"
#include "leveldb/table.h"
#include "leveldb/write_batch.h"
#include "util/logging.h"
#include "util/mutexlock.h"
#include "util/testharness.h"
#include "util/testutil.h"
namespace leveldb {
static const int kValueSize = 1000;
static const int kMaxNumValues = 2000;
static const size_t kNumIterations = 3;
class FaultInjectionTestEnv;
namespace {
// Assume a filename, and not a directory name like "/foo/bar/"
static std::string GetDirName(const std::string filename) {
size_t found = filename.find_last_of("/\\");
if (found == std::string::npos) {
return "";
} else {
return filename.substr(0, found);
}
}
Status SyncDir(const std::string& dir) {
// As this is a test it isn't required to *actually* sync this directory.
return Status::OK();
}
// A basic file truncation function suitable for this test.
Status Truncate(const std::string& filename, uint64_t length) {
leveldb::Env* env = leveldb::Env::Default();
SequentialFile* orig_file;
Status s = env->NewSequentialFile(filename, &orig_file);
if (!s.ok())
return s;
char* scratch = new char[length];
leveldb::Slice result;
s = orig_file->Read(length, &result, scratch);
delete orig_file;
if (s.ok()) {
std::string tmp_name = GetDirName(filename) + "/truncate.tmp";
WritableFile* tmp_file;
s = env->NewWritableFile(tmp_name, &tmp_file);
if (s.ok()) {
s = tmp_file->Append(result);
delete tmp_file;
if (s.ok()) {
s = env->RenameFile(tmp_name, filename);
} else {
env->DeleteFile(tmp_name);
}
}
}
delete[] scratch;
return s;
}
struct FileState {
std::string filename_;
ssize_t pos_;
ssize_t pos_at_last_sync_;
ssize_t pos_at_last_flush_;
FileState(const std::string& filename)
: filename_(filename),
pos_(-1),
pos_at_last_sync_(-1),
pos_at_last_flush_(-1) { }
FileState() : pos_(-1), pos_at_last_sync_(-1), pos_at_last_flush_(-1) {}
bool IsFullySynced() const { return pos_ <= 0 || pos_ == pos_at_last_sync_; }
Status DropUnsyncedData() const;
};
} // anonymous namespace
// A wrapper around WritableFile which informs another Env whenever this file
// is written to or sync'ed.
class TestWritableFile : public WritableFile {
public:
TestWritableFile(const FileState& state,
WritableFile* f,
FaultInjectionTestEnv* env);
virtual ~TestWritableFile();
virtual Status Append(const Slice& data);
virtual Status Close();
virtual Status Flush();
virtual Status Sync();
private:
FileState state_;
WritableFile* target_;
bool writable_file_opened_;
FaultInjectionTestEnv* env_;
Status SyncParent();
};
class FaultInjectionTestEnv : public EnvWrapper {
public:
FaultInjectionTestEnv() : EnvWrapper(Env::Default()), filesystem_active_(true) {}
virtual ~FaultInjectionTestEnv() { }
virtual Status NewWritableFile(const std::string& fname,
WritableFile** result);
virtual Status NewAppendableFile(const std::string& fname,
WritableFile** result);
virtual Status DeleteFile(const std::string& f);
virtual Status RenameFile(const std::string& s, const std::string& t);
void WritableFileClosed(const FileState& state);
Status DropUnsyncedFileData();
Status DeleteFilesCreatedAfterLastDirSync();
void DirWasSynced();
bool IsFileCreatedSinceLastDirSync(const std::string& filename);
void ResetState();
void UntrackFile(const std::string& f);
// Setting the filesystem to inactive is the test equivalent to simulating a
// system reset. Setting to inactive will freeze our saved filesystem state so
// that it will stop being recorded. It can then be reset back to the state at
// the time of the reset.
bool IsFilesystemActive() const { return filesystem_active_; }
void SetFilesystemActive(bool active) { filesystem_active_ = active; }
private:
port::Mutex mutex_;
std::map<std::string, FileState> db_file_state_;
std::set<std::string> new_files_since_last_dir_sync_;
bool filesystem_active_; // Record flushes, syncs, writes
};
TestWritableFile::TestWritableFile(const FileState& state,
WritableFile* f,
FaultInjectionTestEnv* env)
: state_(state),
target_(f),
writable_file_opened_(true),
env_(env) {
assert(f != NULL);
}
TestWritableFile::~TestWritableFile() {
if (writable_file_opened_) {
Close();
}
delete target_;
}
Status TestWritableFile::Append(const Slice& data) {
Status s = target_->Append(data);
if (s.ok() && env_->IsFilesystemActive()) {
state_.pos_ += data.size();
}
return s;
}
Status TestWritableFile::Close() {
writable_file_opened_ = false;
Status s = target_->Close();
if (s.ok()) {
env_->WritableFileClosed(state_);
}
return s;
}
Status TestWritableFile::Flush() {
Status s = target_->Flush();
if (s.ok() && env_->IsFilesystemActive()) {
state_.pos_at_last_flush_ = state_.pos_;
}
return s;
}
Status TestWritableFile::SyncParent() {
Status s = SyncDir(GetDirName(state_.filename_));
if (s.ok()) {
env_->DirWasSynced();
}
return s;
}
Status TestWritableFile::Sync() {
if (!env_->IsFilesystemActive()) {
return Status::OK();
}
// Ensure new files referred to by the manifest are in the filesystem.
Status s = target_->Sync();
if (s.ok()) {
state_.pos_at_last_sync_ = state_.pos_;
}
if (env_->IsFileCreatedSinceLastDirSync(state_.filename_)) {
Status ps = SyncParent();
if (s.ok() && !ps.ok()) {
s = ps;
}
}
return s;
}
Status FaultInjectionTestEnv::NewWritableFile(const std::string& fname,
WritableFile** result) {
WritableFile* actual_writable_file;
Status s = target()->NewWritableFile(fname, &actual_writable_file);
if (s.ok()) {
FileState state(fname);
state.pos_ = 0;
*result = new TestWritableFile(state, actual_writable_file, this);
// NewWritableFile doesn't append to files, so if the same file is
// opened again then it will be truncated - so forget our saved
// state.
UntrackFile(fname);
MutexLock l(&mutex_);
new_files_since_last_dir_sync_.insert(fname);
}
return s;
}
Status FaultInjectionTestEnv::NewAppendableFile(const std::string& fname,
WritableFile** result) {
WritableFile* actual_writable_file;
Status s = target()->NewAppendableFile(fname, &actual_writable_file);
if (s.ok()) {
FileState state(fname);
state.pos_ = 0;
{
MutexLock l(&mutex_);
if (db_file_state_.count(fname) == 0) {
new_files_since_last_dir_sync_.insert(fname);
} else {
state = db_file_state_[fname];
}
}
*result = new TestWritableFile(state, actual_writable_file, this);
}
return s;
}
Status FaultInjectionTestEnv::DropUnsyncedFileData() {
Status s;
MutexLock l(&mutex_);
for (std::map<std::string, FileState>::const_iterator it =
db_file_state_.begin();
s.ok() && it != db_file_state_.end(); ++it) {
const FileState& state = it->second;
if (!state.IsFullySynced()) {
s = state.DropUnsyncedData();
}
}
return s;
}
void FaultInjectionTestEnv::DirWasSynced() {
MutexLock l(&mutex_);
new_files_since_last_dir_sync_.clear();
}
bool FaultInjectionTestEnv::IsFileCreatedSinceLastDirSync(
const std::string& filename) {
MutexLock l(&mutex_);
return new_files_since_last_dir_sync_.find(filename) !=
new_files_since_last_dir_sync_.end();
}
void FaultInjectionTestEnv::UntrackFile(const std::string& f) {
MutexLock l(&mutex_);
db_file_state_.erase(f);
new_files_since_last_dir_sync_.erase(f);
}
Status FaultInjectionTestEnv::DeleteFile(const std::string& f) {
Status s = EnvWrapper::DeleteFile(f);
ASSERT_OK(s);
if (s.ok()) {
UntrackFile(f);
}
return s;
}
Status FaultInjectionTestEnv::RenameFile(const std::string& s,
const std::string& t) {
Status ret = EnvWrapper::RenameFile(s, t);
if (ret.ok()) {
MutexLock l(&mutex_);
if (db_file_state_.find(s) != db_file_state_.end()) {
db_file_state_[t] = db_file_state_[s];
db_file_state_.erase(s);
}
if (new_files_since_last_dir_sync_.erase(s) != 0) {
assert(new_files_since_last_dir_sync_.find(t) ==
new_files_since_last_dir_sync_.end());
new_files_since_last_dir_sync_.insert(t);
}
}
return ret;
}
void FaultInjectionTestEnv::ResetState() {
// Since we are not destroying the database, the existing files
// should keep their recorded synced/flushed state. Therefore
// we do not reset db_file_state_ and new_files_since_last_dir_sync_.
MutexLock l(&mutex_);
SetFilesystemActive(true);
}
Status FaultInjectionTestEnv::DeleteFilesCreatedAfterLastDirSync() {
// Because DeleteFile access this container make a copy to avoid deadlock
mutex_.Lock();
std::set<std::string> new_files(new_files_since_last_dir_sync_.begin(),
new_files_since_last_dir_sync_.end());
mutex_.Unlock();
Status s;
std::set<std::string>::const_iterator it;
for (it = new_files.begin(); s.ok() && it != new_files.end(); ++it) {
s = DeleteFile(*it);
}
return s;
}
void FaultInjectionTestEnv::WritableFileClosed(const FileState& state) {
MutexLock l(&mutex_);
db_file_state_[state.filename_] = state;
}
Status FileState::DropUnsyncedData() const {
ssize_t sync_pos = pos_at_last_sync_ == -1 ? 0 : pos_at_last_sync_;
return Truncate(filename_, sync_pos);
}
class FaultInjectionTest {
public:
enum ExpectedVerifResult { VAL_EXPECT_NO_ERROR, VAL_EXPECT_ERROR };
enum ResetMethod { RESET_DROP_UNSYNCED_DATA, RESET_DELETE_UNSYNCED_FILES };
FaultInjectionTestEnv* env_;
std::string dbname_;
Cache* tiny_cache_;
Options options_;
DB* db_;
FaultInjectionTest()
: env_(new FaultInjectionTestEnv),
tiny_cache_(NewLRUCache(100)),
db_(NULL) {
dbname_ = test::TmpDir() + "/fault_test";
DestroyDB(dbname_, Options()); // Destroy any db from earlier run
options_.reuse_logs = true;
options_.env = env_;
options_.paranoid_checks = true;
options_.block_cache = tiny_cache_;
options_.create_if_missing = true;
}
~FaultInjectionTest() {
CloseDB();
DestroyDB(dbname_, Options());
delete tiny_cache_;
delete env_;
}
void ReuseLogs(bool reuse) {
options_.reuse_logs = reuse;
}
void Build(int start_idx, int num_vals) {
std::string key_space, value_space;
WriteBatch batch;
for (int i = start_idx; i < start_idx + num_vals; i++) {
Slice key = Key(i, &key_space);
batch.Clear();
batch.Put(key, Value(i, &value_space));
WriteOptions options;
ASSERT_OK(db_->Write(options, &batch));
}
}
Status ReadValue(int i, std::string* val) const {
std::string key_space, value_space;
Slice key = Key(i, &key_space);
Value(i, &value_space);
ReadOptions options;
return db_->Get(options, key, val);
}
Status Verify(int start_idx, int num_vals,
ExpectedVerifResult expected) const {
std::string val;
std::string value_space;
Status s;
for (int i = start_idx; i < start_idx + num_vals && s.ok(); i++) {
Value(i, &value_space);
s = ReadValue(i, &val);
if (expected == VAL_EXPECT_NO_ERROR) {
if (s.ok()) {
ASSERT_EQ(value_space, val);
}
} else if (s.ok()) {
fprintf(stderr, "Expected an error at %d, but was OK\n", i);
s = Status::IOError(dbname_, "Expected value error:");
} else {
s = Status::OK(); // An expected error
}
}
return s;
}
// Return the ith key
Slice Key(int i, std::string* storage) const {
char buf[100];
snprintf(buf, sizeof(buf), "%016d", i);
storage->assign(buf, strlen(buf));
return Slice(*storage);
}
// Return the value to associate with the specified key
Slice Value(int k, std::string* storage) const {
Random r(k);
return test::RandomString(&r, kValueSize, storage);
}
Status OpenDB() {
delete db_;
db_ = NULL;
env_->ResetState();
return DB::Open(options_, dbname_, &db_);
}
void CloseDB() {
delete db_;
db_ = NULL;
}
void DeleteAllData() {
Iterator* iter = db_->NewIterator(ReadOptions());
WriteOptions options;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
ASSERT_OK(db_->Delete(WriteOptions(), iter->key()));
}
delete iter;
}
void ResetDBState(ResetMethod reset_method) {
switch (reset_method) {
case RESET_DROP_UNSYNCED_DATA:
ASSERT_OK(env_->DropUnsyncedFileData());
break;
case RESET_DELETE_UNSYNCED_FILES:
ASSERT_OK(env_->DeleteFilesCreatedAfterLastDirSync());
break;
default:
assert(false);
}
}
void PartialCompactTestPreFault(int num_pre_sync, int num_post_sync) {
DeleteAllData();
Build(0, num_pre_sync);
db_->CompactRange(NULL, NULL);
Build(num_pre_sync, num_post_sync);
}
void PartialCompactTestReopenWithFault(ResetMethod reset_method,
int num_pre_sync,
int num_post_sync) {
env_->SetFilesystemActive(false);
CloseDB();
ResetDBState(reset_method);
ASSERT_OK(OpenDB());
ASSERT_OK(Verify(0, num_pre_sync, FaultInjectionTest::VAL_EXPECT_NO_ERROR));
ASSERT_OK(Verify(num_pre_sync, num_post_sync, FaultInjectionTest::VAL_EXPECT_ERROR));
}
void NoWriteTestPreFault() {
}
void NoWriteTestReopenWithFault(ResetMethod reset_method) {
CloseDB();
ResetDBState(reset_method);
ASSERT_OK(OpenDB());
}
void DoTest() {
Random rnd(0);
ASSERT_OK(OpenDB());
for (size_t idx = 0; idx < kNumIterations; idx++) {
int num_pre_sync = rnd.Uniform(kMaxNumValues);
int num_post_sync = rnd.Uniform(kMaxNumValues);
PartialCompactTestPreFault(num_pre_sync, num_post_sync);
PartialCompactTestReopenWithFault(RESET_DROP_UNSYNCED_DATA,
num_pre_sync,
num_post_sync);
NoWriteTestPreFault();
NoWriteTestReopenWithFault(RESET_DROP_UNSYNCED_DATA);
PartialCompactTestPreFault(num_pre_sync, num_post_sync);
// No new files created so we expect all values since no files will be
// dropped.
PartialCompactTestReopenWithFault(RESET_DELETE_UNSYNCED_FILES,
num_pre_sync + num_post_sync,
0);
NoWriteTestPreFault();
NoWriteTestReopenWithFault(RESET_DELETE_UNSYNCED_FILES);
}
}
};
TEST(FaultInjectionTest, FaultTestNoLogReuse) {
ReuseLogs(false);
DoTest();
}
TEST(FaultInjectionTest, FaultTestWithLogReuse) {
ReuseLogs(true);
DoTest();
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include <ctype.h>
#include <stdio.h>
#include "db/filename.h"
#include "db/dbformat.h"
#include "leveldb/env.h"
#include "util/logging.h"
namespace leveldb {
// A utility routine: write "data" to the named file and Sync() it.
extern Status WriteStringToFileSync(Env* env, const Slice& data,
const std::string& fname);
static std::string MakeFileName(const std::string& name, uint64_t number,
const char* suffix) {
char buf[100];
snprintf(buf, sizeof(buf), "/%06llu.%s",
static_cast<unsigned long long>(number),
suffix);
return name + buf;
}
std::string LogFileName(const std::string& name, uint64_t number) {
assert(number > 0);
return MakeFileName(name, number, "log");
}
std::string TableFileName(const std::string& name, uint64_t number) {
assert(number > 0);
return MakeFileName(name, number, "ldb");
}
std::string SSTTableFileName(const std::string& name, uint64_t number) {
assert(number > 0);
return MakeFileName(name, number, "sst");
}
std::string DescriptorFileName(const std::string& dbname, uint64_t number) {
assert(number > 0);
char buf[100];
snprintf(buf, sizeof(buf), "/MANIFEST-%06llu",
static_cast<unsigned long long>(number));
return dbname + buf;
}
std::string CurrentFileName(const std::string& dbname) {
return dbname + "/CURRENT";
}
std::string LockFileName(const std::string& dbname) {
return dbname + "/LOCK";
}
std::string TempFileName(const std::string& dbname, uint64_t number) {
assert(number > 0);
return MakeFileName(dbname, number, "dbtmp");
}
std::string InfoLogFileName(const std::string& dbname) {
return dbname + "/LOG";
}
// Return the name of the old info log file for "dbname".
std::string OldInfoLogFileName(const std::string& dbname) {
return dbname + "/LOG.old";
}
// Owned filenames have the form:
// dbname/CURRENT
// dbname/LOCK
// dbname/LOG
// dbname/LOG.old
// dbname/MANIFEST-[0-9]+
// dbname/[0-9]+.(log|sst|ldb)
bool ParseFileName(const std::string& fname,
uint64_t* number,
FileType* type) {
Slice rest(fname);
if (rest == "CURRENT") {
*number = 0;
*type = kCurrentFile;
} else if (rest == "LOCK") {
*number = 0;
*type = kDBLockFile;
} else if (rest == "LOG" || rest == "LOG.old") {
*number = 0;
*type = kInfoLogFile;
} else if (rest.starts_with("MANIFEST-")) {
rest.remove_prefix(strlen("MANIFEST-"));
uint64_t num;
if (!ConsumeDecimalNumber(&rest, &num)) {
return false;
}
if (!rest.empty()) {
return false;
}
*type = kDescriptorFile;
*number = num;
} else {
// Avoid strtoull() to keep filename format independent of the
// current locale
uint64_t num;
if (!ConsumeDecimalNumber(&rest, &num)) {
return false;
}
Slice suffix = rest;
if (suffix == Slice(".log")) {
*type = kLogFile;
} else if (suffix == Slice(".sst") || suffix == Slice(".ldb")) {
*type = kTableFile;
} else if (suffix == Slice(".dbtmp")) {
*type = kTempFile;
} else {
return false;
}
*number = num;
}
return true;
}
Status SetCurrentFile(Env* env, const std::string& dbname,
uint64_t descriptor_number) {
// Remove leading "dbname/" and add newline to manifest file name
std::string manifest = DescriptorFileName(dbname, descriptor_number);
Slice contents = manifest;
assert(contents.starts_with(dbname + "/"));
contents.remove_prefix(dbname.size() + 1);
std::string tmp = TempFileName(dbname, descriptor_number);
Status s = WriteStringToFileSync(env, contents.ToString() + "\n", tmp);
if (s.ok()) {
s = env->RenameFile(tmp, CurrentFileName(dbname));
}
if (!s.ok()) {
env->DeleteFile(tmp);
}
return s;
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// File names used by DB code
#ifndef STORAGE_LEVELDB_DB_FILENAME_H_
#define STORAGE_LEVELDB_DB_FILENAME_H_
#include <stdint.h>
#include <string>
#include "leveldb/slice.h"
#include "leveldb/status.h"
#include "port/port.h"
namespace leveldb {
class Env;
enum FileType {
kLogFile,
kDBLockFile,
kTableFile,
kDescriptorFile,
kCurrentFile,
kTempFile,
kInfoLogFile // Either the current one, or an old one
};
// Return the name of the log file with the specified number
// in the db named by "dbname". The result will be prefixed with
// "dbname".
extern std::string LogFileName(const std::string& dbname, uint64_t number);
// Return the name of the sstable with the specified number
// in the db named by "dbname". The result will be prefixed with
// "dbname".
extern std::string TableFileName(const std::string& dbname, uint64_t number);
// Return the legacy file name for an sstable with the specified number
// in the db named by "dbname". The result will be prefixed with
// "dbname".
extern std::string SSTTableFileName(const std::string& dbname, uint64_t number);
// Return the name of the descriptor file for the db named by
// "dbname" and the specified incarnation number. The result will be
// prefixed with "dbname".
extern std::string DescriptorFileName(const std::string& dbname,
uint64_t number);
// Return the name of the current file. This file contains the name
// of the current manifest file. The result will be prefixed with
// "dbname".
extern std::string CurrentFileName(const std::string& dbname);
// Return the name of the lock file for the db named by
// "dbname". The result will be prefixed with "dbname".
extern std::string LockFileName(const std::string& dbname);
// Return the name of a temporary file owned by the db named "dbname".
// The result will be prefixed with "dbname".
extern std::string TempFileName(const std::string& dbname, uint64_t number);
// Return the name of the info log file for "dbname".
extern std::string InfoLogFileName(const std::string& dbname);
// Return the name of the old info log file for "dbname".
extern std::string OldInfoLogFileName(const std::string& dbname);
// If filename is a leveldb file, store the type of the file in *type.
// The number encoded in the filename is stored in *number. If the
// filename was successfully parsed, returns true. Else return false.
extern bool ParseFileName(const std::string& filename,
uint64_t* number,
FileType* type);
// Make the CURRENT file point to the descriptor file with the
// specified number.
extern Status SetCurrentFile(Env* env, const std::string& dbname,
uint64_t descriptor_number);
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_FILENAME_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/filename.h"
#include "db/dbformat.h"
#include "port/port.h"
#include "util/logging.h"
#include "util/testharness.h"
namespace leveldb {
class FileNameTest { };
TEST(FileNameTest, Parse) {
Slice db;
FileType type;
uint64_t number;
// Successful parses
static struct {
const char* fname;
uint64_t number;
FileType type;
} cases[] = {
{ "100.log", 100, kLogFile },
{ "0.log", 0, kLogFile },
{ "0.sst", 0, kTableFile },
{ "0.ldb", 0, kTableFile },
{ "CURRENT", 0, kCurrentFile },
{ "LOCK", 0, kDBLockFile },
{ "MANIFEST-2", 2, kDescriptorFile },
{ "MANIFEST-7", 7, kDescriptorFile },
{ "LOG", 0, kInfoLogFile },
{ "LOG.old", 0, kInfoLogFile },
{ "18446744073709551615.log", 18446744073709551615ull, kLogFile },
};
for (int i = 0; i < sizeof(cases) / sizeof(cases[0]); i++) {
std::string f = cases[i].fname;
ASSERT_TRUE(ParseFileName(f, &number, &type)) << f;
ASSERT_EQ(cases[i].type, type) << f;
ASSERT_EQ(cases[i].number, number) << f;
}
// Errors
static const char* errors[] = {
"",
"foo",
"foo-dx-100.log",
".log",
"",
"manifest",
"CURREN",
"CURRENTX",
"MANIFES",
"MANIFEST",
"MANIFEST-",
"XMANIFEST-3",
"MANIFEST-3x",
"LOC",
"LOCKx",
"LO",
"LOGx",
"18446744073709551616.log",
"184467440737095516150.log",
"100",
"100.",
"100.lop"
};
for (int i = 0; i < sizeof(errors) / sizeof(errors[0]); i++) {
std::string f = errors[i];
ASSERT_TRUE(!ParseFileName(f, &number, &type)) << f;
}
}
TEST(FileNameTest, Construction) {
uint64_t number;
FileType type;
std::string fname;
fname = CurrentFileName("foo");
ASSERT_EQ("foo/", std::string(fname.data(), 4));
ASSERT_TRUE(ParseFileName(fname.c_str() + 4, &number, &type));
ASSERT_EQ(0, number);
ASSERT_EQ(kCurrentFile, type);
fname = LockFileName("foo");
ASSERT_EQ("foo/", std::string(fname.data(), 4));
ASSERT_TRUE(ParseFileName(fname.c_str() + 4, &number, &type));
ASSERT_EQ(0, number);
ASSERT_EQ(kDBLockFile, type);
fname = LogFileName("foo", 192);
ASSERT_EQ("foo/", std::string(fname.data(), 4));
ASSERT_TRUE(ParseFileName(fname.c_str() + 4, &number, &type));
ASSERT_EQ(192, number);
ASSERT_EQ(kLogFile, type);
fname = TableFileName("bar", 200);
ASSERT_EQ("bar/", std::string(fname.data(), 4));
ASSERT_TRUE(ParseFileName(fname.c_str() + 4, &number, &type));
ASSERT_EQ(200, number);
ASSERT_EQ(kTableFile, type);
fname = DescriptorFileName("bar", 100);
ASSERT_EQ("bar/", std::string(fname.data(), 4));
ASSERT_TRUE(ParseFileName(fname.c_str() + 4, &number, &type));
ASSERT_EQ(100, number);
ASSERT_EQ(kDescriptorFile, type);
fname = TempFileName("tmp", 999);
ASSERT_EQ("tmp/", std::string(fname.data(), 4));
ASSERT_TRUE(ParseFileName(fname.c_str() + 4, &number, &type));
ASSERT_EQ(999, number);
ASSERT_EQ(kTempFile, type);
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include <stdio.h>
#include "leveldb/dumpfile.h"
#include "leveldb/env.h"
#include "leveldb/status.h"
namespace leveldb {
namespace {
class StdoutPrinter : public WritableFile {
public:
virtual Status Append(const Slice& data) {
fwrite(data.data(), 1, data.size(), stdout);
return Status::OK();
}
virtual Status Close() { return Status::OK(); }
virtual Status Flush() { return Status::OK(); }
virtual Status Sync() { return Status::OK(); }
};
bool HandleDumpCommand(Env* env, char** files, int num) {
StdoutPrinter printer;
bool ok = true;
for (int i = 0; i < num; i++) {
Status s = DumpFile(env, files[i], &printer);
if (!s.ok()) {
fprintf(stderr, "%s\n", s.ToString().c_str());
ok = false;
}
}
return ok;
}
} // namespace
} // namespace leveldb
static void Usage() {
fprintf(
stderr,
"Usage: leveldbutil command...\n"
" dump files... -- dump contents of specified files\n"
);
}
int main(int argc, char** argv) {
leveldb::Env* env = leveldb::Env::Default();
bool ok = true;
if (argc < 2) {
Usage();
ok = false;
} else {
std::string command = argv[1];
if (command == "dump") {
ok = leveldb::HandleDumpCommand(env, argv+2, argc-2);
} else {
Usage();
ok = false;
}
}
return (ok ? 0 : 1);
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// Log format information shared by reader and writer.
// See ../doc/log_format.md for more detail.
#ifndef STORAGE_LEVELDB_DB_LOG_FORMAT_H_
#define STORAGE_LEVELDB_DB_LOG_FORMAT_H_
namespace leveldb {
namespace log {
enum RecordType {
// Zero is reserved for preallocated files
kZeroType = 0,
kFullType = 1,
// For fragments
kFirstType = 2,
kMiddleType = 3,
kLastType = 4
};
static const int kMaxRecordType = kLastType;
static const int kBlockSize = 32768;
// Header is checksum (4 bytes), length (2 bytes), type (1 byte).
static const int kHeaderSize = 4 + 2 + 1;
} // namespace log
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_LOG_FORMAT_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/log_reader.h"
#include <stdio.h>
#include "leveldb/env.h"
#include "util/coding.h"
#include "util/crc32c.h"
namespace leveldb {
namespace log {
Reader::Reporter::~Reporter() {
}
Reader::Reader(SequentialFile* file, Reporter* reporter, bool checksum,
uint64_t initial_offset)
: file_(file),
reporter_(reporter),
checksum_(checksum),
backing_store_(new char[kBlockSize]),
buffer_(),
eof_(false),
last_record_offset_(0),
end_of_buffer_offset_(0),
initial_offset_(initial_offset),
resyncing_(initial_offset > 0) {
}
Reader::~Reader() {
delete[] backing_store_;
}
bool Reader::SkipToInitialBlock() {
size_t offset_in_block = initial_offset_ % kBlockSize;
uint64_t block_start_location = initial_offset_ - offset_in_block;
// Don't search a block if we'd be in the trailer
if (offset_in_block > kBlockSize - 6) {
offset_in_block = 0;
block_start_location += kBlockSize;
}
end_of_buffer_offset_ = block_start_location;
// Skip to start of first block that can contain the initial record
if (block_start_location > 0) {
Status skip_status = file_->Skip(block_start_location);
if (!skip_status.ok()) {
ReportDrop(block_start_location, skip_status);
return false;
}
}
return true;
}
bool Reader::ReadRecord(Slice* record, std::string* scratch) {
if (last_record_offset_ < initial_offset_) {
if (!SkipToInitialBlock()) {
return false;
}
}
scratch->clear();
record->clear();
bool in_fragmented_record = false;
// Record offset of the logical record that we're reading
// 0 is a dummy value to make compilers happy
uint64_t prospective_record_offset = 0;
Slice fragment;
while (true) {
const unsigned int record_type = ReadPhysicalRecord(&fragment);
// ReadPhysicalRecord may have only had an empty trailer remaining in its
// internal buffer. Calculate the offset of the next physical record now
// that it has returned, properly accounting for its header size.
uint64_t physical_record_offset =
end_of_buffer_offset_ - buffer_.size() - kHeaderSize - fragment.size();
if (resyncing_) {
if (record_type == kMiddleType) {
continue;
} else if (record_type == kLastType) {
resyncing_ = false;
continue;
} else {
resyncing_ = false;
}
}
switch (record_type) {
case kFullType:
if (in_fragmented_record) {
// Handle bug in earlier versions of log::Writer where
// it could emit an empty kFirstType record at the tail end
// of a block followed by a kFullType or kFirstType record
// at the beginning of the next block.
if (scratch->empty()) {
in_fragmented_record = false;
} else {
ReportCorruption(scratch->size(), "partial record without end(1)");
}
}
prospective_record_offset = physical_record_offset;
scratch->clear();
*record = fragment;
last_record_offset_ = prospective_record_offset;
return true;
case kFirstType:
if (in_fragmented_record) {
// Handle bug in earlier versions of log::Writer where
// it could emit an empty kFirstType record at the tail end
// of a block followed by a kFullType or kFirstType record
// at the beginning of the next block.
if (scratch->empty()) {
in_fragmented_record = false;
} else {
ReportCorruption(scratch->size(), "partial record without end(2)");
}
}
prospective_record_offset = physical_record_offset;
scratch->assign(fragment.data(), fragment.size());
in_fragmented_record = true;
break;
case kMiddleType:
if (!in_fragmented_record) {
ReportCorruption(fragment.size(),
"missing start of fragmented record(1)");
} else {
scratch->append(fragment.data(), fragment.size());
}
break;
case kLastType:
if (!in_fragmented_record) {
ReportCorruption(fragment.size(),
"missing start of fragmented record(2)");
} else {
scratch->append(fragment.data(), fragment.size());
*record = Slice(*scratch);
last_record_offset_ = prospective_record_offset;
return true;
}
break;
case kEof:
if (in_fragmented_record) {
// This can be caused by the writer dying immediately after
// writing a physical record but before completing the next; don't
// treat it as a corruption, just ignore the entire logical record.
scratch->clear();
}
return false;
case kBadRecord:
if (in_fragmented_record) {
ReportCorruption(scratch->size(), "error in middle of record");
in_fragmented_record = false;
scratch->clear();
}
break;
default: {
char buf[40];
snprintf(buf, sizeof(buf), "unknown record type %u", record_type);
ReportCorruption(
(fragment.size() + (in_fragmented_record ? scratch->size() : 0)),
buf);
in_fragmented_record = false;
scratch->clear();
break;
}
}
}
return false;
}
uint64_t Reader::LastRecordOffset() {
return last_record_offset_;
}
void Reader::ReportCorruption(uint64_t bytes, const char* reason) {
ReportDrop(bytes, Status::Corruption(reason));
}
void Reader::ReportDrop(uint64_t bytes, const Status& reason) {
if (reporter_ != NULL &&
end_of_buffer_offset_ - buffer_.size() - bytes >= initial_offset_) {
reporter_->Corruption(static_cast<size_t>(bytes), reason);
}
}
unsigned int Reader::ReadPhysicalRecord(Slice* result) {
while (true) {
if (buffer_.size() < kHeaderSize) {
if (!eof_) {
// Last read was a full read, so this is a trailer to skip
buffer_.clear();
Status status = file_->Read(kBlockSize, &buffer_, backing_store_);
end_of_buffer_offset_ += buffer_.size();
if (!status.ok()) {
buffer_.clear();
ReportDrop(kBlockSize, status);
eof_ = true;
return kEof;
} else if (buffer_.size() < kBlockSize) {
eof_ = true;
}
continue;
} else {
// Note that if buffer_ is non-empty, we have a truncated header at the
// end of the file, which can be caused by the writer crashing in the
// middle of writing the header. Instead of considering this an error,
// just report EOF.
buffer_.clear();
return kEof;
}
}
// Parse the header
const char* header = buffer_.data();
const uint32_t a = static_cast<uint32_t>(header[4]) & 0xff;
const uint32_t b = static_cast<uint32_t>(header[5]) & 0xff;
const unsigned int type = header[6];
const uint32_t length = a | (b << 8);
if (kHeaderSize + length > buffer_.size()) {
size_t drop_size = buffer_.size();
buffer_.clear();
if (!eof_) {
ReportCorruption(drop_size, "bad record length");
return kBadRecord;
}
// If the end of the file has been reached without reading |length| bytes
// of payload, assume the writer died in the middle of writing the record.
// Don't report a corruption.
return kEof;
}
if (type == kZeroType && length == 0) {
// Skip zero length record without reporting any drops since
// such records are produced by the mmap based writing code in
// env_posix.cc that preallocates file regions.
buffer_.clear();
return kBadRecord;
}
// Check crc
if (checksum_) {
uint32_t expected_crc = crc32c::Unmask(DecodeFixed32(header));
uint32_t actual_crc = crc32c::Value(header + 6, 1 + length);
if (actual_crc != expected_crc) {
// Drop the rest of the buffer since "length" itself may have
// been corrupted and if we trust it, we could find some
// fragment of a real log record that just happens to look
// like a valid log record.
size_t drop_size = buffer_.size();
buffer_.clear();
ReportCorruption(drop_size, "checksum mismatch");
return kBadRecord;
}
}
buffer_.remove_prefix(kHeaderSize + length);
// Skip physical record that started before initial_offset_
if (end_of_buffer_offset_ - buffer_.size() - kHeaderSize - length <
initial_offset_) {
result->clear();
return kBadRecord;
}
*result = Slice(header + kHeaderSize, length);
return type;
}
}
} // namespace log
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_LOG_READER_H_
#define STORAGE_LEVELDB_DB_LOG_READER_H_
#include <stdint.h>
#include "db/log_format.h"
#include "leveldb/slice.h"
#include "leveldb/status.h"
namespace leveldb {
class SequentialFile;
namespace log {
class Reader {
public:
// Interface for reporting errors.
class Reporter {
public:
virtual ~Reporter();
// Some corruption was detected. "size" is the approximate number
// of bytes dropped due to the corruption.
virtual void Corruption(size_t bytes, const Status& status) = 0;
};
// Create a reader that will return log records from "*file".
// "*file" must remain live while this Reader is in use.
//
// If "reporter" is non-NULL, it is notified whenever some data is
// dropped due to a detected corruption. "*reporter" must remain
// live while this Reader is in use.
//
// If "checksum" is true, verify checksums if available.
//
// The Reader will start reading at the first record located at physical
// position >= initial_offset within the file.
Reader(SequentialFile* file, Reporter* reporter, bool checksum,
uint64_t initial_offset);
~Reader();
// Read the next record into *record. Returns true if read
// successfully, false if we hit end of the input. May use
// "*scratch" as temporary storage. The contents filled in *record
// will only be valid until the next mutating operation on this
// reader or the next mutation to *scratch.
bool ReadRecord(Slice* record, std::string* scratch);
// Returns the physical offset of the last record returned by ReadRecord.
//
// Undefined before the first call to ReadRecord.
uint64_t LastRecordOffset();
private:
SequentialFile* const file_;
Reporter* const reporter_;
bool const checksum_;
char* const backing_store_;
Slice buffer_;
bool eof_; // Last Read() indicated EOF by returning < kBlockSize
// Offset of the last record returned by ReadRecord.
uint64_t last_record_offset_;
// Offset of the first location past the end of buffer_.
uint64_t end_of_buffer_offset_;
// Offset at which to start looking for the first record to return
uint64_t const initial_offset_;
// True if we are resynchronizing after a seek (initial_offset_ > 0). In
// particular, a run of kMiddleType and kLastType records can be silently
// skipped in this mode
bool resyncing_;
// Extend record types with the following special values
enum {
kEof = kMaxRecordType + 1,
// Returned whenever we find an invalid physical record.
// Currently there are three situations in which this happens:
// * The record has an invalid CRC (ReadPhysicalRecord reports a drop)
// * The record is a 0-length record (No drop is reported)
// * The record is below constructor's initial_offset (No drop is reported)
kBadRecord = kMaxRecordType + 2
};
// Skips all blocks that are completely before "initial_offset_".
//
// Returns true on success. Handles reporting.
bool SkipToInitialBlock();
// Return type, or one of the preceding special values
unsigned int ReadPhysicalRecord(Slice* result);
// Reports dropped bytes to the reporter.
// buffer_ must be updated to remove the dropped bytes prior to invocation.
void ReportCorruption(uint64_t bytes, const char* reason);
void ReportDrop(uint64_t bytes, const Status& reason);
// No copying allowed
Reader(const Reader&);
void operator=(const Reader&);
};
} // namespace log
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_LOG_READER_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/log_reader.h"
#include "db/log_writer.h"
#include "leveldb/env.h"
#include "util/coding.h"
#include "util/crc32c.h"
#include "util/random.h"
#include "util/testharness.h"
namespace leveldb {
namespace log {
// Construct a string of the specified length made out of the supplied
// partial string.
static std::string BigString(const std::string& partial_string, size_t n) {
std::string result;
while (result.size() < n) {
result.append(partial_string);
}
result.resize(n);
return result;
}
// Construct a string from a number
static std::string NumberString(int n) {
char buf[50];
snprintf(buf, sizeof(buf), "%d.", n);
return std::string(buf);
}
// Return a skewed potentially long string
static std::string RandomSkewedString(int i, Random* rnd) {
return BigString(NumberString(i), rnd->Skewed(17));
}
class LogTest {
private:
class StringDest : public WritableFile {
public:
std::string contents_;
virtual Status Close() { return Status::OK(); }
virtual Status Flush() { return Status::OK(); }
virtual Status Sync() { return Status::OK(); }
virtual Status Append(const Slice& slice) {
contents_.append(slice.data(), slice.size());
return Status::OK();
}
};
class StringSource : public SequentialFile {
public:
Slice contents_;
bool force_error_;
bool returned_partial_;
StringSource() : force_error_(false), returned_partial_(false) { }
virtual Status Read(size_t n, Slice* result, char* scratch) {
ASSERT_TRUE(!returned_partial_) << "must not Read() after eof/error";
if (force_error_) {
force_error_ = false;
returned_partial_ = true;
return Status::Corruption("read error");
}
if (contents_.size() < n) {
n = contents_.size();
returned_partial_ = true;
}
*result = Slice(contents_.data(), n);
contents_.remove_prefix(n);
return Status::OK();
}
virtual Status Skip(uint64_t n) {
if (n > contents_.size()) {
contents_.clear();
return Status::NotFound("in-memory file skipped past end");
}
contents_.remove_prefix(n);
return Status::OK();
}
};
class ReportCollector : public Reader::Reporter {
public:
size_t dropped_bytes_;
std::string message_;
ReportCollector() : dropped_bytes_(0) { }
virtual void Corruption(size_t bytes, const Status& status) {
dropped_bytes_ += bytes;
message_.append(status.ToString());
}
};
StringDest dest_;
StringSource source_;
ReportCollector report_;
bool reading_;
Writer* writer_;
Reader* reader_;
// Record metadata for testing initial offset functionality
static size_t initial_offset_record_sizes_[];
static uint64_t initial_offset_last_record_offsets_[];
static int num_initial_offset_records_;
public:
LogTest() : reading_(false),
writer_(new Writer(&dest_)),
reader_(new Reader(&source_, &report_, true/*checksum*/,
0/*initial_offset*/)) {
}
~LogTest() {
delete writer_;
delete reader_;
}
void ReopenForAppend() {
delete writer_;
writer_ = new Writer(&dest_, dest_.contents_.size());
}
void Write(const std::string& msg) {
ASSERT_TRUE(!reading_) << "Write() after starting to read";
writer_->AddRecord(Slice(msg));
}
size_t WrittenBytes() const {
return dest_.contents_.size();
}
std::string Read() {
if (!reading_) {
reading_ = true;
source_.contents_ = Slice(dest_.contents_);
}
std::string scratch;
Slice record;
if (reader_->ReadRecord(&record, &scratch)) {
return record.ToString();
} else {
return "EOF";
}
}
void IncrementByte(int offset, int delta) {
dest_.contents_[offset] += delta;
}
void SetByte(int offset, char new_byte) {
dest_.contents_[offset] = new_byte;
}
void ShrinkSize(int bytes) {
dest_.contents_.resize(dest_.contents_.size() - bytes);
}
void FixChecksum(int header_offset, int len) {
// Compute crc of type/len/data
uint32_t crc = crc32c::Value(&dest_.contents_[header_offset+6], 1 + len);
crc = crc32c::Mask(crc);
EncodeFixed32(&dest_.contents_[header_offset], crc);
}
void ForceError() {
source_.force_error_ = true;
}
size_t DroppedBytes() const {
return report_.dropped_bytes_;
}
std::string ReportMessage() const {
return report_.message_;
}
// Returns OK iff recorded error message contains "msg"
std::string MatchError(const std::string& msg) const {
if (report_.message_.find(msg) == std::string::npos) {
return report_.message_;
} else {
return "OK";
}
}
void WriteInitialOffsetLog() {
for (int i = 0; i < num_initial_offset_records_; i++) {
std::string record(initial_offset_record_sizes_[i],
static_cast<char>('a' + i));
Write(record);
}
}
void StartReadingAt(uint64_t initial_offset) {
delete reader_;
reader_ = new Reader(&source_, &report_, true/*checksum*/, initial_offset);
}
void CheckOffsetPastEndReturnsNoRecords(uint64_t offset_past_end) {
WriteInitialOffsetLog();
reading_ = true;
source_.contents_ = Slice(dest_.contents_);
Reader* offset_reader = new Reader(&source_, &report_, true/*checksum*/,
WrittenBytes() + offset_past_end);
Slice record;
std::string scratch;
ASSERT_TRUE(!offset_reader->ReadRecord(&record, &scratch));
delete offset_reader;
}
void CheckInitialOffsetRecord(uint64_t initial_offset,
int expected_record_offset) {
WriteInitialOffsetLog();
reading_ = true;
source_.contents_ = Slice(dest_.contents_);
Reader* offset_reader = new Reader(&source_, &report_, true/*checksum*/,
initial_offset);
// Read all records from expected_record_offset through the last one.
ASSERT_LT(expected_record_offset, num_initial_offset_records_);
for (; expected_record_offset < num_initial_offset_records_;
++expected_record_offset) {
Slice record;
std::string scratch;
ASSERT_TRUE(offset_reader->ReadRecord(&record, &scratch));
ASSERT_EQ(initial_offset_record_sizes_[expected_record_offset],
record.size());
ASSERT_EQ(initial_offset_last_record_offsets_[expected_record_offset],
offset_reader->LastRecordOffset());
ASSERT_EQ((char)('a' + expected_record_offset), record.data()[0]);
}
delete offset_reader;
}
};
size_t LogTest::initial_offset_record_sizes_[] =
{10000, // Two sizable records in first block
10000,
2 * log::kBlockSize - 1000, // Span three blocks
1,
13716, // Consume all but two bytes of block 3.
log::kBlockSize - kHeaderSize, // Consume the entirety of block 4.
};
uint64_t LogTest::initial_offset_last_record_offsets_[] =
{0,
kHeaderSize + 10000,
2 * (kHeaderSize + 10000),
2 * (kHeaderSize + 10000) +
(2 * log::kBlockSize - 1000) + 3 * kHeaderSize,
2 * (kHeaderSize + 10000) +
(2 * log::kBlockSize - 1000) + 3 * kHeaderSize
+ kHeaderSize + 1,
3 * log::kBlockSize,
};
// LogTest::initial_offset_last_record_offsets_ must be defined before this.
int LogTest::num_initial_offset_records_ =
sizeof(LogTest::initial_offset_last_record_offsets_)/sizeof(uint64_t);
TEST(LogTest, Empty) {
ASSERT_EQ("EOF", Read());
}
TEST(LogTest, ReadWrite) {
Write("foo");
Write("bar");
Write("");
Write("xxxx");
ASSERT_EQ("foo", Read());
ASSERT_EQ("bar", Read());
ASSERT_EQ("", Read());
ASSERT_EQ("xxxx", Read());
ASSERT_EQ("EOF", Read());
ASSERT_EQ("EOF", Read()); // Make sure reads at eof work
}
TEST(LogTest, ManyBlocks) {
for (int i = 0; i < 100000; i++) {
Write(NumberString(i));
}
for (int i = 0; i < 100000; i++) {
ASSERT_EQ(NumberString(i), Read());
}
ASSERT_EQ("EOF", Read());
}
TEST(LogTest, Fragmentation) {
Write("small");
Write(BigString("medium", 50000));
Write(BigString("large", 100000));
ASSERT_EQ("small", Read());
ASSERT_EQ(BigString("medium", 50000), Read());
ASSERT_EQ(BigString("large", 100000), Read());
ASSERT_EQ("EOF", Read());
}
TEST(LogTest, MarginalTrailer) {
// Make a trailer that is exactly the same length as an empty record.
const int n = kBlockSize - 2*kHeaderSize;
Write(BigString("foo", n));
ASSERT_EQ(kBlockSize - kHeaderSize, WrittenBytes());
Write("");
Write("bar");
ASSERT_EQ(BigString("foo", n), Read());
ASSERT_EQ("", Read());
ASSERT_EQ("bar", Read());
ASSERT_EQ("EOF", Read());
}
TEST(LogTest, MarginalTrailer2) {
// Make a trailer that is exactly the same length as an empty record.
const int n = kBlockSize - 2*kHeaderSize;
Write(BigString("foo", n));
ASSERT_EQ(kBlockSize - kHeaderSize, WrittenBytes());
Write("bar");
ASSERT_EQ(BigString("foo", n), Read());
ASSERT_EQ("bar", Read());
ASSERT_EQ("EOF", Read());
ASSERT_EQ(0, DroppedBytes());
ASSERT_EQ("", ReportMessage());
}
TEST(LogTest, ShortTrailer) {
const int n = kBlockSize - 2*kHeaderSize + 4;
Write(BigString("foo", n));
ASSERT_EQ(kBlockSize - kHeaderSize + 4, WrittenBytes());
Write("");
Write("bar");
ASSERT_EQ(BigString("foo", n), Read());
ASSERT_EQ("", Read());
ASSERT_EQ("bar", Read());
ASSERT_EQ("EOF", Read());
}
TEST(LogTest, AlignedEof) {
const int n = kBlockSize - 2*kHeaderSize + 4;
Write(BigString("foo", n));
ASSERT_EQ(kBlockSize - kHeaderSize + 4, WrittenBytes());
ASSERT_EQ(BigString("foo", n), Read());
ASSERT_EQ("EOF", Read());
}
TEST(LogTest, OpenForAppend) {
Write("hello");
ReopenForAppend();
Write("world");
ASSERT_EQ("hello", Read());
ASSERT_EQ("world", Read());
ASSERT_EQ("EOF", Read());
}
TEST(LogTest, RandomRead) {
const int N = 500;
Random write_rnd(301);
for (int i = 0; i < N; i++) {
Write(RandomSkewedString(i, &write_rnd));
}
Random read_rnd(301);
for (int i = 0; i < N; i++) {
ASSERT_EQ(RandomSkewedString(i, &read_rnd), Read());
}
ASSERT_EQ("EOF", Read());
}
// Tests of all the error paths in log_reader.cc follow:
TEST(LogTest, ReadError) {
Write("foo");
ForceError();
ASSERT_EQ("EOF", Read());
ASSERT_EQ(kBlockSize, DroppedBytes());
ASSERT_EQ("OK", MatchError("read error"));
}
TEST(LogTest, BadRecordType) {
Write("foo");
// Type is stored in header[6]
IncrementByte(6, 100);
FixChecksum(0, 3);
ASSERT_EQ("EOF", Read());
ASSERT_EQ(3, DroppedBytes());
ASSERT_EQ("OK", MatchError("unknown record type"));
}
TEST(LogTest, TruncatedTrailingRecordIsIgnored) {
Write("foo");
ShrinkSize(4); // Drop all payload as well as a header byte
ASSERT_EQ("EOF", Read());
// Truncated last record is ignored, not treated as an error.
ASSERT_EQ(0, DroppedBytes());
ASSERT_EQ("", ReportMessage());
}
TEST(LogTest, BadLength) {
const int kPayloadSize = kBlockSize - kHeaderSize;
Write(BigString("bar", kPayloadSize));
Write("foo");
// Least significant size byte is stored in header[4].
IncrementByte(4, 1);
ASSERT_EQ("foo", Read());
ASSERT_EQ(kBlockSize, DroppedBytes());
ASSERT_EQ("OK", MatchError("bad record length"));
}
TEST(LogTest, BadLengthAtEndIsIgnored) {
Write("foo");
ShrinkSize(1);
ASSERT_EQ("EOF", Read());
ASSERT_EQ(0, DroppedBytes());
ASSERT_EQ("", ReportMessage());
}
TEST(LogTest, ChecksumMismatch) {
Write("foo");
IncrementByte(0, 10);
ASSERT_EQ("EOF", Read());
ASSERT_EQ(10, DroppedBytes());
ASSERT_EQ("OK", MatchError("checksum mismatch"));
}
TEST(LogTest, UnexpectedMiddleType) {
Write("foo");
SetByte(6, kMiddleType);
FixChecksum(0, 3);
ASSERT_EQ("EOF", Read());
ASSERT_EQ(3, DroppedBytes());
ASSERT_EQ("OK", MatchError("missing start"));
}
TEST(LogTest, UnexpectedLastType) {
Write("foo");
SetByte(6, kLastType);
FixChecksum(0, 3);
ASSERT_EQ("EOF", Read());
ASSERT_EQ(3, DroppedBytes());
ASSERT_EQ("OK", MatchError("missing start"));
}
TEST(LogTest, UnexpectedFullType) {
Write("foo");
Write("bar");
SetByte(6, kFirstType);
FixChecksum(0, 3);
ASSERT_EQ("bar", Read());
ASSERT_EQ("EOF", Read());
ASSERT_EQ(3, DroppedBytes());
ASSERT_EQ("OK", MatchError("partial record without end"));
}
TEST(LogTest, UnexpectedFirstType) {
Write("foo");
Write(BigString("bar", 100000));
SetByte(6, kFirstType);
FixChecksum(0, 3);
ASSERT_EQ(BigString("bar", 100000), Read());
ASSERT_EQ("EOF", Read());
ASSERT_EQ(3, DroppedBytes());
ASSERT_EQ("OK", MatchError("partial record without end"));
}
TEST(LogTest, MissingLastIsIgnored) {
Write(BigString("bar", kBlockSize));
// Remove the LAST block, including header.
ShrinkSize(14);
ASSERT_EQ("EOF", Read());
ASSERT_EQ("", ReportMessage());
ASSERT_EQ(0, DroppedBytes());
}
TEST(LogTest, PartialLastIsIgnored) {
Write(BigString("bar", kBlockSize));
// Cause a bad record length in the LAST block.
ShrinkSize(1);
ASSERT_EQ("EOF", Read());
ASSERT_EQ("", ReportMessage());
ASSERT_EQ(0, DroppedBytes());
}
TEST(LogTest, SkipIntoMultiRecord) {
// Consider a fragmented record:
// first(R1), middle(R1), last(R1), first(R2)
// If initial_offset points to a record after first(R1) but before first(R2)
// incomplete fragment errors are not actual errors, and must be suppressed
// until a new first or full record is encountered.
Write(BigString("foo", 3*kBlockSize));
Write("correct");
StartReadingAt(kBlockSize);
ASSERT_EQ("correct", Read());
ASSERT_EQ("", ReportMessage());
ASSERT_EQ(0, DroppedBytes());
ASSERT_EQ("EOF", Read());
}
TEST(LogTest, ErrorJoinsRecords) {
// Consider two fragmented records:
// first(R1) last(R1) first(R2) last(R2)
// where the middle two fragments disappear. We do not want
// first(R1),last(R2) to get joined and returned as a valid record.
// Write records that span two blocks
Write(BigString("foo", kBlockSize));
Write(BigString("bar", kBlockSize));
Write("correct");
// Wipe the middle block
for (int offset = kBlockSize; offset < 2*kBlockSize; offset++) {
SetByte(offset, 'x');
}
ASSERT_EQ("correct", Read());
ASSERT_EQ("EOF", Read());
const size_t dropped = DroppedBytes();
ASSERT_LE(dropped, 2*kBlockSize + 100);
ASSERT_GE(dropped, 2*kBlockSize);
}
TEST(LogTest, ReadStart) {
CheckInitialOffsetRecord(0, 0);
}
TEST(LogTest, ReadSecondOneOff) {
CheckInitialOffsetRecord(1, 1);
}
TEST(LogTest, ReadSecondTenThousand) {
CheckInitialOffsetRecord(10000, 1);
}
TEST(LogTest, ReadSecondStart) {
CheckInitialOffsetRecord(10007, 1);
}
TEST(LogTest, ReadThirdOneOff) {
CheckInitialOffsetRecord(10008, 2);
}
TEST(LogTest, ReadThirdStart) {
CheckInitialOffsetRecord(20014, 2);
}
TEST(LogTest, ReadFourthOneOff) {
CheckInitialOffsetRecord(20015, 3);
}
TEST(LogTest, ReadFourthFirstBlockTrailer) {
CheckInitialOffsetRecord(log::kBlockSize - 4, 3);
}
TEST(LogTest, ReadFourthMiddleBlock) {
CheckInitialOffsetRecord(log::kBlockSize + 1, 3);
}
TEST(LogTest, ReadFourthLastBlock) {
CheckInitialOffsetRecord(2 * log::kBlockSize + 1, 3);
}
TEST(LogTest, ReadFourthStart) {
CheckInitialOffsetRecord(
2 * (kHeaderSize + 1000) + (2 * log::kBlockSize - 1000) + 3 * kHeaderSize,
3);
}
TEST(LogTest, ReadInitialOffsetIntoBlockPadding) {
CheckInitialOffsetRecord(3 * log::kBlockSize - 3, 5);
}
TEST(LogTest, ReadEnd) {
CheckOffsetPastEndReturnsNoRecords(0);
}
TEST(LogTest, ReadPastEnd) {
CheckOffsetPastEndReturnsNoRecords(5);
}
} // namespace log
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/log_writer.h"
#include <stdint.h>
#include "leveldb/env.h"
#include "util/coding.h"
#include "util/crc32c.h"
namespace leveldb {
namespace log {
static void InitTypeCrc(uint32_t* type_crc) {
for (int i = 0; i <= kMaxRecordType; i++) {
char t = static_cast<char>(i);
type_crc[i] = crc32c::Value(&t, 1);
}
}
Writer::Writer(WritableFile* dest)
: dest_(dest),
block_offset_(0) {
InitTypeCrc(type_crc_);
}
Writer::Writer(WritableFile* dest, uint64_t dest_length)
: dest_(dest), block_offset_(dest_length % kBlockSize) {
InitTypeCrc(type_crc_);
}
Writer::~Writer() {
}
Status Writer::AddRecord(const Slice& slice) {
const char* ptr = slice.data();
size_t left = slice.size();
// Fragment the record if necessary and emit it. Note that if slice
// is empty, we still want to iterate once to emit a single
// zero-length record
Status s;
bool begin = true;
do {
const int leftover = kBlockSize - block_offset_;
assert(leftover >= 0);
if (leftover < kHeaderSize) {
// Switch to a new block
if (leftover > 0) {
// Fill the trailer (literal below relies on kHeaderSize being 7)
assert(kHeaderSize == 7);
dest_->Append(Slice("\x00\x00\x00\x00\x00\x00", leftover));
}
block_offset_ = 0;
}
// Invariant: we never leave < kHeaderSize bytes in a block.
assert(kBlockSize - block_offset_ - kHeaderSize >= 0);
const size_t avail = kBlockSize - block_offset_ - kHeaderSize;
const size_t fragment_length = (left < avail) ? left : avail;
RecordType type;
const bool end = (left == fragment_length);
if (begin && end) {
type = kFullType;
} else if (begin) {
type = kFirstType;
} else if (end) {
type = kLastType;
} else {
type = kMiddleType;
}
s = EmitPhysicalRecord(type, ptr, fragment_length);
ptr += fragment_length;
left -= fragment_length;
begin = false;
} while (s.ok() && left > 0);
return s;
}
Status Writer::EmitPhysicalRecord(RecordType t, const char* ptr, size_t n) {
assert(n <= 0xffff); // Must fit in two bytes
assert(block_offset_ + kHeaderSize + n <= kBlockSize);
// Format the header
char buf[kHeaderSize];
buf[4] = static_cast<char>(n & 0xff);
buf[5] = static_cast<char>(n >> 8);
buf[6] = static_cast<char>(t);
// Compute the crc of the record type and the payload.
uint32_t crc = crc32c::Extend(type_crc_[t], ptr, n);
crc = crc32c::Mask(crc); // Adjust for storage
EncodeFixed32(buf, crc);
// Write the header and the payload
Status s = dest_->Append(Slice(buf, kHeaderSize));
if (s.ok()) {
s = dest_->Append(Slice(ptr, n));
if (s.ok()) {
s = dest_->Flush();
}
}
block_offset_ += kHeaderSize + n;
return s;
}
} // namespace log
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_LOG_WRITER_H_
#define STORAGE_LEVELDB_DB_LOG_WRITER_H_
#include <stdint.h>
#include "db/log_format.h"
#include "leveldb/slice.h"
#include "leveldb/status.h"
namespace leveldb {
class WritableFile;
namespace log {
class Writer {
public:
// Create a writer that will append data to "*dest".
// "*dest" must be initially empty.
// "*dest" must remain live while this Writer is in use.
explicit Writer(WritableFile* dest);
// Create a writer that will append data to "*dest".
// "*dest" must have initial length "dest_length".
// "*dest" must remain live while this Writer is in use.
Writer(WritableFile* dest, uint64_t dest_length);
~Writer();
Status AddRecord(const Slice& slice);
private:
WritableFile* dest_;
int block_offset_; // Current offset in block
// crc32c values for all supported record types. These are
// pre-computed to reduce the overhead of computing the crc of the
// record type stored in the header.
uint32_t type_crc_[kMaxRecordType + 1];
Status EmitPhysicalRecord(RecordType type, const char* ptr, size_t length);
// No copying allowed
Writer(const Writer&);
void operator=(const Writer&);
};
} // namespace log
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_LOG_WRITER_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/memtable.h"
#include "db/dbformat.h"
#include "leveldb/comparator.h"
#include "leveldb/env.h"
#include "leveldb/iterator.h"
#include "util/coding.h"
namespace leveldb {
static Slice GetLengthPrefixedSlice(const char* data) {
uint32_t len;
const char* p = data;
p = GetVarint32Ptr(p, p + 5, &len); // +5: we assume "p" is not corrupted
return Slice(p, len);
}
MemTable::MemTable(const InternalKeyComparator& cmp)
: comparator_(cmp),
refs_(0),
table_(comparator_, &arena_) {
}
MemTable::~MemTable() {
assert(refs_ == 0);
}
size_t MemTable::ApproximateMemoryUsage() { return arena_.MemoryUsage(); }
int MemTable::KeyComparator::operator()(const char* aptr, const char* bptr)
const {
// Internal keys are encoded as length-prefixed strings.
Slice a = GetLengthPrefixedSlice(aptr);
Slice b = GetLengthPrefixedSlice(bptr);
return comparator.Compare(a, b);
}
// Encode a suitable internal key target for "target" and return it.
// Uses *scratch as scratch space, and the returned pointer will point
// into this scratch space.
static const char* EncodeKey(std::string* scratch, const Slice& target) {
scratch->clear();
PutVarint32(scratch, target.size());
scratch->append(target.data(), target.size());
return scratch->data();
}
class MemTableIterator: public Iterator {
public:
explicit MemTableIterator(MemTable::Table* table) : iter_(table) { }
virtual bool Valid() const { return iter_.Valid(); }
virtual void Seek(const Slice& k) { iter_.Seek(EncodeKey(&tmp_, k)); }
virtual void SeekToFirst() { iter_.SeekToFirst(); }
virtual void SeekToLast() { iter_.SeekToLast(); }
virtual void Next() { iter_.Next(); }
virtual void Prev() { iter_.Prev(); }
virtual Slice key() const { return GetLengthPrefixedSlice(iter_.key()); }
virtual Slice value() const {
Slice key_slice = GetLengthPrefixedSlice(iter_.key());
return GetLengthPrefixedSlice(key_slice.data() + key_slice.size());
}
virtual Status status() const { return Status::OK(); }
private:
MemTable::Table::Iterator iter_;
std::string tmp_; // For passing to EncodeKey
// No copying allowed
MemTableIterator(const MemTableIterator&);
void operator=(const MemTableIterator&);
};
Iterator* MemTable::NewIterator() {
return new MemTableIterator(&table_);
}
void MemTable::Add(SequenceNumber s, ValueType type,
const Slice& key,
const Slice& value) {
// Format of an entry is concatenation of:
// key_size : varint32 of internal_key.size()
// key bytes : char[internal_key.size()]
// value_size : varint32 of value.size()
// value bytes : char[value.size()]
size_t key_size = key.size();
size_t val_size = value.size();
size_t internal_key_size = key_size + 8;
const size_t encoded_len =
VarintLength(internal_key_size) + internal_key_size +
VarintLength(val_size) + val_size;
char* buf = arena_.Allocate(encoded_len);
char* p = EncodeVarint32(buf, internal_key_size);
memcpy(p, key.data(), key_size);
p += key_size;
EncodeFixed64(p, (s << 8) | type);
p += 8;
p = EncodeVarint32(p, val_size);
memcpy(p, value.data(), val_size);
assert((p + val_size) - buf == encoded_len);
table_.Insert(buf);
}
bool MemTable::Get(const LookupKey& key, std::string* value, Status* s) {
Slice memkey = key.memtable_key();
Table::Iterator iter(&table_);
iter.Seek(memkey.data());
if (iter.Valid()) {
// entry format is:
// klength varint32
// userkey char[klength]
// tag uint64
// vlength varint32
// value char[vlength]
// Check that it belongs to same user key. We do not check the
// sequence number since the Seek() call above should have skipped
// all entries with overly large sequence numbers.
const char* entry = iter.key();
uint32_t key_length;
const char* key_ptr = GetVarint32Ptr(entry, entry+5, &key_length);
if (comparator_.comparator.user_comparator()->Compare(
Slice(key_ptr, key_length - 8),
key.user_key()) == 0) {
// Correct user key
const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
switch (static_cast<ValueType>(tag & 0xff)) {
case kTypeValue: {
Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
value->assign(v.data(), v.size());
return true;
}
case kTypeDeletion:
*s = Status::NotFound(Slice());
return true;
}
}
}
return false;
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_MEMTABLE_H_
#define STORAGE_LEVELDB_DB_MEMTABLE_H_
#include <string>
#include "leveldb/db.h"
#include "db/dbformat.h"
#include "db/skiplist.h"
#include "util/arena.h"
namespace leveldb {
class InternalKeyComparator;
class Mutex;
class MemTableIterator;
class MemTable {
public:
// MemTables are reference counted. The initial reference count
// is zero and the caller must call Ref() at least once.
explicit MemTable(const InternalKeyComparator& comparator);
// Increase reference count.
void Ref() { ++refs_; }
// Drop reference count. Delete if no more references exist.
void Unref() {
--refs_;
assert(refs_ >= 0);
if (refs_ <= 0) {
delete this;
}
}
// Returns an estimate of the number of bytes of data in use by this
// data structure. It is safe to call when MemTable is being modified.
size_t ApproximateMemoryUsage();
// Return an iterator that yields the contents of the memtable.
//
// The caller must ensure that the underlying MemTable remains live
// while the returned iterator is live. The keys returned by this
// iterator are internal keys encoded by AppendInternalKey in the
// db/format.{h,cc} module.
Iterator* NewIterator();
// Add an entry into memtable that maps key to value at the
// specified sequence number and with the specified type.
// Typically value will be empty if type==kTypeDeletion.
void Add(SequenceNumber seq, ValueType type,
const Slice& key,
const Slice& value);
// If memtable contains a value for key, store it in *value and return true.
// If memtable contains a deletion for key, store a NotFound() error
// in *status and return true.
// Else, return false.
bool Get(const LookupKey& key, std::string* value, Status* s);
private:
~MemTable(); // Private since only Unref() should be used to delete it
struct KeyComparator {
const InternalKeyComparator comparator;
explicit KeyComparator(const InternalKeyComparator& c) : comparator(c) { }
int operator()(const char* a, const char* b) const;
};
friend class MemTableIterator;
friend class MemTableBackwardIterator;
typedef SkipList<const char*, KeyComparator> Table;
KeyComparator comparator_;
int refs_;
Arena arena_;
Table table_;
// No copying allowed
MemTable(const MemTable&);
void operator=(const MemTable&);
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_MEMTABLE_H_

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// Copyright (c) 2014 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/db_impl.h"
#include "db/filename.h"
#include "db/version_set.h"
#include "db/write_batch_internal.h"
#include "leveldb/db.h"
#include "leveldb/env.h"
#include "leveldb/write_batch.h"
#include "util/logging.h"
#include "util/testharness.h"
#include "util/testutil.h"
namespace leveldb {
class RecoveryTest {
public:
RecoveryTest() : env_(Env::Default()), db_(NULL) {
dbname_ = test::TmpDir() + "/recovery_test";
DestroyDB(dbname_, Options());
Open();
}
~RecoveryTest() {
Close();
DestroyDB(dbname_, Options());
}
DBImpl* dbfull() const { return reinterpret_cast<DBImpl*>(db_); }
Env* env() const { return env_; }
bool CanAppend() {
WritableFile* tmp;
Status s = env_->NewAppendableFile(CurrentFileName(dbname_), &tmp);
delete tmp;
if (s.IsNotSupportedError()) {
return false;
} else {
return true;
}
}
void Close() {
delete db_;
db_ = NULL;
}
void Open(Options* options = NULL) {
Close();
Options opts;
if (options != NULL) {
opts = *options;
} else {
opts.reuse_logs = true; // TODO(sanjay): test both ways
opts.create_if_missing = true;
}
if (opts.env == NULL) {
opts.env = env_;
}
ASSERT_OK(DB::Open(opts, dbname_, &db_));
ASSERT_EQ(1, NumLogs());
}
Status Put(const std::string& k, const std::string& v) {
return db_->Put(WriteOptions(), k, v);
}
std::string Get(const std::string& k, const Snapshot* snapshot = NULL) {
std::string result;
Status s = db_->Get(ReadOptions(), k, &result);
if (s.IsNotFound()) {
result = "NOT_FOUND";
} else if (!s.ok()) {
result = s.ToString();
}
return result;
}
std::string ManifestFileName() {
std::string current;
ASSERT_OK(ReadFileToString(env_, CurrentFileName(dbname_), &current));
size_t len = current.size();
if (len > 0 && current[len-1] == '\n') {
current.resize(len - 1);
}
return dbname_ + "/" + current;
}
std::string LogName(uint64_t number) {
return LogFileName(dbname_, number);
}
size_t DeleteLogFiles() {
std::vector<uint64_t> logs = GetFiles(kLogFile);
for (size_t i = 0; i < logs.size(); i++) {
ASSERT_OK(env_->DeleteFile(LogName(logs[i]))) << LogName(logs[i]);
}
return logs.size();
}
uint64_t FirstLogFile() {
return GetFiles(kLogFile)[0];
}
std::vector<uint64_t> GetFiles(FileType t) {
std::vector<std::string> filenames;
ASSERT_OK(env_->GetChildren(dbname_, &filenames));
std::vector<uint64_t> result;
for (size_t i = 0; i < filenames.size(); i++) {
uint64_t number;
FileType type;
if (ParseFileName(filenames[i], &number, &type) && type == t) {
result.push_back(number);
}
}
return result;
}
int NumLogs() {
return GetFiles(kLogFile).size();
}
int NumTables() {
return GetFiles(kTableFile).size();
}
uint64_t FileSize(const std::string& fname) {
uint64_t result;
ASSERT_OK(env_->GetFileSize(fname, &result)) << fname;
return result;
}
void CompactMemTable() {
dbfull()->TEST_CompactMemTable();
}
// Directly construct a log file that sets key to val.
void MakeLogFile(uint64_t lognum, SequenceNumber seq, Slice key, Slice val) {
std::string fname = LogFileName(dbname_, lognum);
WritableFile* file;
ASSERT_OK(env_->NewWritableFile(fname, &file));
log::Writer writer(file);
WriteBatch batch;
batch.Put(key, val);
WriteBatchInternal::SetSequence(&batch, seq);
ASSERT_OK(writer.AddRecord(WriteBatchInternal::Contents(&batch)));
ASSERT_OK(file->Flush());
delete file;
}
private:
std::string dbname_;
Env* env_;
DB* db_;
};
TEST(RecoveryTest, ManifestReused) {
if (!CanAppend()) {
fprintf(stderr, "skipping test because env does not support appending\n");
return;
}
ASSERT_OK(Put("foo", "bar"));
Close();
std::string old_manifest = ManifestFileName();
Open();
ASSERT_EQ(old_manifest, ManifestFileName());
ASSERT_EQ("bar", Get("foo"));
Open();
ASSERT_EQ(old_manifest, ManifestFileName());
ASSERT_EQ("bar", Get("foo"));
}
TEST(RecoveryTest, LargeManifestCompacted) {
if (!CanAppend()) {
fprintf(stderr, "skipping test because env does not support appending\n");
return;
}
ASSERT_OK(Put("foo", "bar"));
Close();
std::string old_manifest = ManifestFileName();
// Pad with zeroes to make manifest file very big.
{
uint64_t len = FileSize(old_manifest);
WritableFile* file;
ASSERT_OK(env()->NewAppendableFile(old_manifest, &file));
std::string zeroes(3*1048576 - static_cast<size_t>(len), 0);
ASSERT_OK(file->Append(zeroes));
ASSERT_OK(file->Flush());
delete file;
}
Open();
std::string new_manifest = ManifestFileName();
ASSERT_NE(old_manifest, new_manifest);
ASSERT_GT(10000, FileSize(new_manifest));
ASSERT_EQ("bar", Get("foo"));
Open();
ASSERT_EQ(new_manifest, ManifestFileName());
ASSERT_EQ("bar", Get("foo"));
}
TEST(RecoveryTest, NoLogFiles) {
ASSERT_OK(Put("foo", "bar"));
ASSERT_EQ(1, DeleteLogFiles());
Open();
ASSERT_EQ("NOT_FOUND", Get("foo"));
Open();
ASSERT_EQ("NOT_FOUND", Get("foo"));
}
TEST(RecoveryTest, LogFileReuse) {
if (!CanAppend()) {
fprintf(stderr, "skipping test because env does not support appending\n");
return;
}
for (int i = 0; i < 2; i++) {
ASSERT_OK(Put("foo", "bar"));
if (i == 0) {
// Compact to ensure current log is empty
CompactMemTable();
}
Close();
ASSERT_EQ(1, NumLogs());
uint64_t number = FirstLogFile();
if (i == 0) {
ASSERT_EQ(0, FileSize(LogName(number)));
} else {
ASSERT_LT(0, FileSize(LogName(number)));
}
Open();
ASSERT_EQ(1, NumLogs());
ASSERT_EQ(number, FirstLogFile()) << "did not reuse log file";
ASSERT_EQ("bar", Get("foo"));
Open();
ASSERT_EQ(1, NumLogs());
ASSERT_EQ(number, FirstLogFile()) << "did not reuse log file";
ASSERT_EQ("bar", Get("foo"));
}
}
TEST(RecoveryTest, MultipleMemTables) {
// Make a large log.
const int kNum = 1000;
for (int i = 0; i < kNum; i++) {
char buf[100];
snprintf(buf, sizeof(buf), "%050d", i);
ASSERT_OK(Put(buf, buf));
}
ASSERT_EQ(0, NumTables());
Close();
ASSERT_EQ(0, NumTables());
ASSERT_EQ(1, NumLogs());
uint64_t old_log_file = FirstLogFile();
// Force creation of multiple memtables by reducing the write buffer size.
Options opt;
opt.reuse_logs = true;
opt.write_buffer_size = (kNum*100) / 2;
Open(&opt);
ASSERT_LE(2, NumTables());
ASSERT_EQ(1, NumLogs());
ASSERT_NE(old_log_file, FirstLogFile()) << "must not reuse log";
for (int i = 0; i < kNum; i++) {
char buf[100];
snprintf(buf, sizeof(buf), "%050d", i);
ASSERT_EQ(buf, Get(buf));
}
}
TEST(RecoveryTest, MultipleLogFiles) {
ASSERT_OK(Put("foo", "bar"));
Close();
ASSERT_EQ(1, NumLogs());
// Make a bunch of uncompacted log files.
uint64_t old_log = FirstLogFile();
MakeLogFile(old_log+1, 1000, "hello", "world");
MakeLogFile(old_log+2, 1001, "hi", "there");
MakeLogFile(old_log+3, 1002, "foo", "bar2");
// Recover and check that all log files were processed.
Open();
ASSERT_LE(1, NumTables());
ASSERT_EQ(1, NumLogs());
uint64_t new_log = FirstLogFile();
ASSERT_LE(old_log+3, new_log);
ASSERT_EQ("bar2", Get("foo"));
ASSERT_EQ("world", Get("hello"));
ASSERT_EQ("there", Get("hi"));
// Test that previous recovery produced recoverable state.
Open();
ASSERT_LE(1, NumTables());
ASSERT_EQ(1, NumLogs());
if (CanAppend()) {
ASSERT_EQ(new_log, FirstLogFile());
}
ASSERT_EQ("bar2", Get("foo"));
ASSERT_EQ("world", Get("hello"));
ASSERT_EQ("there", Get("hi"));
// Check that introducing an older log file does not cause it to be re-read.
Close();
MakeLogFile(old_log+1, 2000, "hello", "stale write");
Open();
ASSERT_LE(1, NumTables());
ASSERT_EQ(1, NumLogs());
if (CanAppend()) {
ASSERT_EQ(new_log, FirstLogFile());
}
ASSERT_EQ("bar2", Get("foo"));
ASSERT_EQ("world", Get("hello"));
ASSERT_EQ("there", Get("hi"));
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// We recover the contents of the descriptor from the other files we find.
// (1) Any log files are first converted to tables
// (2) We scan every table to compute
// (a) smallest/largest for the table
// (b) largest sequence number in the table
// (3) We generate descriptor contents:
// - log number is set to zero
// - next-file-number is set to 1 + largest file number we found
// - last-sequence-number is set to largest sequence# found across
// all tables (see 2c)
// - compaction pointers are cleared
// - every table file is added at level 0
//
// Possible optimization 1:
// (a) Compute total size and use to pick appropriate max-level M
// (b) Sort tables by largest sequence# in the table
// (c) For each table: if it overlaps earlier table, place in level-0,
// else place in level-M.
// Possible optimization 2:
// Store per-table metadata (smallest, largest, largest-seq#, ...)
// in the table's meta section to speed up ScanTable.
#include "db/builder.h"
#include "db/db_impl.h"
#include "db/dbformat.h"
#include "db/filename.h"
#include "db/log_reader.h"
#include "db/log_writer.h"
#include "db/memtable.h"
#include "db/table_cache.h"
#include "db/version_edit.h"
#include "db/write_batch_internal.h"
#include "leveldb/comparator.h"
#include "leveldb/db.h"
#include "leveldb/env.h"
namespace leveldb {
namespace {
class Repairer {
public:
Repairer(const std::string& dbname, const Options& options)
: dbname_(dbname),
env_(options.env),
icmp_(options.comparator),
ipolicy_(options.filter_policy),
options_(SanitizeOptions(dbname, &icmp_, &ipolicy_, options)),
owns_info_log_(options_.info_log != options.info_log),
owns_cache_(options_.block_cache != options.block_cache),
next_file_number_(1) {
// TableCache can be small since we expect each table to be opened once.
table_cache_ = new TableCache(dbname_, &options_, 10);
}
~Repairer() {
delete table_cache_;
if (owns_info_log_) {
delete options_.info_log;
}
if (owns_cache_) {
delete options_.block_cache;
}
}
Status Run() {
Status status = FindFiles();
if (status.ok()) {
ConvertLogFilesToTables();
ExtractMetaData();
status = WriteDescriptor();
}
if (status.ok()) {
unsigned long long bytes = 0;
for (size_t i = 0; i < tables_.size(); i++) {
bytes += tables_[i].meta.file_size;
}
Log(options_.info_log,
"**** Repaired leveldb %s; "
"recovered %d files; %llu bytes. "
"Some data may have been lost. "
"****",
dbname_.c_str(),
static_cast<int>(tables_.size()),
bytes);
}
return status;
}
private:
struct TableInfo {
FileMetaData meta;
SequenceNumber max_sequence;
};
std::string const dbname_;
Env* const env_;
InternalKeyComparator const icmp_;
InternalFilterPolicy const ipolicy_;
Options const options_;
bool owns_info_log_;
bool owns_cache_;
TableCache* table_cache_;
VersionEdit edit_;
std::vector<std::string> manifests_;
std::vector<uint64_t> table_numbers_;
std::vector<uint64_t> logs_;
std::vector<TableInfo> tables_;
uint64_t next_file_number_;
Status FindFiles() {
std::vector<std::string> filenames;
Status status = env_->GetChildren(dbname_, &filenames);
if (!status.ok()) {
return status;
}
if (filenames.empty()) {
return Status::IOError(dbname_, "repair found no files");
}
uint64_t number;
FileType type;
for (size_t i = 0; i < filenames.size(); i++) {
if (ParseFileName(filenames[i], &number, &type)) {
if (type == kDescriptorFile) {
manifests_.push_back(filenames[i]);
} else {
if (number + 1 > next_file_number_) {
next_file_number_ = number + 1;
}
if (type == kLogFile) {
logs_.push_back(number);
} else if (type == kTableFile) {
table_numbers_.push_back(number);
} else {
// Ignore other files
}
}
}
}
return status;
}
void ConvertLogFilesToTables() {
for (size_t i = 0; i < logs_.size(); i++) {
std::string logname = LogFileName(dbname_, logs_[i]);
Status status = ConvertLogToTable(logs_[i]);
if (!status.ok()) {
Log(options_.info_log, "Log #%llu: ignoring conversion error: %s",
(unsigned long long) logs_[i],
status.ToString().c_str());
}
ArchiveFile(logname);
}
}
Status ConvertLogToTable(uint64_t log) {
struct LogReporter : public log::Reader::Reporter {
Env* env;
Logger* info_log;
uint64_t lognum;
virtual void Corruption(size_t bytes, const Status& s) {
// We print error messages for corruption, but continue repairing.
Log(info_log, "Log #%llu: dropping %d bytes; %s",
(unsigned long long) lognum,
static_cast<int>(bytes),
s.ToString().c_str());
}
};
// Open the log file
std::string logname = LogFileName(dbname_, log);
SequentialFile* lfile;
Status status = env_->NewSequentialFile(logname, &lfile);
if (!status.ok()) {
return status;
}
// Create the log reader.
LogReporter reporter;
reporter.env = env_;
reporter.info_log = options_.info_log;
reporter.lognum = log;
// We intentionally make log::Reader do checksumming so that
// corruptions cause entire commits to be skipped instead of
// propagating bad information (like overly large sequence
// numbers).
log::Reader reader(lfile, &reporter, false/*do not checksum*/,
0/*initial_offset*/);
// Read all the records and add to a memtable
std::string scratch;
Slice record;
WriteBatch batch;
MemTable* mem = new MemTable(icmp_);
mem->Ref();
int counter = 0;
while (reader.ReadRecord(&record, &scratch)) {
if (record.size() < 12) {
reporter.Corruption(
record.size(), Status::Corruption("log record too small"));
continue;
}
WriteBatchInternal::SetContents(&batch, record);
status = WriteBatchInternal::InsertInto(&batch, mem);
if (status.ok()) {
counter += WriteBatchInternal::Count(&batch);
} else {
Log(options_.info_log, "Log #%llu: ignoring %s",
(unsigned long long) log,
status.ToString().c_str());
status = Status::OK(); // Keep going with rest of file
}
}
delete lfile;
// Do not record a version edit for this conversion to a Table
// since ExtractMetaData() will also generate edits.
FileMetaData meta;
meta.number = next_file_number_++;
Iterator* iter = mem->NewIterator();
status = BuildTable(dbname_, env_, options_, table_cache_, iter, &meta);
delete iter;
mem->Unref();
mem = NULL;
if (status.ok()) {
if (meta.file_size > 0) {
table_numbers_.push_back(meta.number);
}
}
Log(options_.info_log, "Log #%llu: %d ops saved to Table #%llu %s",
(unsigned long long) log,
counter,
(unsigned long long) meta.number,
status.ToString().c_str());
return status;
}
void ExtractMetaData() {
for (size_t i = 0; i < table_numbers_.size(); i++) {
ScanTable(table_numbers_[i]);
}
}
Iterator* NewTableIterator(const FileMetaData& meta) {
// Same as compaction iterators: if paranoid_checks are on, turn
// on checksum verification.
ReadOptions r;
r.verify_checksums = options_.paranoid_checks;
return table_cache_->NewIterator(r, meta.number, meta.file_size);
}
void ScanTable(uint64_t number) {
TableInfo t;
t.meta.number = number;
std::string fname = TableFileName(dbname_, number);
Status status = env_->GetFileSize(fname, &t.meta.file_size);
if (!status.ok()) {
// Try alternate file name.
fname = SSTTableFileName(dbname_, number);
Status s2 = env_->GetFileSize(fname, &t.meta.file_size);
if (s2.ok()) {
status = Status::OK();
}
}
if (!status.ok()) {
ArchiveFile(TableFileName(dbname_, number));
ArchiveFile(SSTTableFileName(dbname_, number));
Log(options_.info_log, "Table #%llu: dropped: %s",
(unsigned long long) t.meta.number,
status.ToString().c_str());
return;
}
// Extract metadata by scanning through table.
int counter = 0;
Iterator* iter = NewTableIterator(t.meta);
bool empty = true;
ParsedInternalKey parsed;
t.max_sequence = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
Slice key = iter->key();
if (!ParseInternalKey(key, &parsed)) {
Log(options_.info_log, "Table #%llu: unparsable key %s",
(unsigned long long) t.meta.number,
EscapeString(key).c_str());
continue;
}
counter++;
if (empty) {
empty = false;
t.meta.smallest.DecodeFrom(key);
}
t.meta.largest.DecodeFrom(key);
if (parsed.sequence > t.max_sequence) {
t.max_sequence = parsed.sequence;
}
}
if (!iter->status().ok()) {
status = iter->status();
}
delete iter;
Log(options_.info_log, "Table #%llu: %d entries %s",
(unsigned long long) t.meta.number,
counter,
status.ToString().c_str());
if (status.ok()) {
tables_.push_back(t);
} else {
RepairTable(fname, t); // RepairTable archives input file.
}
}
void RepairTable(const std::string& src, TableInfo t) {
// We will copy src contents to a new table and then rename the
// new table over the source.
// Create builder.
std::string copy = TableFileName(dbname_, next_file_number_++);
WritableFile* file;
Status s = env_->NewWritableFile(copy, &file);
if (!s.ok()) {
return;
}
TableBuilder* builder = new TableBuilder(options_, file);
// Copy data.
Iterator* iter = NewTableIterator(t.meta);
int counter = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
builder->Add(iter->key(), iter->value());
counter++;
}
delete iter;
ArchiveFile(src);
if (counter == 0) {
builder->Abandon(); // Nothing to save
} else {
s = builder->Finish();
if (s.ok()) {
t.meta.file_size = builder->FileSize();
}
}
delete builder;
builder = NULL;
if (s.ok()) {
s = file->Close();
}
delete file;
file = NULL;
if (counter > 0 && s.ok()) {
std::string orig = TableFileName(dbname_, t.meta.number);
s = env_->RenameFile(copy, orig);
if (s.ok()) {
Log(options_.info_log, "Table #%llu: %d entries repaired",
(unsigned long long) t.meta.number, counter);
tables_.push_back(t);
}
}
if (!s.ok()) {
env_->DeleteFile(copy);
}
}
Status WriteDescriptor() {
std::string tmp = TempFileName(dbname_, 1);
WritableFile* file;
Status status = env_->NewWritableFile(tmp, &file);
if (!status.ok()) {
return status;
}
SequenceNumber max_sequence = 0;
for (size_t i = 0; i < tables_.size(); i++) {
if (max_sequence < tables_[i].max_sequence) {
max_sequence = tables_[i].max_sequence;
}
}
edit_.SetComparatorName(icmp_.user_comparator()->Name());
edit_.SetLogNumber(0);
edit_.SetNextFile(next_file_number_);
edit_.SetLastSequence(max_sequence);
for (size_t i = 0; i < tables_.size(); i++) {
// TODO(opt): separate out into multiple levels
const TableInfo& t = tables_[i];
edit_.AddFile(0, t.meta.number, t.meta.file_size,
t.meta.smallest, t.meta.largest);
}
//fprintf(stderr, "NewDescriptor:\n%s\n", edit_.DebugString().c_str());
{
log::Writer log(file);
std::string record;
edit_.EncodeTo(&record);
status = log.AddRecord(record);
}
if (status.ok()) {
status = file->Close();
}
delete file;
file = NULL;
if (!status.ok()) {
env_->DeleteFile(tmp);
} else {
// Discard older manifests
for (size_t i = 0; i < manifests_.size(); i++) {
ArchiveFile(dbname_ + "/" + manifests_[i]);
}
// Install new manifest
status = env_->RenameFile(tmp, DescriptorFileName(dbname_, 1));
if (status.ok()) {
status = SetCurrentFile(env_, dbname_, 1);
} else {
env_->DeleteFile(tmp);
}
}
return status;
}
void ArchiveFile(const std::string& fname) {
// Move into another directory. E.g., for
// dir/foo
// rename to
// dir/lost/foo
const char* slash = strrchr(fname.c_str(), '/');
std::string new_dir;
if (slash != NULL) {
new_dir.assign(fname.data(), slash - fname.data());
}
new_dir.append("/lost");
env_->CreateDir(new_dir); // Ignore error
std::string new_file = new_dir;
new_file.append("/");
new_file.append((slash == NULL) ? fname.c_str() : slash + 1);
Status s = env_->RenameFile(fname, new_file);
Log(options_.info_log, "Archiving %s: %s\n",
fname.c_str(), s.ToString().c_str());
}
};
} // namespace
Status RepairDB(const std::string& dbname, const Options& options) {
Repairer repairer(dbname, options);
return repairer.Run();
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_SKIPLIST_H_
#define STORAGE_LEVELDB_DB_SKIPLIST_H_
// Thread safety
// -------------
//
// Writes require external synchronization, most likely a mutex.
// Reads require a guarantee that the SkipList will not be destroyed
// while the read is in progress. Apart from that, reads progress
// without any internal locking or synchronization.
//
// Invariants:
//
// (1) Allocated nodes are never deleted until the SkipList is
// destroyed. This is trivially guaranteed by the code since we
// never delete any skip list nodes.
//
// (2) The contents of a Node except for the next/prev pointers are
// immutable after the Node has been linked into the SkipList.
// Only Insert() modifies the list, and it is careful to initialize
// a node and use release-stores to publish the nodes in one or
// more lists.
//
// ... prev vs. next pointer ordering ...
#include <assert.h>
#include <stdlib.h>
#include "port/port.h"
#include "util/arena.h"
#include "util/random.h"
namespace leveldb {
class Arena;
template<typename Key, class Comparator>
class SkipList {
private:
struct Node;
public:
// Create a new SkipList object that will use "cmp" for comparing keys,
// and will allocate memory using "*arena". Objects allocated in the arena
// must remain allocated for the lifetime of the skiplist object.
explicit SkipList(Comparator cmp, Arena* arena);
// Insert key into the list.
// REQUIRES: nothing that compares equal to key is currently in the list.
void Insert(const Key& key);
// Returns true iff an entry that compares equal to key is in the list.
bool Contains(const Key& key) const;
// Iteration over the contents of a skip list
class Iterator {
public:
// Initialize an iterator over the specified list.
// The returned iterator is not valid.
explicit Iterator(const SkipList* list);
// Returns true iff the iterator is positioned at a valid node.
bool Valid() const;
// Returns the key at the current position.
// REQUIRES: Valid()
const Key& key() const;
// Advances to the next position.
// REQUIRES: Valid()
void Next();
// Advances to the previous position.
// REQUIRES: Valid()
void Prev();
// Advance to the first entry with a key >= target
void Seek(const Key& target);
// Position at the first entry in list.
// Final state of iterator is Valid() iff list is not empty.
void SeekToFirst();
// Position at the last entry in list.
// Final state of iterator is Valid() iff list is not empty.
void SeekToLast();
private:
const SkipList* list_;
Node* node_;
// Intentionally copyable
};
private:
enum { kMaxHeight = 12 };
// Immutable after construction
Comparator const compare_;
Arena* const arena_; // Arena used for allocations of nodes
Node* const head_;
// Modified only by Insert(). Read racily by readers, but stale
// values are ok.
port::AtomicPointer max_height_; // Height of the entire list
inline int GetMaxHeight() const {
return static_cast<int>(
reinterpret_cast<intptr_t>(max_height_.NoBarrier_Load()));
}
// Read/written only by Insert().
Random rnd_;
Node* NewNode(const Key& key, int height);
int RandomHeight();
bool Equal(const Key& a, const Key& b) const { return (compare_(a, b) == 0); }
// Return true if key is greater than the data stored in "n"
bool KeyIsAfterNode(const Key& key, Node* n) const;
// Return the earliest node that comes at or after key.
// Return NULL if there is no such node.
//
// If prev is non-NULL, fills prev[level] with pointer to previous
// node at "level" for every level in [0..max_height_-1].
Node* FindGreaterOrEqual(const Key& key, Node** prev) const;
// Return the latest node with a key < key.
// Return head_ if there is no such node.
Node* FindLessThan(const Key& key) const;
// Return the last node in the list.
// Return head_ if list is empty.
Node* FindLast() const;
// No copying allowed
SkipList(const SkipList&);
void operator=(const SkipList&);
};
// Implementation details follow
template<typename Key, class Comparator>
struct SkipList<Key,Comparator>::Node {
explicit Node(const Key& k) : key(k) { }
Key const key;
// Accessors/mutators for links. Wrapped in methods so we can
// add the appropriate barriers as necessary.
Node* Next(int n) {
assert(n >= 0);
// Use an 'acquire load' so that we observe a fully initialized
// version of the returned Node.
return reinterpret_cast<Node*>(next_[n].Acquire_Load());
}
void SetNext(int n, Node* x) {
assert(n >= 0);
// Use a 'release store' so that anybody who reads through this
// pointer observes a fully initialized version of the inserted node.
next_[n].Release_Store(x);
}
// No-barrier variants that can be safely used in a few locations.
Node* NoBarrier_Next(int n) {
assert(n >= 0);
return reinterpret_cast<Node*>(next_[n].NoBarrier_Load());
}
void NoBarrier_SetNext(int n, Node* x) {
assert(n >= 0);
next_[n].NoBarrier_Store(x);
}
private:
// Array of length equal to the node height. next_[0] is lowest level link.
port::AtomicPointer next_[1];
};
template<typename Key, class Comparator>
typename SkipList<Key,Comparator>::Node*
SkipList<Key,Comparator>::NewNode(const Key& key, int height) {
char* mem = arena_->AllocateAligned(
sizeof(Node) + sizeof(port::AtomicPointer) * (height - 1));
return new (mem) Node(key);
}
template<typename Key, class Comparator>
inline SkipList<Key,Comparator>::Iterator::Iterator(const SkipList* list) {
list_ = list;
node_ = NULL;
}
template<typename Key, class Comparator>
inline bool SkipList<Key,Comparator>::Iterator::Valid() const {
return node_ != NULL;
}
template<typename Key, class Comparator>
inline const Key& SkipList<Key,Comparator>::Iterator::key() const {
assert(Valid());
return node_->key;
}
template<typename Key, class Comparator>
inline void SkipList<Key,Comparator>::Iterator::Next() {
assert(Valid());
node_ = node_->Next(0);
}
template<typename Key, class Comparator>
inline void SkipList<Key,Comparator>::Iterator::Prev() {
// Instead of using explicit "prev" links, we just search for the
// last node that falls before key.
assert(Valid());
node_ = list_->FindLessThan(node_->key);
if (node_ == list_->head_) {
node_ = NULL;
}
}
template<typename Key, class Comparator>
inline void SkipList<Key,Comparator>::Iterator::Seek(const Key& target) {
node_ = list_->FindGreaterOrEqual(target, NULL);
}
template<typename Key, class Comparator>
inline void SkipList<Key,Comparator>::Iterator::SeekToFirst() {
node_ = list_->head_->Next(0);
}
template<typename Key, class Comparator>
inline void SkipList<Key,Comparator>::Iterator::SeekToLast() {
node_ = list_->FindLast();
if (node_ == list_->head_) {
node_ = NULL;
}
}
template<typename Key, class Comparator>
int SkipList<Key,Comparator>::RandomHeight() {
// Increase height with probability 1 in kBranching
static const unsigned int kBranching = 4;
int height = 1;
while (height < kMaxHeight && ((rnd_.Next() % kBranching) == 0)) {
height++;
}
assert(height > 0);
assert(height <= kMaxHeight);
return height;
}
template<typename Key, class Comparator>
bool SkipList<Key,Comparator>::KeyIsAfterNode(const Key& key, Node* n) const {
// NULL n is considered infinite
return (n != NULL) && (compare_(n->key, key) < 0);
}
template<typename Key, class Comparator>
typename SkipList<Key,Comparator>::Node* SkipList<Key,Comparator>::FindGreaterOrEqual(const Key& key, Node** prev)
const {
Node* x = head_;
int level = GetMaxHeight() - 1;
while (true) {
Node* next = x->Next(level);
if (KeyIsAfterNode(key, next)) {
// Keep searching in this list
x = next;
} else {
if (prev != NULL) prev[level] = x;
if (level == 0) {
return next;
} else {
// Switch to next list
level--;
}
}
}
}
template<typename Key, class Comparator>
typename SkipList<Key,Comparator>::Node*
SkipList<Key,Comparator>::FindLessThan(const Key& key) const {
Node* x = head_;
int level = GetMaxHeight() - 1;
while (true) {
assert(x == head_ || compare_(x->key, key) < 0);
Node* next = x->Next(level);
if (next == NULL || compare_(next->key, key) >= 0) {
if (level == 0) {
return x;
} else {
// Switch to next list
level--;
}
} else {
x = next;
}
}
}
template<typename Key, class Comparator>
typename SkipList<Key,Comparator>::Node* SkipList<Key,Comparator>::FindLast()
const {
Node* x = head_;
int level = GetMaxHeight() - 1;
while (true) {
Node* next = x->Next(level);
if (next == NULL) {
if (level == 0) {
return x;
} else {
// Switch to next list
level--;
}
} else {
x = next;
}
}
}
template<typename Key, class Comparator>
SkipList<Key,Comparator>::SkipList(Comparator cmp, Arena* arena)
: compare_(cmp),
arena_(arena),
head_(NewNode(0 /* any key will do */, kMaxHeight)),
max_height_(reinterpret_cast<void*>(1)),
rnd_(0xdeadbeef) {
for (int i = 0; i < kMaxHeight; i++) {
head_->SetNext(i, NULL);
}
}
template<typename Key, class Comparator>
void SkipList<Key,Comparator>::Insert(const Key& key) {
// TODO(opt): We can use a barrier-free variant of FindGreaterOrEqual()
// here since Insert() is externally synchronized.
Node* prev[kMaxHeight];
Node* x = FindGreaterOrEqual(key, prev);
// Our data structure does not allow duplicate insertion
assert(x == NULL || !Equal(key, x->key));
int height = RandomHeight();
if (height > GetMaxHeight()) {
for (int i = GetMaxHeight(); i < height; i++) {
prev[i] = head_;
}
//fprintf(stderr, "Change height from %d to %d\n", max_height_, height);
// It is ok to mutate max_height_ without any synchronization
// with concurrent readers. A concurrent reader that observes
// the new value of max_height_ will see either the old value of
// new level pointers from head_ (NULL), or a new value set in
// the loop below. In the former case the reader will
// immediately drop to the next level since NULL sorts after all
// keys. In the latter case the reader will use the new node.
max_height_.NoBarrier_Store(reinterpret_cast<void*>(height));
}
x = NewNode(key, height);
for (int i = 0; i < height; i++) {
// NoBarrier_SetNext() suffices since we will add a barrier when
// we publish a pointer to "x" in prev[i].
x->NoBarrier_SetNext(i, prev[i]->NoBarrier_Next(i));
prev[i]->SetNext(i, x);
}
}
template<typename Key, class Comparator>
bool SkipList<Key,Comparator>::Contains(const Key& key) const {
Node* x = FindGreaterOrEqual(key, NULL);
if (x != NULL && Equal(key, x->key)) {
return true;
} else {
return false;
}
}
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_SKIPLIST_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/skiplist.h"
#include <set>
#include "leveldb/env.h"
#include "util/arena.h"
#include "util/hash.h"
#include "util/random.h"
#include "util/testharness.h"
namespace leveldb {
typedef uint64_t Key;
struct Comparator {
int operator()(const Key& a, const Key& b) const {
if (a < b) {
return -1;
} else if (a > b) {
return +1;
} else {
return 0;
}
}
};
class SkipTest { };
TEST(SkipTest, Empty) {
Arena arena;
Comparator cmp;
SkipList<Key, Comparator> list(cmp, &arena);
ASSERT_TRUE(!list.Contains(10));
SkipList<Key, Comparator>::Iterator iter(&list);
ASSERT_TRUE(!iter.Valid());
iter.SeekToFirst();
ASSERT_TRUE(!iter.Valid());
iter.Seek(100);
ASSERT_TRUE(!iter.Valid());
iter.SeekToLast();
ASSERT_TRUE(!iter.Valid());
}
TEST(SkipTest, InsertAndLookup) {
const int N = 2000;
const int R = 5000;
Random rnd(1000);
std::set<Key> keys;
Arena arena;
Comparator cmp;
SkipList<Key, Comparator> list(cmp, &arena);
for (int i = 0; i < N; i++) {
Key key = rnd.Next() % R;
if (keys.insert(key).second) {
list.Insert(key);
}
}
for (int i = 0; i < R; i++) {
if (list.Contains(i)) {
ASSERT_EQ(keys.count(i), 1);
} else {
ASSERT_EQ(keys.count(i), 0);
}
}
// Simple iterator tests
{
SkipList<Key, Comparator>::Iterator iter(&list);
ASSERT_TRUE(!iter.Valid());
iter.Seek(0);
ASSERT_TRUE(iter.Valid());
ASSERT_EQ(*(keys.begin()), iter.key());
iter.SeekToFirst();
ASSERT_TRUE(iter.Valid());
ASSERT_EQ(*(keys.begin()), iter.key());
iter.SeekToLast();
ASSERT_TRUE(iter.Valid());
ASSERT_EQ(*(keys.rbegin()), iter.key());
}
// Forward iteration test
for (int i = 0; i < R; i++) {
SkipList<Key, Comparator>::Iterator iter(&list);
iter.Seek(i);
// Compare against model iterator
std::set<Key>::iterator model_iter = keys.lower_bound(i);
for (int j = 0; j < 3; j++) {
if (model_iter == keys.end()) {
ASSERT_TRUE(!iter.Valid());
break;
} else {
ASSERT_TRUE(iter.Valid());
ASSERT_EQ(*model_iter, iter.key());
++model_iter;
iter.Next();
}
}
}
// Backward iteration test
{
SkipList<Key, Comparator>::Iterator iter(&list);
iter.SeekToLast();
// Compare against model iterator
for (std::set<Key>::reverse_iterator model_iter = keys.rbegin();
model_iter != keys.rend();
++model_iter) {
ASSERT_TRUE(iter.Valid());
ASSERT_EQ(*model_iter, iter.key());
iter.Prev();
}
ASSERT_TRUE(!iter.Valid());
}
}
// We want to make sure that with a single writer and multiple
// concurrent readers (with no synchronization other than when a
// reader's iterator is created), the reader always observes all the
// data that was present in the skip list when the iterator was
// constructor. Because insertions are happening concurrently, we may
// also observe new values that were inserted since the iterator was
// constructed, but we should never miss any values that were present
// at iterator construction time.
//
// We generate multi-part keys:
// <key,gen,hash>
// where:
// key is in range [0..K-1]
// gen is a generation number for key
// hash is hash(key,gen)
//
// The insertion code picks a random key, sets gen to be 1 + the last
// generation number inserted for that key, and sets hash to Hash(key,gen).
//
// At the beginning of a read, we snapshot the last inserted
// generation number for each key. We then iterate, including random
// calls to Next() and Seek(). For every key we encounter, we
// check that it is either expected given the initial snapshot or has
// been concurrently added since the iterator started.
class ConcurrentTest {
private:
static const uint32_t K = 4;
static uint64_t key(Key key) { return (key >> 40); }
static uint64_t gen(Key key) { return (key >> 8) & 0xffffffffu; }
static uint64_t hash(Key key) { return key & 0xff; }
static uint64_t HashNumbers(uint64_t k, uint64_t g) {
uint64_t data[2] = { k, g };
return Hash(reinterpret_cast<char*>(data), sizeof(data), 0);
}
static Key MakeKey(uint64_t k, uint64_t g) {
assert(sizeof(Key) == sizeof(uint64_t));
assert(k <= K); // We sometimes pass K to seek to the end of the skiplist
assert(g <= 0xffffffffu);
return ((k << 40) | (g << 8) | (HashNumbers(k, g) & 0xff));
}
static bool IsValidKey(Key k) {
return hash(k) == (HashNumbers(key(k), gen(k)) & 0xff);
}
static Key RandomTarget(Random* rnd) {
switch (rnd->Next() % 10) {
case 0:
// Seek to beginning
return MakeKey(0, 0);
case 1:
// Seek to end
return MakeKey(K, 0);
default:
// Seek to middle
return MakeKey(rnd->Next() % K, 0);
}
}
// Per-key generation
struct State {
port::AtomicPointer generation[K];
void Set(int k, intptr_t v) {
generation[k].Release_Store(reinterpret_cast<void*>(v));
}
intptr_t Get(int k) {
return reinterpret_cast<intptr_t>(generation[k].Acquire_Load());
}
State() {
for (int k = 0; k < K; k++) {
Set(k, 0);
}
}
};
// Current state of the test
State current_;
Arena arena_;
// SkipList is not protected by mu_. We just use a single writer
// thread to modify it.
SkipList<Key, Comparator> list_;
public:
ConcurrentTest() : list_(Comparator(), &arena_) { }
// REQUIRES: External synchronization
void WriteStep(Random* rnd) {
const uint32_t k = rnd->Next() % K;
const intptr_t g = current_.Get(k) + 1;
const Key key = MakeKey(k, g);
list_.Insert(key);
current_.Set(k, g);
}
void ReadStep(Random* rnd) {
// Remember the initial committed state of the skiplist.
State initial_state;
for (int k = 0; k < K; k++) {
initial_state.Set(k, current_.Get(k));
}
Key pos = RandomTarget(rnd);
SkipList<Key, Comparator>::Iterator iter(&list_);
iter.Seek(pos);
while (true) {
Key current;
if (!iter.Valid()) {
current = MakeKey(K, 0);
} else {
current = iter.key();
ASSERT_TRUE(IsValidKey(current)) << current;
}
ASSERT_LE(pos, current) << "should not go backwards";
// Verify that everything in [pos,current) was not present in
// initial_state.
while (pos < current) {
ASSERT_LT(key(pos), K) << pos;
// Note that generation 0 is never inserted, so it is ok if
// <*,0,*> is missing.
ASSERT_TRUE((gen(pos) == 0) ||
(gen(pos) > static_cast<Key>(initial_state.Get(key(pos))))
) << "key: " << key(pos)
<< "; gen: " << gen(pos)
<< "; initgen: "
<< initial_state.Get(key(pos));
// Advance to next key in the valid key space
if (key(pos) < key(current)) {
pos = MakeKey(key(pos) + 1, 0);
} else {
pos = MakeKey(key(pos), gen(pos) + 1);
}
}
if (!iter.Valid()) {
break;
}
if (rnd->Next() % 2) {
iter.Next();
pos = MakeKey(key(pos), gen(pos) + 1);
} else {
Key new_target = RandomTarget(rnd);
if (new_target > pos) {
pos = new_target;
iter.Seek(new_target);
}
}
}
}
};
const uint32_t ConcurrentTest::K;
// Simple test that does single-threaded testing of the ConcurrentTest
// scaffolding.
TEST(SkipTest, ConcurrentWithoutThreads) {
ConcurrentTest test;
Random rnd(test::RandomSeed());
for (int i = 0; i < 10000; i++) {
test.ReadStep(&rnd);
test.WriteStep(&rnd);
}
}
class TestState {
public:
ConcurrentTest t_;
int seed_;
port::AtomicPointer quit_flag_;
enum ReaderState {
STARTING,
RUNNING,
DONE
};
explicit TestState(int s)
: seed_(s),
quit_flag_(NULL),
state_(STARTING),
state_cv_(&mu_) {}
void Wait(ReaderState s) {
mu_.Lock();
while (state_ != s) {
state_cv_.Wait();
}
mu_.Unlock();
}
void Change(ReaderState s) {
mu_.Lock();
state_ = s;
state_cv_.Signal();
mu_.Unlock();
}
private:
port::Mutex mu_;
ReaderState state_;
port::CondVar state_cv_;
};
static void ConcurrentReader(void* arg) {
TestState* state = reinterpret_cast<TestState*>(arg);
Random rnd(state->seed_);
int64_t reads = 0;
state->Change(TestState::RUNNING);
while (!state->quit_flag_.Acquire_Load()) {
state->t_.ReadStep(&rnd);
++reads;
}
state->Change(TestState::DONE);
}
static void RunConcurrent(int run) {
const int seed = test::RandomSeed() + (run * 100);
Random rnd(seed);
const int N = 1000;
const int kSize = 1000;
for (int i = 0; i < N; i++) {
if ((i % 100) == 0) {
fprintf(stderr, "Run %d of %d\n", i, N);
}
TestState state(seed + 1);
Env::Default()->Schedule(ConcurrentReader, &state);
state.Wait(TestState::RUNNING);
for (int i = 0; i < kSize; i++) {
state.t_.WriteStep(&rnd);
}
state.quit_flag_.Release_Store(&state); // Any non-NULL arg will do
state.Wait(TestState::DONE);
}
}
TEST(SkipTest, Concurrent1) { RunConcurrent(1); }
TEST(SkipTest, Concurrent2) { RunConcurrent(2); }
TEST(SkipTest, Concurrent3) { RunConcurrent(3); }
TEST(SkipTest, Concurrent4) { RunConcurrent(4); }
TEST(SkipTest, Concurrent5) { RunConcurrent(5); }
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_SNAPSHOT_H_
#define STORAGE_LEVELDB_DB_SNAPSHOT_H_
#include "db/dbformat.h"
#include "leveldb/db.h"
namespace leveldb {
class SnapshotList;
// Snapshots are kept in a doubly-linked list in the DB.
// Each SnapshotImpl corresponds to a particular sequence number.
class SnapshotImpl : public Snapshot {
public:
SequenceNumber number_; // const after creation
private:
friend class SnapshotList;
// SnapshotImpl is kept in a doubly-linked circular list
SnapshotImpl* prev_;
SnapshotImpl* next_;
SnapshotList* list_; // just for sanity checks
};
class SnapshotList {
public:
SnapshotList() {
list_.prev_ = &list_;
list_.next_ = &list_;
}
bool empty() const { return list_.next_ == &list_; }
SnapshotImpl* oldest() const { assert(!empty()); return list_.next_; }
SnapshotImpl* newest() const { assert(!empty()); return list_.prev_; }
const SnapshotImpl* New(SequenceNumber seq) {
SnapshotImpl* s = new SnapshotImpl;
s->number_ = seq;
s->list_ = this;
s->next_ = &list_;
s->prev_ = list_.prev_;
s->prev_->next_ = s;
s->next_->prev_ = s;
return s;
}
void Delete(const SnapshotImpl* s) {
assert(s->list_ == this);
s->prev_->next_ = s->next_;
s->next_->prev_ = s->prev_;
delete s;
}
private:
// Dummy head of doubly-linked list of snapshots
SnapshotImpl list_;
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_SNAPSHOT_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/table_cache.h"
#include "db/filename.h"
#include "leveldb/env.h"
#include "leveldb/table.h"
#include "util/coding.h"
namespace leveldb {
struct TableAndFile {
RandomAccessFile* file;
Table* table;
};
static void DeleteEntry(const Slice& key, void* value) {
TableAndFile* tf = reinterpret_cast<TableAndFile*>(value);
delete tf->table;
delete tf->file;
delete tf;
}
static void UnrefEntry(void* arg1, void* arg2) {
Cache* cache = reinterpret_cast<Cache*>(arg1);
Cache::Handle* h = reinterpret_cast<Cache::Handle*>(arg2);
cache->Release(h);
}
TableCache::TableCache(const std::string& dbname,
const Options* options,
int entries)
: env_(options->env),
dbname_(dbname),
options_(options),
cache_(NewLRUCache(entries)) {
}
TableCache::~TableCache() {
delete cache_;
}
Status TableCache::FindTable(uint64_t file_number, uint64_t file_size,
Cache::Handle** handle) {
Status s;
char buf[sizeof(file_number)];
EncodeFixed64(buf, file_number);
Slice key(buf, sizeof(buf));
*handle = cache_->Lookup(key);
if (*handle == NULL) {
std::string fname = TableFileName(dbname_, file_number);
RandomAccessFile* file = NULL;
Table* table = NULL;
s = env_->NewRandomAccessFile(fname, &file);
if (!s.ok()) {
std::string old_fname = SSTTableFileName(dbname_, file_number);
if (env_->NewRandomAccessFile(old_fname, &file).ok()) {
s = Status::OK();
}
}
if (s.ok()) {
s = Table::Open(*options_, file, file_size, &table);
}
if (!s.ok()) {
assert(table == NULL);
delete file;
// We do not cache error results so that if the error is transient,
// or somebody repairs the file, we recover automatically.
} else {
TableAndFile* tf = new TableAndFile;
tf->file = file;
tf->table = table;
*handle = cache_->Insert(key, tf, 1, &DeleteEntry);
}
}
return s;
}
Iterator* TableCache::NewIterator(const ReadOptions& options,
uint64_t file_number,
uint64_t file_size,
Table** tableptr) {
if (tableptr != NULL) {
*tableptr = NULL;
}
Cache::Handle* handle = NULL;
Status s = FindTable(file_number, file_size, &handle);
if (!s.ok()) {
return NewErrorIterator(s);
}
Table* table = reinterpret_cast<TableAndFile*>(cache_->Value(handle))->table;
Iterator* result = table->NewIterator(options);
result->RegisterCleanup(&UnrefEntry, cache_, handle);
if (tableptr != NULL) {
*tableptr = table;
}
return result;
}
Status TableCache::Get(const ReadOptions& options,
uint64_t file_number,
uint64_t file_size,
const Slice& k,
void* arg,
void (*saver)(void*, const Slice&, const Slice&)) {
Cache::Handle* handle = NULL;
Status s = FindTable(file_number, file_size, &handle);
if (s.ok()) {
Table* t = reinterpret_cast<TableAndFile*>(cache_->Value(handle))->table;
s = t->InternalGet(options, k, arg, saver);
cache_->Release(handle);
}
return s;
}
void TableCache::Evict(uint64_t file_number) {
char buf[sizeof(file_number)];
EncodeFixed64(buf, file_number);
cache_->Erase(Slice(buf, sizeof(buf)));
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// Thread-safe (provides internal synchronization)
#ifndef STORAGE_LEVELDB_DB_TABLE_CACHE_H_
#define STORAGE_LEVELDB_DB_TABLE_CACHE_H_
#include <string>
#include <stdint.h>
#include "db/dbformat.h"
#include "leveldb/cache.h"
#include "leveldb/table.h"
#include "port/port.h"
namespace leveldb {
class Env;
class TableCache {
public:
TableCache(const std::string& dbname, const Options* options, int entries);
~TableCache();
// Return an iterator for the specified file number (the corresponding
// file length must be exactly "file_size" bytes). If "tableptr" is
// non-NULL, also sets "*tableptr" to point to the Table object
// underlying the returned iterator, or NULL if no Table object underlies
// the returned iterator. The returned "*tableptr" object is owned by
// the cache and should not be deleted, and is valid for as long as the
// returned iterator is live.
Iterator* NewIterator(const ReadOptions& options,
uint64_t file_number,
uint64_t file_size,
Table** tableptr = NULL);
// If a seek to internal key "k" in specified file finds an entry,
// call (*handle_result)(arg, found_key, found_value).
Status Get(const ReadOptions& options,
uint64_t file_number,
uint64_t file_size,
const Slice& k,
void* arg,
void (*handle_result)(void*, const Slice&, const Slice&));
// Evict any entry for the specified file number
void Evict(uint64_t file_number);
private:
Env* const env_;
const std::string dbname_;
const Options* options_;
Cache* cache_;
Status FindTable(uint64_t file_number, uint64_t file_size, Cache::Handle**);
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_TABLE_CACHE_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/version_edit.h"
#include "db/version_set.h"
#include "util/coding.h"
namespace leveldb {
// Tag numbers for serialized VersionEdit. These numbers are written to
// disk and should not be changed.
enum Tag {
kComparator = 1,
kLogNumber = 2,
kNextFileNumber = 3,
kLastSequence = 4,
kCompactPointer = 5,
kDeletedFile = 6,
kNewFile = 7,
// 8 was used for large value refs
kPrevLogNumber = 9
};
void VersionEdit::Clear() {
comparator_.clear();
log_number_ = 0;
prev_log_number_ = 0;
last_sequence_ = 0;
next_file_number_ = 0;
has_comparator_ = false;
has_log_number_ = false;
has_prev_log_number_ = false;
has_next_file_number_ = false;
has_last_sequence_ = false;
deleted_files_.clear();
new_files_.clear();
}
void VersionEdit::EncodeTo(std::string* dst) const {
if (has_comparator_) {
PutVarint32(dst, kComparator);
PutLengthPrefixedSlice(dst, comparator_);
}
if (has_log_number_) {
PutVarint32(dst, kLogNumber);
PutVarint64(dst, log_number_);
}
if (has_prev_log_number_) {
PutVarint32(dst, kPrevLogNumber);
PutVarint64(dst, prev_log_number_);
}
if (has_next_file_number_) {
PutVarint32(dst, kNextFileNumber);
PutVarint64(dst, next_file_number_);
}
if (has_last_sequence_) {
PutVarint32(dst, kLastSequence);
PutVarint64(dst, last_sequence_);
}
for (size_t i = 0; i < compact_pointers_.size(); i++) {
PutVarint32(dst, kCompactPointer);
PutVarint32(dst, compact_pointers_[i].first); // level
PutLengthPrefixedSlice(dst, compact_pointers_[i].second.Encode());
}
for (DeletedFileSet::const_iterator iter = deleted_files_.begin();
iter != deleted_files_.end();
++iter) {
PutVarint32(dst, kDeletedFile);
PutVarint32(dst, iter->first); // level
PutVarint64(dst, iter->second); // file number
}
for (size_t i = 0; i < new_files_.size(); i++) {
const FileMetaData& f = new_files_[i].second;
PutVarint32(dst, kNewFile);
PutVarint32(dst, new_files_[i].first); // level
PutVarint64(dst, f.number);
PutVarint64(dst, f.file_size);
PutLengthPrefixedSlice(dst, f.smallest.Encode());
PutLengthPrefixedSlice(dst, f.largest.Encode());
}
}
static bool GetInternalKey(Slice* input, InternalKey* dst) {
Slice str;
if (GetLengthPrefixedSlice(input, &str)) {
dst->DecodeFrom(str);
return true;
} else {
return false;
}
}
static bool GetLevel(Slice* input, int* level) {
uint32_t v;
if (GetVarint32(input, &v) &&
v < config::kNumLevels) {
*level = v;
return true;
} else {
return false;
}
}
Status VersionEdit::DecodeFrom(const Slice& src) {
Clear();
Slice input = src;
const char* msg = NULL;
uint32_t tag;
// Temporary storage for parsing
int level;
uint64_t number;
FileMetaData f;
Slice str;
InternalKey key;
while (msg == NULL && GetVarint32(&input, &tag)) {
switch (tag) {
case kComparator:
if (GetLengthPrefixedSlice(&input, &str)) {
comparator_ = str.ToString();
has_comparator_ = true;
} else {
msg = "comparator name";
}
break;
case kLogNumber:
if (GetVarint64(&input, &log_number_)) {
has_log_number_ = true;
} else {
msg = "log number";
}
break;
case kPrevLogNumber:
if (GetVarint64(&input, &prev_log_number_)) {
has_prev_log_number_ = true;
} else {
msg = "previous log number";
}
break;
case kNextFileNumber:
if (GetVarint64(&input, &next_file_number_)) {
has_next_file_number_ = true;
} else {
msg = "next file number";
}
break;
case kLastSequence:
if (GetVarint64(&input, &last_sequence_)) {
has_last_sequence_ = true;
} else {
msg = "last sequence number";
}
break;
case kCompactPointer:
if (GetLevel(&input, &level) &&
GetInternalKey(&input, &key)) {
compact_pointers_.push_back(std::make_pair(level, key));
} else {
msg = "compaction pointer";
}
break;
case kDeletedFile:
if (GetLevel(&input, &level) &&
GetVarint64(&input, &number)) {
deleted_files_.insert(std::make_pair(level, number));
} else {
msg = "deleted file";
}
break;
case kNewFile:
if (GetLevel(&input, &level) &&
GetVarint64(&input, &f.number) &&
GetVarint64(&input, &f.file_size) &&
GetInternalKey(&input, &f.smallest) &&
GetInternalKey(&input, &f.largest)) {
new_files_.push_back(std::make_pair(level, f));
} else {
msg = "new-file entry";
}
break;
default:
msg = "unknown tag";
break;
}
}
if (msg == NULL && !input.empty()) {
msg = "invalid tag";
}
Status result;
if (msg != NULL) {
result = Status::Corruption("VersionEdit", msg);
}
return result;
}
std::string VersionEdit::DebugString() const {
std::string r;
r.append("VersionEdit {");
if (has_comparator_) {
r.append("\n Comparator: ");
r.append(comparator_);
}
if (has_log_number_) {
r.append("\n LogNumber: ");
AppendNumberTo(&r, log_number_);
}
if (has_prev_log_number_) {
r.append("\n PrevLogNumber: ");
AppendNumberTo(&r, prev_log_number_);
}
if (has_next_file_number_) {
r.append("\n NextFile: ");
AppendNumberTo(&r, next_file_number_);
}
if (has_last_sequence_) {
r.append("\n LastSeq: ");
AppendNumberTo(&r, last_sequence_);
}
for (size_t i = 0; i < compact_pointers_.size(); i++) {
r.append("\n CompactPointer: ");
AppendNumberTo(&r, compact_pointers_[i].first);
r.append(" ");
r.append(compact_pointers_[i].second.DebugString());
}
for (DeletedFileSet::const_iterator iter = deleted_files_.begin();
iter != deleted_files_.end();
++iter) {
r.append("\n DeleteFile: ");
AppendNumberTo(&r, iter->first);
r.append(" ");
AppendNumberTo(&r, iter->second);
}
for (size_t i = 0; i < new_files_.size(); i++) {
const FileMetaData& f = new_files_[i].second;
r.append("\n AddFile: ");
AppendNumberTo(&r, new_files_[i].first);
r.append(" ");
AppendNumberTo(&r, f.number);
r.append(" ");
AppendNumberTo(&r, f.file_size);
r.append(" ");
r.append(f.smallest.DebugString());
r.append(" .. ");
r.append(f.largest.DebugString());
}
r.append("\n}\n");
return r;
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_VERSION_EDIT_H_
#define STORAGE_LEVELDB_DB_VERSION_EDIT_H_
#include <set>
#include <utility>
#include <vector>
#include "db/dbformat.h"
namespace leveldb {
class VersionSet;
struct FileMetaData {
int refs;
int allowed_seeks; // Seeks allowed until compaction
uint64_t number;
uint64_t file_size; // File size in bytes
InternalKey smallest; // Smallest internal key served by table
InternalKey largest; // Largest internal key served by table
FileMetaData() : refs(0), allowed_seeks(1 << 30), file_size(0) { }
};
class VersionEdit {
public:
VersionEdit() { Clear(); }
~VersionEdit() { }
void Clear();
void SetComparatorName(const Slice& name) {
has_comparator_ = true;
comparator_ = name.ToString();
}
void SetLogNumber(uint64_t num) {
has_log_number_ = true;
log_number_ = num;
}
void SetPrevLogNumber(uint64_t num) {
has_prev_log_number_ = true;
prev_log_number_ = num;
}
void SetNextFile(uint64_t num) {
has_next_file_number_ = true;
next_file_number_ = num;
}
void SetLastSequence(SequenceNumber seq) {
has_last_sequence_ = true;
last_sequence_ = seq;
}
void SetCompactPointer(int level, const InternalKey& key) {
compact_pointers_.push_back(std::make_pair(level, key));
}
// Add the specified file at the specified number.
// REQUIRES: This version has not been saved (see VersionSet::SaveTo)
// REQUIRES: "smallest" and "largest" are smallest and largest keys in file
void AddFile(int level, uint64_t file,
uint64_t file_size,
const InternalKey& smallest,
const InternalKey& largest) {
FileMetaData f;
f.number = file;
f.file_size = file_size;
f.smallest = smallest;
f.largest = largest;
new_files_.push_back(std::make_pair(level, f));
}
// Delete the specified "file" from the specified "level".
void DeleteFile(int level, uint64_t file) {
deleted_files_.insert(std::make_pair(level, file));
}
void EncodeTo(std::string* dst) const;
Status DecodeFrom(const Slice& src);
std::string DebugString() const;
private:
friend class VersionSet;
typedef std::set< std::pair<int, uint64_t> > DeletedFileSet;
std::string comparator_;
uint64_t log_number_;
uint64_t prev_log_number_;
uint64_t next_file_number_;
SequenceNumber last_sequence_;
bool has_comparator_;
bool has_log_number_;
bool has_prev_log_number_;
bool has_next_file_number_;
bool has_last_sequence_;
std::vector< std::pair<int, InternalKey> > compact_pointers_;
DeletedFileSet deleted_files_;
std::vector< std::pair<int, FileMetaData> > new_files_;
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_VERSION_EDIT_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/version_edit.h"
#include "util/testharness.h"
namespace leveldb {
static void TestEncodeDecode(const VersionEdit& edit) {
std::string encoded, encoded2;
edit.EncodeTo(&encoded);
VersionEdit parsed;
Status s = parsed.DecodeFrom(encoded);
ASSERT_TRUE(s.ok()) << s.ToString();
parsed.EncodeTo(&encoded2);
ASSERT_EQ(encoded, encoded2);
}
class VersionEditTest { };
TEST(VersionEditTest, EncodeDecode) {
static const uint64_t kBig = 1ull << 50;
VersionEdit edit;
for (int i = 0; i < 4; i++) {
TestEncodeDecode(edit);
edit.AddFile(3, kBig + 300 + i, kBig + 400 + i,
InternalKey("foo", kBig + 500 + i, kTypeValue),
InternalKey("zoo", kBig + 600 + i, kTypeDeletion));
edit.DeleteFile(4, kBig + 700 + i);
edit.SetCompactPointer(i, InternalKey("x", kBig + 900 + i, kTypeValue));
}
edit.SetComparatorName("foo");
edit.SetLogNumber(kBig + 100);
edit.SetNextFile(kBig + 200);
edit.SetLastSequence(kBig + 1000);
TestEncodeDecode(edit);
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// The representation of a DBImpl consists of a set of Versions. The
// newest version is called "current". Older versions may be kept
// around to provide a consistent view to live iterators.
//
// Each Version keeps track of a set of Table files per level. The
// entire set of versions is maintained in a VersionSet.
//
// Version,VersionSet are thread-compatible, but require external
// synchronization on all accesses.
#ifndef STORAGE_LEVELDB_DB_VERSION_SET_H_
#define STORAGE_LEVELDB_DB_VERSION_SET_H_
#include <map>
#include <set>
#include <vector>
#include "db/dbformat.h"
#include "db/version_edit.h"
#include "port/port.h"
#include "port/thread_annotations.h"
namespace leveldb {
namespace log { class Writer; }
class Compaction;
class Iterator;
class MemTable;
class TableBuilder;
class TableCache;
class Version;
class VersionSet;
class WritableFile;
// Return the smallest index i such that files[i]->largest >= key.
// Return files.size() if there is no such file.
// REQUIRES: "files" contains a sorted list of non-overlapping files.
extern int FindFile(const InternalKeyComparator& icmp,
const std::vector<FileMetaData*>& files,
const Slice& key);
// Returns true iff some file in "files" overlaps the user key range
// [*smallest,*largest].
// smallest==NULL represents a key smaller than all keys in the DB.
// largest==NULL represents a key largest than all keys in the DB.
// REQUIRES: If disjoint_sorted_files, files[] contains disjoint ranges
// in sorted order.
extern bool SomeFileOverlapsRange(
const InternalKeyComparator& icmp,
bool disjoint_sorted_files,
const std::vector<FileMetaData*>& files,
const Slice* smallest_user_key,
const Slice* largest_user_key);
class Version {
public:
// Append to *iters a sequence of iterators that will
// yield the contents of this Version when merged together.
// REQUIRES: This version has been saved (see VersionSet::SaveTo)
void AddIterators(const ReadOptions&, std::vector<Iterator*>* iters);
// Lookup the value for key. If found, store it in *val and
// return OK. Else return a non-OK status. Fills *stats.
// REQUIRES: lock is not held
struct GetStats {
FileMetaData* seek_file;
int seek_file_level;
};
Status Get(const ReadOptions&, const LookupKey& key, std::string* val,
GetStats* stats);
// Adds "stats" into the current state. Returns true if a new
// compaction may need to be triggered, false otherwise.
// REQUIRES: lock is held
bool UpdateStats(const GetStats& stats);
// Record a sample of bytes read at the specified internal key.
// Samples are taken approximately once every config::kReadBytesPeriod
// bytes. Returns true if a new compaction may need to be triggered.
// REQUIRES: lock is held
bool RecordReadSample(Slice key);
// Reference count management (so Versions do not disappear out from
// under live iterators)
void Ref();
void Unref();
void GetOverlappingInputs(
int level,
const InternalKey* begin, // NULL means before all keys
const InternalKey* end, // NULL means after all keys
std::vector<FileMetaData*>* inputs);
// Returns true iff some file in the specified level overlaps
// some part of [*smallest_user_key,*largest_user_key].
// smallest_user_key==NULL represents a key smaller than all keys in the DB.
// largest_user_key==NULL represents a key largest than all keys in the DB.
bool OverlapInLevel(int level,
const Slice* smallest_user_key,
const Slice* largest_user_key);
// Return the level at which we should place a new memtable compaction
// result that covers the range [smallest_user_key,largest_user_key].
int PickLevelForMemTableOutput(const Slice& smallest_user_key,
const Slice& largest_user_key);
int NumFiles(int level) const { return files_[level].size(); }
// Return a human readable string that describes this version's contents.
std::string DebugString() const;
private:
friend class Compaction;
friend class VersionSet;
class LevelFileNumIterator;
Iterator* NewConcatenatingIterator(const ReadOptions&, int level) const;
// Call func(arg, level, f) for every file that overlaps user_key in
// order from newest to oldest. If an invocation of func returns
// false, makes no more calls.
//
// REQUIRES: user portion of internal_key == user_key.
void ForEachOverlapping(Slice user_key, Slice internal_key,
void* arg,
bool (*func)(void*, int, FileMetaData*));
VersionSet* vset_; // VersionSet to which this Version belongs
Version* next_; // Next version in linked list
Version* prev_; // Previous version in linked list
int refs_; // Number of live refs to this version
// List of files per level
std::vector<FileMetaData*> files_[config::kNumLevels];
// Next file to compact based on seek stats.
FileMetaData* file_to_compact_;
int file_to_compact_level_;
// Level that should be compacted next and its compaction score.
// Score < 1 means compaction is not strictly needed. These fields
// are initialized by Finalize().
double compaction_score_;
int compaction_level_;
explicit Version(VersionSet* vset)
: vset_(vset), next_(this), prev_(this), refs_(0),
file_to_compact_(NULL),
file_to_compact_level_(-1),
compaction_score_(-1),
compaction_level_(-1) {
}
~Version();
// No copying allowed
Version(const Version&);
void operator=(const Version&);
};
class VersionSet {
public:
VersionSet(const std::string& dbname,
const Options* options,
TableCache* table_cache,
const InternalKeyComparator*);
~VersionSet();
// Apply *edit to the current version to form a new descriptor that
// is both saved to persistent state and installed as the new
// current version. Will release *mu while actually writing to the file.
// REQUIRES: *mu is held on entry.
// REQUIRES: no other thread concurrently calls LogAndApply()
Status LogAndApply(VersionEdit* edit, port::Mutex* mu)
EXCLUSIVE_LOCKS_REQUIRED(mu);
// Recover the last saved descriptor from persistent storage.
Status Recover(bool *save_manifest);
// Return the current version.
Version* current() const { return current_; }
// Return the current manifest file number
uint64_t ManifestFileNumber() const { return manifest_file_number_; }
// Allocate and return a new file number
uint64_t NewFileNumber() { return next_file_number_++; }
// Arrange to reuse "file_number" unless a newer file number has
// already been allocated.
// REQUIRES: "file_number" was returned by a call to NewFileNumber().
void ReuseFileNumber(uint64_t file_number) {
if (next_file_number_ == file_number + 1) {
next_file_number_ = file_number;
}
}
// Return the number of Table files at the specified level.
int NumLevelFiles(int level) const;
// Return the combined file size of all files at the specified level.
int64_t NumLevelBytes(int level) const;
// Return the last sequence number.
uint64_t LastSequence() const { return last_sequence_; }
// Set the last sequence number to s.
void SetLastSequence(uint64_t s) {
assert(s >= last_sequence_);
last_sequence_ = s;
}
// Mark the specified file number as used.
void MarkFileNumberUsed(uint64_t number);
// Return the current log file number.
uint64_t LogNumber() const { return log_number_; }
// Return the log file number for the log file that is currently
// being compacted, or zero if there is no such log file.
uint64_t PrevLogNumber() const { return prev_log_number_; }
// Pick level and inputs for a new compaction.
// Returns NULL if there is no compaction to be done.
// Otherwise returns a pointer to a heap-allocated object that
// describes the compaction. Caller should delete the result.
Compaction* PickCompaction();
// Return a compaction object for compacting the range [begin,end] in
// the specified level. Returns NULL if there is nothing in that
// level that overlaps the specified range. Caller should delete
// the result.
Compaction* CompactRange(
int level,
const InternalKey* begin,
const InternalKey* end);
// Return the maximum overlapping data (in bytes) at next level for any
// file at a level >= 1.
int64_t MaxNextLevelOverlappingBytes();
// Create an iterator that reads over the compaction inputs for "*c".
// The caller should delete the iterator when no longer needed.
Iterator* MakeInputIterator(Compaction* c);
// Returns true iff some level needs a compaction.
bool NeedsCompaction() const {
Version* v = current_;
return (v->compaction_score_ >= 1) || (v->file_to_compact_ != NULL);
}
// Add all files listed in any live version to *live.
// May also mutate some internal state.
void AddLiveFiles(std::set<uint64_t>* live);
// Return the approximate offset in the database of the data for
// "key" as of version "v".
uint64_t ApproximateOffsetOf(Version* v, const InternalKey& key);
// Return a human-readable short (single-line) summary of the number
// of files per level. Uses *scratch as backing store.
struct LevelSummaryStorage {
char buffer[100];
};
const char* LevelSummary(LevelSummaryStorage* scratch) const;
private:
class Builder;
friend class Compaction;
friend class Version;
bool ReuseManifest(const std::string& dscname, const std::string& dscbase);
void Finalize(Version* v);
void GetRange(const std::vector<FileMetaData*>& inputs,
InternalKey* smallest,
InternalKey* largest);
void GetRange2(const std::vector<FileMetaData*>& inputs1,
const std::vector<FileMetaData*>& inputs2,
InternalKey* smallest,
InternalKey* largest);
void SetupOtherInputs(Compaction* c);
// Save current contents to *log
Status WriteSnapshot(log::Writer* log);
void AppendVersion(Version* v);
Env* const env_;
const std::string dbname_;
const Options* const options_;
TableCache* const table_cache_;
const InternalKeyComparator icmp_;
uint64_t next_file_number_;
uint64_t manifest_file_number_;
uint64_t last_sequence_;
uint64_t log_number_;
uint64_t prev_log_number_; // 0 or backing store for memtable being compacted
// Opened lazily
WritableFile* descriptor_file_;
log::Writer* descriptor_log_;
Version dummy_versions_; // Head of circular doubly-linked list of versions.
Version* current_; // == dummy_versions_.prev_
// Per-level key at which the next compaction at that level should start.
// Either an empty string, or a valid InternalKey.
std::string compact_pointer_[config::kNumLevels];
// No copying allowed
VersionSet(const VersionSet&);
void operator=(const VersionSet&);
};
// A Compaction encapsulates information about a compaction.
class Compaction {
public:
~Compaction();
// Return the level that is being compacted. Inputs from "level"
// and "level+1" will be merged to produce a set of "level+1" files.
int level() const { return level_; }
// Return the object that holds the edits to the descriptor done
// by this compaction.
VersionEdit* edit() { return &edit_; }
// "which" must be either 0 or 1
int num_input_files(int which) const { return inputs_[which].size(); }
// Return the ith input file at "level()+which" ("which" must be 0 or 1).
FileMetaData* input(int which, int i) const { return inputs_[which][i]; }
// Maximum size of files to build during this compaction.
uint64_t MaxOutputFileSize() const { return max_output_file_size_; }
// Is this a trivial compaction that can be implemented by just
// moving a single input file to the next level (no merging or splitting)
bool IsTrivialMove() const;
// Add all inputs to this compaction as delete operations to *edit.
void AddInputDeletions(VersionEdit* edit);
// Returns true if the information we have available guarantees that
// the compaction is producing data in "level+1" for which no data exists
// in levels greater than "level+1".
bool IsBaseLevelForKey(const Slice& user_key);
// Returns true iff we should stop building the current output
// before processing "internal_key".
bool ShouldStopBefore(const Slice& internal_key);
// Release the input version for the compaction, once the compaction
// is successful.
void ReleaseInputs();
private:
friend class Version;
friend class VersionSet;
Compaction(const Options* options, int level);
int level_;
uint64_t max_output_file_size_;
Version* input_version_;
VersionEdit edit_;
// Each compaction reads inputs from "level_" and "level_+1"
std::vector<FileMetaData*> inputs_[2]; // The two sets of inputs
// State used to check for number of of overlapping grandparent files
// (parent == level_ + 1, grandparent == level_ + 2)
std::vector<FileMetaData*> grandparents_;
size_t grandparent_index_; // Index in grandparent_starts_
bool seen_key_; // Some output key has been seen
int64_t overlapped_bytes_; // Bytes of overlap between current output
// and grandparent files
// State for implementing IsBaseLevelForKey
// level_ptrs_ holds indices into input_version_->levels_: our state
// is that we are positioned at one of the file ranges for each
// higher level than the ones involved in this compaction (i.e. for
// all L >= level_ + 2).
size_t level_ptrs_[config::kNumLevels];
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_VERSION_SET_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/version_set.h"
#include "util/logging.h"
#include "util/testharness.h"
#include "util/testutil.h"
namespace leveldb {
class FindFileTest {
public:
std::vector<FileMetaData*> files_;
bool disjoint_sorted_files_;
FindFileTest() : disjoint_sorted_files_(true) { }
~FindFileTest() {
for (int i = 0; i < files_.size(); i++) {
delete files_[i];
}
}
void Add(const char* smallest, const char* largest,
SequenceNumber smallest_seq = 100,
SequenceNumber largest_seq = 100) {
FileMetaData* f = new FileMetaData;
f->number = files_.size() + 1;
f->smallest = InternalKey(smallest, smallest_seq, kTypeValue);
f->largest = InternalKey(largest, largest_seq, kTypeValue);
files_.push_back(f);
}
int Find(const char* key) {
InternalKey target(key, 100, kTypeValue);
InternalKeyComparator cmp(BytewiseComparator());
return FindFile(cmp, files_, target.Encode());
}
bool Overlaps(const char* smallest, const char* largest) {
InternalKeyComparator cmp(BytewiseComparator());
Slice s(smallest != NULL ? smallest : "");
Slice l(largest != NULL ? largest : "");
return SomeFileOverlapsRange(cmp, disjoint_sorted_files_, files_,
(smallest != NULL ? &s : NULL),
(largest != NULL ? &l : NULL));
}
};
TEST(FindFileTest, Empty) {
ASSERT_EQ(0, Find("foo"));
ASSERT_TRUE(! Overlaps("a", "z"));
ASSERT_TRUE(! Overlaps(NULL, "z"));
ASSERT_TRUE(! Overlaps("a", NULL));
ASSERT_TRUE(! Overlaps(NULL, NULL));
}
TEST(FindFileTest, Single) {
Add("p", "q");
ASSERT_EQ(0, Find("a"));
ASSERT_EQ(0, Find("p"));
ASSERT_EQ(0, Find("p1"));
ASSERT_EQ(0, Find("q"));
ASSERT_EQ(1, Find("q1"));
ASSERT_EQ(1, Find("z"));
ASSERT_TRUE(! Overlaps("a", "b"));
ASSERT_TRUE(! Overlaps("z1", "z2"));
ASSERT_TRUE(Overlaps("a", "p"));
ASSERT_TRUE(Overlaps("a", "q"));
ASSERT_TRUE(Overlaps("a", "z"));
ASSERT_TRUE(Overlaps("p", "p1"));
ASSERT_TRUE(Overlaps("p", "q"));
ASSERT_TRUE(Overlaps("p", "z"));
ASSERT_TRUE(Overlaps("p1", "p2"));
ASSERT_TRUE(Overlaps("p1", "z"));
ASSERT_TRUE(Overlaps("q", "q"));
ASSERT_TRUE(Overlaps("q", "q1"));
ASSERT_TRUE(! Overlaps(NULL, "j"));
ASSERT_TRUE(! Overlaps("r", NULL));
ASSERT_TRUE(Overlaps(NULL, "p"));
ASSERT_TRUE(Overlaps(NULL, "p1"));
ASSERT_TRUE(Overlaps("q", NULL));
ASSERT_TRUE(Overlaps(NULL, NULL));
}
TEST(FindFileTest, Multiple) {
Add("150", "200");
Add("200", "250");
Add("300", "350");
Add("400", "450");
ASSERT_EQ(0, Find("100"));
ASSERT_EQ(0, Find("150"));
ASSERT_EQ(0, Find("151"));
ASSERT_EQ(0, Find("199"));
ASSERT_EQ(0, Find("200"));
ASSERT_EQ(1, Find("201"));
ASSERT_EQ(1, Find("249"));
ASSERT_EQ(1, Find("250"));
ASSERT_EQ(2, Find("251"));
ASSERT_EQ(2, Find("299"));
ASSERT_EQ(2, Find("300"));
ASSERT_EQ(2, Find("349"));
ASSERT_EQ(2, Find("350"));
ASSERT_EQ(3, Find("351"));
ASSERT_EQ(3, Find("400"));
ASSERT_EQ(3, Find("450"));
ASSERT_EQ(4, Find("451"));
ASSERT_TRUE(! Overlaps("100", "149"));
ASSERT_TRUE(! Overlaps("251", "299"));
ASSERT_TRUE(! Overlaps("451", "500"));
ASSERT_TRUE(! Overlaps("351", "399"));
ASSERT_TRUE(Overlaps("100", "150"));
ASSERT_TRUE(Overlaps("100", "200"));
ASSERT_TRUE(Overlaps("100", "300"));
ASSERT_TRUE(Overlaps("100", "400"));
ASSERT_TRUE(Overlaps("100", "500"));
ASSERT_TRUE(Overlaps("375", "400"));
ASSERT_TRUE(Overlaps("450", "450"));
ASSERT_TRUE(Overlaps("450", "500"));
}
TEST(FindFileTest, MultipleNullBoundaries) {
Add("150", "200");
Add("200", "250");
Add("300", "350");
Add("400", "450");
ASSERT_TRUE(! Overlaps(NULL, "149"));
ASSERT_TRUE(! Overlaps("451", NULL));
ASSERT_TRUE(Overlaps(NULL, NULL));
ASSERT_TRUE(Overlaps(NULL, "150"));
ASSERT_TRUE(Overlaps(NULL, "199"));
ASSERT_TRUE(Overlaps(NULL, "200"));
ASSERT_TRUE(Overlaps(NULL, "201"));
ASSERT_TRUE(Overlaps(NULL, "400"));
ASSERT_TRUE(Overlaps(NULL, "800"));
ASSERT_TRUE(Overlaps("100", NULL));
ASSERT_TRUE(Overlaps("200", NULL));
ASSERT_TRUE(Overlaps("449", NULL));
ASSERT_TRUE(Overlaps("450", NULL));
}
TEST(FindFileTest, OverlapSequenceChecks) {
Add("200", "200", 5000, 3000);
ASSERT_TRUE(! Overlaps("199", "199"));
ASSERT_TRUE(! Overlaps("201", "300"));
ASSERT_TRUE(Overlaps("200", "200"));
ASSERT_TRUE(Overlaps("190", "200"));
ASSERT_TRUE(Overlaps("200", "210"));
}
TEST(FindFileTest, OverlappingFiles) {
Add("150", "600");
Add("400", "500");
disjoint_sorted_files_ = false;
ASSERT_TRUE(! Overlaps("100", "149"));
ASSERT_TRUE(! Overlaps("601", "700"));
ASSERT_TRUE(Overlaps("100", "150"));
ASSERT_TRUE(Overlaps("100", "200"));
ASSERT_TRUE(Overlaps("100", "300"));
ASSERT_TRUE(Overlaps("100", "400"));
ASSERT_TRUE(Overlaps("100", "500"));
ASSERT_TRUE(Overlaps("375", "400"));
ASSERT_TRUE(Overlaps("450", "450"));
ASSERT_TRUE(Overlaps("450", "500"));
ASSERT_TRUE(Overlaps("450", "700"));
ASSERT_TRUE(Overlaps("600", "700"));
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// WriteBatch::rep_ :=
// sequence: fixed64
// count: fixed32
// data: record[count]
// record :=
// kTypeValue varstring varstring |
// kTypeDeletion varstring
// varstring :=
// len: varint32
// data: uint8[len]
#include "leveldb/write_batch.h"
#include "leveldb/db.h"
#include "db/dbformat.h"
#include "db/memtable.h"
#include "db/write_batch_internal.h"
#include "util/coding.h"
namespace leveldb {
// WriteBatch header has an 8-byte sequence number followed by a 4-byte count.
static const size_t kHeader = 12;
WriteBatch::WriteBatch() {
Clear();
}
WriteBatch::~WriteBatch() { }
WriteBatch::Handler::~Handler() { }
void WriteBatch::Clear() {
rep_.clear();
rep_.resize(kHeader);
}
Status WriteBatch::Iterate(Handler* handler) const {
Slice input(rep_);
if (input.size() < kHeader) {
return Status::Corruption("malformed WriteBatch (too small)");
}
input.remove_prefix(kHeader);
Slice key, value;
int found = 0;
while (!input.empty()) {
found++;
char tag = input[0];
input.remove_prefix(1);
switch (tag) {
case kTypeValue:
if (GetLengthPrefixedSlice(&input, &key) &&
GetLengthPrefixedSlice(&input, &value)) {
handler->Put(key, value);
} else {
return Status::Corruption("bad WriteBatch Put");
}
break;
case kTypeDeletion:
if (GetLengthPrefixedSlice(&input, &key)) {
handler->Delete(key);
} else {
return Status::Corruption("bad WriteBatch Delete");
}
break;
default:
return Status::Corruption("unknown WriteBatch tag");
}
}
if (found != WriteBatchInternal::Count(this)) {
return Status::Corruption("WriteBatch has wrong count");
} else {
return Status::OK();
}
}
int WriteBatchInternal::Count(const WriteBatch* b) {
return DecodeFixed32(b->rep_.data() + 8);
}
void WriteBatchInternal::SetCount(WriteBatch* b, int n) {
EncodeFixed32(&b->rep_[8], n);
}
SequenceNumber WriteBatchInternal::Sequence(const WriteBatch* b) {
return SequenceNumber(DecodeFixed64(b->rep_.data()));
}
void WriteBatchInternal::SetSequence(WriteBatch* b, SequenceNumber seq) {
EncodeFixed64(&b->rep_[0], seq);
}
void WriteBatch::Put(const Slice& key, const Slice& value) {
WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
rep_.push_back(static_cast<char>(kTypeValue));
PutLengthPrefixedSlice(&rep_, key);
PutLengthPrefixedSlice(&rep_, value);
}
void WriteBatch::Delete(const Slice& key) {
WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
rep_.push_back(static_cast<char>(kTypeDeletion));
PutLengthPrefixedSlice(&rep_, key);
}
namespace {
class MemTableInserter : public WriteBatch::Handler {
public:
SequenceNumber sequence_;
MemTable* mem_;
virtual void Put(const Slice& key, const Slice& value) {
mem_->Add(sequence_, kTypeValue, key, value);
sequence_++;
}
virtual void Delete(const Slice& key) {
mem_->Add(sequence_, kTypeDeletion, key, Slice());
sequence_++;
}
};
} // namespace
Status WriteBatchInternal::InsertInto(const WriteBatch* b,
MemTable* memtable) {
MemTableInserter inserter;
inserter.sequence_ = WriteBatchInternal::Sequence(b);
inserter.mem_ = memtable;
return b->Iterate(&inserter);
}
void WriteBatchInternal::SetContents(WriteBatch* b, const Slice& contents) {
assert(contents.size() >= kHeader);
b->rep_.assign(contents.data(), contents.size());
}
void WriteBatchInternal::Append(WriteBatch* dst, const WriteBatch* src) {
SetCount(dst, Count(dst) + Count(src));
assert(src->rep_.size() >= kHeader);
dst->rep_.append(src->rep_.data() + kHeader, src->rep_.size() - kHeader);
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_DB_WRITE_BATCH_INTERNAL_H_
#define STORAGE_LEVELDB_DB_WRITE_BATCH_INTERNAL_H_
#include "db/dbformat.h"
#include "leveldb/write_batch.h"
namespace leveldb {
class MemTable;
// WriteBatchInternal provides static methods for manipulating a
// WriteBatch that we don't want in the public WriteBatch interface.
class WriteBatchInternal {
public:
// Return the number of entries in the batch.
static int Count(const WriteBatch* batch);
// Set the count for the number of entries in the batch.
static void SetCount(WriteBatch* batch, int n);
// Return the sequence number for the start of this batch.
static SequenceNumber Sequence(const WriteBatch* batch);
// Store the specified number as the sequence number for the start of
// this batch.
static void SetSequence(WriteBatch* batch, SequenceNumber seq);
static Slice Contents(const WriteBatch* batch) {
return Slice(batch->rep_);
}
static size_t ByteSize(const WriteBatch* batch) {
return batch->rep_.size();
}
static void SetContents(WriteBatch* batch, const Slice& contents);
static Status InsertInto(const WriteBatch* batch, MemTable* memtable);
static void Append(WriteBatch* dst, const WriteBatch* src);
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_WRITE_BATCH_INTERNAL_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "leveldb/db.h"
#include "db/memtable.h"
#include "db/write_batch_internal.h"
#include "leveldb/env.h"
#include "util/logging.h"
#include "util/testharness.h"
namespace leveldb {
static std::string PrintContents(WriteBatch* b) {
InternalKeyComparator cmp(BytewiseComparator());
MemTable* mem = new MemTable(cmp);
mem->Ref();
std::string state;
Status s = WriteBatchInternal::InsertInto(b, mem);
int count = 0;
Iterator* iter = mem->NewIterator();
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
ParsedInternalKey ikey;
ASSERT_TRUE(ParseInternalKey(iter->key(), &ikey));
switch (ikey.type) {
case kTypeValue:
state.append("Put(");
state.append(ikey.user_key.ToString());
state.append(", ");
state.append(iter->value().ToString());
state.append(")");
count++;
break;
case kTypeDeletion:
state.append("Delete(");
state.append(ikey.user_key.ToString());
state.append(")");
count++;
break;
}
state.append("@");
state.append(NumberToString(ikey.sequence));
}
delete iter;
if (!s.ok()) {
state.append("ParseError()");
} else if (count != WriteBatchInternal::Count(b)) {
state.append("CountMismatch()");
}
mem->Unref();
return state;
}
class WriteBatchTest { };
TEST(WriteBatchTest, Empty) {
WriteBatch batch;
ASSERT_EQ("", PrintContents(&batch));
ASSERT_EQ(0, WriteBatchInternal::Count(&batch));
}
TEST(WriteBatchTest, Multiple) {
WriteBatch batch;
batch.Put(Slice("foo"), Slice("bar"));
batch.Delete(Slice("box"));
batch.Put(Slice("baz"), Slice("boo"));
WriteBatchInternal::SetSequence(&batch, 100);
ASSERT_EQ(100, WriteBatchInternal::Sequence(&batch));
ASSERT_EQ(3, WriteBatchInternal::Count(&batch));
ASSERT_EQ("Put(baz, boo)@102"
"Delete(box)@101"
"Put(foo, bar)@100",
PrintContents(&batch));
}
TEST(WriteBatchTest, Corruption) {
WriteBatch batch;
batch.Put(Slice("foo"), Slice("bar"));
batch.Delete(Slice("box"));
WriteBatchInternal::SetSequence(&batch, 200);
Slice contents = WriteBatchInternal::Contents(&batch);
WriteBatchInternal::SetContents(&batch,
Slice(contents.data(),contents.size()-1));
ASSERT_EQ("Put(foo, bar)@200"
"ParseError()",
PrintContents(&batch));
}
TEST(WriteBatchTest, Append) {
WriteBatch b1, b2;
WriteBatchInternal::SetSequence(&b1, 200);
WriteBatchInternal::SetSequence(&b2, 300);
WriteBatchInternal::Append(&b1, &b2);
ASSERT_EQ("",
PrintContents(&b1));
b2.Put("a", "va");
WriteBatchInternal::Append(&b1, &b2);
ASSERT_EQ("Put(a, va)@200",
PrintContents(&b1));
b2.Clear();
b2.Put("b", "vb");
WriteBatchInternal::Append(&b1, &b2);
ASSERT_EQ("Put(a, va)@200"
"Put(b, vb)@201",
PrintContents(&b1));
b2.Delete("foo");
WriteBatchInternal::Append(&b1, &b2);
ASSERT_EQ("Put(a, va)@200"
"Put(b, vb)@202"
"Put(b, vb)@201"
"Delete(foo)@203",
PrintContents(&b1));
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "helpers/memenv/memenv.h"
#include "leveldb/env.h"
#include "leveldb/status.h"
#include "port/port.h"
#include "util/mutexlock.h"
#include <map>
#include <string.h>
#include <string>
#include <vector>
namespace leveldb {
namespace {
class FileState {
public:
// FileStates are reference counted. The initial reference count is zero
// and the caller must call Ref() at least once.
FileState() : refs_(0), size_(0) {}
// Increase the reference count.
void Ref() {
MutexLock lock(&refs_mutex_);
++refs_;
}
// Decrease the reference count. Delete if this is the last reference.
void Unref() {
bool do_delete = false;
{
MutexLock lock(&refs_mutex_);
--refs_;
assert(refs_ >= 0);
if (refs_ <= 0) {
do_delete = true;
}
}
if (do_delete) {
delete this;
}
}
uint64_t Size() const { return size_; }
Status Read(uint64_t offset, size_t n, Slice* result, char* scratch) const {
if (offset > size_) {
return Status::IOError("Offset greater than file size.");
}
const uint64_t available = size_ - offset;
if (n > available) {
n = static_cast<size_t>(available);
}
if (n == 0) {
*result = Slice();
return Status::OK();
}
assert(offset / kBlockSize <= SIZE_MAX);
size_t block = static_cast<size_t>(offset / kBlockSize);
size_t block_offset = offset % kBlockSize;
if (n <= kBlockSize - block_offset) {
// The requested bytes are all in the first block.
*result = Slice(blocks_[block] + block_offset, n);
return Status::OK();
}
size_t bytes_to_copy = n;
char* dst = scratch;
while (bytes_to_copy > 0) {
size_t avail = kBlockSize - block_offset;
if (avail > bytes_to_copy) {
avail = bytes_to_copy;
}
memcpy(dst, blocks_[block] + block_offset, avail);
bytes_to_copy -= avail;
dst += avail;
block++;
block_offset = 0;
}
*result = Slice(scratch, n);
return Status::OK();
}
Status Append(const Slice& data) {
const char* src = data.data();
size_t src_len = data.size();
while (src_len > 0) {
size_t avail;
size_t offset = size_ % kBlockSize;
if (offset != 0) {
// There is some room in the last block.
avail = kBlockSize - offset;
} else {
// No room in the last block; push new one.
blocks_.push_back(new char[kBlockSize]);
avail = kBlockSize;
}
if (avail > src_len) {
avail = src_len;
}
memcpy(blocks_.back() + offset, src, avail);
src_len -= avail;
src += avail;
size_ += avail;
}
return Status::OK();
}
private:
// Private since only Unref() should be used to delete it.
~FileState() {
for (std::vector<char*>::iterator i = blocks_.begin(); i != blocks_.end();
++i) {
delete [] *i;
}
}
// No copying allowed.
FileState(const FileState&);
void operator=(const FileState&);
port::Mutex refs_mutex_;
int refs_; // Protected by refs_mutex_;
// The following fields are not protected by any mutex. They are only mutable
// while the file is being written, and concurrent access is not allowed
// to writable files.
std::vector<char*> blocks_;
uint64_t size_;
enum { kBlockSize = 8 * 1024 };
};
class SequentialFileImpl : public SequentialFile {
public:
explicit SequentialFileImpl(FileState* file) : file_(file), pos_(0) {
file_->Ref();
}
~SequentialFileImpl() {
file_->Unref();
}
virtual Status Read(size_t n, Slice* result, char* scratch) {
Status s = file_->Read(pos_, n, result, scratch);
if (s.ok()) {
pos_ += result->size();
}
return s;
}
virtual Status Skip(uint64_t n) {
if (pos_ > file_->Size()) {
return Status::IOError("pos_ > file_->Size()");
}
const uint64_t available = file_->Size() - pos_;
if (n > available) {
n = available;
}
pos_ += n;
return Status::OK();
}
private:
FileState* file_;
uint64_t pos_;
};
class RandomAccessFileImpl : public RandomAccessFile {
public:
explicit RandomAccessFileImpl(FileState* file) : file_(file) {
file_->Ref();
}
~RandomAccessFileImpl() {
file_->Unref();
}
virtual Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const {
return file_->Read(offset, n, result, scratch);
}
private:
FileState* file_;
};
class WritableFileImpl : public WritableFile {
public:
WritableFileImpl(FileState* file) : file_(file) {
file_->Ref();
}
~WritableFileImpl() {
file_->Unref();
}
virtual Status Append(const Slice& data) {
return file_->Append(data);
}
virtual Status Close() { return Status::OK(); }
virtual Status Flush() { return Status::OK(); }
virtual Status Sync() { return Status::OK(); }
private:
FileState* file_;
};
class NoOpLogger : public Logger {
public:
virtual void Logv(const char* format, va_list ap) { }
};
class InMemoryEnv : public EnvWrapper {
public:
explicit InMemoryEnv(Env* base_env) : EnvWrapper(base_env) { }
virtual ~InMemoryEnv() {
for (FileSystem::iterator i = file_map_.begin(); i != file_map_.end(); ++i){
i->second->Unref();
}
}
// Partial implementation of the Env interface.
virtual Status NewSequentialFile(const std::string& fname,
SequentialFile** result) {
MutexLock lock(&mutex_);
if (file_map_.find(fname) == file_map_.end()) {
*result = NULL;
return Status::IOError(fname, "File not found");
}
*result = new SequentialFileImpl(file_map_[fname]);
return Status::OK();
}
virtual Status NewRandomAccessFile(const std::string& fname,
RandomAccessFile** result) {
MutexLock lock(&mutex_);
if (file_map_.find(fname) == file_map_.end()) {
*result = NULL;
return Status::IOError(fname, "File not found");
}
*result = new RandomAccessFileImpl(file_map_[fname]);
return Status::OK();
}
virtual Status NewWritableFile(const std::string& fname,
WritableFile** result) {
MutexLock lock(&mutex_);
if (file_map_.find(fname) != file_map_.end()) {
DeleteFileInternal(fname);
}
FileState* file = new FileState();
file->Ref();
file_map_[fname] = file;
*result = new WritableFileImpl(file);
return Status::OK();
}
virtual Status NewAppendableFile(const std::string& fname,
WritableFile** result) {
MutexLock lock(&mutex_);
FileState** sptr = &file_map_[fname];
FileState* file = *sptr;
if (file == NULL) {
file = new FileState();
file->Ref();
}
*result = new WritableFileImpl(file);
return Status::OK();
}
virtual bool FileExists(const std::string& fname) {
MutexLock lock(&mutex_);
return file_map_.find(fname) != file_map_.end();
}
virtual Status GetChildren(const std::string& dir,
std::vector<std::string>* result) {
MutexLock lock(&mutex_);
result->clear();
for (FileSystem::iterator i = file_map_.begin(); i != file_map_.end(); ++i){
const std::string& filename = i->first;
if (filename.size() >= dir.size() + 1 && filename[dir.size()] == '/' &&
Slice(filename).starts_with(Slice(dir))) {
result->push_back(filename.substr(dir.size() + 1));
}
}
return Status::OK();
}
void DeleteFileInternal(const std::string& fname) {
if (file_map_.find(fname) == file_map_.end()) {
return;
}
file_map_[fname]->Unref();
file_map_.erase(fname);
}
virtual Status DeleteFile(const std::string& fname) {
MutexLock lock(&mutex_);
if (file_map_.find(fname) == file_map_.end()) {
return Status::IOError(fname, "File not found");
}
DeleteFileInternal(fname);
return Status::OK();
}
virtual Status CreateDir(const std::string& dirname) {
return Status::OK();
}
virtual Status DeleteDir(const std::string& dirname) {
return Status::OK();
}
virtual Status GetFileSize(const std::string& fname, uint64_t* file_size) {
MutexLock lock(&mutex_);
if (file_map_.find(fname) == file_map_.end()) {
return Status::IOError(fname, "File not found");
}
*file_size = file_map_[fname]->Size();
return Status::OK();
}
virtual Status RenameFile(const std::string& src,
const std::string& target) {
MutexLock lock(&mutex_);
if (file_map_.find(src) == file_map_.end()) {
return Status::IOError(src, "File not found");
}
DeleteFileInternal(target);
file_map_[target] = file_map_[src];
file_map_.erase(src);
return Status::OK();
}
virtual Status LockFile(const std::string& fname, FileLock** lock) {
*lock = new FileLock;
return Status::OK();
}
virtual Status UnlockFile(FileLock* lock) {
delete lock;
return Status::OK();
}
virtual Status GetTestDirectory(std::string* path) {
*path = "/test";
return Status::OK();
}
virtual Status NewLogger(const std::string& fname, Logger** result) {
*result = new NoOpLogger;
return Status::OK();
}
private:
// Map from filenames to FileState objects, representing a simple file system.
typedef std::map<std::string, FileState*> FileSystem;
port::Mutex mutex_;
FileSystem file_map_; // Protected by mutex_.
};
} // namespace
Env* NewMemEnv(Env* base_env) {
return new InMemoryEnv(base_env);
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_HELPERS_MEMENV_MEMENV_H_
#define STORAGE_LEVELDB_HELPERS_MEMENV_MEMENV_H_
namespace leveldb {
class Env;
// Returns a new environment that stores its data in memory and delegates
// all non-file-storage tasks to base_env. The caller must delete the result
// when it is no longer needed.
// *base_env must remain live while the result is in use.
Env* NewMemEnv(Env* base_env);
} // namespace leveldb
#endif // STORAGE_LEVELDB_HELPERS_MEMENV_MEMENV_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "helpers/memenv/memenv.h"
#include "db/db_impl.h"
#include "leveldb/db.h"
#include "leveldb/env.h"
#include "util/testharness.h"
#include <string>
#include <vector>
namespace leveldb {
class MemEnvTest {
public:
Env* env_;
MemEnvTest()
: env_(NewMemEnv(Env::Default())) {
}
~MemEnvTest() {
delete env_;
}
};
TEST(MemEnvTest, Basics) {
uint64_t file_size;
WritableFile* writable_file;
std::vector<std::string> children;
ASSERT_OK(env_->CreateDir("/dir"));
// Check that the directory is empty.
ASSERT_TRUE(!env_->FileExists("/dir/non_existent"));
ASSERT_TRUE(!env_->GetFileSize("/dir/non_existent", &file_size).ok());
ASSERT_OK(env_->GetChildren("/dir", &children));
ASSERT_EQ(0, children.size());
// Create a file.
ASSERT_OK(env_->NewWritableFile("/dir/f", &writable_file));
ASSERT_OK(env_->GetFileSize("/dir/f", &file_size));
ASSERT_EQ(0, file_size);
delete writable_file;
// Check that the file exists.
ASSERT_TRUE(env_->FileExists("/dir/f"));
ASSERT_OK(env_->GetFileSize("/dir/f", &file_size));
ASSERT_EQ(0, file_size);
ASSERT_OK(env_->GetChildren("/dir", &children));
ASSERT_EQ(1, children.size());
ASSERT_EQ("f", children[0]);
// Write to the file.
ASSERT_OK(env_->NewWritableFile("/dir/f", &writable_file));
ASSERT_OK(writable_file->Append("abc"));
delete writable_file;
// Check that append works.
ASSERT_OK(env_->NewAppendableFile("/dir/f", &writable_file));
ASSERT_OK(env_->GetFileSize("/dir/f", &file_size));
ASSERT_EQ(3, file_size);
ASSERT_OK(writable_file->Append("hello"));
delete writable_file;
// Check for expected size.
ASSERT_OK(env_->GetFileSize("/dir/f", &file_size));
ASSERT_EQ(8, file_size);
// Check that renaming works.
ASSERT_TRUE(!env_->RenameFile("/dir/non_existent", "/dir/g").ok());
ASSERT_OK(env_->RenameFile("/dir/f", "/dir/g"));
ASSERT_TRUE(!env_->FileExists("/dir/f"));
ASSERT_TRUE(env_->FileExists("/dir/g"));
ASSERT_OK(env_->GetFileSize("/dir/g", &file_size));
ASSERT_EQ(8, file_size);
// Check that opening non-existent file fails.
SequentialFile* seq_file;
RandomAccessFile* rand_file;
ASSERT_TRUE(!env_->NewSequentialFile("/dir/non_existent", &seq_file).ok());
ASSERT_TRUE(!seq_file);
ASSERT_TRUE(!env_->NewRandomAccessFile("/dir/non_existent", &rand_file).ok());
ASSERT_TRUE(!rand_file);
// Check that deleting works.
ASSERT_TRUE(!env_->DeleteFile("/dir/non_existent").ok());
ASSERT_OK(env_->DeleteFile("/dir/g"));
ASSERT_TRUE(!env_->FileExists("/dir/g"));
ASSERT_OK(env_->GetChildren("/dir", &children));
ASSERT_EQ(0, children.size());
ASSERT_OK(env_->DeleteDir("/dir"));
}
TEST(MemEnvTest, ReadWrite) {
WritableFile* writable_file;
SequentialFile* seq_file;
RandomAccessFile* rand_file;
Slice result;
char scratch[100];
ASSERT_OK(env_->CreateDir("/dir"));
ASSERT_OK(env_->NewWritableFile("/dir/f", &writable_file));
ASSERT_OK(writable_file->Append("hello "));
ASSERT_OK(writable_file->Append("world"));
delete writable_file;
// Read sequentially.
ASSERT_OK(env_->NewSequentialFile("/dir/f", &seq_file));
ASSERT_OK(seq_file->Read(5, &result, scratch)); // Read "hello".
ASSERT_EQ(0, result.compare("hello"));
ASSERT_OK(seq_file->Skip(1));
ASSERT_OK(seq_file->Read(1000, &result, scratch)); // Read "world".
ASSERT_EQ(0, result.compare("world"));
ASSERT_OK(seq_file->Read(1000, &result, scratch)); // Try reading past EOF.
ASSERT_EQ(0, result.size());
ASSERT_OK(seq_file->Skip(100)); // Try to skip past end of file.
ASSERT_OK(seq_file->Read(1000, &result, scratch));
ASSERT_EQ(0, result.size());
delete seq_file;
// Random reads.
ASSERT_OK(env_->NewRandomAccessFile("/dir/f", &rand_file));
ASSERT_OK(rand_file->Read(6, 5, &result, scratch)); // Read "world".
ASSERT_EQ(0, result.compare("world"));
ASSERT_OK(rand_file->Read(0, 5, &result, scratch)); // Read "hello".
ASSERT_EQ(0, result.compare("hello"));
ASSERT_OK(rand_file->Read(10, 100, &result, scratch)); // Read "d".
ASSERT_EQ(0, result.compare("d"));
// Too high offset.
ASSERT_TRUE(!rand_file->Read(1000, 5, &result, scratch).ok());
delete rand_file;
}
TEST(MemEnvTest, Locks) {
FileLock* lock;
// These are no-ops, but we test they return success.
ASSERT_OK(env_->LockFile("some file", &lock));
ASSERT_OK(env_->UnlockFile(lock));
}
TEST(MemEnvTest, Misc) {
std::string test_dir;
ASSERT_OK(env_->GetTestDirectory(&test_dir));
ASSERT_TRUE(!test_dir.empty());
WritableFile* writable_file;
ASSERT_OK(env_->NewWritableFile("/a/b", &writable_file));
// These are no-ops, but we test they return success.
ASSERT_OK(writable_file->Sync());
ASSERT_OK(writable_file->Flush());
ASSERT_OK(writable_file->Close());
delete writable_file;
}
TEST(MemEnvTest, LargeWrite) {
const size_t kWriteSize = 300 * 1024;
char* scratch = new char[kWriteSize * 2];
std::string write_data;
for (size_t i = 0; i < kWriteSize; ++i) {
write_data.append(1, static_cast<char>(i));
}
WritableFile* writable_file;
ASSERT_OK(env_->NewWritableFile("/dir/f", &writable_file));
ASSERT_OK(writable_file->Append("foo"));
ASSERT_OK(writable_file->Append(write_data));
delete writable_file;
SequentialFile* seq_file;
Slice result;
ASSERT_OK(env_->NewSequentialFile("/dir/f", &seq_file));
ASSERT_OK(seq_file->Read(3, &result, scratch)); // Read "foo".
ASSERT_EQ(0, result.compare("foo"));
size_t read = 0;
std::string read_data;
while (read < kWriteSize) {
ASSERT_OK(seq_file->Read(kWriteSize - read, &result, scratch));
read_data.append(result.data(), result.size());
read += result.size();
}
ASSERT_TRUE(write_data == read_data);
delete seq_file;
delete [] scratch;
}
TEST(MemEnvTest, DBTest) {
Options options;
options.create_if_missing = true;
options.env = env_;
DB* db;
const Slice keys[] = {Slice("aaa"), Slice("bbb"), Slice("ccc")};
const Slice vals[] = {Slice("foo"), Slice("bar"), Slice("baz")};
ASSERT_OK(DB::Open(options, "/dir/db", &db));
for (size_t i = 0; i < 3; ++i) {
ASSERT_OK(db->Put(WriteOptions(), keys[i], vals[i]));
}
for (size_t i = 0; i < 3; ++i) {
std::string res;
ASSERT_OK(db->Get(ReadOptions(), keys[i], &res));
ASSERT_TRUE(res == vals[i]);
}
Iterator* iterator = db->NewIterator(ReadOptions());
iterator->SeekToFirst();
for (size_t i = 0; i < 3; ++i) {
ASSERT_TRUE(iterator->Valid());
ASSERT_TRUE(keys[i] == iterator->key());
ASSERT_TRUE(vals[i] == iterator->value());
iterator->Next();
}
ASSERT_TRUE(!iterator->Valid());
delete iterator;
DBImpl* dbi = reinterpret_cast<DBImpl*>(db);
ASSERT_OK(dbi->TEST_CompactMemTable());
for (size_t i = 0; i < 3; ++i) {
std::string res;
ASSERT_OK(db->Get(ReadOptions(), keys[i], &res));
ASSERT_TRUE(res == vals[i]);
}
delete db;
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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/* Copyright (c) 2011 The LevelDB Authors. All rights reserved.
Use of this source code is governed by a BSD-style license that can be
found in the LICENSE file. See the AUTHORS file for names of contributors.
C bindings for leveldb. May be useful as a stable ABI that can be
used by programs that keep leveldb in a shared library, or for
a JNI api.
Does not support:
. getters for the option types
. custom comparators that implement key shortening
. custom iter, db, env, cache implementations using just the C bindings
Some conventions:
(1) We expose just opaque struct pointers and functions to clients.
This allows us to change internal representations without having to
recompile clients.
(2) For simplicity, there is no equivalent to the Slice type. Instead,
the caller has to pass the pointer and length as separate
arguments.
(3) Errors are represented by a null-terminated c string. NULL
means no error. All operations that can raise an error are passed
a "char** errptr" as the last argument. One of the following must
be true on entry:
*errptr == NULL
*errptr points to a malloc()ed null-terminated error message
(On Windows, *errptr must have been malloc()-ed by this library.)
On success, a leveldb routine leaves *errptr unchanged.
On failure, leveldb frees the old value of *errptr and
set *errptr to a malloc()ed error message.
(4) Bools have the type unsigned char (0 == false; rest == true)
(5) All of the pointer arguments must be non-NULL.
*/
#ifndef STORAGE_LEVELDB_INCLUDE_C_H_
#define STORAGE_LEVELDB_INCLUDE_C_H_
#ifdef __cplusplus
extern "C" {
#endif
#include <stdarg.h>
#include <stddef.h>
#include <stdint.h>
/* Exported types */
typedef struct leveldb_t leveldb_t;
typedef struct leveldb_cache_t leveldb_cache_t;
typedef struct leveldb_comparator_t leveldb_comparator_t;
typedef struct leveldb_env_t leveldb_env_t;
typedef struct leveldb_filelock_t leveldb_filelock_t;
typedef struct leveldb_filterpolicy_t leveldb_filterpolicy_t;
typedef struct leveldb_iterator_t leveldb_iterator_t;
typedef struct leveldb_logger_t leveldb_logger_t;
typedef struct leveldb_options_t leveldb_options_t;
typedef struct leveldb_randomfile_t leveldb_randomfile_t;
typedef struct leveldb_readoptions_t leveldb_readoptions_t;
typedef struct leveldb_seqfile_t leveldb_seqfile_t;
typedef struct leveldb_snapshot_t leveldb_snapshot_t;
typedef struct leveldb_writablefile_t leveldb_writablefile_t;
typedef struct leveldb_writebatch_t leveldb_writebatch_t;
typedef struct leveldb_writeoptions_t leveldb_writeoptions_t;
/* DB operations */
extern leveldb_t* leveldb_open(
const leveldb_options_t* options,
const char* name,
char** errptr);
extern void leveldb_close(leveldb_t* db);
extern void leveldb_put(
leveldb_t* db,
const leveldb_writeoptions_t* options,
const char* key, size_t keylen,
const char* val, size_t vallen,
char** errptr);
extern void leveldb_delete(
leveldb_t* db,
const leveldb_writeoptions_t* options,
const char* key, size_t keylen,
char** errptr);
extern void leveldb_write(
leveldb_t* db,
const leveldb_writeoptions_t* options,
leveldb_writebatch_t* batch,
char** errptr);
/* Returns NULL if not found. A malloc()ed array otherwise.
Stores the length of the array in *vallen. */
extern char* leveldb_get(
leveldb_t* db,
const leveldb_readoptions_t* options,
const char* key, size_t keylen,
size_t* vallen,
char** errptr);
extern leveldb_iterator_t* leveldb_create_iterator(
leveldb_t* db,
const leveldb_readoptions_t* options);
extern const leveldb_snapshot_t* leveldb_create_snapshot(
leveldb_t* db);
extern void leveldb_release_snapshot(
leveldb_t* db,
const leveldb_snapshot_t* snapshot);
/* Returns NULL if property name is unknown.
Else returns a pointer to a malloc()-ed null-terminated value. */
extern char* leveldb_property_value(
leveldb_t* db,
const char* propname);
extern void leveldb_approximate_sizes(
leveldb_t* db,
int num_ranges,
const char* const* range_start_key, const size_t* range_start_key_len,
const char* const* range_limit_key, const size_t* range_limit_key_len,
uint64_t* sizes);
extern void leveldb_compact_range(
leveldb_t* db,
const char* start_key, size_t start_key_len,
const char* limit_key, size_t limit_key_len);
/* Management operations */
extern void leveldb_destroy_db(
const leveldb_options_t* options,
const char* name,
char** errptr);
extern void leveldb_repair_db(
const leveldb_options_t* options,
const char* name,
char** errptr);
/* Iterator */
extern void leveldb_iter_destroy(leveldb_iterator_t*);
extern unsigned char leveldb_iter_valid(const leveldb_iterator_t*);
extern void leveldb_iter_seek_to_first(leveldb_iterator_t*);
extern void leveldb_iter_seek_to_last(leveldb_iterator_t*);
extern void leveldb_iter_seek(leveldb_iterator_t*, const char* k, size_t klen);
extern void leveldb_iter_next(leveldb_iterator_t*);
extern void leveldb_iter_prev(leveldb_iterator_t*);
extern const char* leveldb_iter_key(const leveldb_iterator_t*, size_t* klen);
extern const char* leveldb_iter_value(const leveldb_iterator_t*, size_t* vlen);
extern void leveldb_iter_get_error(const leveldb_iterator_t*, char** errptr);
/* Write batch */
extern leveldb_writebatch_t* leveldb_writebatch_create();
extern void leveldb_writebatch_destroy(leveldb_writebatch_t*);
extern void leveldb_writebatch_clear(leveldb_writebatch_t*);
extern void leveldb_writebatch_put(
leveldb_writebatch_t*,
const char* key, size_t klen,
const char* val, size_t vlen);
extern void leveldb_writebatch_delete(
leveldb_writebatch_t*,
const char* key, size_t klen);
extern void leveldb_writebatch_iterate(
leveldb_writebatch_t*,
void* state,
void (*put)(void*, const char* k, size_t klen, const char* v, size_t vlen),
void (*deleted)(void*, const char* k, size_t klen));
/* Options */
extern leveldb_options_t* leveldb_options_create();
extern void leveldb_options_destroy(leveldb_options_t*);
extern void leveldb_options_set_comparator(
leveldb_options_t*,
leveldb_comparator_t*);
extern void leveldb_options_set_filter_policy(
leveldb_options_t*,
leveldb_filterpolicy_t*);
extern void leveldb_options_set_create_if_missing(
leveldb_options_t*, unsigned char);
extern void leveldb_options_set_error_if_exists(
leveldb_options_t*, unsigned char);
extern void leveldb_options_set_paranoid_checks(
leveldb_options_t*, unsigned char);
extern void leveldb_options_set_env(leveldb_options_t*, leveldb_env_t*);
extern void leveldb_options_set_info_log(leveldb_options_t*, leveldb_logger_t*);
extern void leveldb_options_set_write_buffer_size(leveldb_options_t*, size_t);
extern void leveldb_options_set_max_open_files(leveldb_options_t*, int);
extern void leveldb_options_set_cache(leveldb_options_t*, leveldb_cache_t*);
extern void leveldb_options_set_block_size(leveldb_options_t*, size_t);
extern void leveldb_options_set_block_restart_interval(leveldb_options_t*, int);
enum {
leveldb_no_compression = 0,
leveldb_snappy_compression = 1
};
extern void leveldb_options_set_compression(leveldb_options_t*, int);
/* Comparator */
extern leveldb_comparator_t* leveldb_comparator_create(
void* state,
void (*destructor)(void*),
int (*compare)(
void*,
const char* a, size_t alen,
const char* b, size_t blen),
const char* (*name)(void*));
extern void leveldb_comparator_destroy(leveldb_comparator_t*);
/* Filter policy */
extern leveldb_filterpolicy_t* leveldb_filterpolicy_create(
void* state,
void (*destructor)(void*),
char* (*create_filter)(
void*,
const char* const* key_array, const size_t* key_length_array,
int num_keys,
size_t* filter_length),
unsigned char (*key_may_match)(
void*,
const char* key, size_t length,
const char* filter, size_t filter_length),
const char* (*name)(void*));
extern void leveldb_filterpolicy_destroy(leveldb_filterpolicy_t*);
extern leveldb_filterpolicy_t* leveldb_filterpolicy_create_bloom(
int bits_per_key);
/* Read options */
extern leveldb_readoptions_t* leveldb_readoptions_create();
extern void leveldb_readoptions_destroy(leveldb_readoptions_t*);
extern void leveldb_readoptions_set_verify_checksums(
leveldb_readoptions_t*,
unsigned char);
extern void leveldb_readoptions_set_fill_cache(
leveldb_readoptions_t*, unsigned char);
extern void leveldb_readoptions_set_snapshot(
leveldb_readoptions_t*,
const leveldb_snapshot_t*);
/* Write options */
extern leveldb_writeoptions_t* leveldb_writeoptions_create();
extern void leveldb_writeoptions_destroy(leveldb_writeoptions_t*);
extern void leveldb_writeoptions_set_sync(
leveldb_writeoptions_t*, unsigned char);
/* Cache */
extern leveldb_cache_t* leveldb_cache_create_lru(size_t capacity);
extern void leveldb_cache_destroy(leveldb_cache_t* cache);
/* Env */
extern leveldb_env_t* leveldb_create_default_env();
extern void leveldb_env_destroy(leveldb_env_t*);
/* Utility */
/* Calls free(ptr).
REQUIRES: ptr was malloc()-ed and returned by one of the routines
in this file. Note that in certain cases (typically on Windows), you
may need to call this routine instead of free(ptr) to dispose of
malloc()-ed memory returned by this library. */
extern void leveldb_free(void* ptr);
/* Return the major version number for this release. */
extern int leveldb_major_version();
/* Return the minor version number for this release. */
extern int leveldb_minor_version();
#ifdef __cplusplus
} /* end extern "C" */
#endif
#endif /* STORAGE_LEVELDB_INCLUDE_C_H_ */

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// A Cache is an interface that maps keys to values. It has internal
// synchronization and may be safely accessed concurrently from
// multiple threads. It may automatically evict entries to make room
// for new entries. Values have a specified charge against the cache
// capacity. For example, a cache where the values are variable
// length strings, may use the length of the string as the charge for
// the string.
//
// A builtin cache implementation with a least-recently-used eviction
// policy is provided. Clients may use their own implementations if
// they want something more sophisticated (like scan-resistance, a
// custom eviction policy, variable cache sizing, etc.)
#ifndef STORAGE_LEVELDB_INCLUDE_CACHE_H_
#define STORAGE_LEVELDB_INCLUDE_CACHE_H_
#include <stdint.h>
#include "leveldb/slice.h"
namespace leveldb {
class Cache;
// Create a new cache with a fixed size capacity. This implementation
// of Cache uses a least-recently-used eviction policy.
extern Cache* NewLRUCache(size_t capacity);
class Cache {
public:
Cache() { }
// Destroys all existing entries by calling the "deleter"
// function that was passed to the constructor.
virtual ~Cache();
// Opaque handle to an entry stored in the cache.
struct Handle { };
// Insert a mapping from key->value into the cache and assign it
// the specified charge against the total cache capacity.
//
// Returns a handle that corresponds to the mapping. The caller
// must call this->Release(handle) when the returned mapping is no
// longer needed.
//
// When the inserted entry is no longer needed, the key and
// value will be passed to "deleter".
virtual Handle* Insert(const Slice& key, void* value, size_t charge,
void (*deleter)(const Slice& key, void* value)) = 0;
// If the cache has no mapping for "key", returns NULL.
//
// Else return a handle that corresponds to the mapping. The caller
// must call this->Release(handle) when the returned mapping is no
// longer needed.
virtual Handle* Lookup(const Slice& key) = 0;
// Release a mapping returned by a previous Lookup().
// REQUIRES: handle must not have been released yet.
// REQUIRES: handle must have been returned by a method on *this.
virtual void Release(Handle* handle) = 0;
// Return the value encapsulated in a handle returned by a
// successful Lookup().
// REQUIRES: handle must not have been released yet.
// REQUIRES: handle must have been returned by a method on *this.
virtual void* Value(Handle* handle) = 0;
// If the cache contains entry for key, erase it. Note that the
// underlying entry will be kept around until all existing handles
// to it have been released.
virtual void Erase(const Slice& key) = 0;
// Return a new numeric id. May be used by multiple clients who are
// sharing the same cache to partition the key space. Typically the
// client will allocate a new id at startup and prepend the id to
// its cache keys.
virtual uint64_t NewId() = 0;
// Remove all cache entries that are not actively in use. Memory-constrained
// applications may wish to call this method to reduce memory usage.
// Default implementation of Prune() does nothing. Subclasses are strongly
// encouraged to override the default implementation. A future release of
// leveldb may change Prune() to a pure abstract method.
virtual void Prune() {}
// Return an estimate of the combined charges of all elements stored in the
// cache.
virtual size_t TotalCharge() const = 0;
private:
void LRU_Remove(Handle* e);
void LRU_Append(Handle* e);
void Unref(Handle* e);
struct Rep;
Rep* rep_;
// No copying allowed
Cache(const Cache&);
void operator=(const Cache&);
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_CACHE_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_INCLUDE_COMPARATOR_H_
#define STORAGE_LEVELDB_INCLUDE_COMPARATOR_H_
#include <string>
namespace leveldb {
class Slice;
// A Comparator object provides a total order across slices that are
// used as keys in an sstable or a database. A Comparator implementation
// must be thread-safe since leveldb may invoke its methods concurrently
// from multiple threads.
class Comparator {
public:
virtual ~Comparator();
// Three-way comparison. Returns value:
// < 0 iff "a" < "b",
// == 0 iff "a" == "b",
// > 0 iff "a" > "b"
virtual int Compare(const Slice& a, const Slice& b) const = 0;
// The name of the comparator. Used to check for comparator
// mismatches (i.e., a DB created with one comparator is
// accessed using a different comparator.
//
// The client of this package should switch to a new name whenever
// the comparator implementation changes in a way that will cause
// the relative ordering of any two keys to change.
//
// Names starting with "leveldb." are reserved and should not be used
// by any clients of this package.
virtual const char* Name() const = 0;
// Advanced functions: these are used to reduce the space requirements
// for internal data structures like index blocks.
// If *start < limit, changes *start to a short string in [start,limit).
// Simple comparator implementations may return with *start unchanged,
// i.e., an implementation of this method that does nothing is correct.
virtual void FindShortestSeparator(
std::string* start,
const Slice& limit) const = 0;
// Changes *key to a short string >= *key.
// Simple comparator implementations may return with *key unchanged,
// i.e., an implementation of this method that does nothing is correct.
virtual void FindShortSuccessor(std::string* key) const = 0;
};
// Return a builtin comparator that uses lexicographic byte-wise
// ordering. The result remains the property of this module and
// must not be deleted.
extern const Comparator* BytewiseComparator();
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_COMPARATOR_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_INCLUDE_DB_H_
#define STORAGE_LEVELDB_INCLUDE_DB_H_
#include <stdint.h>
#include <stdio.h>
#include "leveldb/iterator.h"
#include "leveldb/options.h"
namespace leveldb {
// Update Makefile if you change these
static const int kMajorVersion = 1;
static const int kMinorVersion = 20;
struct Options;
struct ReadOptions;
struct WriteOptions;
class WriteBatch;
// Abstract handle to particular state of a DB.
// A Snapshot is an immutable object and can therefore be safely
// accessed from multiple threads without any external synchronization.
class Snapshot {
protected:
virtual ~Snapshot();
};
// A range of keys
struct Range {
Slice start; // Included in the range
Slice limit; // Not included in the range
Range() { }
Range(const Slice& s, const Slice& l) : start(s), limit(l) { }
};
// A DB is a persistent ordered map from keys to values.
// A DB is safe for concurrent access from multiple threads without
// any external synchronization.
class DB {
public:
// Open the database with the specified "name".
// Stores a pointer to a heap-allocated database in *dbptr and returns
// OK on success.
// Stores NULL in *dbptr and returns a non-OK status on error.
// Caller should delete *dbptr when it is no longer needed.
static Status Open(const Options& options,
const std::string& name,
DB** dbptr);
DB() { }
virtual ~DB();
// Set the database entry for "key" to "value". Returns OK on success,
// and a non-OK status on error.
// Note: consider setting options.sync = true.
virtual Status Put(const WriteOptions& options,
const Slice& key,
const Slice& value) = 0;
// Remove the database entry (if any) for "key". Returns OK on
// success, and a non-OK status on error. It is not an error if "key"
// did not exist in the database.
// Note: consider setting options.sync = true.
virtual Status Delete(const WriteOptions& options, const Slice& key) = 0;
// Apply the specified updates to the database.
// Returns OK on success, non-OK on failure.
// Note: consider setting options.sync = true.
virtual Status Write(const WriteOptions& options, WriteBatch* updates) = 0;
// If the database contains an entry for "key" store the
// corresponding value in *value and return OK.
//
// If there is no entry for "key" leave *value unchanged and return
// a status for which Status::IsNotFound() returns true.
//
// May return some other Status on an error.
virtual Status Get(const ReadOptions& options,
const Slice& key, std::string* value) = 0;
// Return a heap-allocated iterator over the contents of the database.
// The result of NewIterator() is initially invalid (caller must
// call one of the Seek methods on the iterator before using it).
//
// Caller should delete the iterator when it is no longer needed.
// The returned iterator should be deleted before this db is deleted.
virtual Iterator* NewIterator(const ReadOptions& options) = 0;
// Return a handle to the current DB state. Iterators created with
// this handle will all observe a stable snapshot of the current DB
// state. The caller must call ReleaseSnapshot(result) when the
// snapshot is no longer needed.
virtual const Snapshot* GetSnapshot() = 0;
// Release a previously acquired snapshot. The caller must not
// use "snapshot" after this call.
virtual void ReleaseSnapshot(const Snapshot* snapshot) = 0;
// DB implementations can export properties about their state
// via this method. If "property" is a valid property understood by this
// DB implementation, fills "*value" with its current value and returns
// true. Otherwise returns false.
//
//
// Valid property names include:
//
// "leveldb.num-files-at-level<N>" - return the number of files at level <N>,
// where <N> is an ASCII representation of a level number (e.g. "0").
// "leveldb.stats" - returns a multi-line string that describes statistics
// about the internal operation of the DB.
// "leveldb.sstables" - returns a multi-line string that describes all
// of the sstables that make up the db contents.
// "leveldb.approximate-memory-usage" - returns the approximate number of
// bytes of memory in use by the DB.
virtual bool GetProperty(const Slice& property, std::string* value) = 0;
// For each i in [0,n-1], store in "sizes[i]", the approximate
// file system space used by keys in "[range[i].start .. range[i].limit)".
//
// Note that the returned sizes measure file system space usage, so
// if the user data compresses by a factor of ten, the returned
// sizes will be one-tenth the size of the corresponding user data size.
//
// The results may not include the sizes of recently written data.
virtual void GetApproximateSizes(const Range* range, int n,
uint64_t* sizes) = 0;
// Compact the underlying storage for the key range [*begin,*end].
// In particular, deleted and overwritten versions are discarded,
// and the data is rearranged to reduce the cost of operations
// needed to access the data. This operation should typically only
// be invoked by users who understand the underlying implementation.
//
// begin==NULL is treated as a key before all keys in the database.
// end==NULL is treated as a key after all keys in the database.
// Therefore the following call will compact the entire database:
// db->CompactRange(NULL, NULL);
virtual void CompactRange(const Slice* begin, const Slice* end) = 0;
private:
// No copying allowed
DB(const DB&);
void operator=(const DB&);
};
// Destroy the contents of the specified database.
// Be very careful using this method.
Status DestroyDB(const std::string& name, const Options& options);
// If a DB cannot be opened, you may attempt to call this method to
// resurrect as much of the contents of the database as possible.
// Some data may be lost, so be careful when calling this function
// on a database that contains important information.
Status RepairDB(const std::string& dbname, const Options& options);
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_DB_H_

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// Copyright (c) 2014 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_INCLUDE_DUMPFILE_H_
#define STORAGE_LEVELDB_INCLUDE_DUMPFILE_H_
#include <string>
#include "leveldb/env.h"
#include "leveldb/status.h"
namespace leveldb {
// Dump the contents of the file named by fname in text format to
// *dst. Makes a sequence of dst->Append() calls; each call is passed
// the newline-terminated text corresponding to a single item found
// in the file.
//
// Returns a non-OK result if fname does not name a leveldb storage
// file, or if the file cannot be read.
Status DumpFile(Env* env, const std::string& fname, WritableFile* dst);
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_DUMPFILE_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// An Env is an interface used by the leveldb implementation to access
// operating system functionality like the filesystem etc. Callers
// may wish to provide a custom Env object when opening a database to
// get fine gain control; e.g., to rate limit file system operations.
//
// All Env implementations are safe for concurrent access from
// multiple threads without any external synchronization.
#ifndef STORAGE_LEVELDB_INCLUDE_ENV_H_
#define STORAGE_LEVELDB_INCLUDE_ENV_H_
#include <string>
#include <vector>
#include <stdarg.h>
#include <stdint.h>
#include "leveldb/status.h"
namespace leveldb {
class FileLock;
class Logger;
class RandomAccessFile;
class SequentialFile;
class Slice;
class WritableFile;
class Env {
public:
Env() { }
virtual ~Env();
// Return a default environment suitable for the current operating
// system. Sophisticated users may wish to provide their own Env
// implementation instead of relying on this default environment.
//
// The result of Default() belongs to leveldb and must never be deleted.
static Env* Default();
// Create a brand new sequentially-readable file with the specified name.
// On success, stores a pointer to the new file in *result and returns OK.
// On failure stores NULL in *result and returns non-OK. If the file does
// not exist, returns a non-OK status.
//
// The returned file will only be accessed by one thread at a time.
virtual Status NewSequentialFile(const std::string& fname,
SequentialFile** result) = 0;
// Create a brand new random access read-only file with the
// specified name. On success, stores a pointer to the new file in
// *result and returns OK. On failure stores NULL in *result and
// returns non-OK. If the file does not exist, returns a non-OK
// status.
//
// The returned file may be concurrently accessed by multiple threads.
virtual Status NewRandomAccessFile(const std::string& fname,
RandomAccessFile** result) = 0;
// Create an object that writes to a new file with the specified
// name. Deletes any existing file with the same name and creates a
// new file. On success, stores a pointer to the new file in
// *result and returns OK. On failure stores NULL in *result and
// returns non-OK.
//
// The returned file will only be accessed by one thread at a time.
virtual Status NewWritableFile(const std::string& fname,
WritableFile** result) = 0;
// Create an object that either appends to an existing file, or
// writes to a new file (if the file does not exist to begin with).
// On success, stores a pointer to the new file in *result and
// returns OK. On failure stores NULL in *result and returns
// non-OK.
//
// The returned file will only be accessed by one thread at a time.
//
// May return an IsNotSupportedError error if this Env does
// not allow appending to an existing file. Users of Env (including
// the leveldb implementation) must be prepared to deal with
// an Env that does not support appending.
virtual Status NewAppendableFile(const std::string& fname,
WritableFile** result);
// Returns true iff the named file exists.
virtual bool FileExists(const std::string& fname) = 0;
// Store in *result the names of the children of the specified directory.
// The names are relative to "dir".
// Original contents of *results are dropped.
virtual Status GetChildren(const std::string& dir,
std::vector<std::string>* result) = 0;
// Delete the named file.
virtual Status DeleteFile(const std::string& fname) = 0;
// Create the specified directory.
virtual Status CreateDir(const std::string& dirname) = 0;
// Delete the specified directory.
virtual Status DeleteDir(const std::string& dirname) = 0;
// Store the size of fname in *file_size.
virtual Status GetFileSize(const std::string& fname, uint64_t* file_size) = 0;
// Rename file src to target.
virtual Status RenameFile(const std::string& src,
const std::string& target) = 0;
// Lock the specified file. Used to prevent concurrent access to
// the same db by multiple processes. On failure, stores NULL in
// *lock and returns non-OK.
//
// On success, stores a pointer to the object that represents the
// acquired lock in *lock and returns OK. The caller should call
// UnlockFile(*lock) to release the lock. If the process exits,
// the lock will be automatically released.
//
// If somebody else already holds the lock, finishes immediately
// with a failure. I.e., this call does not wait for existing locks
// to go away.
//
// May create the named file if it does not already exist.
virtual Status LockFile(const std::string& fname, FileLock** lock) = 0;
// Release the lock acquired by a previous successful call to LockFile.
// REQUIRES: lock was returned by a successful LockFile() call
// REQUIRES: lock has not already been unlocked.
virtual Status UnlockFile(FileLock* lock) = 0;
// Arrange to run "(*function)(arg)" once in a background thread.
//
// "function" may run in an unspecified thread. Multiple functions
// added to the same Env may run concurrently in different threads.
// I.e., the caller may not assume that background work items are
// serialized.
virtual void Schedule(
void (*function)(void* arg),
void* arg) = 0;
// Start a new thread, invoking "function(arg)" within the new thread.
// When "function(arg)" returns, the thread will be destroyed.
virtual void StartThread(void (*function)(void* arg), void* arg) = 0;
// *path is set to a temporary directory that can be used for testing. It may
// or many not have just been created. The directory may or may not differ
// between runs of the same process, but subsequent calls will return the
// same directory.
virtual Status GetTestDirectory(std::string* path) = 0;
// Create and return a log file for storing informational messages.
virtual Status NewLogger(const std::string& fname, Logger** result) = 0;
// Returns the number of micro-seconds since some fixed point in time. Only
// useful for computing deltas of time.
virtual uint64_t NowMicros() = 0;
// Sleep/delay the thread for the prescribed number of micro-seconds.
virtual void SleepForMicroseconds(int micros) = 0;
private:
// No copying allowed
Env(const Env&);
void operator=(const Env&);
};
// A file abstraction for reading sequentially through a file
class SequentialFile {
public:
SequentialFile() { }
virtual ~SequentialFile();
// Read up to "n" bytes from the file. "scratch[0..n-1]" may be
// written by this routine. Sets "*result" to the data that was
// read (including if fewer than "n" bytes were successfully read).
// May set "*result" to point at data in "scratch[0..n-1]", so
// "scratch[0..n-1]" must be live when "*result" is used.
// If an error was encountered, returns a non-OK status.
//
// REQUIRES: External synchronization
virtual Status Read(size_t n, Slice* result, char* scratch) = 0;
// Skip "n" bytes from the file. This is guaranteed to be no
// slower that reading the same data, but may be faster.
//
// If end of file is reached, skipping will stop at the end of the
// file, and Skip will return OK.
//
// REQUIRES: External synchronization
virtual Status Skip(uint64_t n) = 0;
private:
// No copying allowed
SequentialFile(const SequentialFile&);
void operator=(const SequentialFile&);
};
// A file abstraction for randomly reading the contents of a file.
class RandomAccessFile {
public:
RandomAccessFile() { }
virtual ~RandomAccessFile();
// Read up to "n" bytes from the file starting at "offset".
// "scratch[0..n-1]" may be written by this routine. Sets "*result"
// to the data that was read (including if fewer than "n" bytes were
// successfully read). May set "*result" to point at data in
// "scratch[0..n-1]", so "scratch[0..n-1]" must be live when
// "*result" is used. If an error was encountered, returns a non-OK
// status.
//
// Safe for concurrent use by multiple threads.
virtual Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const = 0;
private:
// No copying allowed
RandomAccessFile(const RandomAccessFile&);
void operator=(const RandomAccessFile&);
};
// A file abstraction for sequential writing. The implementation
// must provide buffering since callers may append small fragments
// at a time to the file.
class WritableFile {
public:
WritableFile() { }
virtual ~WritableFile();
virtual Status Append(const Slice& data) = 0;
virtual Status Close() = 0;
virtual Status Flush() = 0;
virtual Status Sync() = 0;
private:
// No copying allowed
WritableFile(const WritableFile&);
void operator=(const WritableFile&);
};
// An interface for writing log messages.
class Logger {
public:
Logger() { }
virtual ~Logger();
// Write an entry to the log file with the specified format.
virtual void Logv(const char* format, va_list ap) = 0;
private:
// No copying allowed
Logger(const Logger&);
void operator=(const Logger&);
};
// Identifies a locked file.
class FileLock {
public:
FileLock() { }
virtual ~FileLock();
private:
// No copying allowed
FileLock(const FileLock&);
void operator=(const FileLock&);
};
// Log the specified data to *info_log if info_log is non-NULL.
extern void Log(Logger* info_log, const char* format, ...)
# if defined(__GNUC__) || defined(__clang__)
__attribute__((__format__ (__printf__, 2, 3)))
# endif
;
// A utility routine: write "data" to the named file.
extern Status WriteStringToFile(Env* env, const Slice& data,
const std::string& fname);
// A utility routine: read contents of named file into *data
extern Status ReadFileToString(Env* env, const std::string& fname,
std::string* data);
// An implementation of Env that forwards all calls to another Env.
// May be useful to clients who wish to override just part of the
// functionality of another Env.
class EnvWrapper : public Env {
public:
// Initialize an EnvWrapper that delegates all calls to *t
explicit EnvWrapper(Env* t) : target_(t) { }
virtual ~EnvWrapper();
// Return the target to which this Env forwards all calls
Env* target() const { return target_; }
// The following text is boilerplate that forwards all methods to target()
Status NewSequentialFile(const std::string& f, SequentialFile** r) {
return target_->NewSequentialFile(f, r);
}
Status NewRandomAccessFile(const std::string& f, RandomAccessFile** r) {
return target_->NewRandomAccessFile(f, r);
}
Status NewWritableFile(const std::string& f, WritableFile** r) {
return target_->NewWritableFile(f, r);
}
Status NewAppendableFile(const std::string& f, WritableFile** r) {
return target_->NewAppendableFile(f, r);
}
bool FileExists(const std::string& f) { return target_->FileExists(f); }
Status GetChildren(const std::string& dir, std::vector<std::string>* r) {
return target_->GetChildren(dir, r);
}
Status DeleteFile(const std::string& f) { return target_->DeleteFile(f); }
Status CreateDir(const std::string& d) { return target_->CreateDir(d); }
Status DeleteDir(const std::string& d) { return target_->DeleteDir(d); }
Status GetFileSize(const std::string& f, uint64_t* s) {
return target_->GetFileSize(f, s);
}
Status RenameFile(const std::string& s, const std::string& t) {
return target_->RenameFile(s, t);
}
Status LockFile(const std::string& f, FileLock** l) {
return target_->LockFile(f, l);
}
Status UnlockFile(FileLock* l) { return target_->UnlockFile(l); }
void Schedule(void (*f)(void*), void* a) {
return target_->Schedule(f, a);
}
void StartThread(void (*f)(void*), void* a) {
return target_->StartThread(f, a);
}
virtual Status GetTestDirectory(std::string* path) {
return target_->GetTestDirectory(path);
}
virtual Status NewLogger(const std::string& fname, Logger** result) {
return target_->NewLogger(fname, result);
}
uint64_t NowMicros() {
return target_->NowMicros();
}
void SleepForMicroseconds(int micros) {
target_->SleepForMicroseconds(micros);
}
private:
Env* target_;
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_ENV_H_

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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// A database can be configured with a custom FilterPolicy object.
// This object is responsible for creating a small filter from a set
// of keys. These filters are stored in leveldb and are consulted
// automatically by leveldb to decide whether or not to read some
// information from disk. In many cases, a filter can cut down the
// number of disk seeks form a handful to a single disk seek per
// DB::Get() call.
//
// Most people will want to use the builtin bloom filter support (see
// NewBloomFilterPolicy() below).
#ifndef STORAGE_LEVELDB_INCLUDE_FILTER_POLICY_H_
#define STORAGE_LEVELDB_INCLUDE_FILTER_POLICY_H_
#include <string>
namespace leveldb {
class Slice;
class FilterPolicy {
public:
virtual ~FilterPolicy();
// Return the name of this policy. Note that if the filter encoding
// changes in an incompatible way, the name returned by this method
// must be changed. Otherwise, old incompatible filters may be
// passed to methods of this type.
virtual const char* Name() const = 0;
// keys[0,n-1] contains a list of keys (potentially with duplicates)
// that are ordered according to the user supplied comparator.
// Append a filter that summarizes keys[0,n-1] to *dst.
//
// Warning: do not change the initial contents of *dst. Instead,
// append the newly constructed filter to *dst.
virtual void CreateFilter(const Slice* keys, int n, std::string* dst)
const = 0;
// "filter" contains the data appended by a preceding call to
// CreateFilter() on this class. This method must return true if
// the key was in the list of keys passed to CreateFilter().
// This method may return true or false if the key was not on the
// list, but it should aim to return false with a high probability.
virtual bool KeyMayMatch(const Slice& key, const Slice& filter) const = 0;
};
// Return a new filter policy that uses a bloom filter with approximately
// the specified number of bits per key. A good value for bits_per_key
// is 10, which yields a filter with ~ 1% false positive rate.
//
// Callers must delete the result after any database that is using the
// result has been closed.
//
// Note: if you are using a custom comparator that ignores some parts
// of the keys being compared, you must not use NewBloomFilterPolicy()
// and must provide your own FilterPolicy that also ignores the
// corresponding parts of the keys. For example, if the comparator
// ignores trailing spaces, it would be incorrect to use a
// FilterPolicy (like NewBloomFilterPolicy) that does not ignore
// trailing spaces in keys.
extern const FilterPolicy* NewBloomFilterPolicy(int bits_per_key);
}
#endif // STORAGE_LEVELDB_INCLUDE_FILTER_POLICY_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// An iterator yields a sequence of key/value pairs from a source.
// The following class defines the interface. Multiple implementations
// are provided by this library. In particular, iterators are provided
// to access the contents of a Table or a DB.
//
// Multiple threads can invoke const methods on an Iterator without
// external synchronization, but if any of the threads may call a
// non-const method, all threads accessing the same Iterator must use
// external synchronization.
#ifndef STORAGE_LEVELDB_INCLUDE_ITERATOR_H_
#define STORAGE_LEVELDB_INCLUDE_ITERATOR_H_
#include "leveldb/slice.h"
#include "leveldb/status.h"
namespace leveldb {
class Iterator {
public:
Iterator();
virtual ~Iterator();
// An iterator is either positioned at a key/value pair, or
// not valid. This method returns true iff the iterator is valid.
virtual bool Valid() const = 0;
// Position at the first key in the source. The iterator is Valid()
// after this call iff the source is not empty.
virtual void SeekToFirst() = 0;
// Position at the last key in the source. The iterator is
// Valid() after this call iff the source is not empty.
virtual void SeekToLast() = 0;
// Position at the first key in the source that is at or past target.
// The iterator is Valid() after this call iff the source contains
// an entry that comes at or past target.
virtual void Seek(const Slice& target) = 0;
// Moves to the next entry in the source. After this call, Valid() is
// true iff the iterator was not positioned at the last entry in the source.
// REQUIRES: Valid()
virtual void Next() = 0;
// Moves to the previous entry in the source. After this call, Valid() is
// true iff the iterator was not positioned at the first entry in source.
// REQUIRES: Valid()
virtual void Prev() = 0;
// Return the key for the current entry. The underlying storage for
// the returned slice is valid only until the next modification of
// the iterator.
// REQUIRES: Valid()
virtual Slice key() const = 0;
// Return the value for the current entry. The underlying storage for
// the returned slice is valid only until the next modification of
// the iterator.
// REQUIRES: Valid()
virtual Slice value() const = 0;
// If an error has occurred, return it. Else return an ok status.
virtual Status status() const = 0;
// Clients are allowed to register function/arg1/arg2 triples that
// will be invoked when this iterator is destroyed.
//
// Note that unlike all of the preceding methods, this method is
// not abstract and therefore clients should not override it.
typedef void (*CleanupFunction)(void* arg1, void* arg2);
void RegisterCleanup(CleanupFunction function, void* arg1, void* arg2);
private:
struct Cleanup {
CleanupFunction function;
void* arg1;
void* arg2;
Cleanup* next;
};
Cleanup cleanup_;
// No copying allowed
Iterator(const Iterator&);
void operator=(const Iterator&);
};
// Return an empty iterator (yields nothing).
extern Iterator* NewEmptyIterator();
// Return an empty iterator with the specified status.
extern Iterator* NewErrorIterator(const Status& status);
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_ITERATOR_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_INCLUDE_OPTIONS_H_
#define STORAGE_LEVELDB_INCLUDE_OPTIONS_H_
#include <stddef.h>
namespace leveldb {
class Cache;
class Comparator;
class Env;
class FilterPolicy;
class Logger;
class Snapshot;
// DB contents are stored in a set of blocks, each of which holds a
// sequence of key,value pairs. Each block may be compressed before
// being stored in a file. The following enum describes which
// compression method (if any) is used to compress a block.
enum CompressionType {
// NOTE: do not change the values of existing entries, as these are
// part of the persistent format on disk.
kNoCompression = 0x0,
kSnappyCompression = 0x1
};
// Options to control the behavior of a database (passed to DB::Open)
struct Options {
// -------------------
// Parameters that affect behavior
// Comparator used to define the order of keys in the table.
// Default: a comparator that uses lexicographic byte-wise ordering
//
// REQUIRES: The client must ensure that the comparator supplied
// here has the same name and orders keys *exactly* the same as the
// comparator provided to previous open calls on the same DB.
const Comparator* comparator;
// If true, the database will be created if it is missing.
// Default: false
bool create_if_missing;
// If true, an error is raised if the database already exists.
// Default: false
bool error_if_exists;
// If true, the implementation will do aggressive checking of the
// data it is processing and will stop early if it detects any
// errors. This may have unforeseen ramifications: for example, a
// corruption of one DB entry may cause a large number of entries to
// become unreadable or for the entire DB to become unopenable.
// Default: false
bool paranoid_checks;
// Use the specified object to interact with the environment,
// e.g. to read/write files, schedule background work, etc.
// Default: Env::Default()
Env* env;
// Any internal progress/error information generated by the db will
// be written to info_log if it is non-NULL, or to a file stored
// in the same directory as the DB contents if info_log is NULL.
// Default: NULL
Logger* info_log;
// -------------------
// Parameters that affect performance
// Amount of data to build up in memory (backed by an unsorted log
// on disk) before converting to a sorted on-disk file.
//
// Larger values increase performance, especially during bulk loads.
// Up to two write buffers may be held in memory at the same time,
// so you may wish to adjust this parameter to control memory usage.
// Also, a larger write buffer will result in a longer recovery time
// the next time the database is opened.
//
// Default: 4MB
size_t write_buffer_size;
// Number of open files that can be used by the DB. You may need to
// increase this if your database has a large working set (budget
// one open file per 2MB of working set).
//
// Default: 1000
int max_open_files;
// Control over blocks (user data is stored in a set of blocks, and
// a block is the unit of reading from disk).
// If non-NULL, use the specified cache for blocks.
// If NULL, leveldb will automatically create and use an 8MB internal cache.
// Default: NULL
Cache* block_cache;
// Approximate size of user data packed per block. Note that the
// block size specified here corresponds to uncompressed data. The
// actual size of the unit read from disk may be smaller if
// compression is enabled. This parameter can be changed dynamically.
//
// Default: 4K
size_t block_size;
// Number of keys between restart points for delta encoding of keys.
// This parameter can be changed dynamically. Most clients should
// leave this parameter alone.
//
// Default: 16
int block_restart_interval;
// Leveldb will write up to this amount of bytes to a file before
// switching to a new one.
// Most clients should leave this parameter alone. However if your
// filesystem is more efficient with larger files, you could
// consider increasing the value. The downside will be longer
// compactions and hence longer latency/performance hiccups.
// Another reason to increase this parameter might be when you are
// initially populating a large database.
//
// Default: 2MB
size_t max_file_size;
// Compress blocks using the specified compression algorithm. This
// parameter can be changed dynamically.
//
// Default: kSnappyCompression, which gives lightweight but fast
// compression.
//
// Typical speeds of kSnappyCompression on an Intel(R) Core(TM)2 2.4GHz:
// ~200-500MB/s compression
// ~400-800MB/s decompression
// Note that these speeds are significantly faster than most
// persistent storage speeds, and therefore it is typically never
// worth switching to kNoCompression. Even if the input data is
// incompressible, the kSnappyCompression implementation will
// efficiently detect that and will switch to uncompressed mode.
CompressionType compression;
// EXPERIMENTAL: If true, append to existing MANIFEST and log files
// when a database is opened. This can significantly speed up open.
//
// Default: currently false, but may become true later.
bool reuse_logs;
// If non-NULL, use the specified filter policy to reduce disk reads.
// Many applications will benefit from passing the result of
// NewBloomFilterPolicy() here.
//
// Default: NULL
const FilterPolicy* filter_policy;
// Create an Options object with default values for all fields.
Options();
};
// Options that control read operations
struct ReadOptions {
// If true, all data read from underlying storage will be
// verified against corresponding checksums.
// Default: false
bool verify_checksums;
// Should the data read for this iteration be cached in memory?
// Callers may wish to set this field to false for bulk scans.
// Default: true
bool fill_cache;
// If "snapshot" is non-NULL, read as of the supplied snapshot
// (which must belong to the DB that is being read and which must
// not have been released). If "snapshot" is NULL, use an implicit
// snapshot of the state at the beginning of this read operation.
// Default: NULL
const Snapshot* snapshot;
ReadOptions()
: verify_checksums(false),
fill_cache(true),
snapshot(NULL) {
}
};
// Options that control write operations
struct WriteOptions {
// If true, the write will be flushed from the operating system
// buffer cache (by calling WritableFile::Sync()) before the write
// is considered complete. If this flag is true, writes will be
// slower.
//
// If this flag is false, and the machine crashes, some recent
// writes may be lost. Note that if it is just the process that
// crashes (i.e., the machine does not reboot), no writes will be
// lost even if sync==false.
//
// In other words, a DB write with sync==false has similar
// crash semantics as the "write()" system call. A DB write
// with sync==true has similar crash semantics to a "write()"
// system call followed by "fsync()".
//
// Default: false
bool sync;
WriteOptions()
: sync(false) {
}
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_OPTIONS_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// Slice is a simple structure containing a pointer into some external
// storage and a size. The user of a Slice must ensure that the slice
// is not used after the corresponding external storage has been
// deallocated.
//
// Multiple threads can invoke const methods on a Slice without
// external synchronization, but if any of the threads may call a
// non-const method, all threads accessing the same Slice must use
// external synchronization.
#ifndef STORAGE_LEVELDB_INCLUDE_SLICE_H_
#define STORAGE_LEVELDB_INCLUDE_SLICE_H_
#include <assert.h>
#include <stddef.h>
#include <string.h>
#include <string>
namespace leveldb {
class Slice {
public:
// Create an empty slice.
Slice() : data_(""), size_(0) { }
// Create a slice that refers to d[0,n-1].
Slice(const char* d, size_t n) : data_(d), size_(n) { }
// Create a slice that refers to the contents of "s"
Slice(const std::string& s) : data_(s.data()), size_(s.size()) { }
// Create a slice that refers to s[0,strlen(s)-1]
Slice(const char* s) : data_(s), size_(strlen(s)) { }
// Return a pointer to the beginning of the referenced data
const char* data() const { return data_; }
// Return the length (in bytes) of the referenced data
size_t size() const { return size_; }
// Return true iff the length of the referenced data is zero
bool empty() const { return size_ == 0; }
// Return the ith byte in the referenced data.
// REQUIRES: n < size()
char operator[](size_t n) const {
assert(n < size());
return data_[n];
}
// Change this slice to refer to an empty array
void clear() { data_ = ""; size_ = 0; }
// Drop the first "n" bytes from this slice.
void remove_prefix(size_t n) {
assert(n <= size());
data_ += n;
size_ -= n;
}
// Return a string that contains the copy of the referenced data.
std::string ToString() const { return std::string(data_, size_); }
// Three-way comparison. Returns value:
// < 0 iff "*this" < "b",
// == 0 iff "*this" == "b",
// > 0 iff "*this" > "b"
int compare(const Slice& b) const;
// Return true iff "x" is a prefix of "*this"
bool starts_with(const Slice& x) const {
return ((size_ >= x.size_) &&
(memcmp(data_, x.data_, x.size_) == 0));
}
private:
const char* data_;
size_t size_;
// Intentionally copyable
};
inline bool operator==(const Slice& x, const Slice& y) {
return ((x.size() == y.size()) &&
(memcmp(x.data(), y.data(), x.size()) == 0));
}
inline bool operator!=(const Slice& x, const Slice& y) {
return !(x == y);
}
inline int Slice::compare(const Slice& b) const {
const size_t min_len = (size_ < b.size_) ? size_ : b.size_;
int r = memcmp(data_, b.data_, min_len);
if (r == 0) {
if (size_ < b.size_) r = -1;
else if (size_ > b.size_) r = +1;
}
return r;
}
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_SLICE_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// A Status encapsulates the result of an operation. It may indicate success,
// or it may indicate an error with an associated error message.
//
// Multiple threads can invoke const methods on a Status without
// external synchronization, but if any of the threads may call a
// non-const method, all threads accessing the same Status must use
// external synchronization.
#ifndef STORAGE_LEVELDB_INCLUDE_STATUS_H_
#define STORAGE_LEVELDB_INCLUDE_STATUS_H_
#include <string>
#include "leveldb/slice.h"
namespace leveldb {
class Status {
public:
// Create a success status.
Status() : state_(NULL) { }
~Status() { delete[] state_; }
// Copy the specified status.
Status(const Status& s);
void operator=(const Status& s);
// Return a success status.
static Status OK() { return Status(); }
// Return error status of an appropriate type.
static Status NotFound(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kNotFound, msg, msg2);
}
static Status Corruption(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kCorruption, msg, msg2);
}
static Status NotSupported(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kNotSupported, msg, msg2);
}
static Status InvalidArgument(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kInvalidArgument, msg, msg2);
}
static Status IOError(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kIOError, msg, msg2);
}
// Returns true iff the status indicates success.
bool ok() const { return (state_ == NULL); }
// Returns true iff the status indicates a NotFound error.
bool IsNotFound() const { return code() == kNotFound; }
// Returns true iff the status indicates a Corruption error.
bool IsCorruption() const { return code() == kCorruption; }
// Returns true iff the status indicates an IOError.
bool IsIOError() const { return code() == kIOError; }
// Returns true iff the status indicates a NotSupportedError.
bool IsNotSupportedError() const { return code() == kNotSupported; }
// Returns true iff the status indicates an InvalidArgument.
bool IsInvalidArgument() const { return code() == kInvalidArgument; }
// Return a string representation of this status suitable for printing.
// Returns the string "OK" for success.
std::string ToString() const;
private:
// OK status has a NULL state_. Otherwise, state_ is a new[] array
// of the following form:
// state_[0..3] == length of message
// state_[4] == code
// state_[5..] == message
const char* state_;
enum Code {
kOk = 0,
kNotFound = 1,
kCorruption = 2,
kNotSupported = 3,
kInvalidArgument = 4,
kIOError = 5
};
Code code() const {
return (state_ == NULL) ? kOk : static_cast<Code>(state_[4]);
}
Status(Code code, const Slice& msg, const Slice& msg2);
static const char* CopyState(const char* s);
};
inline Status::Status(const Status& s) {
state_ = (s.state_ == NULL) ? NULL : CopyState(s.state_);
}
inline void Status::operator=(const Status& s) {
// The following condition catches both aliasing (when this == &s),
// and the common case where both s and *this are ok.
if (state_ != s.state_) {
delete[] state_;
state_ = (s.state_ == NULL) ? NULL : CopyState(s.state_);
}
}
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_STATUS_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_INCLUDE_TABLE_H_
#define STORAGE_LEVELDB_INCLUDE_TABLE_H_
#include <stdint.h>
#include "leveldb/iterator.h"
namespace leveldb {
class Block;
class BlockHandle;
class Footer;
struct Options;
class RandomAccessFile;
struct ReadOptions;
class TableCache;
// A Table is a sorted map from strings to strings. Tables are
// immutable and persistent. A Table may be safely accessed from
// multiple threads without external synchronization.
class Table {
public:
// Attempt to open the table that is stored in bytes [0..file_size)
// of "file", and read the metadata entries necessary to allow
// retrieving data from the table.
//
// If successful, returns ok and sets "*table" to the newly opened
// table. The client should delete "*table" when no longer needed.
// If there was an error while initializing the table, sets "*table"
// to NULL and returns a non-ok status. Does not take ownership of
// "*source", but the client must ensure that "source" remains live
// for the duration of the returned table's lifetime.
//
// *file must remain live while this Table is in use.
static Status Open(const Options& options,
RandomAccessFile* file,
uint64_t file_size,
Table** table);
~Table();
// Returns a new iterator over the table contents.
// The result of NewIterator() is initially invalid (caller must
// call one of the Seek methods on the iterator before using it).
Iterator* NewIterator(const ReadOptions&) const;
// Given a key, return an approximate byte offset in the file where
// the data for that key begins (or would begin if the key were
// present in the file). The returned value is in terms of file
// bytes, and so includes effects like compression of the underlying data.
// E.g., the approximate offset of the last key in the table will
// be close to the file length.
uint64_t ApproximateOffsetOf(const Slice& key) const;
private:
struct Rep;
Rep* rep_;
explicit Table(Rep* rep) { rep_ = rep; }
static Iterator* BlockReader(void*, const ReadOptions&, const Slice&);
// Calls (*handle_result)(arg, ...) with the entry found after a call
// to Seek(key). May not make such a call if filter policy says
// that key is not present.
friend class TableCache;
Status InternalGet(
const ReadOptions&, const Slice& key,
void* arg,
void (*handle_result)(void* arg, const Slice& k, const Slice& v));
void ReadMeta(const Footer& footer);
void ReadFilter(const Slice& filter_handle_value);
// No copying allowed
Table(const Table&);
void operator=(const Table&);
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_TABLE_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// TableBuilder provides the interface used to build a Table
// (an immutable and sorted map from keys to values).
//
// Multiple threads can invoke const methods on a TableBuilder without
// external synchronization, but if any of the threads may call a
// non-const method, all threads accessing the same TableBuilder must use
// external synchronization.
#ifndef STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_
#define STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_
#include <stdint.h>
#include "leveldb/options.h"
#include "leveldb/status.h"
namespace leveldb {
class BlockBuilder;
class BlockHandle;
class WritableFile;
class TableBuilder {
public:
// Create a builder that will store the contents of the table it is
// building in *file. Does not close the file. It is up to the
// caller to close the file after calling Finish().
TableBuilder(const Options& options, WritableFile* file);
// REQUIRES: Either Finish() or Abandon() has been called.
~TableBuilder();
// Change the options used by this builder. Note: only some of the
// option fields can be changed after construction. If a field is
// not allowed to change dynamically and its value in the structure
// passed to the constructor is different from its value in the
// structure passed to this method, this method will return an error
// without changing any fields.
Status ChangeOptions(const Options& options);
// Add key,value to the table being constructed.
// REQUIRES: key is after any previously added key according to comparator.
// REQUIRES: Finish(), Abandon() have not been called
void Add(const Slice& key, const Slice& value);
// Advanced operation: flush any buffered key/value pairs to file.
// Can be used to ensure that two adjacent entries never live in
// the same data block. Most clients should not need to use this method.
// REQUIRES: Finish(), Abandon() have not been called
void Flush();
// Return non-ok iff some error has been detected.
Status status() const;
// Finish building the table. Stops using the file passed to the
// constructor after this function returns.
// REQUIRES: Finish(), Abandon() have not been called
Status Finish();
// Indicate that the contents of this builder should be abandoned. Stops
// using the file passed to the constructor after this function returns.
// If the caller is not going to call Finish(), it must call Abandon()
// before destroying this builder.
// REQUIRES: Finish(), Abandon() have not been called
void Abandon();
// Number of calls to Add() so far.
uint64_t NumEntries() const;
// Size of the file generated so far. If invoked after a successful
// Finish() call, returns the size of the final generated file.
uint64_t FileSize() const;
private:
bool ok() const { return status().ok(); }
void WriteBlock(BlockBuilder* block, BlockHandle* handle);
void WriteRawBlock(const Slice& data, CompressionType, BlockHandle* handle);
struct Rep;
Rep* rep_;
// No copying allowed
TableBuilder(const TableBuilder&);
void operator=(const TableBuilder&);
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// WriteBatch holds a collection of updates to apply atomically to a DB.
//
// The updates are applied in the order in which they are added
// to the WriteBatch. For example, the value of "key" will be "v3"
// after the following batch is written:
//
// batch.Put("key", "v1");
// batch.Delete("key");
// batch.Put("key", "v2");
// batch.Put("key", "v3");
//
// Multiple threads can invoke const methods on a WriteBatch without
// external synchronization, but if any of the threads may call a
// non-const method, all threads accessing the same WriteBatch must use
// external synchronization.
#ifndef STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_
#define STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_
#include <string>
#include "leveldb/status.h"
namespace leveldb {
class Slice;
class WriteBatch {
public:
WriteBatch();
~WriteBatch();
// Store the mapping "key->value" in the database.
void Put(const Slice& key, const Slice& value);
// If the database contains a mapping for "key", erase it. Else do nothing.
void Delete(const Slice& key);
// Clear all updates buffered in this batch.
void Clear();
// Support for iterating over the contents of a batch.
class Handler {
public:
virtual ~Handler();
virtual void Put(const Slice& key, const Slice& value) = 0;
virtual void Delete(const Slice& key) = 0;
};
Status Iterate(Handler* handler) const;
private:
friend class WriteBatchInternal;
std::string rep_; // See comment in write_batch.cc for the format of rep_
// Intentionally copyable
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_

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// Copyright (c) 2013 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
// Test for issue 178: a manual compaction causes deleted data to reappear.
#include <iostream>
#include <sstream>
#include <cstdlib>
#include "leveldb/db.h"
#include "leveldb/write_batch.h"
#include "util/testharness.h"
namespace {
const int kNumKeys = 1100000;
std::string Key1(int i) {
char buf[100];
snprintf(buf, sizeof(buf), "my_key_%d", i);
return buf;
}
std::string Key2(int i) {
return Key1(i) + "_xxx";
}
class Issue178 { };
TEST(Issue178, Test) {
// Get rid of any state from an old run.
std::string dbpath = leveldb::test::TmpDir() + "/leveldb_cbug_test";
DestroyDB(dbpath, leveldb::Options());
// Open database. Disable compression since it affects the creation
// of layers and the code below is trying to test against a very
// specific scenario.
leveldb::DB* db;
leveldb::Options db_options;
db_options.create_if_missing = true;
db_options.compression = leveldb::kNoCompression;
ASSERT_OK(leveldb::DB::Open(db_options, dbpath, &db));
// create first key range
leveldb::WriteBatch batch;
for (size_t i = 0; i < kNumKeys; i++) {
batch.Put(Key1(i), "value for range 1 key");
}
ASSERT_OK(db->Write(leveldb::WriteOptions(), &batch));
// create second key range
batch.Clear();
for (size_t i = 0; i < kNumKeys; i++) {
batch.Put(Key2(i), "value for range 2 key");
}
ASSERT_OK(db->Write(leveldb::WriteOptions(), &batch));
// delete second key range
batch.Clear();
for (size_t i = 0; i < kNumKeys; i++) {
batch.Delete(Key2(i));
}
ASSERT_OK(db->Write(leveldb::WriteOptions(), &batch));
// compact database
std::string start_key = Key1(0);
std::string end_key = Key1(kNumKeys - 1);
leveldb::Slice least(start_key.data(), start_key.size());
leveldb::Slice greatest(end_key.data(), end_key.size());
// commenting out the line below causes the example to work correctly
db->CompactRange(&least, &greatest);
// count the keys
leveldb::Iterator* iter = db->NewIterator(leveldb::ReadOptions());
size_t num_keys = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
num_keys++;
}
delete iter;
ASSERT_EQ(kNumKeys, num_keys) << "Bad number of keys";
// close database
delete db;
DestroyDB(dbpath, leveldb::Options());
}
} // anonymous namespace
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2013 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
// Test for issue 200: when iterator switches direction from backward
// to forward, the current key can be yielded unexpectedly if a new
// mutation has been added just before the current key.
#include "leveldb/db.h"
#include "util/testharness.h"
namespace leveldb {
class Issue200 { };
TEST(Issue200, Test) {
// Get rid of any state from an old run.
std::string dbpath = test::TmpDir() + "/leveldb_issue200_test";
DestroyDB(dbpath, Options());
DB *db;
Options options;
options.create_if_missing = true;
ASSERT_OK(DB::Open(options, dbpath, &db));
WriteOptions write_options;
ASSERT_OK(db->Put(write_options, "1", "b"));
ASSERT_OK(db->Put(write_options, "2", "c"));
ASSERT_OK(db->Put(write_options, "3", "d"));
ASSERT_OK(db->Put(write_options, "4", "e"));
ASSERT_OK(db->Put(write_options, "5", "f"));
ReadOptions read_options;
Iterator *iter = db->NewIterator(read_options);
// Add an element that should not be reflected in the iterator.
ASSERT_OK(db->Put(write_options, "25", "cd"));
iter->Seek("5");
ASSERT_EQ(iter->key().ToString(), "5");
iter->Prev();
ASSERT_EQ(iter->key().ToString(), "4");
iter->Prev();
ASSERT_EQ(iter->key().ToString(), "3");
iter->Next();
ASSERT_EQ(iter->key().ToString(), "4");
iter->Next();
ASSERT_EQ(iter->key().ToString(), "5");
delete iter;
delete db;
DestroyDB(dbpath, options);
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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This directory contains interfaces and implementations that isolate the
rest of the package from platform details.
Code in the rest of the package includes "port.h" from this directory.
"port.h" in turn includes a platform specific "port_<platform>.h" file
that provides the platform specific implementation.
See port_posix.h for an example of what must be provided in a platform
specific header file.

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
// AtomicPointer provides storage for a lock-free pointer.
// Platform-dependent implementation of AtomicPointer:
// - If the platform provides a cheap barrier, we use it with raw pointers
// - If <atomic> is present (on newer versions of gcc, it is), we use
// a <atomic>-based AtomicPointer. However we prefer the memory
// barrier based version, because at least on a gcc 4.4 32-bit build
// on linux, we have encountered a buggy <atomic> implementation.
// Also, some <atomic> implementations are much slower than a memory-barrier
// based implementation (~16ns for <atomic> based acquire-load vs. ~1ns for
// a barrier based acquire-load).
// This code is based on atomicops-internals-* in Google's perftools:
// http://code.google.com/p/google-perftools/source/browse/#svn%2Ftrunk%2Fsrc%2Fbase
#ifndef PORT_ATOMIC_POINTER_H_
#define PORT_ATOMIC_POINTER_H_
#include <stdint.h>
#ifdef LEVELDB_ATOMIC_PRESENT
#include <atomic>
#endif
#ifdef OS_WIN
#include <windows.h>
#endif
#ifdef OS_MACOSX
#include <libkern/OSAtomic.h>
#endif
#if defined(_M_X64) || defined(__x86_64__)
#define ARCH_CPU_X86_FAMILY 1
#elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
#define ARCH_CPU_X86_FAMILY 1
#elif defined(__ARMEL__)
#define ARCH_CPU_ARM_FAMILY 1
#elif defined(__aarch64__)
#define ARCH_CPU_ARM64_FAMILY 1
#elif defined(__ppc__) || defined(__powerpc__) || defined(__powerpc64__)
#define ARCH_CPU_PPC_FAMILY 1
#elif defined(__mips__)
#define ARCH_CPU_MIPS_FAMILY 1
#endif
namespace leveldb {
namespace port {
// Define MemoryBarrier() if available
// Windows on x86
#if defined(OS_WIN) && defined(COMPILER_MSVC) && defined(ARCH_CPU_X86_FAMILY)
// windows.h already provides a MemoryBarrier(void) macro
// http://msdn.microsoft.com/en-us/library/ms684208(v=vs.85).aspx
#define LEVELDB_HAVE_MEMORY_BARRIER
// Mac OS
#elif defined(OS_MACOSX)
inline void MemoryBarrier() {
OSMemoryBarrier();
}
#define LEVELDB_HAVE_MEMORY_BARRIER
// Gcc on x86
#elif defined(ARCH_CPU_X86_FAMILY) && defined(__GNUC__)
inline void MemoryBarrier() {
// See http://gcc.gnu.org/ml/gcc/2003-04/msg01180.html for a discussion on
// this idiom. Also see http://en.wikipedia.org/wiki/Memory_ordering.
__asm__ __volatile__("" : : : "memory");
}
#define LEVELDB_HAVE_MEMORY_BARRIER
// Sun Studio
#elif defined(ARCH_CPU_X86_FAMILY) && defined(__SUNPRO_CC)
inline void MemoryBarrier() {
// See http://gcc.gnu.org/ml/gcc/2003-04/msg01180.html for a discussion on
// this idiom. Also see http://en.wikipedia.org/wiki/Memory_ordering.
asm volatile("" : : : "memory");
}
#define LEVELDB_HAVE_MEMORY_BARRIER
// ARM Linux
#elif defined(ARCH_CPU_ARM_FAMILY) && defined(__linux__)
typedef void (*LinuxKernelMemoryBarrierFunc)(void);
// The Linux ARM kernel provides a highly optimized device-specific memory
// barrier function at a fixed memory address that is mapped in every
// user-level process.
//
// This beats using CPU-specific instructions which are, on single-core
// devices, un-necessary and very costly (e.g. ARMv7-A "dmb" takes more
// than 180ns on a Cortex-A8 like the one on a Nexus One). Benchmarking
// shows that the extra function call cost is completely negligible on
// multi-core devices.
//
inline void MemoryBarrier() {
(*(LinuxKernelMemoryBarrierFunc)0xffff0fa0)();
}
#define LEVELDB_HAVE_MEMORY_BARRIER
// ARM64
#elif defined(ARCH_CPU_ARM64_FAMILY)
inline void MemoryBarrier() {
asm volatile("dmb sy" : : : "memory");
}
#define LEVELDB_HAVE_MEMORY_BARRIER
// PPC
#elif defined(ARCH_CPU_PPC_FAMILY) && defined(__GNUC__)
inline void MemoryBarrier() {
// TODO for some powerpc expert: is there a cheaper suitable variant?
// Perhaps by having separate barriers for acquire and release ops.
asm volatile("sync" : : : "memory");
}
#define LEVELDB_HAVE_MEMORY_BARRIER
// MIPS
#elif defined(ARCH_CPU_MIPS_FAMILY) && defined(__GNUC__)
inline void MemoryBarrier() {
__asm__ __volatile__("sync" : : : "memory");
}
#define LEVELDB_HAVE_MEMORY_BARRIER
#endif
// AtomicPointer built using platform-specific MemoryBarrier()
#if defined(LEVELDB_HAVE_MEMORY_BARRIER)
class AtomicPointer {
private:
void* rep_;
public:
AtomicPointer() { }
explicit AtomicPointer(void* p) : rep_(p) {}
inline void* NoBarrier_Load() const { return rep_; }
inline void NoBarrier_Store(void* v) { rep_ = v; }
inline void* Acquire_Load() const {
void* result = rep_;
MemoryBarrier();
return result;
}
inline void Release_Store(void* v) {
MemoryBarrier();
rep_ = v;
}
};
// AtomicPointer based on <cstdatomic>
#elif defined(LEVELDB_ATOMIC_PRESENT)
class AtomicPointer {
private:
std::atomic<void*> rep_;
public:
AtomicPointer() { }
explicit AtomicPointer(void* v) : rep_(v) { }
inline void* Acquire_Load() const {
return rep_.load(std::memory_order_acquire);
}
inline void Release_Store(void* v) {
rep_.store(v, std::memory_order_release);
}
inline void* NoBarrier_Load() const {
return rep_.load(std::memory_order_relaxed);
}
inline void NoBarrier_Store(void* v) {
rep_.store(v, std::memory_order_relaxed);
}
};
// Atomic pointer based on sparc memory barriers
#elif defined(__sparcv9) && defined(__GNUC__)
class AtomicPointer {
private:
void* rep_;
public:
AtomicPointer() { }
explicit AtomicPointer(void* v) : rep_(v) { }
inline void* Acquire_Load() const {
void* val;
__asm__ __volatile__ (
"ldx [%[rep_]], %[val] \n\t"
"membar #LoadLoad|#LoadStore \n\t"
: [val] "=r" (val)
: [rep_] "r" (&rep_)
: "memory");
return val;
}
inline void Release_Store(void* v) {
__asm__ __volatile__ (
"membar #LoadStore|#StoreStore \n\t"
"stx %[v], [%[rep_]] \n\t"
:
: [rep_] "r" (&rep_), [v] "r" (v)
: "memory");
}
inline void* NoBarrier_Load() const { return rep_; }
inline void NoBarrier_Store(void* v) { rep_ = v; }
};
// Atomic pointer based on ia64 acq/rel
#elif defined(__ia64) && defined(__GNUC__)
class AtomicPointer {
private:
void* rep_;
public:
AtomicPointer() { }
explicit AtomicPointer(void* v) : rep_(v) { }
inline void* Acquire_Load() const {
void* val ;
__asm__ __volatile__ (
"ld8.acq %[val] = [%[rep_]] \n\t"
: [val] "=r" (val)
: [rep_] "r" (&rep_)
: "memory"
);
return val;
}
inline void Release_Store(void* v) {
__asm__ __volatile__ (
"st8.rel [%[rep_]] = %[v] \n\t"
:
: [rep_] "r" (&rep_), [v] "r" (v)
: "memory"
);
}
inline void* NoBarrier_Load() const { return rep_; }
inline void NoBarrier_Store(void* v) { rep_ = v; }
};
// We have neither MemoryBarrier(), nor <atomic>
#else
#error Please implement AtomicPointer for this platform.
#endif
#undef LEVELDB_HAVE_MEMORY_BARRIER
#undef ARCH_CPU_X86_FAMILY
#undef ARCH_CPU_ARM_FAMILY
#undef ARCH_CPU_ARM64_FAMILY
#undef ARCH_CPU_PPC_FAMILY
} // namespace port
} // namespace leveldb
#endif // PORT_ATOMIC_POINTER_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_PORT_PORT_H_
#define STORAGE_LEVELDB_PORT_PORT_H_
#include <string.h>
// Include the appropriate platform specific file below. If you are
// porting to a new platform, see "port_example.h" for documentation
// of what the new port_<platform>.h file must provide.
#if defined(LEVELDB_PLATFORM_UV)
# include "port_uv.h"
#elif defined(LEVELDB_PLATFORM_POSIX)
# include "port/port_posix.h"
#elif defined(LEVELDB_PLATFORM_CHROMIUM)
# include "port/port_chromium.h"
#endif
#endif // STORAGE_LEVELDB_PORT_PORT_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// This file contains the specification, but not the implementations,
// of the types/operations/etc. that should be defined by a platform
// specific port_<platform>.h file. Use this file as a reference for
// how to port this package to a new platform.
#ifndef STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_
#define STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_
namespace leveldb {
namespace port {
// TODO(jorlow): Many of these belong more in the environment class rather than
// here. We should try moving them and see if it affects perf.
// The following boolean constant must be true on a little-endian machine
// and false otherwise.
static const bool kLittleEndian = true /* or some other expression */;
// ------------------ Threading -------------------
// A Mutex represents an exclusive lock.
class Mutex {
public:
Mutex();
~Mutex();
// Lock the mutex. Waits until other lockers have exited.
// Will deadlock if the mutex is already locked by this thread.
void Lock();
// Unlock the mutex.
// REQUIRES: This mutex was locked by this thread.
void Unlock();
// Optionally crash if this thread does not hold this mutex.
// The implementation must be fast, especially if NDEBUG is
// defined. The implementation is allowed to skip all checks.
void AssertHeld();
};
class CondVar {
public:
explicit CondVar(Mutex* mu);
~CondVar();
// Atomically release *mu and block on this condition variable until
// either a call to SignalAll(), or a call to Signal() that picks
// this thread to wakeup.
// REQUIRES: this thread holds *mu
void Wait();
// If there are some threads waiting, wake up at least one of them.
void Signal();
// Wake up all waiting threads.
void SignallAll();
};
// Thread-safe initialization.
// Used as follows:
// static port::OnceType init_control = LEVELDB_ONCE_INIT;
// static void Initializer() { ... do something ...; }
// ...
// port::InitOnce(&init_control, &Initializer);
typedef intptr_t OnceType;
#define LEVELDB_ONCE_INIT 0
extern void InitOnce(port::OnceType*, void (*initializer)());
// A type that holds a pointer that can be read or written atomically
// (i.e., without word-tearing.)
class AtomicPointer {
private:
intptr_t rep_;
public:
// Initialize to arbitrary value
AtomicPointer();
// Initialize to hold v
explicit AtomicPointer(void* v) : rep_(v) { }
// Read and return the stored pointer with the guarantee that no
// later memory access (read or write) by this thread can be
// reordered ahead of this read.
void* Acquire_Load() const;
// Set v as the stored pointer with the guarantee that no earlier
// memory access (read or write) by this thread can be reordered
// after this store.
void Release_Store(void* v);
// Read the stored pointer with no ordering guarantees.
void* NoBarrier_Load() const;
// Set va as the stored pointer with no ordering guarantees.
void NoBarrier_Store(void* v);
};
// ------------------ Compression -------------------
// Store the snappy compression of "input[0,input_length-1]" in *output.
// Returns false if snappy is not supported by this port.
extern bool Snappy_Compress(const char* input, size_t input_length,
std::string* output);
// If input[0,input_length-1] looks like a valid snappy compressed
// buffer, store the size of the uncompressed data in *result and
// return true. Else return false.
extern bool Snappy_GetUncompressedLength(const char* input, size_t length,
size_t* result);
// Attempt to snappy uncompress input[0,input_length-1] into *output.
// Returns true if successful, false if the input is invalid lightweight
// compressed data.
//
// REQUIRES: at least the first "n" bytes of output[] must be writable
// where "n" is the result of a successful call to
// Snappy_GetUncompressedLength.
extern bool Snappy_Uncompress(const char* input_data, size_t input_length,
char* output);
// ------------------ Miscellaneous -------------------
// If heap profiling is not supported, returns false.
// Else repeatedly calls (*func)(arg, data, n) and then returns true.
// The concatenation of all "data[0,n-1]" fragments is the heap profile.
extern bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg);
// Extend the CRC to include the first n bytes of buf.
//
// Returns zero if the CRC cannot be extended using acceleration, else returns
// the newly extended CRC value (which may also be zero).
uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size);
} // namespace port
} // namespace leveldb
#endif // STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "port/port_posix.h"
#include <cstdlib>
#include <stdio.h>
#include <string.h>
namespace leveldb {
namespace port {
static void PthreadCall(const char* label, int result) {
if (result != 0) {
fprintf(stderr, "pthread %s: %s\n", label, strerror(result));
abort();
}
}
Mutex::Mutex() { PthreadCall("init mutex", pthread_mutex_init(&mu_, NULL)); }
Mutex::~Mutex() { PthreadCall("destroy mutex", pthread_mutex_destroy(&mu_)); }
void Mutex::Lock() { PthreadCall("lock", pthread_mutex_lock(&mu_)); }
void Mutex::Unlock() { PthreadCall("unlock", pthread_mutex_unlock(&mu_)); }
CondVar::CondVar(Mutex* mu)
: mu_(mu) {
PthreadCall("init cv", pthread_cond_init(&cv_, NULL));
}
CondVar::~CondVar() { PthreadCall("destroy cv", pthread_cond_destroy(&cv_)); }
void CondVar::Wait() {
PthreadCall("wait", pthread_cond_wait(&cv_, &mu_->mu_));
}
void CondVar::Signal() {
PthreadCall("signal", pthread_cond_signal(&cv_));
}
void CondVar::SignalAll() {
PthreadCall("broadcast", pthread_cond_broadcast(&cv_));
}
void InitOnce(OnceType* once, void (*initializer)()) {
PthreadCall("once", pthread_once(once, initializer));
}
} // namespace port
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// See port_example.h for documentation for the following types/functions.
#ifndef STORAGE_LEVELDB_PORT_PORT_POSIX_H_
#define STORAGE_LEVELDB_PORT_PORT_POSIX_H_
#undef PLATFORM_IS_LITTLE_ENDIAN
#if defined(OS_MACOSX) || defined(OS_IOS)
#include <machine/endian.h>
#if defined(__DARWIN_LITTLE_ENDIAN) && defined(__DARWIN_BYTE_ORDER)
#define PLATFORM_IS_LITTLE_ENDIAN \
(__DARWIN_BYTE_ORDER == __DARWIN_LITTLE_ENDIAN)
#endif
#elif defined(OS_SOLARIS)
#include <sys/isa_defs.h>
#ifdef _LITTLE_ENDIAN
#define PLATFORM_IS_LITTLE_ENDIAN true
#else
#define PLATFORM_IS_LITTLE_ENDIAN false
#endif
#elif defined(OS_FREEBSD) || defined(OS_OPENBSD) ||\
defined(OS_NETBSD) || defined(OS_DRAGONFLYBSD)
#include <sys/types.h>
#include <sys/endian.h>
#define PLATFORM_IS_LITTLE_ENDIAN (_BYTE_ORDER == _LITTLE_ENDIAN)
#elif defined(OS_HPUX)
#define PLATFORM_IS_LITTLE_ENDIAN false
#elif defined(OS_ANDROID)
// Due to a bug in the NDK x86 <sys/endian.h> definition,
// _BYTE_ORDER must be used instead of __BYTE_ORDER on Android.
// See http://code.google.com/p/android/issues/detail?id=39824
#include <endian.h>
#define PLATFORM_IS_LITTLE_ENDIAN (_BYTE_ORDER == _LITTLE_ENDIAN)
#else
#include <endian.h>
#endif
#include <pthread.h>
#ifdef SNAPPY
#include <snappy.h>
#endif
#include <stdint.h>
#include <string>
#include "port/atomic_pointer.h"
#ifndef PLATFORM_IS_LITTLE_ENDIAN
#define PLATFORM_IS_LITTLE_ENDIAN (__BYTE_ORDER == __LITTLE_ENDIAN)
#endif
#if defined(OS_MACOSX) || defined(OS_IOS) || defined(OS_SOLARIS) || defined(OS_FREEBSD) ||\
defined(OS_NETBSD) || defined(OS_OPENBSD) || defined(OS_DRAGONFLYBSD) ||\
defined(OS_ANDROID) || defined(OS_HPUX) || defined(CYGWIN)
// Use fread/fwrite/fflush on platforms without _unlocked variants
#define fread_unlocked fread
#define fwrite_unlocked fwrite
#define fflush_unlocked fflush
#endif
#if defined(OS_MACOSX) || defined(OS_IOS) || defined(OS_FREEBSD) ||\
defined(OS_OPENBSD) || defined(OS_DRAGONFLYBSD)
// Use fsync() on platforms without fdatasync()
#define fdatasync fsync
#endif
#if defined(OS_ANDROID) && __ANDROID_API__ < 9
// fdatasync() was only introduced in API level 9 on Android. Use fsync()
// when targetting older platforms.
#define fdatasync fsync
#endif
namespace leveldb {
namespace port {
static const bool kLittleEndian = PLATFORM_IS_LITTLE_ENDIAN;
#undef PLATFORM_IS_LITTLE_ENDIAN
class CondVar;
class Mutex {
public:
Mutex();
~Mutex();
void Lock();
void Unlock();
void AssertHeld() { }
private:
friend class CondVar;
pthread_mutex_t mu_;
// No copying
Mutex(const Mutex&);
void operator=(const Mutex&);
};
class CondVar {
public:
explicit CondVar(Mutex* mu);
~CondVar();
void Wait();
void Signal();
void SignalAll();
private:
pthread_cond_t cv_;
Mutex* mu_;
};
typedef pthread_once_t OnceType;
#define LEVELDB_ONCE_INIT PTHREAD_ONCE_INIT
extern void InitOnce(OnceType* once, void (*initializer)());
inline bool Snappy_Compress(const char* input, size_t length,
::std::string* output) {
#ifdef SNAPPY
output->resize(snappy::MaxCompressedLength(length));
size_t outlen;
snappy::RawCompress(input, length, &(*output)[0], &outlen);
output->resize(outlen);
return true;
#endif
return false;
}
inline bool Snappy_GetUncompressedLength(const char* input, size_t length,
size_t* result) {
#ifdef SNAPPY
return snappy::GetUncompressedLength(input, length, result);
#else
return false;
#endif
}
inline bool Snappy_Uncompress(const char* input, size_t length,
char* output) {
#ifdef SNAPPY
return snappy::RawUncompress(input, length, output);
#else
return false;
#endif
}
inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
return false;
}
uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size);
} // namespace port
} // namespace leveldb
#endif // STORAGE_LEVELDB_PORT_PORT_POSIX_H_

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// Copyright 2016 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// A portable implementation of crc32c, optimized to handle
// four bytes at a time.
//
// In a separate source file to allow this accelerated CRC32C function to be
// compiled with the appropriate compiler flags to enable x86 SSE 4.2
// instructions.
#include <stdint.h>
#include <string.h>
#include "port/port.h"
#if defined(LEVELDB_PLATFORM_POSIX_SSE)
#if defined(_MSC_VER)
#include <intrin.h>
#elif defined(__GNUC__) && defined(__SSE4_2__)
#include <nmmintrin.h>
#include <cpuid.h>
#endif
#endif // defined(LEVELDB_PLATFORM_POSIX_SSE)
namespace leveldb {
namespace port {
#if defined(LEVELDB_PLATFORM_POSIX_SSE)
// Used to fetch a naturally-aligned 32-bit word in little endian byte-order
static inline uint32_t LE_LOAD32(const uint8_t *p) {
// SSE is x86 only, so ensured that |p| is always little-endian.
uint32_t word;
memcpy(&word, p, sizeof(word));
return word;
}
#if defined(_M_X64) || defined(__x86_64__) // LE_LOAD64 is only used on x64.
// Used to fetch a naturally-aligned 64-bit word in little endian byte-order
static inline uint64_t LE_LOAD64(const uint8_t *p) {
uint64_t dword;
memcpy(&dword, p, sizeof(dword));
return dword;
}
#endif // defined(_M_X64) || defined(__x86_64__)
static inline bool HaveSSE42() {
#if defined(_MSC_VER)
int cpu_info[4];
__cpuid(cpu_info, 1);
return (cpu_info[2] & (1 << 20)) != 0;
#elif defined(__GNUC__)
unsigned int eax, ebx, ecx, edx;
__get_cpuid(1, &eax, &ebx, &ecx, &edx);
return (ecx & (1 << 20)) != 0;
#else
return false;
#endif
}
#endif // defined(LEVELDB_PLATFORM_POSIX_SSE)
// For further improvements see Intel publication at:
// http://download.intel.com/design/intarch/papers/323405.pdf
uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size) {
#if !defined(LEVELDB_PLATFORM_POSIX_SSE)
return 0;
#else
static bool have = HaveSSE42();
if (!have) {
return 0;
}
const uint8_t *p = reinterpret_cast<const uint8_t *>(buf);
const uint8_t *e = p + size;
uint32_t l = crc ^ 0xffffffffu;
#define STEP1 do { \
l = _mm_crc32_u8(l, *p++); \
} while (0)
#define STEP4 do { \
l = _mm_crc32_u32(l, LE_LOAD32(p)); \
p += 4; \
} while (0)
#define STEP8 do { \
l = _mm_crc32_u64(l, LE_LOAD64(p)); \
p += 8; \
} while (0)
if (size > 16) {
// Process unaligned bytes
for (unsigned int i = reinterpret_cast<uintptr_t>(p) % 8; i; --i) {
STEP1;
}
// _mm_crc32_u64 is only available on x64.
#if defined(_M_X64) || defined(__x86_64__)
// Process 8 bytes at a time
while ((e-p) >= 8) {
STEP8;
}
// Process 4 bytes at a time
if ((e-p) >= 4) {
STEP4;
}
#else // !(defined(_M_X64) || defined(__x86_64__))
// Process 4 bytes at a time
while ((e-p) >= 4) {
STEP4;
}
#endif // defined(_M_X64) || defined(__x86_64__)
}
// Process the last few bytes
while (p != e) {
STEP1;
}
#undef STEP8
#undef STEP4
#undef STEP1
return l ^ 0xffffffffu;
#endif // defined(LEVELDB_PLATFORM_POSIX_SSE)
}
} // namespace port
} // namespace leveldb

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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_PORT_THREAD_ANNOTATIONS_H_
#define STORAGE_LEVELDB_PORT_THREAD_ANNOTATIONS_H_
// Some environments provide custom macros to aid in static thread-safety
// analysis. Provide empty definitions of such macros unless they are already
// defined.
#ifndef EXCLUSIVE_LOCKS_REQUIRED
#define EXCLUSIVE_LOCKS_REQUIRED(...)
#endif
#ifndef SHARED_LOCKS_REQUIRED
#define SHARED_LOCKS_REQUIRED(...)
#endif
#ifndef LOCKS_EXCLUDED
#define LOCKS_EXCLUDED(...)
#endif
#ifndef LOCK_RETURNED
#define LOCK_RETURNED(x)
#endif
#ifndef LOCKABLE
#define LOCKABLE
#endif
#ifndef SCOPED_LOCKABLE
#define SCOPED_LOCKABLE
#endif
#ifndef EXCLUSIVE_LOCK_FUNCTION
#define EXCLUSIVE_LOCK_FUNCTION(...)
#endif
#ifndef SHARED_LOCK_FUNCTION
#define SHARED_LOCK_FUNCTION(...)
#endif
#ifndef EXCLUSIVE_TRYLOCK_FUNCTION
#define EXCLUSIVE_TRYLOCK_FUNCTION(...)
#endif
#ifndef SHARED_TRYLOCK_FUNCTION
#define SHARED_TRYLOCK_FUNCTION(...)
#endif
#ifndef UNLOCK_FUNCTION
#define UNLOCK_FUNCTION(...)
#endif
#ifndef NO_THREAD_SAFETY_ANALYSIS
#define NO_THREAD_SAFETY_ANALYSIS
#endif
#endif // STORAGE_LEVELDB_PORT_THREAD_ANNOTATIONS_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
// MSVC didn't ship with this file until the 2010 version.
#ifndef STORAGE_LEVELDB_PORT_WIN_STDINT_H_
#define STORAGE_LEVELDB_PORT_WIN_STDINT_H_
#if !defined(_MSC_VER)
#error This file should only be included when compiling with MSVC.
#endif
// Define C99 equivalent types.
typedef signed char int8_t;
typedef signed short int16_t;
typedef signed int int32_t;
typedef signed long long int64_t;
typedef unsigned char uint8_t;
typedef unsigned short uint16_t;
typedef unsigned int uint32_t;
typedef unsigned long long uint64_t;
#endif // STORAGE_LEVELDB_PORT_WIN_STDINT_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// Decodes the blocks generated by block_builder.cc.
#include "table/block.h"
#include <vector>
#include <algorithm>
#include "leveldb/comparator.h"
#include "table/format.h"
#include "util/coding.h"
#include "util/logging.h"
namespace leveldb {
inline uint32_t Block::NumRestarts() const {
assert(size_ >= sizeof(uint32_t));
return DecodeFixed32(data_ + size_ - sizeof(uint32_t));
}
Block::Block(const BlockContents& contents)
: data_(contents.data.data()),
size_(contents.data.size()),
owned_(contents.heap_allocated) {
if (size_ < sizeof(uint32_t)) {
size_ = 0; // Error marker
} else {
size_t max_restarts_allowed = (size_-sizeof(uint32_t)) / sizeof(uint32_t);
if (NumRestarts() > max_restarts_allowed) {
// The size is too small for NumRestarts()
size_ = 0;
} else {
restart_offset_ = size_ - (1 + NumRestarts()) * sizeof(uint32_t);
}
}
}
Block::~Block() {
if (owned_) {
delete[] data_;
}
}
// Helper routine: decode the next block entry starting at "p",
// storing the number of shared key bytes, non_shared key bytes,
// and the length of the value in "*shared", "*non_shared", and
// "*value_length", respectively. Will not dereference past "limit".
//
// If any errors are detected, returns NULL. Otherwise, returns a
// pointer to the key delta (just past the three decoded values).
static inline const char* DecodeEntry(const char* p, const char* limit,
uint32_t* shared,
uint32_t* non_shared,
uint32_t* value_length) {
if (limit - p < 3) return NULL;
*shared = reinterpret_cast<const unsigned char*>(p)[0];
*non_shared = reinterpret_cast<const unsigned char*>(p)[1];
*value_length = reinterpret_cast<const unsigned char*>(p)[2];
if ((*shared | *non_shared | *value_length) < 128) {
// Fast path: all three values are encoded in one byte each
p += 3;
} else {
if ((p = GetVarint32Ptr(p, limit, shared)) == NULL) return NULL;
if ((p = GetVarint32Ptr(p, limit, non_shared)) == NULL) return NULL;
if ((p = GetVarint32Ptr(p, limit, value_length)) == NULL) return NULL;
}
if (static_cast<uint32_t>(limit - p) < (*non_shared + *value_length)) {
return NULL;
}
return p;
}
class Block::Iter : public Iterator {
private:
const Comparator* const comparator_;
const char* const data_; // underlying block contents
uint32_t const restarts_; // Offset of restart array (list of fixed32)
uint32_t const num_restarts_; // Number of uint32_t entries in restart array
// current_ is offset in data_ of current entry. >= restarts_ if !Valid
uint32_t current_;
uint32_t restart_index_; // Index of restart block in which current_ falls
std::string key_;
Slice value_;
Status status_;
inline int Compare(const Slice& a, const Slice& b) const {
return comparator_->Compare(a, b);
}
// Return the offset in data_ just past the end of the current entry.
inline uint32_t NextEntryOffset() const {
return (value_.data() + value_.size()) - data_;
}
uint32_t GetRestartPoint(uint32_t index) {
assert(index < num_restarts_);
return DecodeFixed32(data_ + restarts_ + index * sizeof(uint32_t));
}
void SeekToRestartPoint(uint32_t index) {
key_.clear();
restart_index_ = index;
// current_ will be fixed by ParseNextKey();
// ParseNextKey() starts at the end of value_, so set value_ accordingly
uint32_t offset = GetRestartPoint(index);
value_ = Slice(data_ + offset, 0);
}
public:
Iter(const Comparator* comparator,
const char* data,
uint32_t restarts,
uint32_t num_restarts)
: comparator_(comparator),
data_(data),
restarts_(restarts),
num_restarts_(num_restarts),
current_(restarts_),
restart_index_(num_restarts_) {
assert(num_restarts_ > 0);
}
virtual bool Valid() const { return current_ < restarts_; }
virtual Status status() const { return status_; }
virtual Slice key() const {
assert(Valid());
return key_;
}
virtual Slice value() const {
assert(Valid());
return value_;
}
virtual void Next() {
assert(Valid());
ParseNextKey();
}
virtual void Prev() {
assert(Valid());
// Scan backwards to a restart point before current_
const uint32_t original = current_;
while (GetRestartPoint(restart_index_) >= original) {
if (restart_index_ == 0) {
// No more entries
current_ = restarts_;
restart_index_ = num_restarts_;
return;
}
restart_index_--;
}
SeekToRestartPoint(restart_index_);
do {
// Loop until end of current entry hits the start of original entry
} while (ParseNextKey() && NextEntryOffset() < original);
}
virtual void Seek(const Slice& target) {
// Binary search in restart array to find the last restart point
// with a key < target
uint32_t left = 0;
uint32_t right = num_restarts_ - 1;
while (left < right) {
uint32_t mid = (left + right + 1) / 2;
uint32_t region_offset = GetRestartPoint(mid);
uint32_t shared, non_shared, value_length;
const char* key_ptr = DecodeEntry(data_ + region_offset,
data_ + restarts_,
&shared, &non_shared, &value_length);
if (key_ptr == NULL || (shared != 0)) {
CorruptionError();
return;
}
Slice mid_key(key_ptr, non_shared);
if (Compare(mid_key, target) < 0) {
// Key at "mid" is smaller than "target". Therefore all
// blocks before "mid" are uninteresting.
left = mid;
} else {
// Key at "mid" is >= "target". Therefore all blocks at or
// after "mid" are uninteresting.
right = mid - 1;
}
}
// Linear search (within restart block) for first key >= target
SeekToRestartPoint(left);
while (true) {
if (!ParseNextKey()) {
return;
}
if (Compare(key_, target) >= 0) {
return;
}
}
}
virtual void SeekToFirst() {
SeekToRestartPoint(0);
ParseNextKey();
}
virtual void SeekToLast() {
SeekToRestartPoint(num_restarts_ - 1);
while (ParseNextKey() && NextEntryOffset() < restarts_) {
// Keep skipping
}
}
private:
void CorruptionError() {
current_ = restarts_;
restart_index_ = num_restarts_;
status_ = Status::Corruption("bad entry in block");
key_.clear();
value_.clear();
}
bool ParseNextKey() {
current_ = NextEntryOffset();
const char* p = data_ + current_;
const char* limit = data_ + restarts_; // Restarts come right after data
if (p >= limit) {
// No more entries to return. Mark as invalid.
current_ = restarts_;
restart_index_ = num_restarts_;
return false;
}
// Decode next entry
uint32_t shared, non_shared, value_length;
p = DecodeEntry(p, limit, &shared, &non_shared, &value_length);
if (p == NULL || key_.size() < shared) {
CorruptionError();
return false;
} else {
key_.resize(shared);
key_.append(p, non_shared);
value_ = Slice(p + non_shared, value_length);
while (restart_index_ + 1 < num_restarts_ &&
GetRestartPoint(restart_index_ + 1) < current_) {
++restart_index_;
}
return true;
}
}
};
Iterator* Block::NewIterator(const Comparator* cmp) {
if (size_ < sizeof(uint32_t)) {
return NewErrorIterator(Status::Corruption("bad block contents"));
}
const uint32_t num_restarts = NumRestarts();
if (num_restarts == 0) {
return NewEmptyIterator();
} else {
return new Iter(cmp, data_, restart_offset_, num_restarts);
}
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_TABLE_BLOCK_H_
#define STORAGE_LEVELDB_TABLE_BLOCK_H_
#include <stddef.h>
#include <stdint.h>
#include "leveldb/iterator.h"
namespace leveldb {
struct BlockContents;
class Comparator;
class Block {
public:
// Initialize the block with the specified contents.
explicit Block(const BlockContents& contents);
~Block();
size_t size() const { return size_; }
Iterator* NewIterator(const Comparator* comparator);
private:
uint32_t NumRestarts() const;
const char* data_;
size_t size_;
uint32_t restart_offset_; // Offset in data_ of restart array
bool owned_; // Block owns data_[]
// No copying allowed
Block(const Block&);
void operator=(const Block&);
class Iter;
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_TABLE_BLOCK_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// BlockBuilder generates blocks where keys are prefix-compressed:
//
// When we store a key, we drop the prefix shared with the previous
// string. This helps reduce the space requirement significantly.
// Furthermore, once every K keys, we do not apply the prefix
// compression and store the entire key. We call this a "restart
// point". The tail end of the block stores the offsets of all of the
// restart points, and can be used to do a binary search when looking
// for a particular key. Values are stored as-is (without compression)
// immediately following the corresponding key.
//
// An entry for a particular key-value pair has the form:
// shared_bytes: varint32
// unshared_bytes: varint32
// value_length: varint32
// key_delta: char[unshared_bytes]
// value: char[value_length]
// shared_bytes == 0 for restart points.
//
// The trailer of the block has the form:
// restarts: uint32[num_restarts]
// num_restarts: uint32
// restarts[i] contains the offset within the block of the ith restart point.
#include "table/block_builder.h"
#include <algorithm>
#include <assert.h>
#include "leveldb/comparator.h"
#include "leveldb/table_builder.h"
#include "util/coding.h"
namespace leveldb {
BlockBuilder::BlockBuilder(const Options* options)
: options_(options),
restarts_(),
counter_(0),
finished_(false) {
assert(options->block_restart_interval >= 1);
restarts_.push_back(0); // First restart point is at offset 0
}
void BlockBuilder::Reset() {
buffer_.clear();
restarts_.clear();
restarts_.push_back(0); // First restart point is at offset 0
counter_ = 0;
finished_ = false;
last_key_.clear();
}
size_t BlockBuilder::CurrentSizeEstimate() const {
return (buffer_.size() + // Raw data buffer
restarts_.size() * sizeof(uint32_t) + // Restart array
sizeof(uint32_t)); // Restart array length
}
Slice BlockBuilder::Finish() {
// Append restart array
for (size_t i = 0; i < restarts_.size(); i++) {
PutFixed32(&buffer_, restarts_[i]);
}
PutFixed32(&buffer_, restarts_.size());
finished_ = true;
return Slice(buffer_);
}
void BlockBuilder::Add(const Slice& key, const Slice& value) {
Slice last_key_piece(last_key_);
assert(!finished_);
assert(counter_ <= options_->block_restart_interval);
assert(buffer_.empty() // No values yet?
|| options_->comparator->Compare(key, last_key_piece) > 0);
size_t shared = 0;
if (counter_ < options_->block_restart_interval) {
// See how much sharing to do with previous string
const size_t min_length = std::min(last_key_piece.size(), key.size());
while ((shared < min_length) && (last_key_piece[shared] == key[shared])) {
shared++;
}
} else {
// Restart compression
restarts_.push_back(buffer_.size());
counter_ = 0;
}
const size_t non_shared = key.size() - shared;
// Add "<shared><non_shared><value_size>" to buffer_
PutVarint32(&buffer_, shared);
PutVarint32(&buffer_, non_shared);
PutVarint32(&buffer_, value.size());
// Add string delta to buffer_ followed by value
buffer_.append(key.data() + shared, non_shared);
buffer_.append(value.data(), value.size());
// Update state
last_key_.resize(shared);
last_key_.append(key.data() + shared, non_shared);
assert(Slice(last_key_) == key);
counter_++;
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_TABLE_BLOCK_BUILDER_H_
#define STORAGE_LEVELDB_TABLE_BLOCK_BUILDER_H_
#include <vector>
#include <stdint.h>
#include "leveldb/slice.h"
namespace leveldb {
struct Options;
class BlockBuilder {
public:
explicit BlockBuilder(const Options* options);
// Reset the contents as if the BlockBuilder was just constructed.
void Reset();
// REQUIRES: Finish() has not been called since the last call to Reset().
// REQUIRES: key is larger than any previously added key
void Add(const Slice& key, const Slice& value);
// Finish building the block and return a slice that refers to the
// block contents. The returned slice will remain valid for the
// lifetime of this builder or until Reset() is called.
Slice Finish();
// Returns an estimate of the current (uncompressed) size of the block
// we are building.
size_t CurrentSizeEstimate() const;
// Return true iff no entries have been added since the last Reset()
bool empty() const {
return buffer_.empty();
}
private:
const Options* options_;
std::string buffer_; // Destination buffer
std::vector<uint32_t> restarts_; // Restart points
int counter_; // Number of entries emitted since restart
bool finished_; // Has Finish() been called?
std::string last_key_;
// No copying allowed
BlockBuilder(const BlockBuilder&);
void operator=(const BlockBuilder&);
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_TABLE_BLOCK_BUILDER_H_

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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "table/filter_block.h"
#include "leveldb/filter_policy.h"
#include "util/coding.h"
namespace leveldb {
// See doc/table_format.md for an explanation of the filter block format.
// Generate new filter every 2KB of data
static const size_t kFilterBaseLg = 11;
static const size_t kFilterBase = 1 << kFilterBaseLg;
FilterBlockBuilder::FilterBlockBuilder(const FilterPolicy* policy)
: policy_(policy) {
}
void FilterBlockBuilder::StartBlock(uint64_t block_offset) {
uint64_t filter_index = (block_offset / kFilterBase);
assert(filter_index >= filter_offsets_.size());
while (filter_index > filter_offsets_.size()) {
GenerateFilter();
}
}
void FilterBlockBuilder::AddKey(const Slice& key) {
Slice k = key;
start_.push_back(keys_.size());
keys_.append(k.data(), k.size());
}
Slice FilterBlockBuilder::Finish() {
if (!start_.empty()) {
GenerateFilter();
}
// Append array of per-filter offsets
const uint32_t array_offset = result_.size();
for (size_t i = 0; i < filter_offsets_.size(); i++) {
PutFixed32(&result_, filter_offsets_[i]);
}
PutFixed32(&result_, array_offset);
result_.push_back(kFilterBaseLg); // Save encoding parameter in result
return Slice(result_);
}
void FilterBlockBuilder::GenerateFilter() {
const size_t num_keys = start_.size();
if (num_keys == 0) {
// Fast path if there are no keys for this filter
filter_offsets_.push_back(result_.size());
return;
}
// Make list of keys from flattened key structure
start_.push_back(keys_.size()); // Simplify length computation
tmp_keys_.resize(num_keys);
for (size_t i = 0; i < num_keys; i++) {
const char* base = keys_.data() + start_[i];
size_t length = start_[i+1] - start_[i];
tmp_keys_[i] = Slice(base, length);
}
// Generate filter for current set of keys and append to result_.
filter_offsets_.push_back(result_.size());
policy_->CreateFilter(&tmp_keys_[0], static_cast<int>(num_keys), &result_);
tmp_keys_.clear();
keys_.clear();
start_.clear();
}
FilterBlockReader::FilterBlockReader(const FilterPolicy* policy,
const Slice& contents)
: policy_(policy),
data_(NULL),
offset_(NULL),
num_(0),
base_lg_(0) {
size_t n = contents.size();
if (n < 5) return; // 1 byte for base_lg_ and 4 for start of offset array
base_lg_ = contents[n-1];
uint32_t last_word = DecodeFixed32(contents.data() + n - 5);
if (last_word > n - 5) return;
data_ = contents.data();
offset_ = data_ + last_word;
num_ = (n - 5 - last_word) / 4;
}
bool FilterBlockReader::KeyMayMatch(uint64_t block_offset, const Slice& key) {
uint64_t index = block_offset >> base_lg_;
if (index < num_) {
uint32_t start = DecodeFixed32(offset_ + index*4);
uint32_t limit = DecodeFixed32(offset_ + index*4 + 4);
if (start <= limit && limit <= static_cast<size_t>(offset_ - data_)) {
Slice filter = Slice(data_ + start, limit - start);
return policy_->KeyMayMatch(key, filter);
} else if (start == limit) {
// Empty filters do not match any keys
return false;
}
}
return true; // Errors are treated as potential matches
}
}

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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// A filter block is stored near the end of a Table file. It contains
// filters (e.g., bloom filters) for all data blocks in the table combined
// into a single filter block.
#ifndef STORAGE_LEVELDB_TABLE_FILTER_BLOCK_H_
#define STORAGE_LEVELDB_TABLE_FILTER_BLOCK_H_
#include <stddef.h>
#include <stdint.h>
#include <string>
#include <vector>
#include "leveldb/slice.h"
#include "util/hash.h"
namespace leveldb {
class FilterPolicy;
// A FilterBlockBuilder is used to construct all of the filters for a
// particular Table. It generates a single string which is stored as
// a special block in the Table.
//
// The sequence of calls to FilterBlockBuilder must match the regexp:
// (StartBlock AddKey*)* Finish
class FilterBlockBuilder {
public:
explicit FilterBlockBuilder(const FilterPolicy*);
void StartBlock(uint64_t block_offset);
void AddKey(const Slice& key);
Slice Finish();
private:
void GenerateFilter();
const FilterPolicy* policy_;
std::string keys_; // Flattened key contents
std::vector<size_t> start_; // Starting index in keys_ of each key
std::string result_; // Filter data computed so far
std::vector<Slice> tmp_keys_; // policy_->CreateFilter() argument
std::vector<uint32_t> filter_offsets_;
// No copying allowed
FilterBlockBuilder(const FilterBlockBuilder&);
void operator=(const FilterBlockBuilder&);
};
class FilterBlockReader {
public:
// REQUIRES: "contents" and *policy must stay live while *this is live.
FilterBlockReader(const FilterPolicy* policy, const Slice& contents);
bool KeyMayMatch(uint64_t block_offset, const Slice& key);
private:
const FilterPolicy* policy_;
const char* data_; // Pointer to filter data (at block-start)
const char* offset_; // Pointer to beginning of offset array (at block-end)
size_t num_; // Number of entries in offset array
size_t base_lg_; // Encoding parameter (see kFilterBaseLg in .cc file)
};
}
#endif // STORAGE_LEVELDB_TABLE_FILTER_BLOCK_H_

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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "table/filter_block.h"
#include "leveldb/filter_policy.h"
#include "util/coding.h"
#include "util/hash.h"
#include "util/logging.h"
#include "util/testharness.h"
#include "util/testutil.h"
namespace leveldb {
// For testing: emit an array with one hash value per key
class TestHashFilter : public FilterPolicy {
public:
virtual const char* Name() const {
return "TestHashFilter";
}
virtual void CreateFilter(const Slice* keys, int n, std::string* dst) const {
for (int i = 0; i < n; i++) {
uint32_t h = Hash(keys[i].data(), keys[i].size(), 1);
PutFixed32(dst, h);
}
}
virtual bool KeyMayMatch(const Slice& key, const Slice& filter) const {
uint32_t h = Hash(key.data(), key.size(), 1);
for (size_t i = 0; i + 4 <= filter.size(); i += 4) {
if (h == DecodeFixed32(filter.data() + i)) {
return true;
}
}
return false;
}
};
class FilterBlockTest {
public:
TestHashFilter policy_;
};
TEST(FilterBlockTest, EmptyBuilder) {
FilterBlockBuilder builder(&policy_);
Slice block = builder.Finish();
ASSERT_EQ("\\x00\\x00\\x00\\x00\\x0b", EscapeString(block));
FilterBlockReader reader(&policy_, block);
ASSERT_TRUE(reader.KeyMayMatch(0, "foo"));
ASSERT_TRUE(reader.KeyMayMatch(100000, "foo"));
}
TEST(FilterBlockTest, SingleChunk) {
FilterBlockBuilder builder(&policy_);
builder.StartBlock(100);
builder.AddKey("foo");
builder.AddKey("bar");
builder.AddKey("box");
builder.StartBlock(200);
builder.AddKey("box");
builder.StartBlock(300);
builder.AddKey("hello");
Slice block = builder.Finish();
FilterBlockReader reader(&policy_, block);
ASSERT_TRUE(reader.KeyMayMatch(100, "foo"));
ASSERT_TRUE(reader.KeyMayMatch(100, "bar"));
ASSERT_TRUE(reader.KeyMayMatch(100, "box"));
ASSERT_TRUE(reader.KeyMayMatch(100, "hello"));
ASSERT_TRUE(reader.KeyMayMatch(100, "foo"));
ASSERT_TRUE(! reader.KeyMayMatch(100, "missing"));
ASSERT_TRUE(! reader.KeyMayMatch(100, "other"));
}
TEST(FilterBlockTest, MultiChunk) {
FilterBlockBuilder builder(&policy_);
// First filter
builder.StartBlock(0);
builder.AddKey("foo");
builder.StartBlock(2000);
builder.AddKey("bar");
// Second filter
builder.StartBlock(3100);
builder.AddKey("box");
// Third filter is empty
// Last filter
builder.StartBlock(9000);
builder.AddKey("box");
builder.AddKey("hello");
Slice block = builder.Finish();
FilterBlockReader reader(&policy_, block);
// Check first filter
ASSERT_TRUE(reader.KeyMayMatch(0, "foo"));
ASSERT_TRUE(reader.KeyMayMatch(2000, "bar"));
ASSERT_TRUE(! reader.KeyMayMatch(0, "box"));
ASSERT_TRUE(! reader.KeyMayMatch(0, "hello"));
// Check second filter
ASSERT_TRUE(reader.KeyMayMatch(3100, "box"));
ASSERT_TRUE(! reader.KeyMayMatch(3100, "foo"));
ASSERT_TRUE(! reader.KeyMayMatch(3100, "bar"));
ASSERT_TRUE(! reader.KeyMayMatch(3100, "hello"));
// Check third filter (empty)
ASSERT_TRUE(! reader.KeyMayMatch(4100, "foo"));
ASSERT_TRUE(! reader.KeyMayMatch(4100, "bar"));
ASSERT_TRUE(! reader.KeyMayMatch(4100, "box"));
ASSERT_TRUE(! reader.KeyMayMatch(4100, "hello"));
// Check last filter
ASSERT_TRUE(reader.KeyMayMatch(9000, "box"));
ASSERT_TRUE(reader.KeyMayMatch(9000, "hello"));
ASSERT_TRUE(! reader.KeyMayMatch(9000, "foo"));
ASSERT_TRUE(! reader.KeyMayMatch(9000, "bar"));
}
} // namespace leveldb
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "table/format.h"
#include "leveldb/env.h"
#include "port/port.h"
#include "table/block.h"
#include "util/coding.h"
#include "util/crc32c.h"
namespace leveldb {
void BlockHandle::EncodeTo(std::string* dst) const {
// Sanity check that all fields have been set
assert(offset_ != ~static_cast<uint64_t>(0));
assert(size_ != ~static_cast<uint64_t>(0));
PutVarint64(dst, offset_);
PutVarint64(dst, size_);
}
Status BlockHandle::DecodeFrom(Slice* input) {
if (GetVarint64(input, &offset_) &&
GetVarint64(input, &size_)) {
return Status::OK();
} else {
return Status::Corruption("bad block handle");
}
}
void Footer::EncodeTo(std::string* dst) const {
const size_t original_size = dst->size();
metaindex_handle_.EncodeTo(dst);
index_handle_.EncodeTo(dst);
dst->resize(2 * BlockHandle::kMaxEncodedLength); // Padding
PutFixed32(dst, static_cast<uint32_t>(kTableMagicNumber & 0xffffffffu));
PutFixed32(dst, static_cast<uint32_t>(kTableMagicNumber >> 32));
assert(dst->size() == original_size + kEncodedLength);
(void)original_size; // Disable unused variable warning.
}
Status Footer::DecodeFrom(Slice* input) {
const char* magic_ptr = input->data() + kEncodedLength - 8;
const uint32_t magic_lo = DecodeFixed32(magic_ptr);
const uint32_t magic_hi = DecodeFixed32(magic_ptr + 4);
const uint64_t magic = ((static_cast<uint64_t>(magic_hi) << 32) |
(static_cast<uint64_t>(magic_lo)));
if (magic != kTableMagicNumber) {
return Status::Corruption("not an sstable (bad magic number)");
}
Status result = metaindex_handle_.DecodeFrom(input);
if (result.ok()) {
result = index_handle_.DecodeFrom(input);
}
if (result.ok()) {
// We skip over any leftover data (just padding for now) in "input"
const char* end = magic_ptr + 8;
*input = Slice(end, input->data() + input->size() - end);
}
return result;
}
Status ReadBlock(RandomAccessFile* file,
const ReadOptions& options,
const BlockHandle& handle,
BlockContents* result) {
result->data = Slice();
result->cachable = false;
result->heap_allocated = false;
// Read the block contents as well as the type/crc footer.
// See table_builder.cc for the code that built this structure.
size_t n = static_cast<size_t>(handle.size());
char* buf = new char[n + kBlockTrailerSize];
Slice contents;
Status s = file->Read(handle.offset(), n + kBlockTrailerSize, &contents, buf);
if (!s.ok()) {
delete[] buf;
return s;
}
if (contents.size() != n + kBlockTrailerSize) {
delete[] buf;
return Status::Corruption("truncated block read");
}
// Check the crc of the type and the block contents
const char* data = contents.data(); // Pointer to where Read put the data
if (options.verify_checksums) {
const uint32_t crc = crc32c::Unmask(DecodeFixed32(data + n + 1));
const uint32_t actual = crc32c::Value(data, n + 1);
if (actual != crc) {
delete[] buf;
s = Status::Corruption("block checksum mismatch");
return s;
}
}
switch (data[n]) {
case kNoCompression:
if (data != buf) {
// File implementation gave us pointer to some other data.
// Use it directly under the assumption that it will be live
// while the file is open.
delete[] buf;
result->data = Slice(data, n);
result->heap_allocated = false;
result->cachable = false; // Do not double-cache
} else {
result->data = Slice(buf, n);
result->heap_allocated = true;
result->cachable = true;
}
// Ok
break;
case kSnappyCompression: {
size_t ulength = 0;
if (!port::Snappy_GetUncompressedLength(data, n, &ulength)) {
delete[] buf;
return Status::Corruption("corrupted compressed block contents");
}
char* ubuf = new char[ulength];
if (!port::Snappy_Uncompress(data, n, ubuf)) {
delete[] buf;
delete[] ubuf;
return Status::Corruption("corrupted compressed block contents");
}
delete[] buf;
result->data = Slice(ubuf, ulength);
result->heap_allocated = true;
result->cachable = true;
break;
}
default:
delete[] buf;
return Status::Corruption("bad block type");
}
return Status::OK();
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_TABLE_FORMAT_H_
#define STORAGE_LEVELDB_TABLE_FORMAT_H_
#include <string>
#include <stdint.h>
#include "leveldb/slice.h"
#include "leveldb/status.h"
#include "leveldb/table_builder.h"
namespace leveldb {
class Block;
class RandomAccessFile;
struct ReadOptions;
// BlockHandle is a pointer to the extent of a file that stores a data
// block or a meta block.
class BlockHandle {
public:
BlockHandle();
// The offset of the block in the file.
uint64_t offset() const { return offset_; }
void set_offset(uint64_t offset) { offset_ = offset; }
// The size of the stored block
uint64_t size() const { return size_; }
void set_size(uint64_t size) { size_ = size; }
void EncodeTo(std::string* dst) const;
Status DecodeFrom(Slice* input);
// Maximum encoding length of a BlockHandle
enum { kMaxEncodedLength = 10 + 10 };
private:
uint64_t offset_;
uint64_t size_;
};
// Footer encapsulates the fixed information stored at the tail
// end of every table file.
class Footer {
public:
Footer() { }
// The block handle for the metaindex block of the table
const BlockHandle& metaindex_handle() const { return metaindex_handle_; }
void set_metaindex_handle(const BlockHandle& h) { metaindex_handle_ = h; }
// The block handle for the index block of the table
const BlockHandle& index_handle() const {
return index_handle_;
}
void set_index_handle(const BlockHandle& h) {
index_handle_ = h;
}
void EncodeTo(std::string* dst) const;
Status DecodeFrom(Slice* input);
// Encoded length of a Footer. Note that the serialization of a
// Footer will always occupy exactly this many bytes. It consists
// of two block handles and a magic number.
enum {
kEncodedLength = 2*BlockHandle::kMaxEncodedLength + 8
};
private:
BlockHandle metaindex_handle_;
BlockHandle index_handle_;
};
// kTableMagicNumber was picked by running
// echo http://code.google.com/p/leveldb/ | sha1sum
// and taking the leading 64 bits.
static const uint64_t kTableMagicNumber = 0xdb4775248b80fb57ull;
// 1-byte type + 32-bit crc
static const size_t kBlockTrailerSize = 5;
struct BlockContents {
Slice data; // Actual contents of data
bool cachable; // True iff data can be cached
bool heap_allocated; // True iff caller should delete[] data.data()
};
// Read the block identified by "handle" from "file". On failure
// return non-OK. On success fill *result and return OK.
extern Status ReadBlock(RandomAccessFile* file,
const ReadOptions& options,
const BlockHandle& handle,
BlockContents* result);
// Implementation details follow. Clients should ignore,
inline BlockHandle::BlockHandle()
: offset_(~static_cast<uint64_t>(0)),
size_(~static_cast<uint64_t>(0)) {
}
} // namespace leveldb
#endif // STORAGE_LEVELDB_TABLE_FORMAT_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "leveldb/iterator.h"
namespace leveldb {
Iterator::Iterator() {
cleanup_.function = NULL;
cleanup_.next = NULL;
}
Iterator::~Iterator() {
if (cleanup_.function != NULL) {
(*cleanup_.function)(cleanup_.arg1, cleanup_.arg2);
for (Cleanup* c = cleanup_.next; c != NULL; ) {
(*c->function)(c->arg1, c->arg2);
Cleanup* next = c->next;
delete c;
c = next;
}
}
}
void Iterator::RegisterCleanup(CleanupFunction func, void* arg1, void* arg2) {
assert(func != NULL);
Cleanup* c;
if (cleanup_.function == NULL) {
c = &cleanup_;
} else {
c = new Cleanup;
c->next = cleanup_.next;
cleanup_.next = c;
}
c->function = func;
c->arg1 = arg1;
c->arg2 = arg2;
}
namespace {
class EmptyIterator : public Iterator {
public:
EmptyIterator(const Status& s) : status_(s) { }
virtual bool Valid() const { return false; }
virtual void Seek(const Slice& target) { }
virtual void SeekToFirst() { }
virtual void SeekToLast() { }
virtual void Next() { assert(false); }
virtual void Prev() { assert(false); }
Slice key() const { assert(false); return Slice(); }
Slice value() const { assert(false); return Slice(); }
virtual Status status() const { return status_; }
private:
Status status_;
};
} // namespace
Iterator* NewEmptyIterator() {
return new EmptyIterator(Status::OK());
}
Iterator* NewErrorIterator(const Status& status) {
return new EmptyIterator(status);
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_TABLE_ITERATOR_WRAPPER_H_
#define STORAGE_LEVELDB_TABLE_ITERATOR_WRAPPER_H_
#include "leveldb/iterator.h"
#include "leveldb/slice.h"
namespace leveldb {
// A internal wrapper class with an interface similar to Iterator that
// caches the valid() and key() results for an underlying iterator.
// This can help avoid virtual function calls and also gives better
// cache locality.
class IteratorWrapper {
public:
IteratorWrapper(): iter_(NULL), valid_(false) { }
explicit IteratorWrapper(Iterator* iter): iter_(NULL) {
Set(iter);
}
~IteratorWrapper() { delete iter_; }
Iterator* iter() const { return iter_; }
// Takes ownership of "iter" and will delete it when destroyed, or
// when Set() is invoked again.
void Set(Iterator* iter) {
delete iter_;
iter_ = iter;
if (iter_ == NULL) {
valid_ = false;
} else {
Update();
}
}
// Iterator interface methods
bool Valid() const { return valid_; }
Slice key() const { assert(Valid()); return key_; }
Slice value() const { assert(Valid()); return iter_->value(); }
// Methods below require iter() != NULL
Status status() const { assert(iter_); return iter_->status(); }
void Next() { assert(iter_); iter_->Next(); Update(); }
void Prev() { assert(iter_); iter_->Prev(); Update(); }
void Seek(const Slice& k) { assert(iter_); iter_->Seek(k); Update(); }
void SeekToFirst() { assert(iter_); iter_->SeekToFirst(); Update(); }
void SeekToLast() { assert(iter_); iter_->SeekToLast(); Update(); }
private:
void Update() {
valid_ = iter_->Valid();
if (valid_) {
key_ = iter_->key();
}
}
Iterator* iter_;
bool valid_;
Slice key_;
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_TABLE_ITERATOR_WRAPPER_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "table/merger.h"
#include "leveldb/comparator.h"
#include "leveldb/iterator.h"
#include "table/iterator_wrapper.h"
namespace leveldb {
namespace {
class MergingIterator : public Iterator {
public:
MergingIterator(const Comparator* comparator, Iterator** children, int n)
: comparator_(comparator),
children_(new IteratorWrapper[n]),
n_(n),
current_(NULL),
direction_(kForward) {
for (int i = 0; i < n; i++) {
children_[i].Set(children[i]);
}
}
virtual ~MergingIterator() {
delete[] children_;
}
virtual bool Valid() const {
return (current_ != NULL);
}
virtual void SeekToFirst() {
for (int i = 0; i < n_; i++) {
children_[i].SeekToFirst();
}
FindSmallest();
direction_ = kForward;
}
virtual void SeekToLast() {
for (int i = 0; i < n_; i++) {
children_[i].SeekToLast();
}
FindLargest();
direction_ = kReverse;
}
virtual void Seek(const Slice& target) {
for (int i = 0; i < n_; i++) {
children_[i].Seek(target);
}
FindSmallest();
direction_ = kForward;
}
virtual void Next() {
assert(Valid());
// Ensure that all children are positioned after key().
// If we are moving in the forward direction, it is already
// true for all of the non-current_ children since current_ is
// the smallest child and key() == current_->key(). Otherwise,
// we explicitly position the non-current_ children.
if (direction_ != kForward) {
for (int i = 0; i < n_; i++) {
IteratorWrapper* child = &children_[i];
if (child != current_) {
child->Seek(key());
if (child->Valid() &&
comparator_->Compare(key(), child->key()) == 0) {
child->Next();
}
}
}
direction_ = kForward;
}
current_->Next();
FindSmallest();
}
virtual void Prev() {
assert(Valid());
// Ensure that all children are positioned before key().
// If we are moving in the reverse direction, it is already
// true for all of the non-current_ children since current_ is
// the largest child and key() == current_->key(). Otherwise,
// we explicitly position the non-current_ children.
if (direction_ != kReverse) {
for (int i = 0; i < n_; i++) {
IteratorWrapper* child = &children_[i];
if (child != current_) {
child->Seek(key());
if (child->Valid()) {
// Child is at first entry >= key(). Step back one to be < key()
child->Prev();
} else {
// Child has no entries >= key(). Position at last entry.
child->SeekToLast();
}
}
}
direction_ = kReverse;
}
current_->Prev();
FindLargest();
}
virtual Slice key() const {
assert(Valid());
return current_->key();
}
virtual Slice value() const {
assert(Valid());
return current_->value();
}
virtual Status status() const {
Status status;
for (int i = 0; i < n_; i++) {
status = children_[i].status();
if (!status.ok()) {
break;
}
}
return status;
}
private:
void FindSmallest();
void FindLargest();
// We might want to use a heap in case there are lots of children.
// For now we use a simple array since we expect a very small number
// of children in leveldb.
const Comparator* comparator_;
IteratorWrapper* children_;
int n_;
IteratorWrapper* current_;
// Which direction is the iterator moving?
enum Direction {
kForward,
kReverse
};
Direction direction_;
};
void MergingIterator::FindSmallest() {
IteratorWrapper* smallest = NULL;
for (int i = 0; i < n_; i++) {
IteratorWrapper* child = &children_[i];
if (child->Valid()) {
if (smallest == NULL) {
smallest = child;
} else if (comparator_->Compare(child->key(), smallest->key()) < 0) {
smallest = child;
}
}
}
current_ = smallest;
}
void MergingIterator::FindLargest() {
IteratorWrapper* largest = NULL;
for (int i = n_-1; i >= 0; i--) {
IteratorWrapper* child = &children_[i];
if (child->Valid()) {
if (largest == NULL) {
largest = child;
} else if (comparator_->Compare(child->key(), largest->key()) > 0) {
largest = child;
}
}
}
current_ = largest;
}
} // namespace
Iterator* NewMergingIterator(const Comparator* cmp, Iterator** list, int n) {
assert(n >= 0);
if (n == 0) {
return NewEmptyIterator();
} else if (n == 1) {
return list[0];
} else {
return new MergingIterator(cmp, list, n);
}
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_TABLE_MERGER_H_
#define STORAGE_LEVELDB_TABLE_MERGER_H_
namespace leveldb {
class Comparator;
class Iterator;
// Return an iterator that provided the union of the data in
// children[0,n-1]. Takes ownership of the child iterators and
// will delete them when the result iterator is deleted.
//
// The result does no duplicate suppression. I.e., if a particular
// key is present in K child iterators, it will be yielded K times.
//
// REQUIRES: n >= 0
extern Iterator* NewMergingIterator(
const Comparator* comparator, Iterator** children, int n);
} // namespace leveldb
#endif // STORAGE_LEVELDB_TABLE_MERGER_H_

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "leveldb/table.h"
#include "leveldb/cache.h"
#include "leveldb/comparator.h"
#include "leveldb/env.h"
#include "leveldb/filter_policy.h"
#include "leveldb/options.h"
#include "table/block.h"
#include "table/filter_block.h"
#include "table/format.h"
#include "table/two_level_iterator.h"
#include "util/coding.h"
namespace leveldb {
struct Table::Rep {
~Rep() {
delete filter;
delete [] filter_data;
delete index_block;
}
Options options;
Status status;
RandomAccessFile* file;
uint64_t cache_id;
FilterBlockReader* filter;
const char* filter_data;
BlockHandle metaindex_handle; // Handle to metaindex_block: saved from footer
Block* index_block;
};
Status Table::Open(const Options& options,
RandomAccessFile* file,
uint64_t size,
Table** table) {
*table = NULL;
if (size < Footer::kEncodedLength) {
return Status::Corruption("file is too short to be an sstable");
}
char footer_space[Footer::kEncodedLength];
Slice footer_input;
Status s = file->Read(size - Footer::kEncodedLength, Footer::kEncodedLength,
&footer_input, footer_space);
if (!s.ok()) return s;
Footer footer;
s = footer.DecodeFrom(&footer_input);
if (!s.ok()) return s;
// Read the index block
BlockContents contents;
Block* index_block = NULL;
if (s.ok()) {
ReadOptions opt;
if (options.paranoid_checks) {
opt.verify_checksums = true;
}
s = ReadBlock(file, opt, footer.index_handle(), &contents);
if (s.ok()) {
index_block = new Block(contents);
}
}
if (s.ok()) {
// We've successfully read the footer and the index block: we're
// ready to serve requests.
Rep* rep = new Table::Rep;
rep->options = options;
rep->file = file;
rep->metaindex_handle = footer.metaindex_handle();
rep->index_block = index_block;
rep->cache_id = (options.block_cache ? options.block_cache->NewId() : 0);
rep->filter_data = NULL;
rep->filter = NULL;
*table = new Table(rep);
(*table)->ReadMeta(footer);
} else {
delete index_block;
}
return s;
}
void Table::ReadMeta(const Footer& footer) {
if (rep_->options.filter_policy == NULL) {
return; // Do not need any metadata
}
// TODO(sanjay): Skip this if footer.metaindex_handle() size indicates
// it is an empty block.
ReadOptions opt;
if (rep_->options.paranoid_checks) {
opt.verify_checksums = true;
}
BlockContents contents;
if (!ReadBlock(rep_->file, opt, footer.metaindex_handle(), &contents).ok()) {
// Do not propagate errors since meta info is not needed for operation
return;
}
Block* meta = new Block(contents);
Iterator* iter = meta->NewIterator(BytewiseComparator());
std::string key = "filter.";
key.append(rep_->options.filter_policy->Name());
iter->Seek(key);
if (iter->Valid() && iter->key() == Slice(key)) {
ReadFilter(iter->value());
}
delete iter;
delete meta;
}
void Table::ReadFilter(const Slice& filter_handle_value) {
Slice v = filter_handle_value;
BlockHandle filter_handle;
if (!filter_handle.DecodeFrom(&v).ok()) {
return;
}
// We might want to unify with ReadBlock() if we start
// requiring checksum verification in Table::Open.
ReadOptions opt;
if (rep_->options.paranoid_checks) {
opt.verify_checksums = true;
}
BlockContents block;
if (!ReadBlock(rep_->file, opt, filter_handle, &block).ok()) {
return;
}
if (block.heap_allocated) {
rep_->filter_data = block.data.data(); // Will need to delete later
}
rep_->filter = new FilterBlockReader(rep_->options.filter_policy, block.data);
}
Table::~Table() {
delete rep_;
}
static void DeleteBlock(void* arg, void* ignored) {
delete reinterpret_cast<Block*>(arg);
}
static void DeleteCachedBlock(const Slice& key, void* value) {
Block* block = reinterpret_cast<Block*>(value);
delete block;
}
static void ReleaseBlock(void* arg, void* h) {
Cache* cache = reinterpret_cast<Cache*>(arg);
Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
cache->Release(handle);
}
// Convert an index iterator value (i.e., an encoded BlockHandle)
// into an iterator over the contents of the corresponding block.
Iterator* Table::BlockReader(void* arg,
const ReadOptions& options,
const Slice& index_value) {
Table* table = reinterpret_cast<Table*>(arg);
Cache* block_cache = table->rep_->options.block_cache;
Block* block = NULL;
Cache::Handle* cache_handle = NULL;
BlockHandle handle;
Slice input = index_value;
Status s = handle.DecodeFrom(&input);
// We intentionally allow extra stuff in index_value so that we
// can add more features in the future.
if (s.ok()) {
BlockContents contents;
if (block_cache != NULL) {
char cache_key_buffer[16];
EncodeFixed64(cache_key_buffer, table->rep_->cache_id);
EncodeFixed64(cache_key_buffer+8, handle.offset());
Slice key(cache_key_buffer, sizeof(cache_key_buffer));
cache_handle = block_cache->Lookup(key);
if (cache_handle != NULL) {
block = reinterpret_cast<Block*>(block_cache->Value(cache_handle));
} else {
s = ReadBlock(table->rep_->file, options, handle, &contents);
if (s.ok()) {
block = new Block(contents);
if (contents.cachable && options.fill_cache) {
cache_handle = block_cache->Insert(
key, block, block->size(), &DeleteCachedBlock);
}
}
}
} else {
s = ReadBlock(table->rep_->file, options, handle, &contents);
if (s.ok()) {
block = new Block(contents);
}
}
}
Iterator* iter;
if (block != NULL) {
iter = block->NewIterator(table->rep_->options.comparator);
if (cache_handle == NULL) {
iter->RegisterCleanup(&DeleteBlock, block, NULL);
} else {
iter->RegisterCleanup(&ReleaseBlock, block_cache, cache_handle);
}
} else {
iter = NewErrorIterator(s);
}
return iter;
}
Iterator* Table::NewIterator(const ReadOptions& options) const {
return NewTwoLevelIterator(
rep_->index_block->NewIterator(rep_->options.comparator),
&Table::BlockReader, const_cast<Table*>(this), options);
}
Status Table::InternalGet(const ReadOptions& options, const Slice& k,
void* arg,
void (*saver)(void*, const Slice&, const Slice&)) {
Status s;
Iterator* iiter = rep_->index_block->NewIterator(rep_->options.comparator);
iiter->Seek(k);
if (iiter->Valid()) {
Slice handle_value = iiter->value();
FilterBlockReader* filter = rep_->filter;
BlockHandle handle;
if (filter != NULL &&
handle.DecodeFrom(&handle_value).ok() &&
!filter->KeyMayMatch(handle.offset(), k)) {
// Not found
} else {
Iterator* block_iter = BlockReader(this, options, iiter->value());
block_iter->Seek(k);
if (block_iter->Valid()) {
(*saver)(arg, block_iter->key(), block_iter->value());
}
s = block_iter->status();
delete block_iter;
}
}
if (s.ok()) {
s = iiter->status();
}
delete iiter;
return s;
}
uint64_t Table::ApproximateOffsetOf(const Slice& key) const {
Iterator* index_iter =
rep_->index_block->NewIterator(rep_->options.comparator);
index_iter->Seek(key);
uint64_t result;
if (index_iter->Valid()) {
BlockHandle handle;
Slice input = index_iter->value();
Status s = handle.DecodeFrom(&input);
if (s.ok()) {
result = handle.offset();
} else {
// Strange: we can't decode the block handle in the index block.
// We'll just return the offset of the metaindex block, which is
// close to the whole file size for this case.
result = rep_->metaindex_handle.offset();
}
} else {
// key is past the last key in the file. Approximate the offset
// by returning the offset of the metaindex block (which is
// right near the end of the file).
result = rep_->metaindex_handle.offset();
}
delete index_iter;
return result;
}
} // namespace leveldb

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "leveldb/table_builder.h"
#include <assert.h>
#include "leveldb/comparator.h"
#include "leveldb/env.h"
#include "leveldb/filter_policy.h"
#include "leveldb/options.h"
#include "table/block_builder.h"
#include "table/filter_block.h"
#include "table/format.h"
#include "util/coding.h"
#include "util/crc32c.h"
namespace leveldb {
struct TableBuilder::Rep {
Options options;
Options index_block_options;
WritableFile* file;
uint64_t offset;
Status status;
BlockBuilder data_block;
BlockBuilder index_block;
std::string last_key;
int64_t num_entries;
bool closed; // Either Finish() or Abandon() has been called.
FilterBlockBuilder* filter_block;
// We do not emit the index entry for a block until we have seen the
// first key for the next data block. This allows us to use shorter
// keys in the index block. For example, consider a block boundary
// between the keys "the quick brown fox" and "the who". We can use
// "the r" as the key for the index block entry since it is >= all
// entries in the first block and < all entries in subsequent
// blocks.
//
// Invariant: r->pending_index_entry is true only if data_block is empty.
bool pending_index_entry;
BlockHandle pending_handle; // Handle to add to index block
std::string compressed_output;
Rep(const Options& opt, WritableFile* f)
: options(opt),
index_block_options(opt),
file(f),
offset(0),
data_block(&options),
index_block(&index_block_options),
num_entries(0),
closed(false),
filter_block(opt.filter_policy == NULL ? NULL
: new FilterBlockBuilder(opt.filter_policy)),
pending_index_entry(false) {
index_block_options.block_restart_interval = 1;
}
};
TableBuilder::TableBuilder(const Options& options, WritableFile* file)
: rep_(new Rep(options, file)) {
if (rep_->filter_block != NULL) {
rep_->filter_block->StartBlock(0);
}
}
TableBuilder::~TableBuilder() {
assert(rep_->closed); // Catch errors where caller forgot to call Finish()
delete rep_->filter_block;
delete rep_;
}
Status TableBuilder::ChangeOptions(const Options& options) {
// Note: if more fields are added to Options, update
// this function to catch changes that should not be allowed to
// change in the middle of building a Table.
if (options.comparator != rep_->options.comparator) {
return Status::InvalidArgument("changing comparator while building table");
}
// Note that any live BlockBuilders point to rep_->options and therefore
// will automatically pick up the updated options.
rep_->options = options;
rep_->index_block_options = options;
rep_->index_block_options.block_restart_interval = 1;
return Status::OK();
}
void TableBuilder::Add(const Slice& key, const Slice& value) {
Rep* r = rep_;
assert(!r->closed);
if (!ok()) return;
if (r->num_entries > 0) {
assert(r->options.comparator->Compare(key, Slice(r->last_key)) > 0);
}
if (r->pending_index_entry) {
assert(r->data_block.empty());
r->options.comparator->FindShortestSeparator(&r->last_key, key);
std::string handle_encoding;
r->pending_handle.EncodeTo(&handle_encoding);
r->index_block.Add(r->last_key, Slice(handle_encoding));
r->pending_index_entry = false;
}
if (r->filter_block != NULL) {
r->filter_block->AddKey(key);
}
r->last_key.assign(key.data(), key.size());
r->num_entries++;
r->data_block.Add(key, value);
const size_t estimated_block_size = r->data_block.CurrentSizeEstimate();
if (estimated_block_size >= r->options.block_size) {
Flush();
}
}
void TableBuilder::Flush() {
Rep* r = rep_;
assert(!r->closed);
if (!ok()) return;
if (r->data_block.empty()) return;
assert(!r->pending_index_entry);
WriteBlock(&r->data_block, &r->pending_handle);
if (ok()) {
r->pending_index_entry = true;
r->status = r->file->Flush();
}
if (r->filter_block != NULL) {
r->filter_block->StartBlock(r->offset);
}
}
void TableBuilder::WriteBlock(BlockBuilder* block, BlockHandle* handle) {
// File format contains a sequence of blocks where each block has:
// block_data: uint8[n]
// type: uint8
// crc: uint32
assert(ok());
Rep* r = rep_;
Slice raw = block->Finish();
Slice block_contents;
CompressionType type = r->options.compression;
// TODO(postrelease): Support more compression options: zlib?
switch (type) {
case kNoCompression:
block_contents = raw;
break;
case kSnappyCompression: {
std::string* compressed = &r->compressed_output;
if (port::Snappy_Compress(raw.data(), raw.size(), compressed) &&
compressed->size() < raw.size() - (raw.size() / 8u)) {
block_contents = *compressed;
} else {
// Snappy not supported, or compressed less than 12.5%, so just
// store uncompressed form
block_contents = raw;
type = kNoCompression;
}
break;
}
}
WriteRawBlock(block_contents, type, handle);
r->compressed_output.clear();
block->Reset();
}
void TableBuilder::WriteRawBlock(const Slice& block_contents,
CompressionType type,
BlockHandle* handle) {
Rep* r = rep_;
handle->set_offset(r->offset);
handle->set_size(block_contents.size());
r->status = r->file->Append(block_contents);
if (r->status.ok()) {
char trailer[kBlockTrailerSize];
trailer[0] = type;
uint32_t crc = crc32c::Value(block_contents.data(), block_contents.size());
crc = crc32c::Extend(crc, trailer, 1); // Extend crc to cover block type
EncodeFixed32(trailer+1, crc32c::Mask(crc));
r->status = r->file->Append(Slice(trailer, kBlockTrailerSize));
if (r->status.ok()) {
r->offset += block_contents.size() + kBlockTrailerSize;
}
}
}
Status TableBuilder::status() const {
return rep_->status;
}
Status TableBuilder::Finish() {
Rep* r = rep_;
Flush();
assert(!r->closed);
r->closed = true;
BlockHandle filter_block_handle, metaindex_block_handle, index_block_handle;
// Write filter block
if (ok() && r->filter_block != NULL) {
WriteRawBlock(r->filter_block->Finish(), kNoCompression,
&filter_block_handle);
}
// Write metaindex block
if (ok()) {
BlockBuilder meta_index_block(&r->options);
if (r->filter_block != NULL) {
// Add mapping from "filter.Name" to location of filter data
std::string key = "filter.";
key.append(r->options.filter_policy->Name());
std::string handle_encoding;
filter_block_handle.EncodeTo(&handle_encoding);
meta_index_block.Add(key, handle_encoding);
}
// TODO(postrelease): Add stats and other meta blocks
WriteBlock(&meta_index_block, &metaindex_block_handle);
}
// Write index block
if (ok()) {
if (r->pending_index_entry) {
r->options.comparator->FindShortSuccessor(&r->last_key);
std::string handle_encoding;
r->pending_handle.EncodeTo(&handle_encoding);
r->index_block.Add(r->last_key, Slice(handle_encoding));
r->pending_index_entry = false;
}
WriteBlock(&r->index_block, &index_block_handle);
}
// Write footer
if (ok()) {
Footer footer;
footer.set_metaindex_handle(metaindex_block_handle);
footer.set_index_handle(index_block_handle);
std::string footer_encoding;
footer.EncodeTo(&footer_encoding);
r->status = r->file->Append(footer_encoding);
if (r->status.ok()) {
r->offset += footer_encoding.size();
}
}
return r->status;
}
void TableBuilder::Abandon() {
Rep* r = rep_;
assert(!r->closed);
r->closed = true;
}
uint64_t TableBuilder::NumEntries() const {
return rep_->num_entries;
}
uint64_t TableBuilder::FileSize() const {
return rep_->offset;
}
} // namespace leveldb

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