Update to MediaWiki 1.22.0

1 files changed, 473 insertions, 0 deletions

diff --git a/includes/job/JobQueueFederated.php b/includes/job/JobQueueFederated.php
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+<?php
+/**
+ * Job queue code for federated queues.
+ *
+ * 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
+ * @author Aaron Schulz
+ */
+
+/**
+ * Class to handle enqueueing and running of background jobs for federated queues
+ *
+ * This class allows for queues to be partitioned into smaller queues.
+ * A partition is defined by the configuration for a JobQueue instance.
+ * For example, one can set $wgJobTypeConf['refreshLinks'] to point to a
+ * JobQueueFederated instance, which itself would consist of three JobQueueRedis
+ * instances, each using their own redis server. This would allow for the jobs
+ * to be split (evenly or based on weights) accross multiple servers if a single
+ * server becomes impractical or expensive. Different JobQueue classes can be mixed.
+ *
+ * The basic queue configuration (e.g. "order", "claimTTL") of a federated queue
+ * is inherited by the partition queues. Additional configuration defines what
+ * section each wiki is in, what partition queues each section uses (and their weight),
+ * and the JobQueue configuration for each partition. Some sections might only need a
+ * single queue partition, like the sections for groups of small wikis.
+ *
+ * If used for performance, then $wgMainCacheType should be set to memcached/redis.
+ * Note that "fifo" cannot be used for the ordering, since the data is distributed.
+ * One can still use "timestamp" instead, as in "roughly timestamp ordered". Also,
+ * queue classes used by this should ignore down servers (with TTL) to avoid slowness.
+ *
+ * @ingroup JobQueue
+ * @since 1.22
+ */
+class JobQueueFederated extends JobQueue {
+	/** @var Array (partition name => weight) reverse sorted by weight */
+	protected $partitionMap = array();
+	/** @var Array (partition name => JobQueue) reverse sorted by weight */
+	protected $partitionQueues = array();
+	/** @var HashRing */
+	protected $partitionPushRing;
+	/** @var BagOStuff */
+	protected $cache;
+
+	const CACHE_TTL_SHORT = 30; // integer; seconds to cache info without re-validating
+	const CACHE_TTL_LONG = 300; // integer; seconds to cache info that is kept up to date
+
+	/**
+	 * @params include:
+	 *  - sectionsByWiki      : A map of wiki IDs to section names.
+	 *                          Wikis will default to using the section "default".
+	 *  - partitionsBySection : Map of section names to maps of (partition name => weight).
+	 *                          A section called 'default' must be defined if not all wikis
+	 *                          have explicitly defined sections.
+	 *  - configByPartition   : Map of queue partition names to configuration arrays.
+	 *                          These configuration arrays are passed to JobQueue::factory().
+	 *                          The options set here are overriden by those passed to this
+	 *                          the federated queue itself (e.g. 'order' and 'claimTTL').
+	 *  - partitionsNoPush    : List of partition names that can handle pop() but not push().
+	 *                          This can be used to migrate away from a certain partition.
+	 * @param array $params
+	 */
+	protected function __construct( array $params ) {
+		parent::__construct( $params );
+		$section = isset( $params['sectionsByWiki'][$this->wiki] )
+			? $params['sectionsByWiki'][$this->wiki]
+			: 'default';
+		if ( !isset( $params['partitionsBySection'][$section] ) ) {
+			throw new MWException( "No configuration for section '$section'." );
+		}
+		// Get the full partition map
+		$this->partitionMap = $params['partitionsBySection'][$section];
+		arsort( $this->partitionMap, SORT_NUMERIC );
+		// Get the partitions jobs can actually be pushed to
+		$partitionPushMap = $this->partitionMap;
+		if ( isset( $params['partitionsNoPush'] ) ) {
+			foreach ( $params['partitionsNoPush'] as $partition ) {
+				unset( $partitionPushMap[$partition] );
+			}
+		}
+		// Get the config to pass to merge into each partition queue config
+		$baseConfig = $params;
+		foreach ( array( 'class', 'sectionsByWiki',
+			'partitionsBySection', 'configByPartition', 'partitionsNoPush' ) as $o )
+		{
+			unset( $baseConfig[$o] );
+		}
+		// Get the partition queue objects
+		foreach ( $this->partitionMap as $partition => $w ) {
+			if ( !isset( $params['configByPartition'][$partition] ) ) {
+				throw new MWException( "No configuration for partition '$partition'." );
+			}
+			$this->partitionQueues[$partition] = JobQueue::factory(
+				$baseConfig + $params['configByPartition'][$partition] );
+		}
+		// Get the ring of partitions to push jobs into
+		$this->partitionPushRing = new HashRing( $partitionPushMap );
+		// Aggregate cache some per-queue values if there are multiple partition queues
+		$this->cache = count( $this->partitionMap ) > 1 ? wfGetMainCache() : new EmptyBagOStuff();
+	}
+
+	protected function supportedOrders() {
+		// No FIFO due to partitioning, though "rough timestamp order" is supported
+		return array( 'undefined', 'random', 'timestamp' );
+	}
+
+	protected function optimalOrder() {
+		return 'undefined'; // defer to the partitions
+	}
+
+	protected function supportsDelayedJobs() {
+		return true; // defer checks to the partitions
+	}
+
+	protected function doIsEmpty() {
+		$key = $this->getCacheKey( 'empty' );
+
+		$isEmpty = $this->cache->get( $key );
+		if ( $isEmpty === 'true' ) {
+			return true;
+		} elseif ( $isEmpty === 'false' ) {
+			return false;
+		}
+
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				if ( !$queue->doIsEmpty() ) {
+					$this->cache->add( $key, 'false', self::CACHE_TTL_LONG );
+					return false;
+				}
+			} catch ( JobQueueError $e ) {
+				MWExceptionHandler::logException( $e );
+			}
+		}
+
+		$this->cache->add( $key, 'true', self::CACHE_TTL_LONG );
+		return true;
+	}
+
+	protected function doGetSize() {
+		return $this->getCrossPartitionSum( 'size', 'doGetSize' );
+	}
+
+	protected function doGetAcquiredCount() {
+		return $this->getCrossPartitionSum( 'acquiredcount', 'doGetAcquiredCount' );
+	}
+
+	protected function doGetDelayedCount() {
+		return $this->getCrossPartitionSum( 'delayedcount', 'doGetDelayedCount' );
+	}
+
+	protected function doGetAbandonedCount() {
+		return $this->getCrossPartitionSum( 'abandonedcount', 'doGetAbandonedCount' );
+	}
+
+	/**
+	 * @param string $type
+	 * @param string $method
+	 * @return integer
+	 */
+	protected function getCrossPartitionSum( $type, $method ) {
+		$key = $this->getCacheKey( $type );
+
+		$count = $this->cache->get( $key );
+		if ( is_int( $count ) ) {
+			return $count;
+		}
+
+		$count = 0;
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				$count += $queue->$method();
+			} catch ( JobQueueError $e ) {
+				MWExceptionHandler::logException( $e );
+			}
+		}
+
+		$this->cache->set( $key, $count, self::CACHE_TTL_SHORT );
+		return $count;
+	}
+
+	protected function doBatchPush( array $jobs, $flags ) {
+		if ( !count( $jobs ) ) {
+			return true; // nothing to do
+		}
+		// Local ring variable that may be changed to point to a new ring on failure
+		$partitionRing = $this->partitionPushRing;
+		// Try to insert the jobs and update $partitionsTry on any failures
+		$jobsLeft = $this->tryJobInsertions( $jobs, $partitionRing, $flags );
+		if ( count( $jobsLeft ) ) { // some jobs failed to insert?
+			// Try to insert the remaning jobs once more, ignoring the bad partitions
+			return !count( $this->tryJobInsertions( $jobsLeft, $partitionRing, $flags ) );
+		}
+		return true;
+	}
+
+	/**
+	 * @param array $jobs
+	 * @param HashRing $partitionRing
+	 * @param integer $flags
+	 * @return array List of Job object that could not be inserted
+	 */
+	protected function tryJobInsertions( array $jobs, HashRing &$partitionRing, $flags ) {
+		$jobsLeft = array();
+
+		// Because jobs are spread across partitions, per-job de-duplication needs
+		// to use a consistent hash to avoid allowing duplicate jobs per partition.
+		// When inserting a batch of de-duplicated jobs, QOS_ATOMIC is disregarded.
+		$uJobsByPartition = array(); // (partition name => job list)
+		foreach ( $jobs as $key => $job ) {
+			if ( $job->ignoreDuplicates() ) {
+				$sha1 = sha1( serialize( $job->getDeduplicationInfo() ) );
+				$uJobsByPartition[$partitionRing->getLocation( $sha1 )][] = $job;
+				unset( $jobs[$key] );
+			}
+		}
+		// Get the batches of jobs that are not de-duplicated
+		if ( $flags & self::QOS_ATOMIC ) {
+			$nuJobBatches = array( $jobs ); // all or nothing
+		} else {
+			// Split the jobs into batches and spread them out over servers if there
+			// are many jobs. This helps keep the partitions even. Otherwise, send all
+			// the jobs to a single partition queue to avoids the extra connections.
+			$nuJobBatches = array_chunk( $jobs, 300 );
+		}
+
+		// Insert the de-duplicated jobs into the queues...
+		foreach ( $uJobsByPartition as $partition => $jobBatch ) {
+			$queue = $this->partitionQueues[$partition];
+			try {
+				$ok = $queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
+			} catch ( JobQueueError $e ) {
+				$ok = false;
+				MWExceptionHandler::logException( $e );
+			}
+			if ( $ok ) {
+				$key = $this->getCacheKey( 'empty' );
+				$this->cache->set( $key, 'false', JobQueueDB::CACHE_TTL_LONG );
+			} else {
+				$partitionRing = $partitionRing->newWithoutLocation( $partition ); // blacklist
+				if ( !$partitionRing ) {
+					throw new JobQueueError( "Could not insert job(s), all partitions are down." );
+				}
+				$jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
+			}
+		}
+
+		// Insert the jobs that are not de-duplicated into the queues...
+		foreach ( $nuJobBatches as $jobBatch ) {
+			$partition = ArrayUtils::pickRandom( $partitionRing->getLocationWeights() );
+			$queue = $this->partitionQueues[$partition];
+			try {
+				$ok = $queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
+			} catch ( JobQueueError $e ) {
+				$ok = false;
+				MWExceptionHandler::logException( $e );
+			}
+			if ( $ok ) {
+				$key = $this->getCacheKey( 'empty' );
+				$this->cache->set( $key, 'false', JobQueueDB::CACHE_TTL_LONG );
+			} else {
+				$partitionRing = $partitionRing->newWithoutLocation( $partition ); // blacklist
+				if ( !$partitionRing ) {
+					throw new JobQueueError( "Could not insert job(s), all partitions are down." );
+				}
+				$jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
+			}
+		}
+
+		return $jobsLeft;
+	}
+
+	protected function doPop() {
+		$key = $this->getCacheKey( 'empty' );
+
+		$isEmpty = $this->cache->get( $key );
+		if ( $isEmpty === 'true' ) {
+			return false;
+		}
+
+		$partitionsTry = $this->partitionMap; // (partition => weight)
+
+		while ( count( $partitionsTry ) ) {
+			$partition = ArrayUtils::pickRandom( $partitionsTry );
+			if ( $partition === false ) {
+				break; // all partitions at 0 weight
+			}
+			$queue = $this->partitionQueues[$partition];
+			try {
+				$job = $queue->pop();
+			} catch ( JobQueueError $e ) {
+				$job = false;
+				MWExceptionHandler::logException( $e );
+			}
+			if ( $job ) {
+				$job->metadata['QueuePartition'] = $partition;
+				return $job;
+			} else {
+				unset( $partitionsTry[$partition] ); // blacklist partition
+			}
+		}
+
+		$this->cache->set( $key, 'true', JobQueueDB::CACHE_TTL_LONG );
+		return false;
+	}
+
+	protected function doAck( Job $job ) {
+		if ( !isset( $job->metadata['QueuePartition'] ) ) {
+			throw new MWException( "The given job has no defined partition name." );
+		}
+		return $this->partitionQueues[$job->metadata['QueuePartition']]->ack( $job );
+	}
+
+	protected function doIsRootJobOldDuplicate( Job $job ) {
+		$params = $job->getRootJobParams();
+		$partitions = $this->partitionPushRing->getLocations( $params['rootJobSignature'], 2 );
+		try {
+			return $this->partitionQueues[$partitions[0]]->doIsRootJobOldDuplicate( $job );
+		} catch ( JobQueueError $e ) {
+			if ( isset( $partitions[1] ) ) { // check fallback partition
+				return $this->partitionQueues[$partitions[1]]->doIsRootJobOldDuplicate( $job );
+			}
+		}
+		return false;
+	}
+
+	protected function doDeduplicateRootJob( Job $job ) {
+		$params = $job->getRootJobParams();
+		$partitions = $this->partitionPushRing->getLocations( $params['rootJobSignature'], 2 );
+		try {
+			return $this->partitionQueues[$partitions[0]]->doDeduplicateRootJob( $job );
+		} catch ( JobQueueError $e ) {
+			if ( isset( $partitions[1] ) ) { // check fallback partition
+				return $this->partitionQueues[$partitions[1]]->doDeduplicateRootJob( $job );
+			}
+		}
+		return false;
+	}
+
+	protected function doDelete() {
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				$queue->doDelete();
+			} catch ( JobQueueError $e ) {
+				MWExceptionHandler::logException( $e );
+			}
+		}
+	}
+
+	protected function doWaitForBackups() {
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				$queue->waitForBackups();
+			} catch ( JobQueueError $e ) {
+				MWExceptionHandler::logException( $e );
+			}
+		}
+	}
+
+	protected function doGetPeriodicTasks() {
+		$tasks = array();
+		foreach ( $this->partitionQueues as $partition => $queue ) {
+			foreach ( $queue->getPeriodicTasks() as $task => $def ) {
+				$tasks["{$partition}:{$task}"] = $def;
+			}
+		}
+		return $tasks;
+	}
+
+	protected function doFlushCaches() {
+		static $types = array(
+			'empty',
+			'size',
+			'acquiredcount',
+			'delayedcount',
+			'abandonedcount'
+		);
+		foreach ( $types as $type ) {
+			$this->cache->delete( $this->getCacheKey( $type ) );
+		}
+		foreach ( $this->partitionQueues as $queue ) {
+			$queue->doFlushCaches();
+		}
+	}
+
+	public function getAllQueuedJobs() {
+		$iterator = new AppendIterator();
+		foreach ( $this->partitionQueues as $queue ) {
+			$iterator->append( $queue->getAllQueuedJobs() );
+		}
+		return $iterator;
+	}
+
+	public function getAllDelayedJobs() {
+		$iterator = new AppendIterator();
+		foreach ( $this->partitionQueues as $queue ) {
+			$iterator->append( $queue->getAllDelayedJobs() );
+		}
+		return $iterator;
+	}
+
+	public function getCoalesceLocationInternal() {
+		return "JobQueueFederated:wiki:{$this->wiki}" .
+			sha1( serialize( array_keys( $this->partitionMap ) ) );
+	}
+
+	protected function doGetSiblingQueuesWithJobs( array $types ) {
+		$result = array();
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				$nonEmpty = $queue->doGetSiblingQueuesWithJobs( $types );
+				if ( is_array( $nonEmpty ) ) {
+					$result = array_unique( array_merge( $result, $nonEmpty ) );
+				} else {
+					return null; // not supported on all partitions; bail
+				}
+				if ( count( $result ) == count( $types ) ) {
+					break; // short-circuit
+				}
+			} catch ( JobQueueError $e ) {
+				MWExceptionHandler::logException( $e );
+			}
+		}
+		return array_values( $result );
+	}
+
+	protected function doGetSiblingQueueSizes( array $types ) {
+		$result = array();
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				$sizes = $queue->doGetSiblingQueueSizes( $types );
+				if ( is_array( $sizes ) ) {
+					foreach ( $sizes as $type => $size ) {
+						$result[$type] = isset( $result[$type] ) ? $result[$type] + $size : $size;
+					}
+				} else {
+					return null; // not supported on all partitions; bail
+				}
+			} catch ( JobQueueError $e ) {
+				MWExceptionHandler::logException( $e );
+			}
+		}
+		return $result;
+	}
+
+	public function setTestingPrefix( $key ) {
+		foreach ( $this->partitionQueues as $queue ) {
+			$queue->setTestingPrefix( $key );
+		}
+	}
+
+	/**
+	 * @return string
+	 */
+	private function getCacheKey( $property ) {
+		list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
+		return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, $property );
+	}
+}