diff options
author | Pierre Schmitz <pierre@archlinux.de> | 2013-12-08 09:55:49 +0100 |
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committer | Pierre Schmitz <pierre@archlinux.de> | 2013-12-08 09:55:49 +0100 |
commit | 4ac9fa081a7c045f6a9f1cfc529d82423f485b2e (patch) | |
tree | af68743f2f4a47d13f2b0eb05f5c4aaf86d8ea37 /includes/filebackend/lockmanager/RedisLockManager.php | |
parent | af4da56f1ad4d3ef7b06557bae365da2ea27a897 (diff) |
Update to MediaWiki 1.22.0
Diffstat (limited to 'includes/filebackend/lockmanager/RedisLockManager.php')
-rw-r--r-- | includes/filebackend/lockmanager/RedisLockManager.php | 288 |
1 files changed, 288 insertions, 0 deletions
diff --git a/includes/filebackend/lockmanager/RedisLockManager.php b/includes/filebackend/lockmanager/RedisLockManager.php new file mode 100644 index 00000000..43b0198a --- /dev/null +++ b/includes/filebackend/lockmanager/RedisLockManager.php @@ -0,0 +1,288 @@ +<?php +/** + * Version of LockManager based on using redis servers. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * http://www.gnu.org/copyleft/gpl.html + * + * @file + * @ingroup LockManager + */ + +/** + * Manage locks using redis servers. + * + * Version of LockManager based on using redis servers. + * This is meant for multi-wiki systems that may share files. + * All locks are non-blocking, which avoids deadlocks. + * + * All lock requests for a resource, identified by a hash string, will map to one + * bucket. Each bucket maps to one or several peer servers, each running redis. + * A majority of peers must agree for a lock to be acquired. + * + * This class requires Redis 2.6 as it makes use Lua scripts for fast atomic operations. + * + * @ingroup LockManager + * @since 1.22 + */ +class RedisLockManager extends QuorumLockManager { + /** @var Array Mapping of lock types to the type actually used */ + protected $lockTypeMap = array( + self::LOCK_SH => self::LOCK_SH, + self::LOCK_UW => self::LOCK_SH, + self::LOCK_EX => self::LOCK_EX + ); + + /** @var RedisConnectionPool */ + protected $redisPool; + /** @var Array Map server names to hostname/IP and port numbers */ + protected $lockServers = array(); + + protected $session = ''; // string; random UUID + + /** + * Construct a new instance from configuration. + * + * $config paramaters include: + * - lockServers : Associative array of server names to "<IP>:<port>" strings. + * - srvsByBucket : Array of 1-16 consecutive integer keys, starting from 0, + * each having an odd-numbered list of server names (peers) as values. + * - redisConfig : Configuration for RedisConnectionPool::__construct(). + * + * @param Array $config + * @throws MWException + */ + public function __construct( array $config ) { + parent::__construct( $config ); + + $this->lockServers = $config['lockServers']; + // Sanitize srvsByBucket config to prevent PHP errors + $this->srvsByBucket = array_filter( $config['srvsByBucket'], 'is_array' ); + $this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive + + $config['redisConfig']['serializer'] = 'none'; + $this->redisPool = RedisConnectionPool::singleton( $config['redisConfig'] ); + + $this->session = wfRandomString( 32 ); + } + + // @TODO: change this code to work in one batch + protected function getLocksOnServer( $lockSrv, array $pathsByType ) { + $status = Status::newGood(); + + $lockedPaths = array(); + foreach ( $pathsByType as $type => $paths ) { + $status->merge( $this->doGetLocksOnServer( $lockSrv, $paths, $type ) ); + if ( $status->isOK() ) { + $lockedPaths[$type] = isset( $lockedPaths[$type] ) + ? array_merge( $lockedPaths[$type], $paths ) + : $paths; + } else { + foreach ( $lockedPaths as $type => $paths ) { + $status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) ); + } + break; + } + } + + return $status; + } + + // @TODO: change this code to work in one batch + protected function freeLocksOnServer( $lockSrv, array $pathsByType ) { + $status = Status::newGood(); + + foreach ( $pathsByType as $type => $paths ) { + $status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) ); + } + + return $status; + } + + protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) { + $status = Status::newGood(); + + $server = $this->lockServers[$lockSrv]; + $conn = $this->redisPool->getConnection( $server ); + if ( !$conn ) { + foreach ( $paths as $path ) { + $status->fatal( 'lockmanager-fail-acquirelock', $path ); + } + return $status; + } + + $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records + + try { + static $script = +<<<LUA + if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then + return redis.error_reply('Unrecognized lock type given (must be EX or SH)') + end + local failed = {} + -- Check that all the locks can be acquired + for i,resourceKey in ipairs(KEYS) do + local keyIsFree = true + local currentLocks = redis.call('hKeys',resourceKey) + for i,lockKey in ipairs(currentLocks) do + local _, _, type, session = string.find(lockKey,"(%w+):(%w+)") + -- Check any locks that are not owned by this session + if session ~= ARGV[2] then + local lockTimestamp = redis.call('hGet',resourceKey,lockKey) + if 1*lockTimestamp < ( ARGV[4] - ARGV[3] ) then + -- Lock is stale, so just prune it out + redis.call('hDel',resourceKey,lockKey) + elseif ARGV[1] == 'EX' or type == 'EX' then + keyIsFree = false + break + end + end + end + if not keyIsFree then + failed[#failed+1] = resourceKey + end + end + -- If all locks could be acquired, then do so + if #failed == 0 then + for i,resourceKey in ipairs(KEYS) do + redis.call('hSet',resourceKey,ARGV[1] .. ':' .. ARGV[2],ARGV[4]) + -- In addition to invalidation logic, be sure to garbage collect + redis.call('expire',resourceKey,ARGV[3]) + end + end + return failed +LUA; + $res = $conn->luaEval( $script, + array_merge( + $keys, // KEYS[0], KEYS[1],...KEYS[N] + array( + $type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1] + $this->session, // ARGV[2] + $this->lockTTL, // ARGV[3] + time() // ARGV[4] + ) + ), + count( $keys ) # number of first argument(s) that are keys + ); + } catch ( RedisException $e ) { + $res = false; + $this->redisPool->handleException( $server, $conn, $e ); + } + + if ( $res === false ) { + foreach ( $paths as $path ) { + $status->fatal( 'lockmanager-fail-acquirelock', $path ); + } + } else { + $pathsByKey = array_combine( $keys, $paths ); + foreach ( $res as $key ) { + $status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] ); + } + } + + return $status; + } + + protected function doFreeLocksOnServer( $lockSrv, array $paths, $type ) { + $status = Status::newGood(); + + $server = $this->lockServers[$lockSrv]; + $conn = $this->redisPool->getConnection( $server ); + if ( !$conn ) { + foreach ( $paths as $path ) { + $status->fatal( 'lockmanager-fail-releaselock', $path ); + } + return $status; + } + + $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records + + try { + static $script = +<<<LUA + if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then + return redis.error_reply('Unrecognized lock type given (must be EX or SH)') + end + local failed = {} + for i,resourceKey in ipairs(KEYS) do + local released = redis.call('hDel',resourceKey,ARGV[1] .. ':' .. ARGV[2]) + if released > 0 then + -- Remove the whole structure if it is now empty + if redis.call('hLen',resourceKey) == 0 then + redis.call('del',resourceKey) + end + else + failed[#failed+1] = resourceKey + end + end + return failed +LUA; + $res = $conn->luaEval( $script, + array_merge( + $keys, // KEYS[0], KEYS[1],...KEYS[N] + array( + $type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1] + $this->session // ARGV[2] + ) + ), + count( $keys ) # number of first argument(s) that are keys + ); + } catch ( RedisException $e ) { + $res = false; + $this->redisPool->handleException( $server, $conn, $e ); + } + + if ( $res === false ) { + foreach ( $paths as $path ) { + $status->fatal( 'lockmanager-fail-releaselock', $path ); + } + } else { + $pathsByKey = array_combine( $keys, $paths ); + foreach ( $res as $key ) { + $status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] ); + } + } + + return $status; + } + + protected function releaseAllLocks() { + return Status::newGood(); // not supported + } + + protected function isServerUp( $lockSrv ) { + return (bool)$this->redisPool->getConnection( $this->lockServers[$lockSrv] ); + } + + /** + * @param $path string + * @return string + */ + protected function recordKeyForPath( $path ) { + return implode( ':', array( __CLASS__, 'locks', $this->sha1Base36Absolute( $path ) ) ); + } + + /** + * Make sure remaining locks get cleared for sanity + */ + function __destruct() { + while ( count( $this->locksHeld ) ) { + foreach ( $this->locksHeld as $path => $locks ) { + $this->doUnlock( array( $path ), self::LOCK_EX ); + $this->doUnlock( array( $path ), self::LOCK_SH ); + } + } + } +} |