From: Aaron Schulz <aschulz@wikimedia.org>
Date: Tue, 19 Feb 2013 02:45:23 +0000 (-0800)
Subject: [LockManager] Added a RedisLockManager class.
X-Git-Tag: 1.31.0-rc.0~19945
X-Git-Url: https://git.cyclocoop.org/admin/?a=commitdiff_plain;h=ed01e813591acaec424e482791f774d800a466bb;p=lhc%2Fweb%2Fwiklou.git

[LockManager] Added a RedisLockManager class.

Change-Id: I7ade74eb307a5075533f36836768af60f106a6b9
---

diff --git a/includes/AutoLoader.php b/includes/AutoLoader.php
index 88bb21b1b6..4a8ecaa69e 100644
--- a/includes/AutoLoader.php
+++ b/includes/AutoLoader.php
@@ -573,8 +573,9 @@ $wgAutoloadLocalClasses = array(
 	'LSLockManager' => 'includes/filebackend/lockmanager/LSLockManager.php',
 	'MemcLockManager' => 'includes/filebackend/lockmanager/MemcLockManager.php',
 	'QuorumLockManager' => 'includes/filebackend/lockmanager/QuorumLockManager.php',
-	'MySqlLockManager' => 'includes/filebackend/lockmanager/DBLockManager.php',
-	'PostgreSqlLockManager' => 'includes/filebackend/lockmanager/DBLockManager.php',
+	'MySqlLockManager'=> 'includes/filebackend/lockmanager/DBLockManager.php',
+	'PostgreSqlLockManager'=> 'includes/filebackend/lockmanager/DBLockManager.php',
+	'RedisLockManager'=> 'includes/filebackend/lockmanager/RedisLockManager.php',
 	'NullLockManager' => 'includes/filebackend/lockmanager/LockManager.php',
 	'FileOp' => 'includes/filebackend/FileOp.php',
 	'FileOpBatch' => 'includes/filebackend/FileOpBatch.php',
diff --git a/includes/filebackend/lockmanager/LockManager.php b/includes/filebackend/lockmanager/LockManager.php
index 9b7a7ff6c7..9c778c7e24 100644
--- a/includes/filebackend/lockmanager/LockManager.php
+++ b/includes/filebackend/lockmanager/LockManager.php
@@ -151,7 +151,7 @@ abstract class LockManager {
 	 *
 	 * @param array $paths List of storage paths
 	 * @param $type integer LockManager::LOCK_* constant
-	 * @return string
+	 * @return Status
 	 */
 	abstract protected function doLock( array $paths, $type );
 
@@ -160,7 +160,7 @@ abstract class LockManager {
 	 *
 	 * @param array $paths List of storage paths
 	 * @param $type integer LockManager::LOCK_* constant
-	 * @return string
+	 * @return Status
 	 */
 	abstract protected function doUnlock( array $paths, $type );
 }
diff --git a/includes/filebackend/lockmanager/RedisLockManager.php b/includes/filebackend/lockmanager/RedisLockManager.php
new file mode 100644
index 0000000000..e8e5996692
--- /dev/null
+++ b/includes/filebackend/lockmanager/RedisLockManager.php
@@ -0,0 +1,255 @@
+<?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 );
+	}
+
+	protected function getLocksOnServer( $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 freeLocksOnServer( $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 );
+			}
+		}
+	}
+}