Update to MediaWiki 1.24.1

24 files changed, 6513 insertions, 0 deletions

diff --git a/includes/jobqueue/Job.php b/includes/jobqueue/Job.php
new file mode 100644
index 00000000..ee3f2c2b
--- /dev/null
+++ b/includes/jobqueue/Job.php
@@ -0,0 +1,350 @@
+<?php
+/**
+ * Job queue task base code.
+ *
+ * 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
+ * @defgroup JobQueue JobQueue
+ */
+
+/**
+ * Class to both describe a background job and handle jobs.
+ * The queue aspects of this class are now deprecated.
+ * Using the class to push jobs onto queues is deprecated (use JobSpecification).
+ *
+ * @ingroup JobQueue
+ */
+abstract class Job implements IJobSpecification {
+	/** @var string */
+	public $command;
+
+	/** @var array|bool Array of job parameters or false if none */
+	public $params;
+
+	/** @var array Additional queue metadata */
+	public $metadata = array();
+
+	/** @var Title */
+	protected $title;
+
+	/** @var bool Expensive jobs may set this to true */
+	protected $removeDuplicates;
+
+	/** @var string Text for error that occurred last */
+	protected $error;
+
+	/*-------------------------------------------------------------------------
+	 * Abstract functions
+	 *------------------------------------------------------------------------*/
+
+	/**
+	 * Run the job
+	 * @return bool Success
+	 */
+	abstract public function run();
+
+	/*-------------------------------------------------------------------------
+	 * Static functions
+	 *------------------------------------------------------------------------*/
+
+	/**
+	 * Create the appropriate object to handle a specific job
+	 *
+	 * @param string $command Job command
+	 * @param Title $title Associated title
+	 * @param array|bool $params Job parameters
+	 * @throws MWException
+	 * @return Job
+	 */
+	public static function factory( $command, Title $title, $params = false ) {
+		global $wgJobClasses;
+		if ( isset( $wgJobClasses[$command] ) ) {
+			$class = $wgJobClasses[$command];
+
+			return new $class( $title, $params );
+		}
+		throw new MWException( "Invalid job command `{$command}`" );
+	}
+
+	/**
+	 * Batch-insert a group of jobs into the queue.
+	 * This will be wrapped in a transaction with a forced commit.
+	 *
+	 * This may add duplicate at insert time, but they will be
+	 * removed later on, when the first one is popped.
+	 *
+	 * @param array $jobs Array of Job objects
+	 * @return bool
+	 * @deprecated since 1.21
+	 */
+	public static function batchInsert( $jobs ) {
+		JobQueueGroup::singleton()->push( $jobs );
+		return true;
+	}
+
+	/**
+	 * Insert a group of jobs into the queue.
+	 *
+	 * Same as batchInsert() but does not commit and can thus
+	 * be rolled-back as part of a larger transaction. However,
+	 * large batches of jobs can cause slave lag.
+	 *
+	 * @param array $jobs Array of Job objects
+	 * @return bool
+	 * @deprecated since 1.21
+	 */
+	public static function safeBatchInsert( $jobs ) {
+		JobQueueGroup::singleton()->push( $jobs, JobQueue::QOS_ATOMIC );
+		return true;
+	}
+
+	/**
+	 * Pop a job of a certain type.  This tries less hard than pop() to
+	 * actually find a job; it may be adversely affected by concurrent job
+	 * runners.
+	 *
+	 * @param string $type
+	 * @return Job|bool Returns false if there are no jobs
+	 * @deprecated since 1.21
+	 */
+	public static function pop_type( $type ) {
+		return JobQueueGroup::singleton()->get( $type )->pop();
+	}
+
+	/**
+	 * Pop a job off the front of the queue.
+	 * This is subject to $wgJobTypesExcludedFromDefaultQueue.
+	 *
+	 * @return Job|bool False if there are no jobs
+	 * @deprecated since 1.21
+	 */
+	public static function pop() {
+		return JobQueueGroup::singleton()->pop();
+	}
+
+	/*-------------------------------------------------------------------------
+	 * Non-static functions
+	 *------------------------------------------------------------------------*/
+
+	/**
+	 * @param string $command
+	 * @param Title $title
+	 * @param array|bool $params
+	 */
+	public function __construct( $command, $title, $params = false ) {
+		$this->command = $command;
+		$this->title = $title;
+		$this->params = $params;
+
+		// expensive jobs may set this to true
+		$this->removeDuplicates = false;
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getType() {
+		return $this->command;
+	}
+
+	/**
+	 * @return Title
+	 */
+	public function getTitle() {
+		return $this->title;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getParams() {
+		return $this->params;
+	}
+
+	/**
+	 * @return int|null UNIX timestamp to delay running this job until, otherwise null
+	 * @since 1.22
+	 */
+	public function getReleaseTimestamp() {
+		return isset( $this->params['jobReleaseTimestamp'] )
+			? wfTimestampOrNull( TS_UNIX, $this->params['jobReleaseTimestamp'] )
+			: null;
+	}
+
+	/**
+	 * @return bool Whether only one of each identical set of jobs should be run
+	 */
+	public function ignoreDuplicates() {
+		return $this->removeDuplicates;
+	}
+
+	/**
+	 * @return bool Whether this job can be retried on failure by job runners
+	 * @since 1.21
+	 */
+	public function allowRetries() {
+		return true;
+	}
+
+	/**
+	 * @return int Number of actually "work items" handled in this job
+	 * @see $wgJobBackoffThrottling
+	 * @since 1.23
+	 */
+	public function workItemCount() {
+		return 1;
+	}
+
+	/**
+	 * Subclasses may need to override this to make duplication detection work.
+	 * The resulting map conveys everything that makes the job unique. This is
+	 * only checked if ignoreDuplicates() returns true, meaning that duplicate
+	 * jobs are supposed to be ignored.
+	 *
+	 * @return array Map of key/values
+	 * @since 1.21
+	 */
+	public function getDeduplicationInfo() {
+		$info = array(
+			'type' => $this->getType(),
+			'namespace' => $this->getTitle()->getNamespace(),
+			'title' => $this->getTitle()->getDBkey(),
+			'params' => $this->getParams()
+		);
+		if ( is_array( $info['params'] ) ) {
+			// Identical jobs with different "root" jobs should count as duplicates
+			unset( $info['params']['rootJobSignature'] );
+			unset( $info['params']['rootJobTimestamp'] );
+			// Likewise for jobs with different delay times
+			unset( $info['params']['jobReleaseTimestamp'] );
+		}
+
+		return $info;
+	}
+
+	/**
+	 * @see JobQueue::deduplicateRootJob()
+	 * @param string $key A key that identifies the task
+	 * @return array Map of:
+	 *   - rootJobSignature : hash (e.g. SHA1) that identifies the task
+	 *   - rootJobTimestamp : TS_MW timestamp of this instance of the task
+	 * @since 1.21
+	 */
+	public static function newRootJobParams( $key ) {
+		return array(
+			'rootJobSignature' => sha1( $key ),
+			'rootJobTimestamp' => wfTimestampNow()
+		);
+	}
+
+	/**
+	 * @see JobQueue::deduplicateRootJob()
+	 * @return array
+	 * @since 1.21
+	 */
+	public function getRootJobParams() {
+		return array(
+			'rootJobSignature' => isset( $this->params['rootJobSignature'] )
+				? $this->params['rootJobSignature']
+				: null,
+			'rootJobTimestamp' => isset( $this->params['rootJobTimestamp'] )
+				? $this->params['rootJobTimestamp']
+				: null
+		);
+	}
+
+	/**
+	 * @see JobQueue::deduplicateRootJob()
+	 * @return bool
+	 * @since 1.22
+	 */
+	public function hasRootJobParams() {
+		return isset( $this->params['rootJobSignature'] )
+			&& isset( $this->params['rootJobTimestamp'] );
+	}
+
+	/**
+	 * Insert a single job into the queue.
+	 * @return bool True on success
+	 * @deprecated since 1.21
+	 */
+	public function insert() {
+		JobQueueGroup::singleton()->push( $this );
+		return true;
+	}
+
+	/**
+	 * @return string
+	 */
+	public function toString() {
+		$truncFunc = function ( $value ) {
+			$value = (string)$value;
+			if ( mb_strlen( $value ) > 1024 ) {
+				$value = "string(" . mb_strlen( $value ) . ")";
+			}
+			return $value;
+		};
+
+		$paramString = '';
+		if ( $this->params ) {
+			foreach ( $this->params as $key => $value ) {
+				if ( $paramString != '' ) {
+					$paramString .= ' ';
+				}
+				if ( is_array( $value ) ) {
+					$filteredValue = array();
+					foreach ( $value as $k => $v ) {
+						if ( is_scalar( $v ) ) {
+							$filteredValue[$k] = $truncFunc( $v );
+						} else {
+							$filteredValue = null;
+							break;
+						}
+					}
+					if ( $filteredValue ) {
+						$value = FormatJson::encode( $filteredValue );
+					} else {
+						$value = "array(" . count( $value ) . ")";
+					}
+				} elseif ( is_object( $value ) && !method_exists( $value, '__toString' ) ) {
+					$value = "object(" . get_class( $value ) . ")";
+				}
+
+				$paramString .= "$key={$truncFunc( $value )}";
+			}
+		}
+
+		if ( is_object( $this->title ) ) {
+			$s = "{$this->command} " . $this->title->getPrefixedDBkey();
+			if ( $paramString !== '' ) {
+				$s .= ' ' . $paramString;
+			}
+
+			return $s;
+		} else {
+			return "{$this->command} $paramString";
+		}
+	}
+
+	protected function setLastError( $error ) {
+		$this->error = $error;
+	}
+
+	public function getLastError() {
+		return $this->error;
+	}
+}
diff --git a/includes/jobqueue/JobQueue.php b/includes/jobqueue/JobQueue.php
new file mode 100644
index 00000000..c00d22e9
--- /dev/null
+++ b/includes/jobqueue/JobQueue.php
@@ -0,0 +1,740 @@
+<?php
+/**
+ * Job queue base code.
+ *
+ * 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
+ * @defgroup JobQueue JobQueue
+ * @author Aaron Schulz
+ */
+
+/**
+ * Class to handle enqueueing and running of background jobs
+ *
+ * @ingroup JobQueue
+ * @since 1.21
+ */
+abstract class JobQueue {
+	/** @var string Wiki ID */
+	protected $wiki;
+
+	/** @var string Job type */
+	protected $type;
+
+	/** @var string Job priority for pop() */
+	protected $order;
+
+	/** @var int Time to live in seconds */
+	protected $claimTTL;
+
+	/** @var int Maximum number of times to try a job */
+	protected $maxTries;
+
+	/** @var bool Allow delayed jobs */
+	protected $checkDelay;
+
+	/** @var BagOStuff */
+	protected $dupCache;
+
+	const QOS_ATOMIC = 1; // integer; "all-or-nothing" job insertions
+
+	const ROOTJOB_TTL = 2419200; // integer; seconds to remember root jobs (28 days)
+
+	/**
+	 * @param array $params
+	 * @throws MWException
+	 */
+	protected function __construct( array $params ) {
+		$this->wiki = $params['wiki'];
+		$this->type = $params['type'];
+		$this->claimTTL = isset( $params['claimTTL'] ) ? $params['claimTTL'] : 0;
+		$this->maxTries = isset( $params['maxTries'] ) ? $params['maxTries'] : 3;
+		if ( isset( $params['order'] ) && $params['order'] !== 'any' ) {
+			$this->order = $params['order'];
+		} else {
+			$this->order = $this->optimalOrder();
+		}
+		if ( !in_array( $this->order, $this->supportedOrders() ) ) {
+			throw new MWException( __CLASS__ . " does not support '{$this->order}' order." );
+		}
+		$this->checkDelay = !empty( $params['checkDelay'] );
+		if ( $this->checkDelay && !$this->supportsDelayedJobs() ) {
+			throw new MWException( __CLASS__ . " does not support delayed jobs." );
+		}
+		$this->dupCache = wfGetCache( CACHE_ANYTHING );
+	}
+
+	/**
+	 * Get a job queue object of the specified type.
+	 * $params includes:
+	 *   - class      : What job class to use (determines job type)
+	 *   - wiki       : wiki ID of the wiki the jobs are for (defaults to current wiki)
+	 *   - type       : The name of the job types this queue handles
+	 *   - order      : Order that pop() selects jobs, one of "fifo", "timestamp" or "random".
+	 *                  If "fifo" is used, the queue will effectively be FIFO. Note that job
+	 *                  completion will not appear to be exactly FIFO if there are multiple
+	 *                  job runners since jobs can take different times to finish once popped.
+	 *                  If "timestamp" is used, the queue will at least be loosely ordered
+	 *                  by timestamp, allowing for some jobs to be popped off out of order.
+	 *                  If "random" is used, pop() will pick jobs in random order.
+	 *                  Note that it may only be weakly random (e.g. a lottery of the oldest X).
+	 *                  If "any" is choosen, the queue will use whatever order is the fastest.
+	 *                  This might be useful for improving concurrency for job acquisition.
+	 *   - claimTTL   : If supported, the queue will recycle jobs that have been popped
+	 *                  but not acknowledged as completed after this many seconds. Recycling
+	 *                  of jobs simple means re-inserting them into the queue. Jobs can be
+	 *                  attempted up to three times before being discarded.
+	 *   - checkDelay : If supported, respect Job::getReleaseTimestamp() in the push functions.
+	 *                  This lets delayed jobs wait in a staging area until a given timestamp is
+	 *                  reached, at which point they will enter the queue. If this is not enabled
+	 *                  or not supported, an exception will be thrown on delayed job insertion.
+	 *
+	 * Queue classes should throw an exception if they do not support the options given.
+	 *
+	 * @param array $params
+	 * @return JobQueue
+	 * @throws MWException
+	 */
+	final public static function factory( array $params ) {
+		$class = $params['class'];
+		if ( !class_exists( $class ) ) {
+			throw new MWException( "Invalid job queue class '$class'." );
+		}
+		$obj = new $class( $params );
+		if ( !( $obj instanceof self ) ) {
+			throw new MWException( "Class '$class' is not a " . __CLASS__ . " class." );
+		}
+
+		return $obj;
+	}
+
+	/**
+	 * @return string Wiki ID
+	 */
+	final public function getWiki() {
+		return $this->wiki;
+	}
+
+	/**
+	 * @return string Job type that this queue handles
+	 */
+	final public function getType() {
+		return $this->type;
+	}
+
+	/**
+	 * @return string One of (random, timestamp, fifo, undefined)
+	 */
+	final public function getOrder() {
+		return $this->order;
+	}
+
+	/**
+	 * @return bool Whether delayed jobs are enabled
+	 * @since 1.22
+	 */
+	final public function delayedJobsEnabled() {
+		return $this->checkDelay;
+	}
+
+	/**
+	 * Get the allowed queue orders for configuration validation
+	 *
+	 * @return array Subset of (random, timestamp, fifo, undefined)
+	 */
+	abstract protected function supportedOrders();
+
+	/**
+	 * Get the default queue order to use if configuration does not specify one
+	 *
+	 * @return string One of (random, timestamp, fifo, undefined)
+	 */
+	abstract protected function optimalOrder();
+
+	/**
+	 * Find out if delayed jobs are supported for configuration validation
+	 *
+	 * @return bool Whether delayed jobs are supported
+	 */
+	protected function supportsDelayedJobs() {
+		return false; // not implemented
+	}
+
+	/**
+	 * Quickly check if the queue has no available (unacquired, non-delayed) jobs.
+	 * Queue classes should use caching if they are any slower without memcached.
+	 *
+	 * If caching is used, this might return false when there are actually no jobs.
+	 * If pop() is called and returns false then it should correct the cache. Also,
+	 * calling flushCaches() first prevents this. However, this affect is typically
+	 * not distinguishable from the race condition between isEmpty() and pop().
+	 *
+	 * @return bool
+	 * @throws JobQueueError
+	 */
+	final public function isEmpty() {
+		wfProfileIn( __METHOD__ );
+		$res = $this->doIsEmpty();
+		wfProfileOut( __METHOD__ );
+
+		return $res;
+	}
+
+	/**
+	 * @see JobQueue::isEmpty()
+	 * @return bool
+	 */
+	abstract protected function doIsEmpty();
+
+	/**
+	 * Get the number of available (unacquired, non-delayed) jobs in the queue.
+	 * Queue classes should use caching if they are any slower without memcached.
+	 *
+	 * If caching is used, this number might be out of date for a minute.
+	 *
+	 * @return int
+	 * @throws JobQueueError
+	 */
+	final public function getSize() {
+		wfProfileIn( __METHOD__ );
+		$res = $this->doGetSize();
+		wfProfileOut( __METHOD__ );
+
+		return $res;
+	}
+
+	/**
+	 * @see JobQueue::getSize()
+	 * @return int
+	 */
+	abstract protected function doGetSize();
+
+	/**
+	 * Get the number of acquired jobs (these are temporarily out of the queue).
+	 * Queue classes should use caching if they are any slower without memcached.
+	 *
+	 * If caching is used, this number might be out of date for a minute.
+	 *
+	 * @return int
+	 * @throws JobQueueError
+	 */
+	final public function getAcquiredCount() {
+		wfProfileIn( __METHOD__ );
+		$res = $this->doGetAcquiredCount();
+		wfProfileOut( __METHOD__ );
+
+		return $res;
+	}
+
+	/**
+	 * @see JobQueue::getAcquiredCount()
+	 * @return int
+	 */
+	abstract protected function doGetAcquiredCount();
+
+	/**
+	 * Get the number of delayed jobs (these are temporarily out of the queue).
+	 * Queue classes should use caching if they are any slower without memcached.
+	 *
+	 * If caching is used, this number might be out of date for a minute.
+	 *
+	 * @return int
+	 * @throws JobQueueError
+	 * @since 1.22
+	 */
+	final public function getDelayedCount() {
+		wfProfileIn( __METHOD__ );
+		$res = $this->doGetDelayedCount();
+		wfProfileOut( __METHOD__ );
+
+		return $res;
+	}
+
+	/**
+	 * @see JobQueue::getDelayedCount()
+	 * @return int
+	 */
+	protected function doGetDelayedCount() {
+		return 0; // not implemented
+	}
+
+	/**
+	 * Get the number of acquired jobs that can no longer be attempted.
+	 * Queue classes should use caching if they are any slower without memcached.
+	 *
+	 * If caching is used, this number might be out of date for a minute.
+	 *
+	 * @return int
+	 * @throws JobQueueError
+	 */
+	final public function getAbandonedCount() {
+		wfProfileIn( __METHOD__ );
+		$res = $this->doGetAbandonedCount();
+		wfProfileOut( __METHOD__ );
+
+		return $res;
+	}
+
+	/**
+	 * @see JobQueue::getAbandonedCount()
+	 * @return int
+	 */
+	protected function doGetAbandonedCount() {
+		return 0; // not implemented
+	}
+
+	/**
+	 * Push one or more jobs into the queue.
+	 * This does not require $wgJobClasses to be set for the given job type.
+	 * Outside callers should use JobQueueGroup::push() instead of this function.
+	 *
+	 * @param Job|array $jobs A single job or an array of Jobs
+	 * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
+	 * @return void
+	 * @throws JobQueueError
+	 */
+	final public function push( $jobs, $flags = 0 ) {
+		$this->batchPush( is_array( $jobs ) ? $jobs : array( $jobs ), $flags );
+	}
+
+	/**
+	 * Push a batch of jobs into the queue.
+	 * This does not require $wgJobClasses to be set for the given job type.
+	 * Outside callers should use JobQueueGroup::push() instead of this function.
+	 *
+	 * @param array $jobs List of Jobs
+	 * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
+	 * @return void
+	 * @throws MWException
+	 */
+	final public function batchPush( array $jobs, $flags = 0 ) {
+		if ( !count( $jobs ) ) {
+			return; // nothing to do
+		}
+
+		foreach ( $jobs as $job ) {
+			if ( $job->getType() !== $this->type ) {
+				throw new MWException(
+					"Got '{$job->getType()}' job; expected a '{$this->type}' job." );
+			} elseif ( $job->getReleaseTimestamp() && !$this->checkDelay ) {
+				throw new MWException(
+					"Got delayed '{$job->getType()}' job; delays are not supported." );
+			}
+		}
+
+		wfProfileIn( __METHOD__ );
+		$this->doBatchPush( $jobs, $flags );
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * @see JobQueue::batchPush()
+	 * @param array $jobs
+	 * @param int $flags
+	 */
+	abstract protected function doBatchPush( array $jobs, $flags );
+
+	/**
+	 * Pop a job off of the queue.
+	 * This requires $wgJobClasses to be set for the given job type.
+	 * Outside callers should use JobQueueGroup::pop() instead of this function.
+	 *
+	 * @throws MWException
+	 * @return Job|bool Returns false if there are no jobs
+	 */
+	final public function pop() {
+		global $wgJobClasses;
+
+		if ( $this->wiki !== wfWikiID() ) {
+			throw new MWException( "Cannot pop '{$this->type}' job off foreign wiki queue." );
+		} elseif ( !isset( $wgJobClasses[$this->type] ) ) {
+			// Do not pop jobs if there is no class for the queue type
+			throw new MWException( "Unrecognized job type '{$this->type}'." );
+		}
+
+		wfProfileIn( __METHOD__ );
+		$job = $this->doPop();
+		wfProfileOut( __METHOD__ );
+
+		// Flag this job as an old duplicate based on its "root" job...
+		try {
+			if ( $job && $this->isRootJobOldDuplicate( $job ) ) {
+				JobQueue::incrStats( 'job-pop-duplicate', $this->type, 1, $this->wiki );
+				$job = DuplicateJob::newFromJob( $job ); // convert to a no-op
+			}
+		} catch ( MWException $e ) {
+			// don't lose jobs over this
+		}
+
+		return $job;
+	}
+
+	/**
+	 * @see JobQueue::pop()
+	 * @return Job
+	 */
+	abstract protected function doPop();
+
+	/**
+	 * Acknowledge that a job was completed.
+	 *
+	 * This does nothing for certain queue classes or if "claimTTL" is not set.
+	 * Outside callers should use JobQueueGroup::ack() instead of this function.
+	 *
+	 * @param Job $job
+	 * @return void
+	 * @throws MWException
+	 */
+	final public function ack( Job $job ) {
+		if ( $job->getType() !== $this->type ) {
+			throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
+		}
+		wfProfileIn( __METHOD__ );
+		$this->doAck( $job );
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * @see JobQueue::ack()
+	 * @param Job $job
+	 */
+	abstract protected function doAck( Job $job );
+
+	/**
+	 * Register the "root job" of a given job into the queue for de-duplication.
+	 * This should only be called right *after* all the new jobs have been inserted.
+	 * This is used to turn older, duplicate, job entries into no-ops. The root job
+	 * information will remain in the registry until it simply falls out of cache.
+	 *
+	 * This requires that $job has two special fields in the "params" array:
+	 *   - rootJobSignature : hash (e.g. SHA1) that identifies the task
+	 *   - rootJobTimestamp : TS_MW timestamp of this instance of the task
+	 *
+	 * A "root job" is a conceptual job that consist of potentially many smaller jobs
+	 * that are actually inserted into the queue. For example, "refreshLinks" jobs are
+	 * spawned when a template is edited. One can think of the task as "update links
+	 * of pages that use template X" and an instance of that task as a "root job".
+	 * However, what actually goes into the queue are range and leaf job subtypes.
+	 * Since these jobs include things like page ID ranges and DB master positions,
+	 * and can morph into smaller jobs recursively, simple duplicate detection
+	 * for individual jobs being identical (like that of job_sha1) is not useful.
+	 *
+	 * In the case of "refreshLinks", if these jobs are still in the queue when the template
+	 * is edited again, we want all of these old refreshLinks jobs for that template to become
+	 * no-ops. This can greatly reduce server load, since refreshLinks jobs involves parsing.
+	 * Essentially, the new batch of jobs belong to a new "root job" and the older ones to a
+	 * previous "root job" for the same task of "update links of pages that use template X".
+	 *
+	 * This does nothing for certain queue classes.
+	 *
+	 * @param Job $job
+	 * @throws MWException
+	 * @return bool
+	 */
+	final public function deduplicateRootJob( Job $job ) {
+		if ( $job->getType() !== $this->type ) {
+			throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
+		}
+		wfProfileIn( __METHOD__ );
+		$ok = $this->doDeduplicateRootJob( $job );
+		wfProfileOut( __METHOD__ );
+
+		return $ok;
+	}
+
+	/**
+	 * @see JobQueue::deduplicateRootJob()
+	 * @param Job $job
+	 * @throws MWException
+	 * @return bool
+	 */
+	protected function doDeduplicateRootJob( Job $job ) {
+		if ( !$job->hasRootJobParams() ) {
+			throw new MWException( "Cannot register root job; missing parameters." );
+		}
+		$params = $job->getRootJobParams();
+
+		$key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
+		// Callers should call batchInsert() and then this function so that if the insert
+		// fails, the de-duplication registration will be aborted. Since the insert is
+		// deferred till "transaction idle", do the same here, so that the ordering is
+		// maintained. Having only the de-duplication registration succeed would cause
+		// jobs to become no-ops without any actual jobs that made them redundant.
+		$timestamp = $this->dupCache->get( $key ); // current last timestamp of this job
+		if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
+			return true; // a newer version of this root job was enqueued
+		}
+
+		// Update the timestamp of the last root job started at the location...
+		return $this->dupCache->set( $key, $params['rootJobTimestamp'], JobQueueDB::ROOTJOB_TTL );
+	}
+
+	/**
+	 * Check if the "root" job of a given job has been superseded by a newer one
+	 *
+	 * @param Job $job
+	 * @throws MWException
+	 * @return bool
+	 */
+	final protected function isRootJobOldDuplicate( Job $job ) {
+		if ( $job->getType() !== $this->type ) {
+			throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
+		}
+		wfProfileIn( __METHOD__ );
+		$isDuplicate = $this->doIsRootJobOldDuplicate( $job );
+		wfProfileOut( __METHOD__ );
+
+		return $isDuplicate;
+	}
+
+	/**
+	 * @see JobQueue::isRootJobOldDuplicate()
+	 * @param Job $job
+	 * @return bool
+	 */
+	protected function doIsRootJobOldDuplicate( Job $job ) {
+		if ( !$job->hasRootJobParams() ) {
+			return false; // job has no de-deplication info
+		}
+		$params = $job->getRootJobParams();
+
+		$key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
+		// Get the last time this root job was enqueued
+		$timestamp = $this->dupCache->get( $key );
+
+		// Check if a new root job was started at the location after this one's...
+		return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
+	}
+
+	/**
+	 * @param string $signature Hash identifier of the root job
+	 * @return string
+	 */
+	protected function getRootJobCacheKey( $signature ) {
+		list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
+
+		return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, 'rootjob', $signature );
+	}
+
+	/**
+	 * Deleted all unclaimed and delayed jobs from the queue
+	 *
+	 * @throws JobQueueError
+	 * @since 1.22
+	 * @return void
+	 */
+	final public function delete() {
+		wfProfileIn( __METHOD__ );
+		$this->doDelete();
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * @see JobQueue::delete()
+	 * @throws MWException
+	 */
+	protected function doDelete() {
+		throw new MWException( "This method is not implemented." );
+	}
+
+	/**
+	 * Wait for any slaves or backup servers to catch up.
+	 *
+	 * This does nothing for certain queue classes.
+	 *
+	 * @return void
+	 * @throws JobQueueError
+	 */
+	final public function waitForBackups() {
+		wfProfileIn( __METHOD__ );
+		$this->doWaitForBackups();
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * @see JobQueue::waitForBackups()
+	 * @return void
+	 */
+	protected function doWaitForBackups() {
+	}
+
+	/**
+	 * Return a map of task names to task definition maps.
+	 * A "task" is a fast periodic queue maintenance action.
+	 * Mutually exclusive tasks must implement their own locking in the callback.
+	 *
+	 * Each task value is an associative array with:
+	 *   - name     : the name of the task
+	 *   - callback : a PHP callable that performs the task
+	 *   - period   : the period in seconds corresponding to the task frequency
+	 *
+	 * @return array
+	 */
+	final public function getPeriodicTasks() {
+		$tasks = $this->doGetPeriodicTasks();
+		foreach ( $tasks as $name => &$def ) {
+			$def['name'] = $name;
+		}
+
+		return $tasks;
+	}
+
+	/**
+	 * @see JobQueue::getPeriodicTasks()
+	 * @return array
+	 */
+	protected function doGetPeriodicTasks() {
+		return array();
+	}
+
+	/**
+	 * Clear any process and persistent caches
+	 *
+	 * @return void
+	 */
+	final public function flushCaches() {
+		wfProfileIn( __METHOD__ );
+		$this->doFlushCaches();
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * @see JobQueue::flushCaches()
+	 * @return void
+	 */
+	protected function doFlushCaches() {
+	}
+
+	/**
+	 * Get an iterator to traverse over all available jobs in this queue.
+	 * This does not include jobs that are currently acquired or delayed.
+	 * Note: results may be stale if the queue is concurrently modified.
+	 *
+	 * @return Iterator
+	 * @throws JobQueueError
+	 */
+	abstract public function getAllQueuedJobs();
+
+	/**
+	 * Get an iterator to traverse over all delayed jobs in this queue.
+	 * Note: results may be stale if the queue is concurrently modified.
+	 *
+	 * @return Iterator
+	 * @throws JobQueueError
+	 * @since 1.22
+	 */
+	public function getAllDelayedJobs() {
+		return new ArrayIterator( array() ); // not implemented
+	}
+
+	/**
+	 * Do not use this function outside of JobQueue/JobQueueGroup
+	 *
+	 * @return string
+	 * @since 1.22
+	 */
+	public function getCoalesceLocationInternal() {
+		return null;
+	}
+
+	/**
+	 * Check whether each of the given queues are empty.
+	 * This is used for batching checks for queues stored at the same place.
+	 *
+	 * @param array $types List of queues types
+	 * @return array|null (list of non-empty queue types) or null if unsupported
+	 * @throws MWException
+	 * @since 1.22
+	 */
+	final public function getSiblingQueuesWithJobs( array $types ) {
+		$section = new ProfileSection( __METHOD__ );
+
+		return $this->doGetSiblingQueuesWithJobs( $types );
+	}
+
+	/**
+	 * @see JobQueue::getSiblingQueuesWithJobs()
+	 * @param array $types List of queues types
+	 * @return array|null (list of queue types) or null if unsupported
+	 */
+	protected function doGetSiblingQueuesWithJobs( array $types ) {
+		return null; // not supported
+	}
+
+	/**
+	 * Check the size of each of the given queues.
+	 * For queues not served by the same store as this one, 0 is returned.
+	 * This is used for batching checks for queues stored at the same place.
+	 *
+	 * @param array $types List of queues types
+	 * @return array|null (job type => whether queue is empty) or null if unsupported
+	 * @throws MWException
+	 * @since 1.22
+	 */
+	final public function getSiblingQueueSizes( array $types ) {
+		$section = new ProfileSection( __METHOD__ );
+
+		return $this->doGetSiblingQueueSizes( $types );
+	}
+
+	/**
+	 * @see JobQueue::getSiblingQueuesSize()
+	 * @param array $types List of queues types
+	 * @return array|null (list of queue types) or null if unsupported
+	 */
+	protected function doGetSiblingQueueSizes( array $types ) {
+		return null; // not supported
+	}
+
+	/**
+	 * Call wfIncrStats() for the queue overall and for the queue type
+	 *
+	 * @param string $key Event type
+	 * @param string $type Job type
+	 * @param int $delta
+	 * @param string $wiki Wiki ID (added in 1.23)
+	 * @since 1.22
+	 */
+	public static function incrStats( $key, $type, $delta = 1, $wiki = null ) {
+		wfIncrStats( $key, $delta );
+		wfIncrStats( "{$key}-{$type}", $delta );
+		if ( $wiki !== null ) {
+			wfIncrStats( "{$key}-{$type}-{$wiki}", $delta );
+		}
+	}
+
+	/**
+	 * Namespace the queue with a key to isolate it for testing
+	 *
+	 * @param string $key
+	 * @return void
+	 * @throws MWException
+	 */
+	public function setTestingPrefix( $key ) {
+		throw new MWException( "Queue namespacing not supported for this queue type." );
+	}
+}
+
+/**
+ * @ingroup JobQueue
+ * @since 1.22
+ */
+class JobQueueError extends MWException {
+}
+
+class JobQueueConnectionError extends JobQueueError {
+}
diff --git a/includes/jobqueue/JobQueueDB.php b/includes/jobqueue/JobQueueDB.php
new file mode 100644
index 00000000..08873cc1
--- /dev/null
+++ b/includes/jobqueue/JobQueueDB.php
@@ -0,0 +1,849 @@
+<?php
+/**
+ * Database-backed job queue code.
+ *
+ * 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 job queues stored in the DB
+ *
+ * @ingroup JobQueue
+ * @since 1.21
+ */
+class JobQueueDB extends JobQueue {
+	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
+	const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed
+	const MAX_JOB_RANDOM = 2147483647; // integer; 2^31 - 1, used for job_random
+	const MAX_OFFSET = 255; // integer; maximum number of rows to skip
+
+	/** @var BagOStuff */
+	protected $cache;
+
+	/** @var bool|string Name of an external DB cluster. False if not set */
+	protected $cluster = false;
+
+	/**
+	 * Additional parameters include:
+	 *   - cluster : The name of an external cluster registered via LBFactory.
+	 *               If not specified, the primary DB cluster for the wiki will be used.
+	 *               This can be overridden with a custom cluster so that DB handles will
+	 *               be retrieved via LBFactory::getExternalLB() and getConnection().
+	 * @param array $params
+	 */
+	protected function __construct( array $params ) {
+		global $wgMemc;
+
+		parent::__construct( $params );
+
+		$this->cluster = isset( $params['cluster'] ) ? $params['cluster'] : false;
+		// Make sure that we don't use the SQL cache, which would be harmful
+		$this->cache = ( $wgMemc instanceof SqlBagOStuff ) ? new EmptyBagOStuff() : $wgMemc;
+	}
+
+	protected function supportedOrders() {
+		return array( 'random', 'timestamp', 'fifo' );
+	}
+
+	protected function optimalOrder() {
+		return 'random';
+	}
+
+	/**
+	 * @see JobQueue::doIsEmpty()
+	 * @return bool
+	 */
+	protected function doIsEmpty() {
+		$key = $this->getCacheKey( 'empty' );
+
+		$isEmpty = $this->cache->get( $key );
+		if ( $isEmpty === 'true' ) {
+			return true;
+		} elseif ( $isEmpty === 'false' ) {
+			return false;
+		}
+
+		$dbr = $this->getSlaveDB();
+		try {
+			$found = $dbr->selectField( // unclaimed job
+				'job', '1', array( 'job_cmd' => $this->type, 'job_token' => '' ), __METHOD__
+			);
+		} catch ( DBError $e ) {
+			$this->throwDBException( $e );
+		}
+		$this->cache->add( $key, $found ? 'false' : 'true', self::CACHE_TTL_LONG );
+
+		return !$found;
+	}
+
+	/**
+	 * @see JobQueue::doGetSize()
+	 * @return int
+	 */
+	protected function doGetSize() {
+		$key = $this->getCacheKey( 'size' );
+
+		$size = $this->cache->get( $key );
+		if ( is_int( $size ) ) {
+			return $size;
+		}
+
+		try {
+			$dbr = $this->getSlaveDB();
+			$size = (int)$dbr->selectField( 'job', 'COUNT(*)',
+				array( 'job_cmd' => $this->type, 'job_token' => '' ),
+				__METHOD__
+			);
+		} catch ( DBError $e ) {
+			$this->throwDBException( $e );
+		}
+		$this->cache->set( $key, $size, self::CACHE_TTL_SHORT );
+
+		return $size;
+	}
+
+	/**
+	 * @see JobQueue::doGetAcquiredCount()
+	 * @return int
+	 */
+	protected function doGetAcquiredCount() {
+		if ( $this->claimTTL <= 0 ) {
+			return 0; // no acknowledgements
+		}
+
+		$key = $this->getCacheKey( 'acquiredcount' );
+
+		$count = $this->cache->get( $key );
+		if ( is_int( $count ) ) {
+			return $count;
+		}
+
+		$dbr = $this->getSlaveDB();
+		try {
+			$count = (int)$dbr->selectField( 'job', 'COUNT(*)',
+				array( 'job_cmd' => $this->type, "job_token != {$dbr->addQuotes( '' )}" ),
+				__METHOD__
+			);
+		} catch ( DBError $e ) {
+			$this->throwDBException( $e );
+		}
+		$this->cache->set( $key, $count, self::CACHE_TTL_SHORT );
+
+		return $count;
+	}
+
+	/**
+	 * @see JobQueue::doGetAbandonedCount()
+	 * @return int
+	 * @throws MWException
+	 */
+	protected function doGetAbandonedCount() {
+		global $wgMemc;
+
+		if ( $this->claimTTL <= 0 ) {
+			return 0; // no acknowledgements
+		}
+
+		$key = $this->getCacheKey( 'abandonedcount' );
+
+		$count = $wgMemc->get( $key );
+		if ( is_int( $count ) ) {
+			return $count;
+		}
+
+		$dbr = $this->getSlaveDB();
+		try {
+			$count = (int)$dbr->selectField( 'job', 'COUNT(*)',
+				array(
+					'job_cmd' => $this->type,
+					"job_token != {$dbr->addQuotes( '' )}",
+					"job_attempts >= " . $dbr->addQuotes( $this->maxTries )
+				),
+				__METHOD__
+			);
+		} catch ( DBError $e ) {
+			$this->throwDBException( $e );
+		}
+		$wgMemc->set( $key, $count, self::CACHE_TTL_SHORT );
+
+		return $count;
+	}
+
+	/**
+	 * @see JobQueue::doBatchPush()
+	 * @param array $jobs
+	 * @param int $flags
+	 * @throws DBError|Exception
+	 * @return void
+	 */
+	protected function doBatchPush( array $jobs, $flags ) {
+		$dbw = $this->getMasterDB();
+
+		$that = $this;
+		$method = __METHOD__;
+		$dbw->onTransactionIdle(
+			function () use ( $dbw, $that, $jobs, $flags, $method ) {
+				$that->doBatchPushInternal( $dbw, $jobs, $flags, $method );
+			}
+		);
+	}
+
+	/**
+	 * This function should *not* be called outside of JobQueueDB
+	 *
+	 * @param IDatabase $dbw
+	 * @param array $jobs
+	 * @param int $flags
+	 * @param string $method
+	 * @throws DBError
+	 * @return void
+	 */
+	public function doBatchPushInternal( IDatabase $dbw, array $jobs, $flags, $method ) {
+		if ( !count( $jobs ) ) {
+			return;
+		}
+
+		$rowSet = array(); // (sha1 => job) map for jobs that are de-duplicated
+		$rowList = array(); // list of jobs for jobs that are are not de-duplicated
+		foreach ( $jobs as $job ) {
+			$row = $this->insertFields( $job );
+			if ( $job->ignoreDuplicates() ) {
+				$rowSet[$row['job_sha1']] = $row;
+			} else {
+				$rowList[] = $row;
+			}
+		}
+
+		if ( $flags & self::QOS_ATOMIC ) {
+			$dbw->begin( $method ); // wrap all the job additions in one transaction
+		}
+		try {
+			// Strip out any duplicate jobs that are already in the queue...
+			if ( count( $rowSet ) ) {
+				$res = $dbw->select( 'job', 'job_sha1',
+					array(
+						// No job_type condition since it's part of the job_sha1 hash
+						'job_sha1' => array_keys( $rowSet ),
+						'job_token' => '' // unclaimed
+					),
+					$method
+				);
+				foreach ( $res as $row ) {
+					wfDebug( "Job with hash '{$row->job_sha1}' is a duplicate.\n" );
+					unset( $rowSet[$row->job_sha1] ); // already enqueued
+				}
+			}
+			// Build the full list of job rows to insert
+			$rows = array_merge( $rowList, array_values( $rowSet ) );
+			// Insert the job rows in chunks to avoid slave lag...
+			foreach ( array_chunk( $rows, 50 ) as $rowBatch ) {
+				$dbw->insert( 'job', $rowBatch, $method );
+			}
+			JobQueue::incrStats( 'job-insert', $this->type, count( $rows ), $this->wiki );
+			JobQueue::incrStats(
+				'job-insert-duplicate',
+				$this->type,
+				count( $rowSet ) + count( $rowList ) - count( $rows ),
+				$this->wiki
+			);
+		} catch ( DBError $e ) {
+			if ( $flags & self::QOS_ATOMIC ) {
+				$dbw->rollback( $method );
+			}
+			throw $e;
+		}
+		if ( $flags & self::QOS_ATOMIC ) {
+			$dbw->commit( $method );
+		}
+
+		$this->cache->set( $this->getCacheKey( 'empty' ), 'false', JobQueueDB::CACHE_TTL_LONG );
+
+		return;
+	}
+
+	/**
+	 * @see JobQueue::doPop()
+	 * @return Job|bool
+	 */
+	protected function doPop() {
+		if ( $this->cache->get( $this->getCacheKey( 'empty' ) ) === 'true' ) {
+			return false; // queue is empty
+		}
+
+		$dbw = $this->getMasterDB();
+		try {
+			$dbw->commit( __METHOD__, 'flush' ); // flush existing transaction
+			$autoTrx = $dbw->getFlag( DBO_TRX ); // get current setting
+			$dbw->clearFlag( DBO_TRX ); // make each query its own transaction
+			$scopedReset = new ScopedCallback( function () use ( $dbw, $autoTrx ) {
+				$dbw->setFlag( $autoTrx ? DBO_TRX : 0 ); // restore old setting
+			} );
+
+			$uuid = wfRandomString( 32 ); // pop attempt
+			$job = false; // job popped off
+			do { // retry when our row is invalid or deleted as a duplicate
+				// Try to reserve a row in the DB...
+				if ( in_array( $this->order, array( 'fifo', 'timestamp' ) ) ) {
+					$row = $this->claimOldest( $uuid );
+				} else { // random first
+					$rand = mt_rand( 0, self::MAX_JOB_RANDOM ); // encourage concurrent UPDATEs
+					$gte = (bool)mt_rand( 0, 1 ); // find rows with rand before/after $rand
+					$row = $this->claimRandom( $uuid, $rand, $gte );
+				}
+				// Check if we found a row to reserve...
+				if ( !$row ) {
+					$this->cache->set( $this->getCacheKey( 'empty' ), 'true', self::CACHE_TTL_LONG );
+					break; // nothing to do
+				}
+				JobQueue::incrStats( 'job-pop', $this->type, 1, $this->wiki );
+				// Get the job object from the row...
+				$title = Title::makeTitleSafe( $row->job_namespace, $row->job_title );
+				if ( !$title ) {
+					$dbw->delete( 'job', array( 'job_id' => $row->job_id ), __METHOD__ );
+					wfDebug( "Row has invalid title '{$row->job_title}'.\n" );
+					continue; // try again
+				}
+				$job = Job::factory( $row->job_cmd, $title,
+					self::extractBlob( $row->job_params ), $row->job_id );
+				$job->metadata['id'] = $row->job_id;
+				break; // done
+			} while ( true );
+		} catch ( DBError $e ) {
+			$this->throwDBException( $e );
+		}
+
+		return $job;
+	}
+
+	/**
+	 * Reserve a row with a single UPDATE without holding row locks over RTTs...
+	 *
+	 * @param string $uuid 32 char hex string
+	 * @param int $rand Random unsigned integer (31 bits)
+	 * @param bool $gte Search for job_random >= $random (otherwise job_random <= $random)
+	 * @return stdClass|bool Row|false
+	 */
+	protected function claimRandom( $uuid, $rand, $gte ) {
+		$dbw = $this->getMasterDB();
+		// Check cache to see if the queue has <= OFFSET items
+		$tinyQueue = $this->cache->get( $this->getCacheKey( 'small' ) );
+
+		$row = false; // the row acquired
+		$invertedDirection = false; // whether one job_random direction was already scanned
+		// This uses a replication safe method for acquiring jobs. One could use UPDATE+LIMIT
+		// instead, but that either uses ORDER BY (in which case it deadlocks in MySQL) or is
+		// not replication safe. Due to http://bugs.mysql.com/bug.php?id=6980, subqueries cannot
+		// be used here with MySQL.
+		do {
+			if ( $tinyQueue ) { // queue has <= MAX_OFFSET rows
+				// For small queues, using OFFSET will overshoot and return no rows more often.
+				// Instead, this uses job_random to pick a row (possibly checking both directions).
+				$ineq = $gte ? '>=' : '<=';
+				$dir = $gte ? 'ASC' : 'DESC';
+				$row = $dbw->selectRow( 'job', self::selectFields(), // find a random job
+					array(
+						'job_cmd' => $this->type,
+						'job_token' => '', // unclaimed
+						"job_random {$ineq} {$dbw->addQuotes( $rand )}" ),
+					__METHOD__,
+					array( 'ORDER BY' => "job_random {$dir}" )
+				);
+				if ( !$row && !$invertedDirection ) {
+					$gte = !$gte;
+					$invertedDirection = true;
+					continue; // try the other direction
+				}
+			} else { // table *may* have >= MAX_OFFSET rows
+				// Bug 42614: "ORDER BY job_random" with a job_random inequality causes high CPU
+				// in MySQL if there are many rows for some reason. This uses a small OFFSET
+				// instead of job_random for reducing excess claim retries.
+				$row = $dbw->selectRow( 'job', self::selectFields(), // find a random job
+					array(
+						'job_cmd' => $this->type,
+						'job_token' => '', // unclaimed
+					),
+					__METHOD__,
+					array( 'OFFSET' => mt_rand( 0, self::MAX_OFFSET ) )
+				);
+				if ( !$row ) {
+					$tinyQueue = true; // we know the queue must have <= MAX_OFFSET rows
+					$this->cache->set( $this->getCacheKey( 'small' ), 1, 30 );
+					continue; // use job_random
+				}
+			}
+
+			if ( $row ) { // claim the job
+				$dbw->update( 'job', // update by PK
+					array(
+						'job_token' => $uuid,
+						'job_token_timestamp' => $dbw->timestamp(),
+						'job_attempts = job_attempts+1' ),
+					array( 'job_cmd' => $this->type, 'job_id' => $row->job_id, 'job_token' => '' ),
+					__METHOD__
+				);
+				// This might get raced out by another runner when claiming the previously
+				// selected row. The use of job_random should minimize this problem, however.
+				if ( !$dbw->affectedRows() ) {
+					$row = false; // raced out
+				}
+			} else {
+				break; // nothing to do
+			}
+		} while ( !$row );
+
+		return $row;
+	}
+
+	/**
+	 * Reserve a row with a single UPDATE without holding row locks over RTTs...
+	 *
+	 * @param string $uuid 32 char hex string
+	 * @return stdClass|bool Row|false
+	 */
+	protected function claimOldest( $uuid ) {
+		$dbw = $this->getMasterDB();
+
+		$row = false; // the row acquired
+		do {
+			if ( $dbw->getType() === 'mysql' ) {
+				// Per http://bugs.mysql.com/bug.php?id=6980, we can't use subqueries on the
+				// same table being changed in an UPDATE query in MySQL (gives Error: 1093).
+				// Oracle and Postgre have no such limitation. However, MySQL offers an
+				// alternative here by supporting ORDER BY + LIMIT for UPDATE queries.
+				$dbw->query( "UPDATE {$dbw->tableName( 'job' )} " .
+					"SET " .
+						"job_token = {$dbw->addQuotes( $uuid ) }, " .
+						"job_token_timestamp = {$dbw->addQuotes( $dbw->timestamp() )}, " .
+						"job_attempts = job_attempts+1 " .
+					"WHERE ( " .
+						"job_cmd = {$dbw->addQuotes( $this->type )} " .
+						"AND job_token = {$dbw->addQuotes( '' )} " .
+					") ORDER BY job_id ASC LIMIT 1",
+					__METHOD__
+				);
+			} else {
+				// Use a subquery to find the job, within an UPDATE to claim it.
+				// This uses as much of the DB wrapper functions as possible.
+				$dbw->update( 'job',
+					array(
+						'job_token' => $uuid,
+						'job_token_timestamp' => $dbw->timestamp(),
+						'job_attempts = job_attempts+1' ),
+					array( 'job_id = (' .
+						$dbw->selectSQLText( 'job', 'job_id',
+							array( 'job_cmd' => $this->type, 'job_token' => '' ),
+							__METHOD__,
+							array( 'ORDER BY' => 'job_id ASC', 'LIMIT' => 1 ) ) .
+						')'
+					),
+					__METHOD__
+				);
+			}
+			// Fetch any row that we just reserved...
+			if ( $dbw->affectedRows() ) {
+				$row = $dbw->selectRow( 'job', self::selectFields(),
+					array( 'job_cmd' => $this->type, 'job_token' => $uuid ), __METHOD__
+				);
+				if ( !$row ) { // raced out by duplicate job removal
+					wfDebug( "Row deleted as duplicate by another process.\n" );
+				}
+			} else {
+				break; // nothing to do
+			}
+		} while ( !$row );
+
+		return $row;
+	}
+
+	/**
+	 * @see JobQueue::doAck()
+	 * @param Job $job
+	 * @throws MWException
+	 * @return Job|bool
+	 */
+	protected function doAck( Job $job ) {
+		if ( !isset( $job->metadata['id'] ) ) {
+			throw new MWException( "Job of type '{$job->getType()}' has no ID." );
+		}
+
+		$dbw = $this->getMasterDB();
+		try {
+			$dbw->commit( __METHOD__, 'flush' ); // flush existing transaction
+			$autoTrx = $dbw->getFlag( DBO_TRX ); // get current setting
+			$dbw->clearFlag( DBO_TRX ); // make each query its own transaction
+			$scopedReset = new ScopedCallback( function () use ( $dbw, $autoTrx ) {
+				$dbw->setFlag( $autoTrx ? DBO_TRX : 0 ); // restore old setting
+			} );
+
+			// Delete a row with a single DELETE without holding row locks over RTTs...
+			$dbw->delete( 'job',
+				array( 'job_cmd' => $this->type, 'job_id' => $job->metadata['id'] ), __METHOD__ );
+		} catch ( DBError $e ) {
+			$this->throwDBException( $e );
+		}
+
+		return true;
+	}
+
+	/**
+	 * @see JobQueue::doDeduplicateRootJob()
+	 * @param Job $job
+	 * @throws MWException
+	 * @return bool
+	 */
+	protected function doDeduplicateRootJob( Job $job ) {
+		$params = $job->getParams();
+		if ( !isset( $params['rootJobSignature'] ) ) {
+			throw new MWException( "Cannot register root job; missing 'rootJobSignature'." );
+		} elseif ( !isset( $params['rootJobTimestamp'] ) ) {
+			throw new MWException( "Cannot register root job; missing 'rootJobTimestamp'." );
+		}
+		$key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
+		// Callers should call batchInsert() and then this function so that if the insert
+		// fails, the de-duplication registration will be aborted. Since the insert is
+		// deferred till "transaction idle", do the same here, so that the ordering is
+		// maintained. Having only the de-duplication registration succeed would cause
+		// jobs to become no-ops without any actual jobs that made them redundant.
+		$dbw = $this->getMasterDB();
+		$cache = $this->dupCache;
+		$dbw->onTransactionIdle( function () use ( $cache, $params, $key, $dbw ) {
+			$timestamp = $cache->get( $key ); // current last timestamp of this job
+			if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
+				return true; // a newer version of this root job was enqueued
+			}
+
+			// Update the timestamp of the last root job started at the location...
+			return $cache->set( $key, $params['rootJobTimestamp'], JobQueueDB::ROOTJOB_TTL );
+		} );
+
+		return true;
+	}
+
+	/**
+	 * @see JobQueue::doDelete()
+	 * @return bool
+	 */
+	protected function doDelete() {
+		$dbw = $this->getMasterDB();
+		try {
+			$dbw->delete( 'job', array( 'job_cmd' => $this->type ) );
+		} catch ( DBError $e ) {
+			$this->throwDBException( $e );
+		}
+
+		return true;
+	}
+
+	/**
+	 * @see JobQueue::doWaitForBackups()
+	 * @return void
+	 */
+	protected function doWaitForBackups() {
+		wfWaitForSlaves();
+	}
+
+	/**
+	 * @return array
+	 */
+	protected function doGetPeriodicTasks() {
+		return array(
+			'recycleAndDeleteStaleJobs' => array(
+				'callback' => array( $this, 'recycleAndDeleteStaleJobs' ),
+				'period' => ceil( $this->claimTTL / 2 )
+			)
+		);
+	}
+
+	/**
+	 * @return void
+	 */
+	protected function doFlushCaches() {
+		foreach ( array( 'empty', 'size', 'acquiredcount' ) as $type ) {
+			$this->cache->delete( $this->getCacheKey( $type ) );
+		}
+	}
+
+	/**
+	 * @see JobQueue::getAllQueuedJobs()
+	 * @return Iterator
+	 */
+	public function getAllQueuedJobs() {
+		$dbr = $this->getSlaveDB();
+		try {
+			return new MappedIterator(
+				$dbr->select( 'job', self::selectFields(),
+					array( 'job_cmd' => $this->getType(), 'job_token' => '' ) ),
+				function ( $row ) use ( $dbr ) {
+					$job = Job::factory(
+						$row->job_cmd,
+						Title::makeTitle( $row->job_namespace, $row->job_title ),
+						strlen( $row->job_params ) ? unserialize( $row->job_params ) : false
+					);
+					$job->metadata['id'] = $row->job_id;
+					return $job;
+				}
+			);
+		} catch ( DBError $e ) {
+			$this->throwDBException( $e );
+		}
+	}
+
+	public function getCoalesceLocationInternal() {
+		return $this->cluster
+			? "DBCluster:{$this->cluster}:{$this->wiki}"
+			: "LBFactory:{$this->wiki}";
+	}
+
+	protected function doGetSiblingQueuesWithJobs( array $types ) {
+		$dbr = $this->getSlaveDB();
+		$res = $dbr->select( 'job', 'DISTINCT job_cmd',
+			array( 'job_cmd' => $types ), __METHOD__ );
+
+		$types = array();
+		foreach ( $res as $row ) {
+			$types[] = $row->job_cmd;
+		}
+
+		return $types;
+	}
+
+	protected function doGetSiblingQueueSizes( array $types ) {
+		$dbr = $this->getSlaveDB();
+		$res = $dbr->select( 'job', array( 'job_cmd', 'COUNT(*) AS count' ),
+			array( 'job_cmd' => $types ), __METHOD__, array( 'GROUP BY' => 'job_cmd' ) );
+
+		$sizes = array();
+		foreach ( $res as $row ) {
+			$sizes[$row->job_cmd] = (int)$row->count;
+		}
+
+		return $sizes;
+	}
+
+	/**
+	 * Recycle or destroy any jobs that have been claimed for too long
+	 *
+	 * @return int Number of jobs recycled/deleted
+	 */
+	public function recycleAndDeleteStaleJobs() {
+		$now = time();
+		$count = 0; // affected rows
+		$dbw = $this->getMasterDB();
+
+		try {
+			if ( !$dbw->lock( "jobqueue-recycle-{$this->type}", __METHOD__, 1 ) ) {
+				return $count; // already in progress
+			}
+
+			// Remove claims on jobs acquired for too long if enabled...
+			if ( $this->claimTTL > 0 ) {
+				$claimCutoff = $dbw->timestamp( $now - $this->claimTTL );
+				// Get the IDs of jobs that have be claimed but not finished after too long.
+				// These jobs can be recycled into the queue by expiring the claim. Selecting
+				// the IDs first means that the UPDATE can be done by primary key (less deadlocks).
+				$res = $dbw->select( 'job', 'job_id',
+					array(
+						'job_cmd' => $this->type,
+						"job_token != {$dbw->addQuotes( '' )}", // was acquired
+						"job_token_timestamp < {$dbw->addQuotes( $claimCutoff )}", // stale
+						"job_attempts < {$dbw->addQuotes( $this->maxTries )}" ), // retries left
+					__METHOD__
+				);
+				$ids = array_map(
+					function ( $o ) {
+						return $o->job_id;
+					}, iterator_to_array( $res )
+				);
+				if ( count( $ids ) ) {
+					// Reset job_token for these jobs so that other runners will pick them up.
+					// Set the timestamp to the current time, as it is useful to now that the job
+					// was already tried before (the timestamp becomes the "released" time).
+					$dbw->update( 'job',
+						array(
+							'job_token' => '',
+							'job_token_timestamp' => $dbw->timestamp( $now ) ), // time of release
+						array(
+							'job_id' => $ids ),
+						__METHOD__
+					);
+					$affected = $dbw->affectedRows();
+					$count += $affected;
+					JobQueue::incrStats( 'job-recycle', $this->type, $affected, $this->wiki );
+					$this->cache->set( $this->getCacheKey( 'empty' ), 'false', self::CACHE_TTL_LONG );
+				}
+			}
+
+			// Just destroy any stale jobs...
+			$pruneCutoff = $dbw->timestamp( $now - self::MAX_AGE_PRUNE );
+			$conds = array(
+				'job_cmd' => $this->type,
+				"job_token != {$dbw->addQuotes( '' )}", // was acquired
+				"job_token_timestamp < {$dbw->addQuotes( $pruneCutoff )}" // stale
+			);
+			if ( $this->claimTTL > 0 ) { // only prune jobs attempted too many times...
+				$conds[] = "job_attempts >= {$dbw->addQuotes( $this->maxTries )}";
+			}
+			// Get the IDs of jobs that are considered stale and should be removed. Selecting
+			// the IDs first means that the UPDATE can be done by primary key (less deadlocks).
+			$res = $dbw->select( 'job', 'job_id', $conds, __METHOD__ );
+			$ids = array_map(
+				function ( $o ) {
+					return $o->job_id;
+				}, iterator_to_array( $res )
+			);
+			if ( count( $ids ) ) {
+				$dbw->delete( 'job', array( 'job_id' => $ids ), __METHOD__ );
+				$affected = $dbw->affectedRows();
+				$count += $affected;
+				JobQueue::incrStats( 'job-abandon', $this->type, $affected, $this->wiki );
+			}
+
+			$dbw->unlock( "jobqueue-recycle-{$this->type}", __METHOD__ );
+		} catch ( DBError $e ) {
+			$this->throwDBException( $e );
+		}
+
+		return $count;
+	}
+
+	/**
+	 * @param IJobSpecification $job
+	 * @return array
+	 */
+	protected function insertFields( IJobSpecification $job ) {
+		$dbw = $this->getMasterDB();
+
+		return array(
+			// Fields that describe the nature of the job
+			'job_cmd' => $job->getType(),
+			'job_namespace' => $job->getTitle()->getNamespace(),
+			'job_title' => $job->getTitle()->getDBkey(),
+			'job_params' => self::makeBlob( $job->getParams() ),
+			// Additional job metadata
+			'job_id' => $dbw->nextSequenceValue( 'job_job_id_seq' ),
+			'job_timestamp' => $dbw->timestamp(),
+			'job_sha1' => wfBaseConvert(
+				sha1( serialize( $job->getDeduplicationInfo() ) ),
+				16, 36, 31
+			),
+			'job_random' => mt_rand( 0, self::MAX_JOB_RANDOM )
+		);
+	}
+
+	/**
+	 * @throws JobQueueConnectionError
+	 * @return DBConnRef
+	 */
+	protected function getSlaveDB() {
+		try {
+			return $this->getDB( DB_SLAVE );
+		} catch ( DBConnectionError $e ) {
+			throw new JobQueueConnectionError( "DBConnectionError:" . $e->getMessage() );
+		}
+	}
+
+	/**
+	 * @throws JobQueueConnectionError
+	 * @return DBConnRef
+	 */
+	protected function getMasterDB() {
+		try {
+			return $this->getDB( DB_MASTER );
+		} catch ( DBConnectionError $e ) {
+			throw new JobQueueConnectionError( "DBConnectionError:" . $e->getMessage() );
+		}
+	}
+
+	/**
+	 * @param int $index (DB_SLAVE/DB_MASTER)
+	 * @return DBConnRef
+	 */
+	protected function getDB( $index ) {
+		$lb = ( $this->cluster !== false )
+			? wfGetLBFactory()->getExternalLB( $this->cluster, $this->wiki )
+			: wfGetLB( $this->wiki );
+
+		return $lb->getConnectionRef( $index, array(), $this->wiki );
+	}
+
+	/**
+	 * @param string $property
+	 * @return string
+	 */
+	private function getCacheKey( $property ) {
+		list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
+		$cluster = is_string( $this->cluster ) ? $this->cluster : 'main';
+
+		return wfForeignMemcKey( $db, $prefix, 'jobqueue', $cluster, $this->type, $property );
+	}
+
+	/**
+	 * @param array|bool $params
+	 * @return string
+	 */
+	protected static function makeBlob( $params ) {
+		if ( $params !== false ) {
+			return serialize( $params );
+		} else {
+			return '';
+		}
+	}
+
+	/**
+	 * @param string $blob
+	 * @return bool|mixed
+	 */
+	protected static function extractBlob( $blob ) {
+		if ( (string)$blob !== '' ) {
+			return unserialize( $blob );
+		} else {
+			return false;
+		}
+	}
+
+	/**
+	 * @param DBError $e
+	 * @throws JobQueueError
+	 */
+	protected function throwDBException( DBError $e ) {
+		throw new JobQueueError( get_class( $e ) . ": " . $e->getMessage() );
+	}
+
+	/**
+	 * Return the list of job fields that should be selected.
+	 * @since 1.23
+	 * @return array
+	 */
+	public static function selectFields() {
+		return array(
+			'job_id',
+			'job_cmd',
+			'job_namespace',
+			'job_title',
+			'job_timestamp',
+			'job_params',
+			'job_random',
+			'job_attempts',
+			'job_token',
+			'job_token_timestamp',
+			'job_sha1',
+		);
+	}
+}
diff --git a/includes/jobqueue/JobQueueFederated.php b/includes/jobqueue/JobQueueFederated.php
new file mode 100644
index 00000000..c4301eed
--- /dev/null
+++ b/includes/jobqueue/JobQueueFederated.php
@@ -0,0 +1,559 @@
+<?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 HashRing */
+	protected $partitionRing;
+	/** @var HashRing */
+	protected $partitionPushRing;
+	/** @var array (partition name => JobQueue) reverse sorted by weight */
+	protected $partitionQueues = array();
+
+	/** @var BagOStuff */
+	protected $cache;
+
+	/** @var int Maximum number of partitions to try */
+	protected $maxPartitionsTry;
+
+	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
+
+	/**
+	 * @param array $params Possible keys:
+	 *  - 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.
+	 *  - maxPartitionsTry    : Maximum number of times to attempt job insertion using
+	 *                          different partition queues. This improves availability
+	 *                          during failure, at the cost of added latency and somewhat
+	 *                          less reliable job de-duplication mechanisms.
+	 * @throws MWException
+	 */
+	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'." );
+		}
+		$this->maxPartitionsTry = isset( $params['maxPartitionsTry'] )
+			? $params['maxPartitionsTry']
+			: 2;
+		// Get the full partition map
+		$partitionMap = $params['partitionsBySection'][$section];
+		arsort( $partitionMap, SORT_NUMERIC );
+		// Get the partitions jobs can actually be pushed to
+		$partitionPushMap = $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', 'maxPartitionsTry',
+			'partitionsBySection', 'configByPartition', 'partitionsNoPush' ) as $o
+		) {
+			unset( $baseConfig[$o] ); // partition queue doesn't care about this
+		}
+		// Get the partition queue objects
+		foreach ( $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] );
+		}
+		// Ring of all partitions
+		$this->partitionRing = new HashRing( $partitionMap );
+		// Get the ring of partitions to push jobs into
+		if ( count( $partitionPushMap ) === count( $partitionMap ) ) {
+			$this->partitionPushRing = clone $this->partitionRing; // faster
+		} else {
+			$this->partitionPushRing = new HashRing( $partitionPushMap );
+		}
+		// Aggregate cache some per-queue values if there are multiple partition queues
+		$this->cache = count( $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;
+		}
+
+		$empty = true;
+		$failed = 0;
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				$empty = $empty && $queue->doIsEmpty();
+			} catch ( JobQueueError $e ) {
+				++$failed;
+				MWExceptionHandler::logException( $e );
+			}
+		}
+		$this->throwErrorIfAllPartitionsDown( $failed );
+
+		$this->cache->add( $key, $empty ? 'true' : 'false', self::CACHE_TTL_LONG );
+		return $empty;
+	}
+
+	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 int
+	 */
+	protected function getCrossPartitionSum( $type, $method ) {
+		$key = $this->getCacheKey( $type );
+
+		$count = $this->cache->get( $key );
+		if ( $count !== false ) {
+			return $count;
+		}
+
+		$failed = 0;
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				$count += $queue->$method();
+			} catch ( JobQueueError $e ) {
+				++$failed;
+				MWExceptionHandler::logException( $e );
+			}
+		}
+		$this->throwErrorIfAllPartitionsDown( $failed );
+
+		$this->cache->set( $key, $count, self::CACHE_TTL_SHORT );
+
+		return $count;
+	}
+
+	protected function doBatchPush( array $jobs, $flags ) {
+		// 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.
+		// Retry to insert any remaning jobs again, ignoring the bad partitions.
+		$jobsLeft = $jobs;
+		// @codingStandardsIgnoreStart Generic.CodeAnalysis.ForLoopWithTestFunctionCall.NotAllowed
+		for ( $i = $this->maxPartitionsTry; $i > 0 && count( $jobsLeft ); --$i ) {
+			// @codingStandardsIgnoreEnd
+			try {
+				$partitionRing->getLiveRing();
+			} catch ( UnexpectedValueException $e ) {
+				break; // all servers down; nothing to insert to
+			}
+			$jobsLeft = $this->tryJobInsertions( $jobsLeft, $partitionRing, $flags );
+		}
+		if ( count( $jobsLeft ) ) {
+			throw new JobQueueError(
+				"Could not insert job(s), {$this->maxPartitionsTry} partitions tried." );
+		}
+	}
+
+	/**
+	 * @param array $jobs
+	 * @param HashRing $partitionRing
+	 * @param int $flags
+	 * @throws JobQueueError
+	 * @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)
+		/** @var Job $job */
+		foreach ( $jobs as $key => $job ) {
+			if ( $job->ignoreDuplicates() ) {
+				$sha1 = sha1( serialize( $job->getDeduplicationInfo() ) );
+				$uJobsByPartition[$partitionRing->getLiveLocation( $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 ) {
+			/** @var JobQueue $queue */
+			$queue = $this->partitionQueues[$partition];
+			try {
+				$ok = true;
+				$queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
+			} catch ( JobQueueError $e ) {
+				$ok = false;
+				MWExceptionHandler::logException( $e );
+			}
+			if ( $ok ) {
+				$key = $this->getCacheKey( 'empty' );
+				$this->cache->set( $key, 'false', self::CACHE_TTL_LONG );
+			} else {
+				if ( !$partitionRing->ejectFromLiveRing( $partition, 5 ) ) { // blacklist
+					throw new JobQueueError( "Could not insert job(s), no partitions available." );
+				}
+				$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->getLiveLocationWeights() );
+			$queue = $this->partitionQueues[$partition];
+			try {
+				$ok = true;
+				$queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
+			} catch ( JobQueueError $e ) {
+				$ok = false;
+				MWExceptionHandler::logException( $e );
+			}
+			if ( $ok ) {
+				$key = $this->getCacheKey( 'empty' );
+				$this->cache->set( $key, 'false', self::CACHE_TTL_LONG );
+			} else {
+				if ( !$partitionRing->ejectFromLiveRing( $partition, 5 ) ) { // blacklist
+					throw new JobQueueError( "Could not insert job(s), no partitions available." );
+				}
+				$jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
+			}
+		}
+
+		return $jobsLeft;
+	}
+
+	protected function doPop() {
+		$partitionsTry = $this->partitionRing->getLiveLocationWeights(); // (partition => weight)
+
+		$failed = 0;
+		while ( count( $partitionsTry ) ) {
+			$partition = ArrayUtils::pickRandom( $partitionsTry );
+			if ( $partition === false ) {
+				break; // all partitions at 0 weight
+			}
+
+			/** @var JobQueue $queue */
+			$queue = $this->partitionQueues[$partition];
+			try {
+				$job = $queue->pop();
+			} catch ( JobQueueError $e ) {
+				++$failed;
+				MWExceptionHandler::logException( $e );
+				$job = false;
+			}
+			if ( $job ) {
+				$job->metadata['QueuePartition'] = $partition;
+
+				return $job;
+			} else {
+				unset( $partitionsTry[$partition] ); // blacklist partition
+			}
+		}
+		$this->throwErrorIfAllPartitionsDown( $failed );
+
+		$key = $this->getCacheKey( 'empty' );
+		$this->cache->set( $key, 'true', self::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();
+		$sigature = $params['rootJobSignature'];
+		$partition = $this->partitionPushRing->getLiveLocation( $sigature );
+		try {
+			return $this->partitionQueues[$partition]->doIsRootJobOldDuplicate( $job );
+		} catch ( JobQueueError $e ) {
+			if ( $this->partitionPushRing->ejectFromLiveRing( $partition, 5 ) ) {
+				$partition = $this->partitionPushRing->getLiveLocation( $sigature );
+				return $this->partitionQueues[$partition]->doIsRootJobOldDuplicate( $job );
+			}
+		}
+
+		return false;
+	}
+
+	protected function doDeduplicateRootJob( Job $job ) {
+		$params = $job->getRootJobParams();
+		$sigature = $params['rootJobSignature'];
+		$partition = $this->partitionPushRing->getLiveLocation( $sigature );
+		try {
+			return $this->partitionQueues[$partition]->doDeduplicateRootJob( $job );
+		} catch ( JobQueueError $e ) {
+			if ( $this->partitionPushRing->ejectFromLiveRing( $partition, 5 ) ) {
+				$partition = $this->partitionPushRing->getLiveLocation( $sigature );
+				return $this->partitionQueues[$partition]->doDeduplicateRootJob( $job );
+			}
+		}
+
+		return false;
+	}
+
+	protected function doDelete() {
+		$failed = 0;
+		/** @var JobQueue $queue */
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				$queue->doDelete();
+			} catch ( JobQueueError $e ) {
+				++$failed;
+				MWExceptionHandler::logException( $e );
+			}
+		}
+		$this->throwErrorIfAllPartitionsDown( $failed );
+		return true;
+	}
+
+	protected function doWaitForBackups() {
+		$failed = 0;
+		/** @var JobQueue $queue */
+		foreach ( $this->partitionQueues as $queue ) {
+			try {
+				$queue->waitForBackups();
+			} catch ( JobQueueError $e ) {
+				++$failed;
+				MWExceptionHandler::logException( $e );
+			}
+		}
+		$this->throwErrorIfAllPartitionsDown( $failed );
+	}
+
+	protected function doGetPeriodicTasks() {
+		$tasks = array();
+		/** @var JobQueue $queue */
+		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 ) );
+		}
+
+		/** @var JobQueue $queue */
+		foreach ( $this->partitionQueues as $queue ) {
+			$queue->doFlushCaches();
+		}
+	}
+
+	public function getAllQueuedJobs() {
+		$iterator = new AppendIterator();
+
+		/** @var JobQueue $queue */
+		foreach ( $this->partitionQueues as $queue ) {
+			$iterator->append( $queue->getAllQueuedJobs() );
+		}
+
+		return $iterator;
+	}
+
+	public function getAllDelayedJobs() {
+		$iterator = new AppendIterator();
+
+		/** @var JobQueue $queue */
+		foreach ( $this->partitionQueues as $queue ) {
+			$iterator->append( $queue->getAllDelayedJobs() );
+		}
+
+		return $iterator;
+	}
+
+	public function getCoalesceLocationInternal() {
+		return "JobQueueFederated:wiki:{$this->wiki}" .
+			sha1( serialize( array_keys( $this->partitionQueues ) ) );
+	}
+
+	protected function doGetSiblingQueuesWithJobs( array $types ) {
+		$result = array();
+
+		$failed = 0;
+		/** @var JobQueue $queue */
+		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 $e ) {
+				++$failed;
+				MWExceptionHandler::logException( $e );
+			}
+		}
+		$this->throwErrorIfAllPartitionsDown( $failed );
+
+		return array_values( $result );
+	}
+
+	protected function doGetSiblingQueueSizes( array $types ) {
+		$result = array();
+		$failed = 0;
+		/** @var JobQueue $queue */
+		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 $e ) {
+				++$failed;
+				MWExceptionHandler::logException( $e );
+			}
+		}
+		$this->throwErrorIfAllPartitionsDown( $failed );
+
+		return $result;
+	}
+
+	/**
+	 * Throw an error if no partitions available
+	 *
+	 * @param int $down The number of up partitions down
+	 * @return void
+	 * @throws JobQueueError
+	 */
+	protected function throwErrorIfAllPartitionsDown( $down ) {
+		if ( $down >= count( $this->partitionQueues ) ) {
+			throw new JobQueueError( 'No queue partitions available.' );
+		}
+	}
+
+	public function setTestingPrefix( $key ) {
+		/** @var JobQueue $queue */
+		foreach ( $this->partitionQueues as $queue ) {
+			$queue->setTestingPrefix( $key );
+		}
+	}
+
+	/**
+	 * @param string $property
+	 * @return string
+	 */
+	private function getCacheKey( $property ) {
+		list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
+
+		return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, $property );
+	}
+}
diff --git a/includes/jobqueue/JobQueueGroup.php b/includes/jobqueue/JobQueueGroup.php
new file mode 100644
index 00000000..98a78c5e
--- /dev/null
+++ b/includes/jobqueue/JobQueueGroup.php
@@ -0,0 +1,440 @@
+<?php
+/**
+ * Job queue base code.
+ *
+ * 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 of background jobs
+ *
+ * @ingroup JobQueue
+ * @since 1.21
+ */
+class JobQueueGroup {
+	/** @var array */
+	protected static $instances = array();
+
+	/** @var ProcessCacheLRU */
+	protected $cache;
+
+	/** @var string Wiki ID */
+	protected $wiki;
+
+	/** @var array Map of (bucket => (queue => JobQueue, types => list of types) */
+	protected $coalescedQueues;
+
+	const TYPE_DEFAULT = 1; // integer; jobs popped by default
+	const TYPE_ANY = 2; // integer; any job
+
+	const USE_CACHE = 1; // integer; use process or persistent cache
+
+	const PROC_CACHE_TTL = 15; // integer; seconds
+
+	const CACHE_VERSION = 1; // integer; cache version
+
+	/**
+	 * @param string $wiki Wiki ID
+	 */
+	protected function __construct( $wiki ) {
+		$this->wiki = $wiki;
+		$this->cache = new ProcessCacheLRU( 10 );
+	}
+
+	/**
+	 * @param bool|string $wiki Wiki ID
+	 * @return JobQueueGroup
+	 */
+	public static function singleton( $wiki = false ) {
+		$wiki = ( $wiki === false ) ? wfWikiID() : $wiki;
+		if ( !isset( self::$instances[$wiki] ) ) {
+			self::$instances[$wiki] = new self( $wiki );
+		}
+
+		return self::$instances[$wiki];
+	}
+
+	/**
+	 * Destroy the singleton instances
+	 *
+	 * @return void
+	 */
+	public static function destroySingletons() {
+		self::$instances = array();
+	}
+
+	/**
+	 * Get the job queue object for a given queue type
+	 *
+	 * @param string $type
+	 * @return JobQueue
+	 */
+	public function get( $type ) {
+		global $wgJobTypeConf;
+
+		$conf = array( 'wiki' => $this->wiki, 'type' => $type );
+		if ( isset( $wgJobTypeConf[$type] ) ) {
+			$conf = $conf + $wgJobTypeConf[$type];
+		} else {
+			$conf = $conf + $wgJobTypeConf['default'];
+		}
+
+		return JobQueue::factory( $conf );
+	}
+
+	/**
+	 * Insert jobs into the respective queues of with the belong.
+	 *
+	 * This inserts the jobs into the queue specified by $wgJobTypeConf
+	 * and updates the aggregate job queue information cache as needed.
+	 *
+	 * @param Job|array $jobs A single Job or a list of Jobs
+	 * @throws MWException
+	 * @return void
+	 */
+	public function push( $jobs ) {
+		$jobs = is_array( $jobs ) ? $jobs : array( $jobs );
+		if ( !count( $jobs ) ) {
+			return;
+		}
+
+		$jobsByType = array(); // (job type => list of jobs)
+		foreach ( $jobs as $job ) {
+			if ( $job instanceof IJobSpecification ) {
+				$jobsByType[$job->getType()][] = $job;
+			} else {
+				throw new MWException( "Attempted to push a non-Job object into a queue." );
+			}
+		}
+
+		foreach ( $jobsByType as $type => $jobs ) {
+			$this->get( $type )->push( $jobs );
+			JobQueueAggregator::singleton()->notifyQueueNonEmpty( $this->wiki, $type );
+		}
+
+		if ( $this->cache->has( 'queues-ready', 'list' ) ) {
+			$list = $this->cache->get( 'queues-ready', 'list' );
+			if ( count( array_diff( array_keys( $jobsByType ), $list ) ) ) {
+				$this->cache->clear( 'queues-ready' );
+			}
+		}
+	}
+
+	/**
+	 * Pop a job off one of the job queues
+	 *
+	 * This pops a job off a queue as specified by $wgJobTypeConf and
+	 * updates the aggregate job queue information cache as needed.
+	 *
+	 * @param int|string $qtype JobQueueGroup::TYPE_* constant or job type string
+	 * @param int $flags Bitfield of JobQueueGroup::USE_* constants
+	 * @param array $blacklist List of job types to ignore
+	 * @return Job|bool Returns false on failure
+	 */
+	public function pop( $qtype = self::TYPE_DEFAULT, $flags = 0, array $blacklist = array() ) {
+		$job = false;
+
+		if ( is_string( $qtype ) ) { // specific job type
+			if ( !in_array( $qtype, $blacklist ) ) {
+				$job = $this->get( $qtype )->pop();
+				if ( !$job ) {
+					JobQueueAggregator::singleton()->notifyQueueEmpty( $this->wiki, $qtype );
+				}
+			}
+		} else { // any job in the "default" jobs types
+			if ( $flags & self::USE_CACHE ) {
+				if ( !$this->cache->has( 'queues-ready', 'list', self::PROC_CACHE_TTL ) ) {
+					$this->cache->set( 'queues-ready', 'list', $this->getQueuesWithJobs() );
+				}
+				$types = $this->cache->get( 'queues-ready', 'list' );
+			} else {
+				$types = $this->getQueuesWithJobs();
+			}
+
+			if ( $qtype == self::TYPE_DEFAULT ) {
+				$types = array_intersect( $types, $this->getDefaultQueueTypes() );
+			}
+
+			$types = array_diff( $types, $blacklist ); // avoid selected types
+			shuffle( $types ); // avoid starvation
+
+			foreach ( $types as $type ) { // for each queue...
+				$job = $this->get( $type )->pop();
+				if ( $job ) { // found
+					break;
+				} else { // not found
+					JobQueueAggregator::singleton()->notifyQueueEmpty( $this->wiki, $type );
+					$this->cache->clear( 'queues-ready' );
+				}
+			}
+		}
+
+		return $job;
+	}
+
+	/**
+	 * Acknowledge that a job was completed
+	 *
+	 * @param Job $job
+	 * @return bool
+	 */
+	public function ack( Job $job ) {
+		return $this->get( $job->getType() )->ack( $job );
+	}
+
+	/**
+	 * Register the "root job" of a given job into the queue for de-duplication.
+	 * This should only be called right *after* all the new jobs have been inserted.
+	 *
+	 * @param Job $job
+	 * @return bool
+	 */
+	public function deduplicateRootJob( Job $job ) {
+		return $this->get( $job->getType() )->deduplicateRootJob( $job );
+	}
+
+	/**
+	 * Wait for any slaves or backup queue servers to catch up.
+	 *
+	 * This does nothing for certain queue classes.
+	 *
+	 * @return void
+	 * @throws MWException
+	 */
+	public function waitForBackups() {
+		global $wgJobTypeConf;
+
+		wfProfileIn( __METHOD__ );
+		// Try to avoid doing this more than once per queue storage medium
+		foreach ( $wgJobTypeConf as $type => $conf ) {
+			$this->get( $type )->waitForBackups();
+		}
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * Get the list of queue types
+	 *
+	 * @return array List of strings
+	 */
+	public function getQueueTypes() {
+		return array_keys( $this->getCachedConfigVar( 'wgJobClasses' ) );
+	}
+
+	/**
+	 * Get the list of default queue types
+	 *
+	 * @return array List of strings
+	 */
+	public function getDefaultQueueTypes() {
+		global $wgJobTypesExcludedFromDefaultQueue;
+
+		return array_diff( $this->getQueueTypes(), $wgJobTypesExcludedFromDefaultQueue );
+	}
+
+	/**
+	 * Check if there are any queues with jobs (this is cached)
+	 *
+	 * @param int $type JobQueueGroup::TYPE_* constant
+	 * @return bool
+	 * @since 1.23
+	 */
+	public function queuesHaveJobs( $type = self::TYPE_ANY ) {
+		global $wgMemc;
+
+		$key = wfMemcKey( 'jobqueue', 'queueshavejobs', $type );
+
+		$value = $wgMemc->get( $key );
+		if ( $value === false ) {
+			$queues = $this->getQueuesWithJobs();
+			if ( $type == self::TYPE_DEFAULT ) {
+				$queues = array_intersect( $queues, $this->getDefaultQueueTypes() );
+			}
+			$value = count( $queues ) ? 'true' : 'false';
+			$wgMemc->add( $key, $value, 15 );
+		}
+
+		return ( $value === 'true' );
+	}
+
+	/**
+	 * Get the list of job types that have non-empty queues
+	 *
+	 * @return array List of job types that have non-empty queues
+	 */
+	public function getQueuesWithJobs() {
+		$types = array();
+		foreach ( $this->getCoalescedQueues() as $info ) {
+			$nonEmpty = $info['queue']->getSiblingQueuesWithJobs( $this->getQueueTypes() );
+			if ( is_array( $nonEmpty ) ) { // batching features supported
+				$types = array_merge( $types, $nonEmpty );
+			} else { // we have to go through the queues in the bucket one-by-one
+				foreach ( $info['types'] as $type ) {
+					if ( !$this->get( $type )->isEmpty() ) {
+						$types[] = $type;
+					}
+				}
+			}
+		}
+
+		return $types;
+	}
+
+	/**
+	 * Get the size of the queus for a list of job types
+	 *
+	 * @return array Map of (job type => size)
+	 */
+	public function getQueueSizes() {
+		$sizeMap = array();
+		foreach ( $this->getCoalescedQueues() as $info ) {
+			$sizes = $info['queue']->getSiblingQueueSizes( $this->getQueueTypes() );
+			if ( is_array( $sizes ) ) { // batching features supported
+				$sizeMap = $sizeMap + $sizes;
+			} else { // we have to go through the queues in the bucket one-by-one
+				foreach ( $info['types'] as $type ) {
+					$sizeMap[$type] = $this->get( $type )->getSize();
+				}
+			}
+		}
+
+		return $sizeMap;
+	}
+
+	/**
+	 * @return array
+	 */
+	protected function getCoalescedQueues() {
+		global $wgJobTypeConf;
+
+		if ( $this->coalescedQueues === null ) {
+			$this->coalescedQueues = array();
+			foreach ( $wgJobTypeConf as $type => $conf ) {
+				$queue = JobQueue::factory(
+					array( 'wiki' => $this->wiki, 'type' => 'null' ) + $conf );
+				$loc = $queue->getCoalesceLocationInternal();
+				if ( !isset( $this->coalescedQueues[$loc] ) ) {
+					$this->coalescedQueues[$loc]['queue'] = $queue;
+					$this->coalescedQueues[$loc]['types'] = array();
+				}
+				if ( $type === 'default' ) {
+					$this->coalescedQueues[$loc]['types'] = array_merge(
+						$this->coalescedQueues[$loc]['types'],
+						array_diff( $this->getQueueTypes(), array_keys( $wgJobTypeConf ) )
+					);
+				} else {
+					$this->coalescedQueues[$loc]['types'][] = $type;
+				}
+			}
+		}
+
+		return $this->coalescedQueues;
+	}
+
+	/**
+	 * Execute any due periodic queue maintenance tasks for all queues.
+	 *
+	 * A task is "due" if the time ellapsed since the last run is greater than
+	 * the defined run period. Concurrent calls to this function will cause tasks
+	 * to be attempted twice, so they may need their own methods of mutual exclusion.
+	 *
+	 * @return int Number of tasks run
+	 */
+	public function executeReadyPeriodicTasks() {
+		global $wgMemc;
+
+		list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
+		$key = wfForeignMemcKey( $db, $prefix, 'jobqueuegroup', 'taskruns', 'v1' );
+		$lastRuns = $wgMemc->get( $key ); // (queue => task => UNIX timestamp)
+
+		$count = 0;
+		$tasksRun = array(); // (queue => task => UNIX timestamp)
+		foreach ( $this->getQueueTypes() as $type ) {
+			$queue = $this->get( $type );
+			foreach ( $queue->getPeriodicTasks() as $task => $definition ) {
+				if ( $definition['period'] <= 0 ) {
+					continue; // disabled
+				} elseif ( !isset( $lastRuns[$type][$task] )
+					|| $lastRuns[$type][$task] < ( time() - $definition['period'] )
+				) {
+					try {
+						if ( call_user_func( $definition['callback'] ) !== null ) {
+							$tasksRun[$type][$task] = time();
+							++$count;
+						}
+					} catch ( JobQueueError $e ) {
+						MWExceptionHandler::logException( $e );
+					}
+				}
+			}
+			// The tasks may have recycled jobs or release delayed jobs into the queue
+			if ( isset( $tasksRun[$type] ) && !$queue->isEmpty() ) {
+				JobQueueAggregator::singleton()->notifyQueueNonEmpty( $this->wiki, $type );
+			}
+		}
+
+		if ( $count === 0 ) {
+			return $count; // nothing to update
+		}
+
+		$wgMemc->merge( $key, function ( $cache, $key, $lastRuns ) use ( $tasksRun ) {
+			if ( is_array( $lastRuns ) ) {
+				foreach ( $tasksRun as $type => $tasks ) {
+					foreach ( $tasks as $task => $timestamp ) {
+						if ( !isset( $lastRuns[$type][$task] )
+							|| $timestamp > $lastRuns[$type][$task]
+						) {
+							$lastRuns[$type][$task] = $timestamp;
+						}
+					}
+				}
+			} else {
+				$lastRuns = $tasksRun;
+			}
+
+			return $lastRuns;
+		} );
+
+		return $count;
+	}
+
+	/**
+	 * @param string $name
+	 * @return mixed
+	 */
+	private function getCachedConfigVar( $name ) {
+		global $wgConf, $wgMemc;
+
+		if ( $this->wiki === wfWikiID() ) {
+			return $GLOBALS[$name]; // common case
+		} else {
+			list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
+			$key = wfForeignMemcKey( $db, $prefix, 'configvalue', $name );
+			$value = $wgMemc->get( $key ); // ('v' => ...) or false
+			if ( is_array( $value ) ) {
+				return $value['v'];
+			} else {
+				$value = $wgConf->getConfig( $this->wiki, $name );
+				$wgMemc->set( $key, array( 'v' => $value ), 86400 + mt_rand( 0, 86400 ) );
+
+				return $value;
+			}
+		}
+	}
+}
diff --git a/includes/jobqueue/JobQueueRedis.php b/includes/jobqueue/JobQueueRedis.php
new file mode 100644
index 00000000..3519eac8
--- /dev/null
+++ b/includes/jobqueue/JobQueueRedis.php
@@ -0,0 +1,865 @@
+<?php
+/**
+ * Redis-backed job queue code.
+ *
+ * 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 job queues stored in Redis
+ *
+ * This is faster, less resource intensive, queue that JobQueueDB.
+ * All data for a queue using this class is placed into one redis server.
+ *
+ * There are eight main redis keys used to track jobs:
+ *   - l-unclaimed  : A list of job IDs used for ready unclaimed jobs
+ *   - z-claimed    : A sorted set of (job ID, UNIX timestamp as score) used for job retries
+ *   - z-abandoned  : A sorted set of (job ID, UNIX timestamp as score) used for broken jobs
+ *   - z-delayed    : A sorted set of (job ID, UNIX timestamp as score) used for delayed jobs
+ *   - h-idBySha1   : A hash of (SHA1 => job ID) for unclaimed jobs used for de-duplication
+ *   - h-sha1ById   : A hash of (job ID => SHA1) for unclaimed jobs used for de-duplication
+ *   - h-attempts   : A hash of (job ID => attempt count) used for job claiming/retries
+ *   - h-data       : A hash of (job ID => serialized blobs) for job storage
+ * A job ID can be in only one of z-delayed, l-unclaimed, z-claimed, and z-abandoned.
+ * If an ID appears in any of those lists, it should have a h-data entry for its ID.
+ * If a job has a SHA1 de-duplication value and its ID is in l-unclaimed or z-delayed, then
+ * there should be no other such jobs with that SHA1. Every h-idBySha1 entry has an h-sha1ById
+ * entry and every h-sha1ById must refer to an ID that is l-unclaimed. If a job has its
+ * ID in z-claimed or z-abandoned, then it must also have an h-attempts entry for its ID.
+ *
+ * Additionally, "rootjob:* keys track "root jobs" used for additional de-duplication.
+ * Aside from root job keys, all keys have no expiry, and are only removed when jobs are run.
+ * All the keys are prefixed with the relevant wiki ID information.
+ *
+ * This class requires Redis 2.6 as it makes use Lua scripts for fast atomic operations.
+ * Additionally, it should be noted that redis has different persistence modes, such
+ * as rdb snapshots, journaling, and no persistent. Appropriate configuration should be
+ * made on the servers based on what queues are using it and what tolerance they have.
+ *
+ * @ingroup JobQueue
+ * @ingroup Redis
+ * @since 1.22
+ */
+class JobQueueRedis extends JobQueue {
+	/** @var RedisConnectionPool */
+	protected $redisPool;
+
+	/** @var string Server address */
+	protected $server;
+	/** @var string Compression method to use */
+	protected $compression;
+	/** @var bool */
+	protected $daemonized;
+
+	const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed (7 days)
+
+	/** @var string Key to prefix the queue keys with (used for testing) */
+	protected $key;
+
+	/**
+	 * @param array $params Possible keys:
+	 *   - redisConfig : An array of parameters to RedisConnectionPool::__construct().
+	 *                   Note that the serializer option is ignored as "none" is always used.
+	 *   - redisServer : A hostname/port combination or the absolute path of a UNIX socket.
+	 *                   If a hostname is specified but no port, the standard port number
+	 *                   6379 will be used. Required.
+	 *   - compression : The type of compression to use; one of (none,gzip).
+	 *   - daemonized  : Set to true if the redisJobRunnerService runs in the background.
+	 *                   This will disable job recycling/undelaying from the MediaWiki side
+	 *                   to avoid redundance and out-of-sync configuration.
+	 */
+	public function __construct( array $params ) {
+		parent::__construct( $params );
+		$params['redisConfig']['serializer'] = 'none'; // make it easy to use Lua
+		$this->server = $params['redisServer'];
+		$this->compression = isset( $params['compression'] ) ? $params['compression'] : 'none';
+		$this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
+		$this->daemonized = !empty( $params['daemonized'] );
+	}
+
+	protected function supportedOrders() {
+		return array( 'timestamp', 'fifo' );
+	}
+
+	protected function optimalOrder() {
+		return 'fifo';
+	}
+
+	protected function supportsDelayedJobs() {
+		return true;
+	}
+
+	/**
+	 * @see JobQueue::doIsEmpty()
+	 * @return bool
+	 * @throws MWException
+	 */
+	protected function doIsEmpty() {
+		return $this->doGetSize() == 0;
+	}
+
+	/**
+	 * @see JobQueue::doGetSize()
+	 * @return int
+	 * @throws MWException
+	 */
+	protected function doGetSize() {
+		$conn = $this->getConnection();
+		try {
+			return $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) );
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	/**
+	 * @see JobQueue::doGetAcquiredCount()
+	 * @return int
+	 * @throws JobQueueError
+	 */
+	protected function doGetAcquiredCount() {
+		if ( $this->claimTTL <= 0 ) {
+			return 0; // no acknowledgements
+		}
+		$conn = $this->getConnection();
+		try {
+			$conn->multi( Redis::PIPELINE );
+			$conn->zSize( $this->getQueueKey( 'z-claimed' ) );
+			$conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
+
+			return array_sum( $conn->exec() );
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	/**
+	 * @see JobQueue::doGetDelayedCount()
+	 * @return int
+	 * @throws JobQueueError
+	 */
+	protected function doGetDelayedCount() {
+		if ( !$this->checkDelay ) {
+			return 0; // no delayed jobs
+		}
+		$conn = $this->getConnection();
+		try {
+			return $conn->zSize( $this->getQueueKey( 'z-delayed' ) );
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	/**
+	 * @see JobQueue::doGetAbandonedCount()
+	 * @return int
+	 * @throws JobQueueError
+	 */
+	protected function doGetAbandonedCount() {
+		if ( $this->claimTTL <= 0 ) {
+			return 0; // no acknowledgements
+		}
+		$conn = $this->getConnection();
+		try {
+			return $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	/**
+	 * @see JobQueue::doBatchPush()
+	 * @param array $jobs
+	 * @param int $flags
+	 * @return void
+	 * @throws JobQueueError
+	 */
+	protected function doBatchPush( array $jobs, $flags ) {
+		// Convert the jobs into field maps (de-duplicated against each other)
+		$items = array(); // (job ID => job fields map)
+		foreach ( $jobs as $job ) {
+			$item = $this->getNewJobFields( $job );
+			if ( strlen( $item['sha1'] ) ) { // hash identifier => de-duplicate
+				$items[$item['sha1']] = $item;
+			} else {
+				$items[$item['uuid']] = $item;
+			}
+		}
+
+		if ( !count( $items ) ) {
+			return; // nothing to do
+		}
+
+		$conn = $this->getConnection();
+		try {
+			// Actually push the non-duplicate jobs into the queue...
+			if ( $flags & self::QOS_ATOMIC ) {
+				$batches = array( $items ); // all or nothing
+			} else {
+				$batches = array_chunk( $items, 500 ); // avoid tying up the server
+			}
+			$failed = 0;
+			$pushed = 0;
+			foreach ( $batches as $itemBatch ) {
+				$added = $this->pushBlobs( $conn, $itemBatch );
+				if ( is_int( $added ) ) {
+					$pushed += $added;
+				} else {
+					$failed += count( $itemBatch );
+				}
+			}
+			if ( $failed > 0 ) {
+				wfDebugLog( 'JobQueueRedis', "Could not insert {$failed} {$this->type} job(s)." );
+
+				throw new RedisException( "Could not insert {$failed} {$this->type} job(s)." );
+			}
+			JobQueue::incrStats( 'job-insert', $this->type, count( $items ), $this->wiki );
+			JobQueue::incrStats( 'job-insert-duplicate', $this->type,
+				count( $items ) - $failed - $pushed, $this->wiki );
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	/**
+	 * @param RedisConnRef $conn
+	 * @param array $items List of results from JobQueueRedis::getNewJobFields()
+	 * @return int Number of jobs inserted (duplicates are ignored)
+	 * @throws RedisException
+	 */
+	protected function pushBlobs( RedisConnRef $conn, array $items ) {
+		$args = array(); // ([id, sha1, rtime, blob [, id, sha1, rtime, blob ... ] ] )
+		foreach ( $items as $item ) {
+			$args[] = (string)$item['uuid'];
+			$args[] = (string)$item['sha1'];
+			$args[] = (string)$item['rtimestamp'];
+			$args[] = (string)$this->serialize( $item );
+		}
+		static $script =
+<<<LUA
+		local kUnclaimed, kSha1ById, kIdBySha1, kDelayed, kData = unpack(KEYS)
+		if #ARGV % 4 ~= 0 then return redis.error_reply('Unmatched arguments') end
+		local pushed = 0
+		for i = 1,#ARGV,4 do
+			local id,sha1,rtimestamp,blob = ARGV[i],ARGV[i+1],ARGV[i+2],ARGV[i+3]
+			if sha1 == '' or redis.call('hExists',kIdBySha1,sha1) == 0 then
+				if 1*rtimestamp > 0 then
+					-- Insert into delayed queue (release time as score)
+					redis.call('zAdd',kDelayed,rtimestamp,id)
+				else
+					-- Insert into unclaimed queue
+					redis.call('lPush',kUnclaimed,id)
+				end
+				if sha1 ~= '' then
+					redis.call('hSet',kSha1ById,id,sha1)
+					redis.call('hSet',kIdBySha1,sha1,id)
+				end
+				redis.call('hSet',kData,id,blob)
+				pushed = pushed + 1
+			end
+		end
+		return pushed
+LUA;
+		return $conn->luaEval( $script,
+			array_merge(
+				array(
+					$this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
+					$this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
+					$this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
+					$this->getQueueKey( 'z-delayed' ), # KEYS[4]
+					$this->getQueueKey( 'h-data' ), # KEYS[5]
+				),
+				$args
+			),
+			5 # number of first argument(s) that are keys
+		);
+	}
+
+	/**
+	 * @see JobQueue::doPop()
+	 * @return Job|bool
+	 * @throws JobQueueError
+	 */
+	protected function doPop() {
+		$job = false;
+
+		// Push ready delayed jobs into the queue every 10 jobs to spread the load.
+		// This is also done as a periodic task, but we don't want too much done at once.
+		if ( $this->checkDelay && mt_rand( 0, 9 ) == 0 ) {
+			$this->recyclePruneAndUndelayJobs();
+		}
+
+		$conn = $this->getConnection();
+		try {
+			do {
+				if ( $this->claimTTL > 0 ) {
+					// Keep the claimed job list down for high-traffic queues
+					if ( mt_rand( 0, 99 ) == 0 ) {
+						$this->recyclePruneAndUndelayJobs();
+					}
+					$blob = $this->popAndAcquireBlob( $conn );
+				} else {
+					$blob = $this->popAndDeleteBlob( $conn );
+				}
+				if ( !is_string( $blob ) ) {
+					break; // no jobs; nothing to do
+				}
+
+				JobQueue::incrStats( 'job-pop', $this->type, 1, $this->wiki );
+				$item = $this->unserialize( $blob );
+				if ( $item === false ) {
+					wfDebugLog( 'JobQueueRedis', "Could not unserialize {$this->type} job." );
+					continue;
+				}
+
+				// If $item is invalid, recyclePruneAndUndelayJobs() will cleanup as needed
+				$job = $this->getJobFromFields( $item ); // may be false
+			} while ( !$job ); // job may be false if invalid
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+
+		return $job;
+	}
+
+	/**
+	 * @param RedisConnRef $conn
+	 * @return array Serialized string or false
+	 * @throws RedisException
+	 */
+	protected function popAndDeleteBlob( RedisConnRef $conn ) {
+		static $script =
+<<<LUA
+		local kUnclaimed, kSha1ById, kIdBySha1, kData = unpack(KEYS)
+		-- Pop an item off the queue
+		local id = redis.call('rpop',kUnclaimed)
+		if not id then return false end
+		-- Get the job data and remove it
+		local item = redis.call('hGet',kData,id)
+		redis.call('hDel',kData,id)
+		-- Allow new duplicates of this job
+		local sha1 = redis.call('hGet',kSha1ById,id)
+		if sha1 then redis.call('hDel',kIdBySha1,sha1) end
+		redis.call('hDel',kSha1ById,id)
+		-- Return the job data
+		return item
+LUA;
+		return $conn->luaEval( $script,
+			array(
+				$this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
+				$this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
+				$this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
+				$this->getQueueKey( 'h-data' ), # KEYS[4]
+			),
+			4 # number of first argument(s) that are keys
+		);
+	}
+
+	/**
+	 * @param RedisConnRef $conn
+	 * @return array Serialized string or false
+	 * @throws RedisException
+	 */
+	protected function popAndAcquireBlob( RedisConnRef $conn ) {
+		static $script =
+<<<LUA
+		local kUnclaimed, kSha1ById, kIdBySha1, kClaimed, kAttempts, kData = unpack(KEYS)
+		-- Pop an item off the queue
+		local id = redis.call('rPop',kUnclaimed)
+		if not id then return false end
+		-- Allow new duplicates of this job
+		local sha1 = redis.call('hGet',kSha1ById,id)
+		if sha1 then redis.call('hDel',kIdBySha1,sha1) end
+		redis.call('hDel',kSha1ById,id)
+		-- Mark the jobs as claimed and return it
+		redis.call('zAdd',kClaimed,ARGV[1],id)
+		redis.call('hIncrBy',kAttempts,id,1)
+		return redis.call('hGet',kData,id)
+LUA;
+		return $conn->luaEval( $script,
+			array(
+				$this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
+				$this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
+				$this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
+				$this->getQueueKey( 'z-claimed' ), # KEYS[4]
+				$this->getQueueKey( 'h-attempts' ), # KEYS[5]
+				$this->getQueueKey( 'h-data' ), # KEYS[6]
+				time(), # ARGV[1] (injected to be replication-safe)
+			),
+			6 # number of first argument(s) that are keys
+		);
+	}
+
+	/**
+	 * @see JobQueue::doAck()
+	 * @param Job $job
+	 * @return Job|bool
+	 * @throws MWException|JobQueueError
+	 */
+	protected function doAck( Job $job ) {
+		if ( !isset( $job->metadata['uuid'] ) ) {
+			throw new MWException( "Job of type '{$job->getType()}' has no UUID." );
+		}
+		if ( $this->claimTTL > 0 ) {
+			$conn = $this->getConnection();
+			try {
+				static $script =
+<<<LUA
+				local kClaimed, kAttempts, kData = unpack(KEYS)
+				-- Unmark the job as claimed
+				redis.call('zRem',kClaimed,ARGV[1])
+				redis.call('hDel',kAttempts,ARGV[1])
+				-- Delete the job data itself
+				return redis.call('hDel',kData,ARGV[1])
+LUA;
+				$res = $conn->luaEval( $script,
+					array(
+						$this->getQueueKey( 'z-claimed' ), # KEYS[1]
+						$this->getQueueKey( 'h-attempts' ), # KEYS[2]
+						$this->getQueueKey( 'h-data' ), # KEYS[3]
+						$job->metadata['uuid'] # ARGV[1]
+					),
+					3 # number of first argument(s) that are keys
+				);
+
+				if ( !$res ) {
+					wfDebugLog( 'JobQueueRedis', "Could not acknowledge {$this->type} job." );
+
+					return false;
+				}
+			} catch ( RedisException $e ) {
+				$this->throwRedisException( $conn, $e );
+			}
+		}
+
+		return true;
+	}
+
+	/**
+	 * @see JobQueue::doDeduplicateRootJob()
+	 * @param Job $job
+	 * @return bool
+	 * @throws MWException|JobQueueError
+	 */
+	protected function doDeduplicateRootJob( Job $job ) {
+		if ( !$job->hasRootJobParams() ) {
+			throw new MWException( "Cannot register root job; missing parameters." );
+		}
+		$params = $job->getRootJobParams();
+
+		$key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
+
+		$conn = $this->getConnection();
+		try {
+			$timestamp = $conn->get( $key ); // current last timestamp of this job
+			if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
+				return true; // a newer version of this root job was enqueued
+			}
+
+			// Update the timestamp of the last root job started at the location...
+			return $conn->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL ); // 2 weeks
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	/**
+	 * @see JobQueue::doIsRootJobOldDuplicate()
+	 * @param Job $job
+	 * @return bool
+	 * @throws JobQueueError
+	 */
+	protected function doIsRootJobOldDuplicate( Job $job ) {
+		if ( !$job->hasRootJobParams() ) {
+			return false; // job has no de-deplication info
+		}
+		$params = $job->getRootJobParams();
+
+		$conn = $this->getConnection();
+		try {
+			// Get the last time this root job was enqueued
+			$timestamp = $conn->get( $this->getRootJobCacheKey( $params['rootJobSignature'] ) );
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+
+		// Check if a new root job was started at the location after this one's...
+		return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
+	}
+
+	/**
+	 * @see JobQueue::doDelete()
+	 * @return bool
+	 * @throws JobQueueError
+	 */
+	protected function doDelete() {
+		static $props = array( 'l-unclaimed', 'z-claimed', 'z-abandoned',
+			'z-delayed', 'h-idBySha1', 'h-sha1ById', 'h-attempts', 'h-data' );
+
+		$conn = $this->getConnection();
+		try {
+			$keys = array();
+			foreach ( $props as $prop ) {
+				$keys[] = $this->getQueueKey( $prop );
+			}
+
+			return ( $conn->delete( $keys ) !== false );
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	/**
+	 * @see JobQueue::getAllQueuedJobs()
+	 * @return Iterator
+	 */
+	public function getAllQueuedJobs() {
+		$conn = $this->getConnection();
+		try {
+			$that = $this;
+
+			return new MappedIterator(
+				$conn->lRange( $this->getQueueKey( 'l-unclaimed' ), 0, -1 ),
+				function ( $uid ) use ( $that, $conn ) {
+					return $that->getJobFromUidInternal( $uid, $conn );
+				},
+				array( 'accept' => function ( $job ) {
+					return is_object( $job );
+				} )
+			);
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	/**
+	 * @see JobQueue::getAllQueuedJobs()
+	 * @return Iterator
+	 */
+	public function getAllDelayedJobs() {
+		$conn = $this->getConnection();
+		try {
+			$that = $this;
+
+			return new MappedIterator( // delayed jobs
+				$conn->zRange( $this->getQueueKey( 'z-delayed' ), 0, -1 ),
+				function ( $uid ) use ( $that, $conn ) {
+					return $that->getJobFromUidInternal( $uid, $conn );
+				},
+				array( 'accept' => function ( $job ) {
+					return is_object( $job );
+				} )
+			);
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	public function getCoalesceLocationInternal() {
+		return "RedisServer:" . $this->server;
+	}
+
+	protected function doGetSiblingQueuesWithJobs( array $types ) {
+		return array_keys( array_filter( $this->doGetSiblingQueueSizes( $types ) ) );
+	}
+
+	protected function doGetSiblingQueueSizes( array $types ) {
+		$sizes = array(); // (type => size)
+		$types = array_values( $types ); // reindex
+		$conn = $this->getConnection();
+		try {
+			$conn->multi( Redis::PIPELINE );
+			foreach ( $types as $type ) {
+				$conn->lSize( $this->getQueueKey( 'l-unclaimed', $type ) );
+			}
+			$res = $conn->exec();
+			if ( is_array( $res ) ) {
+				foreach ( $res as $i => $size ) {
+					$sizes[$types[$i]] = $size;
+				}
+			}
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+
+		return $sizes;
+	}
+
+	/**
+	 * This function should not be called outside JobQueueRedis
+	 *
+	 * @param string $uid
+	 * @param RedisConnRef $conn
+	 * @return Job|bool Returns false if the job does not exist
+	 * @throws MWException|JobQueueError
+	 */
+	public function getJobFromUidInternal( $uid, RedisConnRef $conn ) {
+		try {
+			$data = $conn->hGet( $this->getQueueKey( 'h-data' ), $uid );
+			if ( $data === false ) {
+				return false; // not found
+			}
+			$item = $this->unserialize( $conn->hGet( $this->getQueueKey( 'h-data' ), $uid ) );
+			if ( !is_array( $item ) ) { // this shouldn't happen
+				throw new MWException( "Could not find job with ID '$uid'." );
+			}
+			$title = Title::makeTitle( $item['namespace'], $item['title'] );
+			$job = Job::factory( $item['type'], $title, $item['params'] );
+			$job->metadata['uuid'] = $item['uuid'];
+
+			return $job;
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+	}
+
+	/**
+	 * Recycle or destroy any jobs that have been claimed for too long
+	 * and release any ready delayed jobs into the queue
+	 *
+	 * @return int Number of jobs recycled/deleted/undelayed
+	 * @throws MWException|JobQueueError
+	 */
+	public function recyclePruneAndUndelayJobs() {
+		$count = 0;
+		// For each job item that can be retried, we need to add it back to the
+		// main queue and remove it from the list of currenty claimed job items.
+		// For those that cannot, they are marked as dead and kept around for
+		// investigation and manual job restoration but are eventually deleted.
+		$conn = $this->getConnection();
+		try {
+			$now = time();
+			static $script =
+<<<LUA
+			local kClaimed, kAttempts, kUnclaimed, kData, kAbandoned, kDelayed = unpack(KEYS)
+			local released,abandoned,pruned,undelayed = 0,0,0,0
+			-- Get all non-dead jobs that have an expired claim on them.
+			-- The score for each item is the last claim timestamp (UNIX).
+			local staleClaims = redis.call('zRangeByScore',kClaimed,0,ARGV[1])
+			for k,id in ipairs(staleClaims) do
+				local timestamp = redis.call('zScore',kClaimed,id)
+				local attempts = redis.call('hGet',kAttempts,id)
+				if attempts < ARGV[3] then
+					-- Claim expired and retries left: re-enqueue the job
+					redis.call('lPush',kUnclaimed,id)
+					redis.call('hIncrBy',kAttempts,id,1)
+					released = released + 1
+				else
+					-- Claim expired and no retries left: mark the job as dead
+					redis.call('zAdd',kAbandoned,timestamp,id)
+					abandoned = abandoned + 1
+				end
+				redis.call('zRem',kClaimed,id)
+			end
+			-- Get all of the dead jobs that have been marked as dead for too long.
+			-- The score for each item is the last claim timestamp (UNIX).
+			local deadClaims = redis.call('zRangeByScore',kAbandoned,0,ARGV[2])
+			for k,id in ipairs(deadClaims) do
+				-- Stale and out of retries: remove any traces of the job
+				redis.call('zRem',kAbandoned,id)
+				redis.call('hDel',kAttempts,id)
+				redis.call('hDel',kData,id)
+				pruned = pruned + 1
+			end
+			-- Get the list of ready delayed jobs, sorted by readiness (UNIX timestamp)
+			local ids = redis.call('zRangeByScore',kDelayed,0,ARGV[4])
+			-- Migrate the jobs from the "delayed" set to the "unclaimed" list
+			for k,id in ipairs(ids) do
+				redis.call('lPush',kUnclaimed,id)
+				redis.call('zRem',kDelayed,id)
+			end
+			undelayed = #ids
+			return {released,abandoned,pruned,undelayed}
+LUA;
+			$res = $conn->luaEval( $script,
+				array(
+					$this->getQueueKey( 'z-claimed' ), # KEYS[1]
+					$this->getQueueKey( 'h-attempts' ), # KEYS[2]
+					$this->getQueueKey( 'l-unclaimed' ), # KEYS[3]
+					$this->getQueueKey( 'h-data' ), # KEYS[4]
+					$this->getQueueKey( 'z-abandoned' ), # KEYS[5]
+					$this->getQueueKey( 'z-delayed' ), # KEYS[6]
+					$now - $this->claimTTL, # ARGV[1]
+					$now - self::MAX_AGE_PRUNE, # ARGV[2]
+					$this->maxTries, # ARGV[3]
+					$now # ARGV[4]
+				),
+				6 # number of first argument(s) that are keys
+			);
+			if ( $res ) {
+				list( $released, $abandoned, $pruned, $undelayed ) = $res;
+				$count += $released + $pruned + $undelayed;
+				JobQueue::incrStats( 'job-recycle', $this->type, $released, $this->wiki );
+				JobQueue::incrStats( 'job-abandon', $this->type, $abandoned, $this->wiki );
+				JobQueue::incrStats( 'job-undelay', $this->type, $undelayed, $this->wiki );
+			}
+		} catch ( RedisException $e ) {
+			$this->throwRedisException( $conn, $e );
+		}
+
+		return $count;
+	}
+
+	/**
+	 * @return array
+	 */
+	protected function doGetPeriodicTasks() {
+		if ( $this->daemonized ) {
+			return array(); // managed in the runner loop
+		}
+		$periods = array( 3600 ); // standard cleanup (useful on config change)
+		if ( $this->claimTTL > 0 ) {
+			$periods[] = ceil( $this->claimTTL / 2 ); // avoid bad timing
+		}
+		if ( $this->checkDelay ) {
+			$periods[] = 300; // 5 minutes
+		}
+		$period = min( $periods );
+		$period = max( $period, 30 ); // sanity
+
+		return array(
+			'recyclePruneAndUndelayJobs' => array(
+				'callback' => array( $this, 'recyclePruneAndUndelayJobs' ),
+				'period'   => $period,
+			)
+		);
+	}
+
+	/**
+	 * @param IJobSpecification $job
+	 * @return array
+	 */
+	protected function getNewJobFields( IJobSpecification $job ) {
+		return array(
+			// Fields that describe the nature of the job
+			'type' => $job->getType(),
+			'namespace' => $job->getTitle()->getNamespace(),
+			'title' => $job->getTitle()->getDBkey(),
+			'params' => $job->getParams(),
+			// Some jobs cannot run until a "release timestamp"
+			'rtimestamp' => $job->getReleaseTimestamp() ?: 0,
+			// Additional job metadata
+			'uuid' => UIDGenerator::newRawUUIDv4( UIDGenerator::QUICK_RAND ),
+			'sha1' => $job->ignoreDuplicates()
+				? wfBaseConvert( sha1( serialize( $job->getDeduplicationInfo() ) ), 16, 36, 31 )
+				: '',
+			'timestamp' => time() // UNIX timestamp
+		);
+	}
+
+	/**
+	 * @param array $fields
+	 * @return Job|bool
+	 */
+	protected function getJobFromFields( array $fields ) {
+		$title = Title::makeTitleSafe( $fields['namespace'], $fields['title'] );
+		if ( $title ) {
+			$job = Job::factory( $fields['type'], $title, $fields['params'] );
+			$job->metadata['uuid'] = $fields['uuid'];
+
+			return $job;
+		}
+
+		return false;
+	}
+
+	/**
+	 * @param array $fields
+	 * @return string Serialized and possibly compressed version of $fields
+	 */
+	protected function serialize( array $fields ) {
+		$blob = serialize( $fields );
+		if ( $this->compression === 'gzip'
+			&& strlen( $blob ) >= 1024
+			&& function_exists( 'gzdeflate' )
+		) {
+			$object = (object)array( 'blob' => gzdeflate( $blob ), 'enc' => 'gzip' );
+			$blobz = serialize( $object );
+
+			return ( strlen( $blobz ) < strlen( $blob ) ) ? $blobz : $blob;
+		} else {
+			return $blob;
+		}
+	}
+
+	/**
+	 * @param string $blob
+	 * @return array|bool Unserialized version of $blob or false
+	 */
+	protected function unserialize( $blob ) {
+		$fields = unserialize( $blob );
+		if ( is_object( $fields ) ) {
+			if ( $fields->enc === 'gzip' && function_exists( 'gzinflate' ) ) {
+				$fields = unserialize( gzinflate( $fields->blob ) );
+			} else {
+				$fields = false;
+			}
+		}
+
+		return is_array( $fields ) ? $fields : false;
+	}
+
+	/**
+	 * Get a connection to the server that handles all sub-queues for this queue
+	 *
+	 * @return RedisConnRef
+	 * @throws JobQueueConnectionError
+	 */
+	protected function getConnection() {
+		$conn = $this->redisPool->getConnection( $this->server );
+		if ( !$conn ) {
+			throw new JobQueueConnectionError( "Unable to connect to redis server." );
+		}
+
+		return $conn;
+	}
+
+	/**
+	 * @param RedisConnRef $conn
+	 * @param RedisException $e
+	 * @throws JobQueueError
+	 */
+	protected function throwRedisException( RedisConnRef $conn, $e ) {
+		$this->redisPool->handleError( $conn, $e );
+		throw new JobQueueError( "Redis server error: {$e->getMessage()}\n" );
+	}
+
+	/**
+	 * @param string $prop
+	 * @param string|null $type
+	 * @return string
+	 */
+	private function getQueueKey( $prop, $type = null ) {
+		$type = is_string( $type ) ? $type : $this->type;
+		list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
+		if ( strlen( $this->key ) ) { // namespaced queue (for testing)
+			return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $this->key, $prop );
+		} else {
+			return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $prop );
+		}
+	}
+
+	/**
+	 * @param string $key
+	 * @return void
+	 */
+	public function setTestingPrefix( $key ) {
+		$this->key = $key;
+	}
+}
diff --git a/includes/jobqueue/JobRunner.php b/includes/jobqueue/JobRunner.php
new file mode 100644
index 00000000..8cccedaf
--- /dev/null
+++ b/includes/jobqueue/JobRunner.php
@@ -0,0 +1,350 @@
+<?php
+/**
+ * Job queue runner utility methods
+ *
+ * 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 JobQueue
+ */
+
+/**
+ * Job queue runner utility methods
+ *
+ * @ingroup JobQueue
+ * @since 1.24
+ */
+class JobRunner {
+	/** @var callable|null Debug output handler */
+	protected $debug;
+
+	/**
+	 * @param callable $debug Optional debug output handler
+	 */
+	public function setDebugHandler( $debug ) {
+		$this->debug = $debug;
+	}
+
+	/**
+	 * Run jobs of the specified number/type for the specified time
+	 *
+	 * The response map has a 'job' field that lists status of each job, including:
+	 *   - type   : the job type
+	 *   - status : ok/failed
+	 *   - error  : any error message string
+	 *   - time   : the job run time in ms
+	 * The response map also has:
+	 *   - backoffs : the (job type => seconds) map of backoff times
+	 *   - elapsed  : the total time spent running tasks in ms
+	 *   - reached  : the reason the script finished, one of (none-ready, job-limit, time-limit)
+	 *
+	 * This method outputs status information only if a debug handler was set.
+	 * Any exceptions are caught and logged, but are not reported as output.
+	 *
+	 * @param array $options Map of parameters:
+	 *    - type     : the job type (or false for the default types)
+	 *    - maxJobs  : maximum number of jobs to run
+	 *    - maxTime  : maximum time in seconds before stopping
+	 *    - throttle : whether to respect job backoff configuration
+	 * @return array Summary response that can easily be JSON serialized
+	 */
+	public function run( array $options ) {
+		$response = array( 'jobs' => array(), 'reached' => 'none-ready' );
+
+		$type = isset( $options['type'] ) ? $options['type'] : false;
+		$maxJobs = isset( $options['maxJobs'] ) ? $options['maxJobs'] : false;
+		$maxTime = isset( $options['maxTime'] ) ? $options['maxTime'] : false;
+		$noThrottle = isset( $options['throttle'] ) && !$options['throttle'];
+
+		$group = JobQueueGroup::singleton();
+		// Handle any required periodic queue maintenance
+		$count = $group->executeReadyPeriodicTasks();
+		if ( $count > 0 ) {
+			$this->runJobsLog( "Executed $count periodic queue task(s)." );
+		}
+
+		// Flush any pending DB writes for sanity
+		wfGetLBFactory()->commitMasterChanges();
+
+		// Some jobs types should not run until a certain timestamp
+		$backoffs = array(); // map of (type => UNIX expiry)
+		$backoffDeltas = array(); // map of (type => seconds)
+		$wait = 'wait'; // block to read backoffs the first time
+
+		$jobsRun = 0;
+		$timeMsTotal = 0;
+		$flags = JobQueueGroup::USE_CACHE;
+		$startTime = microtime( true ); // time since jobs started running
+		$lastTime = microtime( true ); // time since last slave check
+		do {
+			// Sync the persistent backoffs with concurrent runners
+			$backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
+			$blacklist = $noThrottle ? array() : array_keys( $backoffs );
+			$wait = 'nowait'; // less important now
+
+			if ( $type === false ) {
+				$job = $group->pop( JobQueueGroup::TYPE_DEFAULT, $flags, $blacklist );
+			} elseif ( in_array( $type, $blacklist ) ) {
+				$job = false; // requested queue in backoff state
+			} else {
+				$job = $group->pop( $type ); // job from a single queue
+			}
+
+			if ( $job ) { // found a job
+				$jType = $job->getType();
+
+				// Back off of certain jobs for a while (for throttling and for errors)
+				$ttw = $this->getBackoffTimeToWait( $job );
+				if ( $ttw > 0 ) {
+					// Always add the delta for other runners in case the time running the
+					// job negated the backoff for each individually but not collectively.
+					$backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
+						? $backoffDeltas[$jType] + $ttw
+						: $ttw;
+					$backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
+				}
+
+				$this->runJobsLog( $job->toString() . " STARTING" );
+
+				// Run the job...
+				wfProfileIn( __METHOD__ . '-' . get_class( $job ) );
+				$jobStartTime = microtime( true );
+				try {
+					++$jobsRun;
+					$status = $job->run();
+					$error = $job->getLastError();
+					wfGetLBFactory()->commitMasterChanges();
+				} catch ( MWException $e ) {
+					MWExceptionHandler::rollbackMasterChangesAndLog( $e );
+					$status = false;
+					$error = get_class( $e ) . ': ' . $e->getMessage();
+					MWExceptionHandler::logException( $e );
+				}
+				$timeMs = intval( ( microtime( true ) - $jobStartTime ) * 1000 );
+				wfProfileOut( __METHOD__ . '-' . get_class( $job ) );
+				$timeMsTotal += $timeMs;
+
+				// Mark the job as done on success or when the job cannot be retried
+				if ( $status !== false || !$job->allowRetries() ) {
+					$group->ack( $job ); // done
+				}
+
+				// Back off of certain jobs for a while (for throttling and for errors)
+				if ( $status === false && mt_rand( 0, 49 ) == 0 ) {
+					$ttw = max( $ttw, 30 ); // too many errors
+					$backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
+						? $backoffDeltas[$jType] + $ttw
+						: $ttw;
+				}
+
+				if ( $status === false ) {
+					$this->runJobsLog( $job->toString() . " t=$timeMs error={$error}" );
+				} else {
+					$this->runJobsLog( $job->toString() . " t=$timeMs good" );
+				}
+
+				$response['jobs'][] = array(
+					'type'   => $jType,
+					'status' => ( $status === false ) ? 'failed' : 'ok',
+					'error'  => $error,
+					'time'   => $timeMs
+				);
+
+				// Break out if we hit the job count or wall time limits...
+				if ( $maxJobs && $jobsRun >= $maxJobs ) {
+					$response['reached'] = 'job-limit';
+					break;
+				} elseif ( $maxTime && ( microtime( true ) - $startTime ) > $maxTime ) {
+					$response['reached'] = 'time-limit';
+					break;
+				}
+
+				// Don't let any of the main DB slaves get backed up
+				$timePassed = microtime( true ) - $lastTime;
+				if ( $timePassed >= 5 || $timePassed < 0 ) {
+					wfWaitForSlaves( $lastTime );
+					$lastTime = microtime( true );
+				}
+				// Don't let any queue slaves/backups fall behind
+				if ( $jobsRun > 0 && ( $jobsRun % 100 ) == 0 ) {
+					$group->waitForBackups();
+				}
+
+				// Bail if near-OOM instead of in a job
+				$this->assertMemoryOK();
+			}
+		} while ( $job ); // stop when there are no jobs
+
+		// Sync the persistent backoffs for the next runJobs.php pass
+		if ( $backoffDeltas ) {
+			$this->syncBackoffDeltas( $backoffs, $backoffDeltas, 'wait' );
+		}
+
+		$response['backoffs'] = $backoffs;
+		$response['elapsed'] = $timeMsTotal;
+
+		return $response;
+	}
+
+	/**
+	 * @param Job $job
+	 * @return int Seconds for this runner to avoid doing more jobs of this type
+	 * @see $wgJobBackoffThrottling
+	 */
+	private function getBackoffTimeToWait( Job $job ) {
+		global $wgJobBackoffThrottling;
+
+		if ( !isset( $wgJobBackoffThrottling[$job->getType()] ) ||
+			$job instanceof DuplicateJob // no work was done
+		) {
+			return 0; // not throttled
+		}
+
+		$itemsPerSecond = $wgJobBackoffThrottling[$job->getType()];
+		if ( $itemsPerSecond <= 0 ) {
+			return 0; // not throttled
+		}
+
+		$seconds = 0;
+		if ( $job->workItemCount() > 0 ) {
+			$exactSeconds = $job->workItemCount() / $itemsPerSecond;
+			// use randomized rounding
+			$seconds = floor( $exactSeconds );
+			$remainder = $exactSeconds - $seconds;
+			$seconds += ( mt_rand() / mt_getrandmax() < $remainder ) ? 1 : 0;
+		}
+
+		return (int)$seconds;
+	}
+
+	/**
+	 * Get the previous backoff expiries from persistent storage
+	 * On I/O or lock acquisition failure this returns the original $backoffs.
+	 *
+	 * @param array $backoffs Map of (job type => UNIX timestamp)
+	 * @param string $mode Lock wait mode - "wait" or "nowait"
+	 * @return array Map of (job type => backoff expiry timestamp)
+	 */
+	private function loadBackoffs( array $backoffs, $mode = 'wait' ) {
+		$section = new ProfileSection( __METHOD__ );
+
+		$file = wfTempDir() . '/mw-runJobs-backoffs.json';
+		if ( is_file( $file ) ) {
+			$noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
+			$handle = fopen( $file, 'rb' );
+			if ( !flock( $handle, LOCK_SH | $noblock ) ) {
+				fclose( $handle );
+				return $backoffs; // don't wait on lock
+			}
+			$content = stream_get_contents( $handle );
+			flock( $handle, LOCK_UN );
+			fclose( $handle );
+			$ctime = microtime( true );
+			$cBackoffs = json_decode( $content, true ) ?: array();
+			foreach ( $cBackoffs as $type => $timestamp ) {
+				if ( $timestamp < $ctime ) {
+					unset( $cBackoffs[$type] );
+				}
+			}
+		} else {
+			$cBackoffs = array();
+		}
+
+		return $cBackoffs;
+	}
+
+	/**
+	 * Merge the current backoff expiries from persistent storage
+	 *
+	 * The $deltas map is set to an empty array on success.
+	 * On I/O or lock acquisition failure this returns the original $backoffs.
+	 *
+	 * @param array $backoffs Map of (job type => UNIX timestamp)
+	 * @param array $deltas Map of (job type => seconds)
+	 * @param string $mode Lock wait mode - "wait" or "nowait"
+	 * @return array The new backoffs account for $backoffs and the latest file data
+	 */
+	private function syncBackoffDeltas( array $backoffs, array &$deltas, $mode = 'wait' ) {
+		$section = new ProfileSection( __METHOD__ );
+
+		if ( !$deltas ) {
+			return $this->loadBackoffs( $backoffs, $mode );
+		}
+
+		$noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
+		$file = wfTempDir() . '/mw-runJobs-backoffs.json';
+		$handle = fopen( $file, 'wb+' );
+		if ( !flock( $handle, LOCK_EX | $noblock ) ) {
+			fclose( $handle );
+			return $backoffs; // don't wait on lock
+		}
+		$ctime = microtime( true );
+		$content = stream_get_contents( $handle );
+		$cBackoffs = json_decode( $content, true ) ?: array();
+		foreach ( $deltas as $type => $seconds ) {
+			$cBackoffs[$type] = isset( $cBackoffs[$type] ) && $cBackoffs[$type] >= $ctime
+				? $cBackoffs[$type] + $seconds
+				: $ctime + $seconds;
+		}
+		foreach ( $cBackoffs as $type => $timestamp ) {
+			if ( $timestamp < $ctime ) {
+				unset( $cBackoffs[$type] );
+			}
+		}
+		ftruncate( $handle, 0 );
+		fwrite( $handle, json_encode( $cBackoffs ) );
+		flock( $handle, LOCK_UN );
+		fclose( $handle );
+
+		$deltas = array();
+
+		return $cBackoffs;
+	}
+
+	/**
+	 * Make sure that this script is not too close to the memory usage limit.
+	 * It is better to die in between jobs than OOM right in the middle of one.
+	 * @throws MWException
+	 */
+	private function assertMemoryOK() {
+		static $maxBytes = null;
+		if ( $maxBytes === null ) {
+			$m = array();
+			if ( preg_match( '!^(\d+)(k|m|g|)$!i', ini_get( 'memory_limit' ), $m ) ) {
+				list( , $num, $unit ) = $m;
+				$conv = array( 'g' => 1073741824, 'm' => 1048576, 'k' => 1024, '' => 1 );
+				$maxBytes = $num * $conv[strtolower( $unit )];
+			} else {
+				$maxBytes = 0;
+			}
+		}
+		$usedBytes = memory_get_usage();
+		if ( $maxBytes && $usedBytes >= 0.95 * $maxBytes ) {
+			throw new MWException( "Detected excessive memory usage ($usedBytes/$maxBytes)." );
+		}
+	}
+
+	/**
+	 * Log the job message
+	 * @param string $msg The message to log
+	 */
+	private function runJobsLog( $msg ) {
+		if ( $this->debug ) {
+			call_user_func_array( $this->debug, array( wfTimestamp( TS_DB ) . " $msg\n" ) );
+		}
+		wfDebugLog( 'runJobs', $msg );
+	}
+}
diff --git a/includes/jobqueue/JobSpecification.php b/includes/jobqueue/JobSpecification.php
new file mode 100644
index 00000000..9fa7747f
--- /dev/null
+++ b/includes/jobqueue/JobSpecification.php
@@ -0,0 +1,189 @@
+<?php
+/**
+ * Job queue task description base code.
+ *
+ * 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 JobQueue
+ */
+
+/**
+ * Job queue task description interface
+ *
+ * @ingroup JobQueue
+ * @since 1.23
+ */
+interface IJobSpecification {
+	/**
+	 * @return string Job type
+	 */
+	public function getType();
+
+	/**
+	 * @return array
+	 */
+	public function getParams();
+
+	/**
+	 * @return int|null UNIX timestamp to delay running this job until, otherwise null
+	 */
+	public function getReleaseTimestamp();
+
+	/**
+	 * @return bool Whether only one of each identical set of jobs should be run
+	 */
+	public function ignoreDuplicates();
+
+	/**
+	 * Subclasses may need to override this to make duplication detection work.
+	 * The resulting map conveys everything that makes the job unique. This is
+	 * only checked if ignoreDuplicates() returns true, meaning that duplicate
+	 * jobs are supposed to be ignored.
+	 *
+	 * @return array Map of key/values
+	 */
+	public function getDeduplicationInfo();
+
+	/**
+	 * @return Title Descriptive title (this can simply be informative)
+	 */
+	public function getTitle();
+}
+
+/**
+ * Job queue task description base code
+ *
+ * Example usage:
+ * <code>
+ * $job = new JobSpecification(
+ *		'null',
+ *		array( 'lives' => 1, 'usleep' => 100, 'pi' => 3.141569 ),
+ *		array( 'removeDuplicates' => 1 ),
+ *		Title::makeTitle( NS_SPECIAL, 'nullity' )
+ * );
+ * JobQueueGroup::singleton()->push( $job )
+ * </code>
+ *
+ * @ingroup JobQueue
+ * @since 1.23
+ */
+class JobSpecification implements IJobSpecification {
+	/** @var string */
+	protected $type;
+
+	/** @var array Array of job parameters or false if none */
+	protected $params;
+
+	/** @var Title */
+	protected $title;
+
+	/** @var bool Expensive jobs may set this to true */
+	protected $ignoreDuplicates;
+
+	/**
+	 * @param string $type
+	 * @param array $params Map of key/values
+	 * @param array $opts Map of key/values
+	 * @param Title $title Optional descriptive title
+	 */
+	public function __construct(
+		$type, array $params, array $opts = array(), Title $title = null
+	) {
+		$this->validateParams( $params );
+
+		$this->type = $type;
+		$this->params = $params;
+		$this->title = $title ?: Title::newMainPage();
+		$this->ignoreDuplicates = !empty( $opts['removeDuplicates'] );
+	}
+
+	/**
+	 * @param array $params
+	 */
+	protected function validateParams( array $params ) {
+		foreach ( $params as $p => $v ) {
+			if ( is_array( $v ) ) {
+				$this->validateParams( $v );
+			} elseif ( !is_scalar( $v ) && $v !== null ) {
+				throw new UnexpectedValueException( "Job parameter $p is not JSON serializable." );
+			}
+		}
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getType() {
+		return $this->type;
+	}
+
+	/**
+	 * @return Title
+	 */
+	public function getTitle() {
+		return $this->title;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getParams() {
+		return $this->params;
+	}
+
+	/**
+	 * @return int|null UNIX timestamp to delay running this job until, otherwise null
+	 */
+	public function getReleaseTimestamp() {
+		return isset( $this->params['jobReleaseTimestamp'] )
+			? wfTimestampOrNull( TS_UNIX, $this->params['jobReleaseTimestamp'] )
+			: null;
+	}
+
+	/**
+	 * @return bool Whether only one of each identical set of jobs should be run
+	 */
+	public function ignoreDuplicates() {
+		return $this->ignoreDuplicates;
+	}
+
+	/**
+	 * Subclasses may need to override this to make duplication detection work.
+	 * The resulting map conveys everything that makes the job unique. This is
+	 * only checked if ignoreDuplicates() returns true, meaning that duplicate
+	 * jobs are supposed to be ignored.
+	 *
+	 * @return array Map of key/values
+	 */
+	public function getDeduplicationInfo() {
+		$info = array(
+			'type' => $this->getType(),
+			'namespace' => $this->getTitle()->getNamespace(),
+			'title' => $this->getTitle()->getDBkey(),
+			'params' => $this->getParams()
+		);
+		if ( is_array( $info['params'] ) ) {
+			// Identical jobs with different "root" jobs should count as duplicates
+			unset( $info['params']['rootJobSignature'] );
+			unset( $info['params']['rootJobTimestamp'] );
+			// Likewise for jobs with different delay times
+			unset( $info['params']['jobReleaseTimestamp'] );
+		}
+
+		return $info;
+	}
+}
diff --git a/includes/jobqueue/README b/includes/jobqueue/README
new file mode 100644
index 00000000..c11d5a78
--- /dev/null
+++ b/includes/jobqueue/README
@@ -0,0 +1,81 @@
+/*!
+\ingroup JobQueue
+\page jobqueue_design Job queue design
+
+Notes on the Job queuing system architecture.
+
+\section intro Introduction
+
+The data model consist of the following main components:
+* The Job object represents a particular deferred task that happens in the
+  background. All jobs subclass the Job object and put the main logic in the
+  function called run().
+* The JobQueue object represents a particular queue of jobs of a certain type.
+  For example there may be a queue for email jobs and a queue for squid purge
+  jobs.
+
+\section jobqueue Job queues
+
+Each job type has its own queue and is associated to a storage medium. One
+queue might save its jobs in redis while another one uses would use a database.
+
+Storage medium are defined in a queue class. Before using it, you must
+define in $wgJobTypeConf a mapping of the job type to a queue class.
+
+The factory class JobQueueGroup provides helper functions:
+- getting the queue for a given job
+- route new job insertions to the proper queue
+
+The following queue classes are available:
+* JobQueueDB (stores jobs in the `job` table in a database)
+* JobQueueRedis (stores jobs in a redis server)
+
+All queue classes support some basic operations (though some may be no-ops):
+* enqueueing a batch of jobs
+* dequeueing a single job
+* acknowledging a job is completed
+* checking if the queue is empty
+
+Some queue classes (like JobQueueDB) may dequeue jobs in random order while other
+queues might dequeue jobs in exact FIFO order. Callers should thus not assume jobs
+are executed in FIFO order.
+
+Also note that not all queue classes will have the same reliability guarantees.
+In-memory queues may lose data when restarted depending on snapshot and journal
+settings (including journal fsync() frequency).  Some queue types may totally remove
+jobs when dequeued while leaving the ack() function as a no-op; if a job is
+dequeued by a job runner, which crashes before completion, the job will be
+lost. Some jobs, like purging squid caches after a template change, may not
+require durable queues, whereas other jobs might be more important.
+
+\section aggregator Job queue aggregator
+
+The aggregators are used by nextJobDB.php, which is a script that will return a
+random ready queue (on any wiki in the farm) that can be used with runJobs.php.
+This can be used in conjunction with any scripts that handle wiki farm job queues.
+Note that $wgLocalDatabases defines what wikis are in the wiki farm.
+
+Since each job type has its own queue, and wiki-farms may have many wikis,
+there might be a large number of queues to keep track of. To avoid wasting
+large amounts of time polling empty queues, aggregators exists to keep track
+of which queues are ready.
+
+The following queue aggregator classes are available:
+* JobQueueAggregatorMemc (uses $wgMemc to track ready queues)
+* JobQueueAggregatorRedis (uses a redis server to track ready queues)
+
+Some aggregators cache data for a few minutes while others may be always up to date.
+This can be an important factor for jobs that need a low pickup time (or latency).
+
+\section jobs Jobs
+
+Callers should also try to make jobs maintain correctness when executed twice.
+This is useful for queues that actually implement ack(), since they may recycle
+dequeued but un-acknowledged jobs back into the queue to be attempted again. If
+a runner dequeues a job, runs it, but then crashes before calling ack(), the
+job may be returned to the queue and run a second time. Jobs like cache purging can
+happen several times without any correctness problems. However, a pathological case
+would be if a bug causes the problem to systematically keep repeating. For example,
+a job may always throw a DB error at the end of run(). This problem is trickier to
+solve and more obnoxious for things like email jobs, for example. For such jobs,
+it might be useful to use a queue that does not retry jobs.
diff --git a/includes/jobqueue/aggregator/JobQueueAggregator.php b/includes/jobqueue/aggregator/JobQueueAggregator.php
new file mode 100644
index 00000000..8600eed9
--- /dev/null
+++ b/includes/jobqueue/aggregator/JobQueueAggregator.php
@@ -0,0 +1,162 @@
+<?php
+/**
+ * Job queue aggregator code.
+ *
+ * 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 tracking information about all queues
+ *
+ * @ingroup JobQueue
+ * @since 1.21
+ */
+abstract class JobQueueAggregator {
+	/** @var JobQueueAggregator */
+	protected static $instance = null;
+
+	/**
+	 * @param array $params
+	 */
+	protected function __construct( array $params ) {
+	}
+
+	/**
+	 * @throws MWException
+	 * @return JobQueueAggregator
+	 */
+	final public static function singleton() {
+		global $wgJobQueueAggregator;
+
+		if ( !isset( self::$instance ) ) {
+			$class = $wgJobQueueAggregator['class'];
+			$obj = new $class( $wgJobQueueAggregator );
+			if ( !( $obj instanceof JobQueueAggregator ) ) {
+				throw new MWException( "Class '$class' is not a JobQueueAggregator class." );
+			}
+			self::$instance = $obj;
+		}
+
+		return self::$instance;
+	}
+
+	/**
+	 * Destroy the singleton instance
+	 *
+	 * @return void
+	 */
+	final public static function destroySingleton() {
+		self::$instance = null;
+	}
+
+	/**
+	 * Mark a queue as being empty
+	 *
+	 * @param string $wiki
+	 * @param string $type
+	 * @return bool Success
+	 */
+	final public function notifyQueueEmpty( $wiki, $type ) {
+		wfProfileIn( __METHOD__ );
+		$ok = $this->doNotifyQueueEmpty( $wiki, $type );
+		wfProfileOut( __METHOD__ );
+
+		return $ok;
+	}
+
+	/**
+	 * @see JobQueueAggregator::notifyQueueEmpty()
+	 */
+	abstract protected function doNotifyQueueEmpty( $wiki, $type );
+
+	/**
+	 * Mark a queue as being non-empty
+	 *
+	 * @param string $wiki
+	 * @param string $type
+	 * @return bool Success
+	 */
+	final public function notifyQueueNonEmpty( $wiki, $type ) {
+		wfProfileIn( __METHOD__ );
+		$ok = $this->doNotifyQueueNonEmpty( $wiki, $type );
+		wfProfileOut( __METHOD__ );
+
+		return $ok;
+	}
+
+	/**
+	 * @see JobQueueAggregator::notifyQueueNonEmpty()
+	 */
+	abstract protected function doNotifyQueueNonEmpty( $wiki, $type );
+
+	/**
+	 * Get the list of all of the queues with jobs
+	 *
+	 * @return array (job type => (list of wiki IDs))
+	 */
+	final public function getAllReadyWikiQueues() {
+		wfProfileIn( __METHOD__ );
+		$res = $this->doGetAllReadyWikiQueues();
+		wfProfileOut( __METHOD__ );
+
+		return $res;
+	}
+
+	/**
+	 * @see JobQueueAggregator::getAllReadyWikiQueues()
+	 */
+	abstract protected function doGetAllReadyWikiQueues();
+
+	/**
+	 * Purge all of the aggregator information
+	 *
+	 * @return bool Success
+	 */
+	final public function purge() {
+		wfProfileIn( __METHOD__ );
+		$res = $this->doPurge();
+		wfProfileOut( __METHOD__ );
+
+		return $res;
+	}
+
+	/**
+	 * @see JobQueueAggregator::purge()
+	 */
+	abstract protected function doPurge();
+
+	/**
+	 * Get all databases that have a pending job.
+	 * This poll all the queues and is this expensive.
+	 *
+	 * @return array (job type => (list of wiki IDs))
+	 */
+	protected function findPendingWikiQueues() {
+		global $wgLocalDatabases;
+
+		$pendingDBs = array(); // (job type => (db list))
+		foreach ( $wgLocalDatabases as $db ) {
+			foreach ( JobQueueGroup::singleton( $db )->getQueuesWithJobs() as $type ) {
+				$pendingDBs[$type][] = $db;
+			}
+		}
+
+		return $pendingDBs;
+	}
+}
diff --git a/includes/jobqueue/aggregator/JobQueueAggregatorMemc.php b/includes/jobqueue/aggregator/JobQueueAggregatorMemc.php
new file mode 100644
index 00000000..ae266ef3
--- /dev/null
+++ b/includes/jobqueue/aggregator/JobQueueAggregatorMemc.php
@@ -0,0 +1,125 @@
+<?php
+/**
+ * Job queue aggregator code that uses BagOStuff.
+ *
+ * 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 tracking information about all queues using BagOStuff
+ *
+ * @ingroup JobQueue
+ * @since 1.21
+ */
+class JobQueueAggregatorMemc extends JobQueueAggregator {
+	/** @var BagOStuff */
+	protected $cache;
+
+	protected $cacheTTL; // integer; seconds
+
+	/**
+	 * @param array $params Possible keys:
+	 *   - objectCache : Name of an object cache registered in $wgObjectCaches.
+	 *                   This defaults to the one specified by $wgMainCacheType.
+	 *   - cacheTTL    : Seconds to cache the aggregate data before regenerating.
+	 */
+	protected function __construct( array $params ) {
+		parent::__construct( $params );
+		$this->cache = isset( $params['objectCache'] )
+			? wfGetCache( $params['objectCache'] )
+			: wfGetMainCache();
+		$this->cacheTTL = isset( $params['cacheTTL'] ) ? $params['cacheTTL'] : 180; // 3 min
+	}
+
+	/**
+	 * @see JobQueueAggregator::doNotifyQueueEmpty()
+	 */
+	protected function doNotifyQueueEmpty( $wiki, $type ) {
+		$key = $this->getReadyQueueCacheKey();
+		// Delist the queue from the "ready queue" list
+		if ( $this->cache->add( "$key:lock", 1, 60 ) ) { // lock
+			$curInfo = $this->cache->get( $key );
+			if ( is_array( $curInfo ) && isset( $curInfo['pendingDBs'][$type] ) ) {
+				if ( in_array( $wiki, $curInfo['pendingDBs'][$type] ) ) {
+					$curInfo['pendingDBs'][$type] = array_diff(
+						$curInfo['pendingDBs'][$type], array( $wiki ) );
+					$this->cache->set( $key, $curInfo );
+				}
+			}
+			$this->cache->delete( "$key:lock" ); // unlock
+		}
+
+		return true;
+	}
+
+	/**
+	 * @see JobQueueAggregator::doNotifyQueueNonEmpty()
+	 */
+	protected function doNotifyQueueNonEmpty( $wiki, $type ) {
+		return true; // updated periodically
+	}
+
+	/**
+	 * @see JobQueueAggregator::doAllGetReadyWikiQueues()
+	 */
+	protected function doGetAllReadyWikiQueues() {
+		$key = $this->getReadyQueueCacheKey();
+		// If the cache entry wasn't present, is stale, or in .1% of cases otherwise,
+		// regenerate the cache. Use any available stale cache if another process is
+		// currently regenerating the pending DB information.
+		$pendingDbInfo = $this->cache->get( $key );
+		if ( !is_array( $pendingDbInfo )
+			|| ( time() - $pendingDbInfo['timestamp'] ) > $this->cacheTTL
+			|| mt_rand( 0, 999 ) == 0
+		) {
+			if ( $this->cache->add( "$key:rebuild", 1, 1800 ) ) { // lock
+				$pendingDbInfo = array(
+					'pendingDBs' => $this->findPendingWikiQueues(),
+					'timestamp' => time()
+				);
+				for ( $attempts = 1; $attempts <= 25; ++$attempts ) {
+					if ( $this->cache->add( "$key:lock", 1, 60 ) ) { // lock
+						$this->cache->set( $key, $pendingDbInfo );
+						$this->cache->delete( "$key:lock" ); // unlock
+						break;
+					}
+				}
+				$this->cache->delete( "$key:rebuild" ); // unlock
+			}
+		}
+
+		return is_array( $pendingDbInfo )
+			? $pendingDbInfo['pendingDBs']
+			: array(); // cache is both empty and locked
+	}
+
+	/**
+	 * @see JobQueueAggregator::doPurge()
+	 */
+	protected function doPurge() {
+		return $this->cache->delete( $this->getReadyQueueCacheKey() );
+	}
+
+	/**
+	 * @return string
+	 */
+	private function getReadyQueueCacheKey() {
+		return "jobqueue:aggregator:ready-queues:v1"; // global
+	}
+}
diff --git a/includes/jobqueue/aggregator/JobQueueAggregatorRedis.php b/includes/jobqueue/aggregator/JobQueueAggregatorRedis.php
new file mode 100644
index 00000000..db9e764c
--- /dev/null
+++ b/includes/jobqueue/aggregator/JobQueueAggregatorRedis.php
@@ -0,0 +1,218 @@
+<?php
+/**
+ * Job queue aggregator code that uses PhpRedis.
+ *
+ * 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 tracking information about all queues using PhpRedis
+ *
+ * @ingroup JobQueue
+ * @ingroup Redis
+ * @since 1.21
+ */
+class JobQueueAggregatorRedis extends JobQueueAggregator {
+	/** @var RedisConnectionPool */
+	protected $redisPool;
+
+	/** @var array List of Redis server addresses */
+	protected $servers;
+
+	/**
+	 * @param array $params Possible keys:
+	 *   - redisConfig  : An array of parameters to RedisConnectionPool::__construct().
+	 *   - redisServers : Array of server entries, the first being the primary and the
+	 *                    others being fallback servers. Each entry is either a hostname/port
+	 *                    combination or the absolute path of a UNIX socket.
+	 *                    If a hostname is specified but no port, the standard port number
+	 *                    6379 will be used. Required.
+	 */
+	protected function __construct( array $params ) {
+		parent::__construct( $params );
+		$this->servers = isset( $params['redisServers'] )
+			? $params['redisServers']
+			: array( $params['redisServer'] ); // b/c
+		$params['redisConfig']['serializer'] = 'none';
+		$this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
+	}
+
+	protected function doNotifyQueueEmpty( $wiki, $type ) {
+		$conn = $this->getConnection();
+		if ( !$conn ) {
+			return false;
+		}
+		try {
+			$conn->hDel( $this->getReadyQueueKey(), $this->encQueueName( $type, $wiki ) );
+
+			return true;
+		} catch ( RedisException $e ) {
+			$this->handleException( $conn, $e );
+
+			return false;
+		}
+	}
+
+	protected function doNotifyQueueNonEmpty( $wiki, $type ) {
+		$conn = $this->getConnection();
+		if ( !$conn ) {
+			return false;
+		}
+		try {
+			$conn->multi( Redis::PIPELINE );
+			$conn->hSetNx( $this->getQueueTypesKey(), $type, 'enabled' );
+			$conn->hSet( $this->getReadyQueueKey(), $this->encQueueName( $type, $wiki ), time() );
+			$conn->exec();
+
+			return true;
+		} catch ( RedisException $e ) {
+			$this->handleException( $conn, $e );
+
+			return false;
+		}
+	}
+
+	protected function doGetAllReadyWikiQueues() {
+		$conn = $this->getConnection();
+		if ( !$conn ) {
+			return array();
+		}
+		try {
+			$map = $conn->hGetAll( $this->getReadyQueueKey() );
+
+			if ( is_array( $map ) && isset( $map['_epoch'] ) ) {
+				unset( $map['_epoch'] ); // ignore
+				$pendingDBs = array(); // (type => list of wikis)
+				foreach ( $map as $key => $time ) {
+					list( $type, $wiki ) = $this->dencQueueName( $key );
+					$pendingDBs[$type][] = $wiki;
+				}
+			} else {
+				// Avoid duplicated effort
+				$rand = wfRandomString( 32 );
+				$conn->multi( Redis::MULTI );
+				$conn->setex( "{$rand}:lock", 3600, 1 );
+				$conn->renamenx( "{$rand}:lock", $this->getReadyQueueKey() . ":lock" );
+				if ( $conn->exec() !== array( true, true ) ) { // lock
+					$conn->delete( "{$rand}:lock" );
+					return array(); // already in progress
+				}
+
+				$pendingDBs = $this->findPendingWikiQueues(); // (type => list of wikis)
+
+				$conn->multi( Redis::PIPELINE );
+				$now = time();
+				$map = array( '_epoch' => time() ); // dummy key for empty Redis collections
+				foreach ( $pendingDBs as $type => $wikis ) {
+					$conn->hSetNx( $this->getQueueTypesKey(), $type, 'enabled' );
+					foreach ( $wikis as $wiki ) {
+						$map[$this->encQueueName( $type, $wiki )] = $now;
+					}
+				}
+				$conn->hMSet( $this->getReadyQueueKey(), $map );
+				$conn->exec();
+
+				$conn->delete( $this->getReadyQueueKey() . ":lock" ); // unlock
+			}
+
+			return $pendingDBs;
+		} catch ( RedisException $e ) {
+			$this->handleException( $conn, $e );
+
+			return array();
+		}
+	}
+
+	protected function doPurge() {
+		$conn = $this->getConnection();
+		if ( !$conn ) {
+			return false;
+		}
+		try {
+			$conn->delete( $this->getReadyQueueKey() );
+			// leave key at getQueueTypesKey() alone
+		} catch ( RedisException $e ) {
+			$this->handleException( $conn, $e );
+
+			return false;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Get a connection to the server that handles all sub-queues for this queue
+	 *
+	 * @return RedisConnRef|bool Returns false on failure
+	 * @throws MWException
+	 */
+	protected function getConnection() {
+		$conn = false;
+		foreach ( $this->servers as $server ) {
+			$conn = $this->redisPool->getConnection( $server );
+			if ( $conn ) {
+				break;
+			}
+		}
+
+		return $conn;
+	}
+
+	/**
+	 * @param RedisConnRef $conn
+	 * @param RedisException $e
+	 * @return void
+	 */
+	protected function handleException( RedisConnRef $conn, $e ) {
+		$this->redisPool->handleError( $conn, $e );
+	}
+
+	/**
+	 * @return string
+	 */
+	private function getReadyQueueKey() {
+		return "jobqueue:aggregator:h-ready-queues:v2"; // global
+	}
+
+	/**
+	 * @return string
+	 */
+	private function getQueueTypesKey() {
+		return "jobqueue:aggregator:h-queue-types:v2"; // global
+	}
+
+	/**
+	 * @param string $type
+	 * @param string $wiki
+	 * @return string
+	 */
+	private function encQueueName( $type, $wiki ) {
+		return rawurlencode( $type ) . '/' . rawurlencode( $wiki );
+	}
+
+	/**
+	 * @param string $name
+	 * @return string
+	 */
+	private function dencQueueName( $name ) {
+		list( $type, $wiki ) = explode( '/', $name, 2 );
+
+		return array( rawurldecode( $type ), rawurldecode( $wiki ) );
+	}
+}
diff --git a/includes/jobqueue/jobs/AssembleUploadChunksJob.php b/includes/jobqueue/jobs/AssembleUploadChunksJob.php
new file mode 100644
index 00000000..9e9bda6f
--- /dev/null
+++ b/includes/jobqueue/jobs/AssembleUploadChunksJob.php
@@ -0,0 +1,136 @@
+<?php
+/**
+ * Assemble the segments of a chunked upload.
+ *
+ * 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 Upload
+ */
+
+/**
+ * Assemble the segments of a chunked upload.
+ *
+ * @ingroup Upload
+ */
+class AssembleUploadChunksJob extends Job {
+	public function __construct( $title, $params ) {
+		parent::__construct( 'AssembleUploadChunks', $title, $params );
+		$this->removeDuplicates = true;
+	}
+
+	public function run() {
+		$scope = RequestContext::importScopedSession( $this->params['session'] );
+		$context = RequestContext::getMain();
+		try {
+			$user = $context->getUser();
+			if ( !$user->isLoggedIn() ) {
+				$this->setLastError( "Could not load the author user from session." );
+
+				return false;
+			}
+
+			if ( count( $_SESSION ) === 0 ) {
+				// Empty session probably indicates that we didn't associate
+				// with the session correctly. Note that being able to load
+				// the user does not necessarily mean the session was loaded.
+				// Most likely cause by suhosin.session.encrypt = On.
+				$this->setLastError( "Error associating with user session. " .
+					"Try setting suhosin.session.encrypt = Off" );
+
+				return false;
+			}
+
+			UploadBase::setSessionStatus(
+				$this->params['filekey'],
+				array( 'result' => 'Poll', 'stage' => 'assembling', 'status' => Status::newGood() )
+			);
+
+			$upload = new UploadFromChunks( $user );
+			$upload->continueChunks(
+				$this->params['filename'],
+				$this->params['filekey'],
+				$context->getRequest()
+			);
+
+			// Combine all of the chunks into a local file and upload that to a new stash file
+			$status = $upload->concatenateChunks();
+			if ( !$status->isGood() ) {
+				UploadBase::setSessionStatus(
+					$this->params['filekey'],
+					array( 'result' => 'Failure', 'stage' => 'assembling', 'status' => $status )
+				);
+				$this->setLastError( $status->getWikiText() );
+
+				return false;
+			}
+
+			// We have a new filekey for the fully concatenated file
+			$newFileKey = $upload->getLocalFile()->getFileKey();
+
+			// Remove the old stash file row and first chunk file
+			$upload->stash->removeFileNoAuth( $this->params['filekey'] );
+
+			// Build the image info array while we have the local reference handy
+			$apiMain = new ApiMain(); // dummy object (XXX)
+			$imageInfo = $upload->getImageInfo( $apiMain->getResult() );
+
+			// Cleanup any temporary local file
+			$upload->cleanupTempFile();
+
+			// Cache the info so the user doesn't have to wait forever to get the final info
+			UploadBase::setSessionStatus(
+				$this->params['filekey'],
+				array(
+					'result' => 'Success',
+					'stage' => 'assembling',
+					'filekey' => $newFileKey,
+					'imageinfo' => $imageInfo,
+					'status' => Status::newGood()
+				)
+			);
+		} catch ( MWException $e ) {
+			UploadBase::setSessionStatus(
+				$this->params['filekey'],
+				array(
+					'result' => 'Failure',
+					'stage' => 'assembling',
+					'status' => Status::newFatal( 'api-error-stashfailed' )
+				)
+			);
+			$this->setLastError( get_class( $e ) . ": " . $e->getText() );
+			// To be extra robust.
+			MWExceptionHandler::rollbackMasterChangesAndLog( $e );
+
+			return false;
+		}
+
+		return true;
+	}
+
+	public function getDeduplicationInfo() {
+		$info = parent::getDeduplicationInfo();
+		if ( is_array( $info['params'] ) ) {
+			$info['params'] = array( 'filekey' => $info['params']['filekey'] );
+		}
+
+		return $info;
+	}
+
+	public function allowRetries() {
+		return false;
+	}
+}
diff --git a/includes/jobqueue/jobs/DoubleRedirectJob.php b/includes/jobqueue/jobs/DoubleRedirectJob.php
new file mode 100644
index 00000000..2561f2f1
--- /dev/null
+++ b/includes/jobqueue/jobs/DoubleRedirectJob.php
@@ -0,0 +1,250 @@
+<?php
+/**
+ * Job to fix double redirects after moving a page.
+ *
+ * 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 JobQueue
+ */
+
+/**
+ * Job to fix double redirects after moving a page
+ *
+ * @ingroup JobQueue
+ */
+class DoubleRedirectJob extends Job {
+	/** @var string Reason for the change, 'maintenance' or 'move'. Suffix fo
+	 *    message key 'double-redirect-fixed-'.
+	 */
+	private $reason;
+
+	/** @var Title The title which has changed, redirects pointing to this
+	 *    title are fixed
+	 */
+	private $redirTitle;
+
+	/** @var User */
+	private static $user;
+
+	/**
+	 * Insert jobs into the job queue to fix redirects to the given title
+	 * @param string $reason The reason for the fix, see message
+	 *   "double-redirect-fixed-<reason>"
+	 * @param Title $redirTitle The title which has changed, redirects
+	 *   pointing to this title are fixed
+	 * @param bool $destTitle Not used
+	 */
+	public static function fixRedirects( $reason, $redirTitle, $destTitle = false ) {
+		# Need to use the master to get the redirect table updated in the same transaction
+		$dbw = wfGetDB( DB_MASTER );
+		$res = $dbw->select(
+			array( 'redirect', 'page' ),
+			array( 'page_namespace', 'page_title' ),
+			array(
+				'page_id = rd_from',
+				'rd_namespace' => $redirTitle->getNamespace(),
+				'rd_title' => $redirTitle->getDBkey()
+			), __METHOD__ );
+		if ( !$res->numRows() ) {
+			return;
+		}
+		$jobs = array();
+		foreach ( $res as $row ) {
+			$title = Title::makeTitle( $row->page_namespace, $row->page_title );
+			if ( !$title ) {
+				continue;
+			}
+
+			$jobs[] = new self( $title, array(
+				'reason' => $reason,
+				'redirTitle' => $redirTitle->getPrefixedDBkey() ) );
+			# Avoid excessive memory usage
+			if ( count( $jobs ) > 10000 ) {
+				JobQueueGroup::singleton()->push( $jobs );
+				$jobs = array();
+			}
+		}
+		JobQueueGroup::singleton()->push( $jobs );
+	}
+
+	/**
+	 * @param Title $title
+	 * @param array|bool $params
+	 */
+	function __construct( $title, $params = false ) {
+		parent::__construct( 'fixDoubleRedirect', $title, $params );
+		$this->reason = $params['reason'];
+		$this->redirTitle = Title::newFromText( $params['redirTitle'] );
+	}
+
+	/**
+	 * @return bool
+	 */
+	function run() {
+		if ( !$this->redirTitle ) {
+			$this->setLastError( 'Invalid title' );
+
+			return false;
+		}
+
+		$targetRev = Revision::newFromTitle( $this->title, false, Revision::READ_LATEST );
+		if ( !$targetRev ) {
+			wfDebug( __METHOD__ . ": target redirect already deleted, ignoring\n" );
+
+			return true;
+		}
+		$content = $targetRev->getContent();
+		$currentDest = $content ? $content->getRedirectTarget() : null;
+		if ( !$currentDest || !$currentDest->equals( $this->redirTitle ) ) {
+			wfDebug( __METHOD__ . ": Redirect has changed since the job was queued\n" );
+
+			return true;
+		}
+
+		// Check for a suppression tag (used e.g. in periodically archived discussions)
+		$mw = MagicWord::get( 'staticredirect' );
+		if ( $content->matchMagicWord( $mw ) ) {
+			wfDebug( __METHOD__ . ": skipping: suppressed with __STATICREDIRECT__\n" );
+
+			return true;
+		}
+
+		// Find the current final destination
+		$newTitle = self::getFinalDestination( $this->redirTitle );
+		if ( !$newTitle ) {
+			wfDebug( __METHOD__ .
+				": skipping: single redirect, circular redirect or invalid redirect destination\n" );
+
+			return true;
+		}
+		if ( $newTitle->equals( $this->redirTitle ) ) {
+			// The redirect is already right, no need to change it
+			// This can happen if the page was moved back (say after vandalism)
+			wfDebug( __METHOD__ . " : skipping, already good\n" );
+		}
+
+		// Preserve fragment (bug 14904)
+		$newTitle = Title::makeTitle( $newTitle->getNamespace(), $newTitle->getDBkey(),
+			$currentDest->getFragment(), $newTitle->getInterwiki() );
+
+		// Fix the text
+		$newContent = $content->updateRedirect( $newTitle );
+
+		if ( $newContent->equals( $content ) ) {
+			$this->setLastError( 'Content unchanged???' );
+
+			return false;
+		}
+
+		$user = $this->getUser();
+		if ( !$user ) {
+			$this->setLastError( 'Invalid user' );
+
+			return false;
+		}
+
+		// Save it
+		global $wgUser;
+		$oldUser = $wgUser;
+		$wgUser = $user;
+		$article = WikiPage::factory( $this->title );
+
+		// Messages: double-redirect-fixed-move, double-redirect-fixed-maintenance
+		$reason = wfMessage( 'double-redirect-fixed-' . $this->reason,
+			$this->redirTitle->getPrefixedText(), $newTitle->getPrefixedText()
+		)->inContentLanguage()->text();
+		$article->doEditContent( $newContent, $reason, EDIT_UPDATE | EDIT_SUPPRESS_RC, false, $user );
+		$wgUser = $oldUser;
+
+		return true;
+	}
+
+	/**
+	 * Get the final destination of a redirect
+	 *
+	 * @param Title $title
+	 *
+	 * @return bool If the specified title is not a redirect, or if it is a circular redirect
+	 */
+	public static function getFinalDestination( $title ) {
+		$dbw = wfGetDB( DB_MASTER );
+
+		// Circular redirect check
+		$seenTitles = array();
+		$dest = false;
+
+		while ( true ) {
+			$titleText = $title->getPrefixedDBkey();
+			if ( isset( $seenTitles[$titleText] ) ) {
+				wfDebug( __METHOD__, "Circular redirect detected, aborting\n" );
+
+				return false;
+			}
+			$seenTitles[$titleText] = true;
+
+			if ( $title->isExternal() ) {
+				// If the target is interwiki, we have to break early (bug 40352).
+				// Otherwise it will look up a row in the local page table
+				// with the namespace/page of the interwiki target which can cause
+				// unexpected results (e.g. X -> foo:Bar -> Bar -> .. )
+				break;
+			}
+
+			$row = $dbw->selectRow(
+				array( 'redirect', 'page' ),
+				array( 'rd_namespace', 'rd_title', 'rd_interwiki' ),
+				array(
+					'rd_from=page_id',
+					'page_namespace' => $title->getNamespace(),
+					'page_title' => $title->getDBkey()
+				), __METHOD__ );
+			if ( !$row ) {
+				# No redirect from here, chain terminates
+				break;
+			} else {
+				$dest = $title = Title::makeTitle(
+					$row->rd_namespace,
+					$row->rd_title,
+					'',
+					$row->rd_interwiki
+				);
+			}
+		}
+
+		return $dest;
+	}
+
+	/**
+	 * Get a user object for doing edits, from a request-lifetime cache
+	 * False will be returned if the user name specified in the
+	 * 'double-redirect-fixer' message is invalid.
+	 *
+	 * @return User|bool
+	 */
+	function getUser() {
+		if ( !self::$user ) {
+			$username = wfMessage( 'double-redirect-fixer' )->inContentLanguage()->text();
+			self::$user = User::newFromName( $username );
+			# User::newFromName() can return false on a badly configured wiki.
+			if ( self::$user && !self::$user->isLoggedIn() ) {
+				self::$user->addToDatabase();
+			}
+		}
+
+		return self::$user;
+	}
+}
diff --git a/includes/jobqueue/jobs/DuplicateJob.php b/includes/jobqueue/jobs/DuplicateJob.php
new file mode 100644
index 00000000..1fa6cefe
--- /dev/null
+++ b/includes/jobqueue/jobs/DuplicateJob.php
@@ -0,0 +1,59 @@
+<?php
+/**
+ * No-op job that does nothing.
+ *
+ * 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 Cache
+ */
+
+/**
+ * No-op job that does nothing. Used to represent duplicates.
+ *
+ * @ingroup JobQueue
+ */
+final class DuplicateJob extends Job {
+	/**
+	 * Callers should use DuplicateJob::newFromJob() instead
+	 *
+	 * @param Title $title
+	 * @param array $params Job parameters
+	 */
+	function __construct( $title, $params ) {
+		parent::__construct( 'duplicate', $title, $params );
+	}
+
+	/**
+	 * Get a duplicate no-op version of a job
+	 *
+	 * @param Job $job
+	 * @return Job
+	 */
+	public static function newFromJob( Job $job ) {
+		$djob = new self( $job->getTitle(), $job->getParams() );
+		$djob->command = $job->getType();
+		$djob->params = is_array( $djob->params ) ? $djob->params : array();
+		$djob->params = array( 'isDuplicate' => true ) + $djob->params;
+		$djob->metadata = $job->metadata;
+
+		return $djob;
+	}
+
+	public function run() {
+		return true;
+	}
+}
diff --git a/includes/jobqueue/jobs/EmaillingJob.php b/includes/jobqueue/jobs/EmaillingJob.php
new file mode 100644
index 00000000..df8ae63e
--- /dev/null
+++ b/includes/jobqueue/jobs/EmaillingJob.php
@@ -0,0 +1,46 @@
+<?php
+/**
+ * Old job for notification emails.
+ *
+ * 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 JobQueue
+ */
+
+/**
+ * Old job used for sending single notification emails;
+ * kept for backwards-compatibility
+ *
+ * @ingroup JobQueue
+ */
+class EmaillingJob extends Job {
+	function __construct( $title, $params ) {
+		parent::__construct( 'sendMail', Title::newMainPage(), $params );
+	}
+
+	function run() {
+		$status = UserMailer::send(
+			$this->params['to'],
+			$this->params['from'],
+			$this->params['subj'],
+			$this->params['body'],
+			$this->params['replyto']
+		);
+
+		return $status->isOK();
+	}
+}
diff --git a/includes/jobqueue/jobs/EnotifNotifyJob.php b/includes/jobqueue/jobs/EnotifNotifyJob.php
new file mode 100644
index 00000000..1ed99a58
--- /dev/null
+++ b/includes/jobqueue/jobs/EnotifNotifyJob.php
@@ -0,0 +1,57 @@
+<?php
+/**
+ * Job for notification emails.
+ *
+ * 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 JobQueue
+ */
+
+/**
+ * Job for email notification mails
+ *
+ * @ingroup JobQueue
+ */
+class EnotifNotifyJob extends Job {
+	function __construct( $title, $params ) {
+		parent::__construct( 'enotifNotify', $title, $params );
+	}
+
+	function run() {
+		$enotif = new EmailNotification();
+		// Get the user from ID (rename safe). Anons are 0, so defer to name.
+		if ( isset( $this->params['editorID'] ) && $this->params['editorID'] ) {
+			$editor = User::newFromId( $this->params['editorID'] );
+		// B/C, only the name might be given.
+		} else {
+			# @todo FIXME: newFromName could return false on a badly configured wiki.
+			$editor = User::newFromName( $this->params['editor'], false );
+		}
+		$enotif->actuallyNotifyOnPageChange(
+			$editor,
+			$this->title,
+			$this->params['timestamp'],
+			$this->params['summary'],
+			$this->params['minorEdit'],
+			$this->params['oldid'],
+			$this->params['watchers'],
+			$this->params['pageStatus']
+		);
+
+		return true;
+	}
+}
diff --git a/includes/jobqueue/jobs/HTMLCacheUpdateJob.php b/includes/jobqueue/jobs/HTMLCacheUpdateJob.php
new file mode 100644
index 00000000..4d1e72c9
--- /dev/null
+++ b/includes/jobqueue/jobs/HTMLCacheUpdateJob.php
@@ -0,0 +1,162 @@
+<?php
+/**
+ * HTML cache invalidation of all pages linking to a given title.
+ *
+ * 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 Cache
+ */
+
+/**
+ * Job to purge the cache for all pages that link to or use another page or file
+ *
+ * This job comes in a few variants:
+ *   - a) Recursive jobs to purge caches for backlink pages for a given title.
+ *        These jobs have have (recursive:true,table:<table>) set.
+ *   - b) Jobs to purge caches for a set of titles (the job title is ignored).
+ *	      These jobs have have (pages:(<page ID>:(<namespace>,<title>),...) set.
+ *
+ * @ingroup JobQueue
+ */
+class HTMLCacheUpdateJob extends Job {
+	function __construct( $title, $params = '' ) {
+		parent::__construct( 'htmlCacheUpdate', $title, $params );
+		// Base backlink purge jobs can be de-duplicated
+		$this->removeDuplicates = ( !isset( $params['range'] ) && !isset( $params['pages'] ) );
+	}
+
+	function run() {
+		global $wgUpdateRowsPerJob, $wgUpdateRowsPerQuery;
+
+		static $expected = array( 'recursive', 'pages' ); // new jobs have one of these
+
+		$oldRangeJob = false;
+		if ( !array_intersect( array_keys( $this->params ), $expected ) ) {
+			// B/C for older job params formats that lack these fields:
+			// a) base jobs with just ("table") and b) range jobs with ("table","start","end")
+			if ( isset( $this->params['start'] ) && isset( $this->params['end'] ) ) {
+				$oldRangeJob = true;
+			} else {
+				$this->params['recursive'] = true; // base job
+			}
+		}
+
+		// Job to purge all (or a range of) backlink pages for a page
+		if ( !empty( $this->params['recursive'] ) ) {
+			// Convert this into no more than $wgUpdateRowsPerJob HTMLCacheUpdateJob per-title
+			// jobs and possibly a recursive HTMLCacheUpdateJob job for the rest of the backlinks
+			$jobs = BacklinkJobUtils::partitionBacklinkJob(
+				$this,
+				$wgUpdateRowsPerJob,
+				$wgUpdateRowsPerQuery, // jobs-per-title
+				// Carry over information for de-duplication
+				array( 'params' => $this->getRootJobParams() )
+			);
+			JobQueueGroup::singleton()->push( $jobs );
+		// Job to purge pages for for a set of titles
+		} elseif ( isset( $this->params['pages'] ) ) {
+			$this->invalidateTitles( $this->params['pages'] );
+		// B/C for job to purge a range of backlink pages for a given page
+		} elseif ( $oldRangeJob ) {
+			$titleArray = $this->title->getBacklinkCache()->getLinks(
+				$this->params['table'], $this->params['start'], $this->params['end'] );
+
+			$pages = array(); // same format BacklinkJobUtils uses
+			foreach ( $titleArray as $tl ) {
+				$pages[$tl->getArticleId()] = array( $tl->getNamespace(), $tl->getDbKey() );
+			}
+
+			$jobs = array();
+			foreach ( array_chunk( $pages, $wgUpdateRowsPerJob ) as $pageChunk ) {
+				$jobs[] = new HTMLCacheUpdateJob( $this->title,
+					array(
+						'table' => $this->params['table'],
+						'pages' => $pageChunk
+					) + $this->getRootJobParams() // carry over information for de-duplication
+				);
+			}
+			JobQueueGroup::singleton()->push( $jobs );
+		}
+
+		return true;
+	}
+
+	/**
+	 * @param array $pages Map of (page ID => (namespace, DB key)) entries
+	 */
+	protected function invalidateTitles( array $pages ) {
+		global $wgUpdateRowsPerQuery, $wgUseFileCache, $wgUseSquid;
+
+		// Get all page IDs in this query into an array
+		$pageIds = array_keys( $pages );
+		if ( !$pageIds ) {
+			return;
+		}
+
+		$dbw = wfGetDB( DB_MASTER );
+
+		// The page_touched field will need to be bumped for these pages.
+		// Only bump it to the present time if no "rootJobTimestamp" was known.
+		// If it is known, it can be used instead, which avoids invalidating output
+		// that was in fact generated *after* the relevant dependency change time
+		// (e.g. template edit). This is particularily useful since refreshLinks jobs
+		// save back parser output and usually run along side htmlCacheUpdate jobs;
+		// their saved output would be invalidated by using the current timestamp.
+		if ( isset( $this->params['rootJobTimestamp'] ) ) {
+			$touchTimestamp = $this->params['rootJobTimestamp'];
+		} else {
+			$touchTimestamp = wfTimestampNow();
+		}
+
+		// Update page_touched (skipping pages already touched since the root job).
+		// Check $wgUpdateRowsPerQuery for sanity; batch jobs are sized by that already.
+		foreach ( array_chunk( $pageIds, $wgUpdateRowsPerQuery ) as $batch ) {
+			$dbw->update( 'page',
+				array( 'page_touched' => $dbw->timestamp( $touchTimestamp ) ),
+				array( 'page_id' => $batch,
+					// don't invalidated pages that were already invalidated
+					"page_touched < " . $dbw->addQuotes( $dbw->timestamp( $touchTimestamp ) )
+				),
+				__METHOD__
+			);
+		}
+		// Get the list of affected pages (races only mean something else did the purge)
+		$titleArray = TitleArray::newFromResult( $dbw->select(
+			'page',
+			array( 'page_namespace', 'page_title' ),
+			array( 'page_id' => $pageIds, 'page_touched' => $dbw->timestamp( $touchTimestamp ) ),
+			__METHOD__
+		) );
+
+		// Update squid
+		if ( $wgUseSquid ) {
+			$u = SquidUpdate::newFromTitles( $titleArray );
+			$u->doUpdate();
+		}
+
+		// Update file cache
+		if ( $wgUseFileCache ) {
+			foreach ( $titleArray as $title ) {
+				HTMLFileCache::clearFileCache( $title );
+			}
+		}
+	}
+
+	public function workItemCount() {
+		return isset( $this->params['pages'] ) ? count( $this->params['pages'] ) : 1;
+	}
+}
diff --git a/includes/jobqueue/jobs/NullJob.php b/includes/jobqueue/jobs/NullJob.php
new file mode 100644
index 00000000..66291e9d
--- /dev/null
+++ b/includes/jobqueue/jobs/NullJob.php
@@ -0,0 +1,76 @@
+<?php
+/**
+ * Degenerate job that does nothing.
+ *
+ * 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 Cache
+ */
+
+/**
+ * Degenerate job that does nothing, but can optionally replace itself
+ * in the queue and/or sleep for a brief time period. These can be used
+ * to represent "no-op" jobs or test lock contention and performance.
+ *
+ * @par Example:
+ * Inserting a null job in the configured job queue:
+ * @code
+ * $ php maintenance/eval.php
+ * > $queue = JobQueueGroup::singleton();
+ * > $job = new NullJob( Title::newMainPage(), array( 'lives' => 10 ) );
+ * > $queue->push( $job );
+ * @endcode
+ * You can then confirm the job has been enqueued by using the showJobs.php
+ * maintenance utility:
+ * @code
+ * $ php maintenance/showJobs.php --group
+ * null: 1 queue; 0 claimed (0 active, 0 abandoned)
+ * $
+ * @endcode
+ *
+ * @ingroup JobQueue
+ */
+class NullJob extends Job {
+	/**
+	 * @param Title $title
+	 * @param array $params Job parameters (lives, usleep)
+	 */
+	function __construct( $title, $params ) {
+		parent::__construct( 'null', $title, $params );
+		if ( !isset( $this->params['lives'] ) ) {
+			$this->params['lives'] = 1;
+		}
+		if ( !isset( $this->params['usleep'] ) ) {
+			$this->params['usleep'] = 0;
+		}
+		$this->removeDuplicates = !empty( $this->params['removeDuplicates'] );
+	}
+
+	public function run() {
+		if ( $this->params['usleep'] > 0 ) {
+			usleep( $this->params['usleep'] );
+		}
+		if ( $this->params['lives'] > 1 ) {
+			$params = $this->params;
+			$params['lives']--;
+			$job = new self( $this->title, $params );
+			JobQueueGroup::singleton()->push( $job );
+		}
+
+		return true;
+	}
+}
diff --git a/includes/jobqueue/jobs/PublishStashedFileJob.php b/includes/jobqueue/jobs/PublishStashedFileJob.php
new file mode 100644
index 00000000..918a392d
--- /dev/null
+++ b/includes/jobqueue/jobs/PublishStashedFileJob.php
@@ -0,0 +1,150 @@
+<?php
+/**
+ * Upload a file from the upload stash into the local file repo.
+ *
+ * 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 Upload
+ */
+
+/**
+ * Upload a file from the upload stash into the local file repo.
+ *
+ * @ingroup Upload
+ */
+class PublishStashedFileJob extends Job {
+	public function __construct( $title, $params ) {
+		parent::__construct( 'PublishStashedFile', $title, $params );
+		$this->removeDuplicates = true;
+	}
+
+	public function run() {
+		$scope = RequestContext::importScopedSession( $this->params['session'] );
+		$context = RequestContext::getMain();
+		try {
+			$user = $context->getUser();
+			if ( !$user->isLoggedIn() ) {
+				$this->setLastError( "Could not load the author user from session." );
+
+				return false;
+			}
+
+			if ( count( $_SESSION ) === 0 ) {
+				// Empty session probably indicates that we didn't associate
+				// with the session correctly. Note that being able to load
+				// the user does not necessarily mean the session was loaded.
+				// Most likely cause by suhosin.session.encrypt = On.
+				$this->setLastError( "Error associating with user session. " .
+					"Try setting suhosin.session.encrypt = Off" );
+
+				return false;
+			}
+
+			UploadBase::setSessionStatus(
+				$this->params['filekey'],
+				array( 'result' => 'Poll', 'stage' => 'publish', 'status' => Status::newGood() )
+			);
+
+			$upload = new UploadFromStash( $user );
+			// @todo initialize() causes a GET, ideally we could frontload the antivirus
+			// checks and anything else to the stash stage (which includes concatenation and
+			// the local file is thus already there). That way, instead of GET+PUT, there could
+			// just be a COPY operation from the stash to the public zone.
+			$upload->initialize( $this->params['filekey'], $this->params['filename'] );
+
+			// Check if the local file checks out (this is generally a no-op)
+			$verification = $upload->verifyUpload();
+			if ( $verification['status'] !== UploadBase::OK ) {
+				$status = Status::newFatal( 'verification-error' );
+				$status->value = array( 'verification' => $verification );
+				UploadBase::setSessionStatus(
+					$this->params['filekey'],
+					array( 'result' => 'Failure', 'stage' => 'publish', 'status' => $status )
+				);
+				$this->setLastError( "Could not verify upload." );
+
+				return false;
+			}
+
+			// Upload the stashed file to a permanent location
+			$status = $upload->performUpload(
+				$this->params['comment'],
+				$this->params['text'],
+				$this->params['watch'],
+				$user
+			);
+			if ( !$status->isGood() ) {
+				UploadBase::setSessionStatus(
+					$this->params['filekey'],
+					array( 'result' => 'Failure', 'stage' => 'publish', 'status' => $status )
+				);
+				$this->setLastError( $status->getWikiText() );
+
+				return false;
+			}
+
+			// Build the image info array while we have the local reference handy
+			$apiMain = new ApiMain(); // dummy object (XXX)
+			$imageInfo = $upload->getImageInfo( $apiMain->getResult() );
+
+			// Cleanup any temporary local file
+			$upload->cleanupTempFile();
+
+			// Cache the info so the user doesn't have to wait forever to get the final info
+			UploadBase::setSessionStatus(
+				$this->params['filekey'],
+				array(
+					'result' => 'Success',
+					'stage' => 'publish',
+					'filename' => $upload->getLocalFile()->getName(),
+					'imageinfo' => $imageInfo,
+					'status' => Status::newGood()
+				)
+			);
+		} catch ( MWException $e ) {
+			UploadBase::setSessionStatus(
+				$this->params['filekey'],
+				array(
+					'result' => 'Failure',
+					'stage' => 'publish',
+					'status' => Status::newFatal( 'api-error-publishfailed' )
+				)
+			);
+			$this->setLastError( get_class( $e ) . ": " . $e->getText() );
+			// To prevent potential database referential integrity issues.
+			// See bug 32551.
+			MWExceptionHandler::rollbackMasterChangesAndLog( $e );
+
+			return false;
+		}
+
+		return true;
+	}
+
+	public function getDeduplicationInfo() {
+		$info = parent::getDeduplicationInfo();
+		if ( is_array( $info['params'] ) ) {
+			$info['params'] = array( 'filekey' => $info['params']['filekey'] );
+		}
+
+		return $info;
+	}
+
+	public function allowRetries() {
+		return false;
+	}
+}
diff --git a/includes/jobqueue/jobs/RefreshLinksJob.php b/includes/jobqueue/jobs/RefreshLinksJob.php
new file mode 100644
index 00000000..f82af273
--- /dev/null
+++ b/includes/jobqueue/jobs/RefreshLinksJob.php
@@ -0,0 +1,199 @@
+<?php
+/**
+ * Job to update link tables for pages
+ *
+ * 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 JobQueue
+ */
+
+/**
+ * Job to update link tables for pages
+ *
+ * This job comes in a few variants:
+ *   - a) Recursive jobs to update links for backlink pages for a given title.
+ *        These jobs have have (recursive:true,table:<table>) set.
+ *   - b) Jobs to update links for a set of pages (the job title is ignored).
+ *	      These jobs have have (pages:(<page ID>:(<namespace>,<title>),...) set.
+ *   - c) Jobs to update links for a single page (the job title)
+ *        These jobs need no extra fields set.
+ *
+ * @ingroup JobQueue
+ */
+class RefreshLinksJob extends Job {
+	const PARSE_THRESHOLD_SEC = 1.0;
+
+	function __construct( $title, $params = '' ) {
+		parent::__construct( 'refreshLinks', $title, $params );
+		// Base backlink update jobs and per-title update jobs can be de-duplicated.
+		// If template A changes twice before any jobs run, a clean queue will have:
+		//		(A base, A base)
+		// The second job is ignored by the queue on insertion.
+		// Suppose, many pages use template A, and that template itself uses template B.
+		// An edit to both will first create two base jobs. A clean FIFO queue will have:
+		//		(A base, B base)
+		// When these jobs run, the queue will have per-title and remnant partition jobs:
+		//		(titleX,titleY,titleZ,...,A remnant,titleM,titleN,titleO,...,B remnant)
+		// Some these jobs will be the same, and will automatically be ignored by
+		// the queue upon insertion. Some title jobs will run before the duplicate is
+		// inserted, so the work will still be done twice in those cases. More titles
+		// can be de-duplicated as the remnant jobs continue to be broken down. This
+		// works best when $wgUpdateRowsPerJob, and either the pages have few backlinks
+		// and/or the backlink sets for pages A and B are almost identical.
+		$this->removeDuplicates = !isset( $params['range'] )
+			&& ( !isset( $params['pages'] ) || count( $params['pages'] ) == 1 );
+	}
+
+	function run() {
+		global $wgUpdateRowsPerJob;
+
+		// Job to update all (or a range of) backlink pages for a page
+		if ( !empty( $this->params['recursive'] ) ) {
+			// Carry over information for de-duplication
+			$extraParams = $this->getRootJobParams();
+			// Avoid slave lag when fetching templates.
+			// When the outermost job is run, we know that the caller that enqueued it must have
+			// committed the relevant changes to the DB by now. At that point, record the master
+			// position and pass it along as the job recursively breaks into smaller range jobs.
+			// Hopefully, when leaf jobs are popped, the slaves will have reached that position.
+			if ( isset( $this->params['masterPos'] ) ) {
+				$extraParams['masterPos'] = $this->params['masterPos'];
+			} elseif ( wfGetLB()->getServerCount() > 1 ) {
+				$extraParams['masterPos'] = wfGetLB()->getMasterPos();
+			} else {
+				$extraParams['masterPos'] = false;
+			}
+			// Convert this into no more than $wgUpdateRowsPerJob RefreshLinks per-title
+			// jobs and possibly a recursive RefreshLinks job for the rest of the backlinks
+			$jobs = BacklinkJobUtils::partitionBacklinkJob(
+				$this,
+				$wgUpdateRowsPerJob,
+				1, // job-per-title
+				array( 'params' => $extraParams )
+			);
+			JobQueueGroup::singleton()->push( $jobs );
+		// Job to update link tables for for a set of titles
+		} elseif ( isset( $this->params['pages'] ) ) {
+			foreach ( $this->params['pages'] as $pageId => $nsAndKey ) {
+				list( $ns, $dbKey ) = $nsAndKey;
+				$this->runForTitle( Title::makeTitleSafe( $ns, $dbKey ) );
+			}
+		// Job to update link tables for a given title
+		} else {
+			$this->runForTitle( $this->title );
+		}
+
+		return true;
+	}
+
+	protected function runForTitle( Title $title = null ) {
+		$linkCache = LinkCache::singleton();
+		$linkCache->clear();
+
+		if ( is_null( $title ) ) {
+			$this->setLastError( "refreshLinks: Invalid title" );
+			return false;
+		}
+
+		// Wait for the DB of the current/next slave DB handle to catch up to the master.
+		// This way, we get the correct page_latest for templates or files that just changed
+		// milliseconds ago, having triggered this job to begin with.
+		if ( isset( $this->params['masterPos'] ) && $this->params['masterPos'] !== false ) {
+			wfGetLB()->waitFor( $this->params['masterPos'] );
+		}
+
+		$page = WikiPage::factory( $title );
+
+		// Fetch the current revision...
+		$revision = Revision::newFromTitle( $title, false, Revision::READ_NORMAL );
+		if ( !$revision ) {
+			$this->setLastError( "refreshLinks: Article not found {$title->getPrefixedDBkey()}" );
+			return false; // XXX: what if it was just deleted?
+		}
+		$content = $revision->getContent( Revision::RAW );
+		if ( !$content ) {
+			// If there is no content, pretend the content is empty
+			$content = $revision->getContentHandler()->makeEmptyContent();
+		}
+
+		$parserOutput = false;
+		$parserOptions = $page->makeParserOptions( 'canonical' );
+		// If page_touched changed after this root job (with a good slave lag skew factor),
+		// then it is likely that any views of the pages already resulted in re-parses which
+		// are now in cache. This can be reused to avoid expensive parsing in some cases.
+		if ( isset( $this->params['rootJobTimestamp'] ) ) {
+			$skewedTimestamp = wfTimestamp( TS_UNIX, $this->params['rootJobTimestamp'] ) + 5;
+			if ( $page->getLinksTimestamp() > wfTimestamp( TS_MW, $skewedTimestamp ) ) {
+				// Something already updated the backlinks since this job was made
+				return true;
+			}
+			if ( $page->getTouched() > wfTimestamp( TS_MW, $skewedTimestamp ) ) {
+				$parserOutput = ParserCache::singleton()->getDirty( $page, $parserOptions );
+				if ( $parserOutput && $parserOutput->getCacheTime() <= $skewedTimestamp ) {
+					$parserOutput = false; // too stale
+				}
+			}
+		}
+		// Fetch the current revision and parse it if necessary...
+		if ( $parserOutput == false ) {
+			$start = microtime( true );
+			// Revision ID must be passed to the parser output to get revision variables correct
+			$parserOutput = $content->getParserOutput(
+				$title, $revision->getId(), $parserOptions, false );
+			$ellapsed = microtime( true ) - $start;
+			// If it took a long time to render, then save this back to the cache to avoid
+			// wasted CPU by other apaches or job runners. We don't want to always save to
+			// cache as this cause cause high cache I/O and LRU churn when a template changes.
+			if ( $ellapsed >= self::PARSE_THRESHOLD_SEC
+				&& $page->isParserCacheUsed( $parserOptions, $revision->getId() )
+				&& $parserOutput->isCacheable()
+			) {
+				$ctime = wfTimestamp( TS_MW, (int)$start ); // cache time
+				ParserCache::singleton()->save(
+					$parserOutput, $page, $parserOptions, $ctime, $revision->getId()
+				);
+			}
+		}
+
+		$updates = $content->getSecondaryDataUpdates( $title, null, false, $parserOutput );
+		DataUpdate::runUpdates( $updates );
+
+		InfoAction::invalidateCache( $title );
+
+		return true;
+	}
+
+	public function getDeduplicationInfo() {
+		$info = parent::getDeduplicationInfo();
+		if ( is_array( $info['params'] ) ) {
+			// Don't let highly unique "masterPos" values ruin duplicate detection
+			unset( $info['params']['masterPos'] );
+			// For per-pages jobs, the job title is that of the template that changed
+			// (or similar), so remove that since it ruins duplicate detection
+			if ( isset( $info['pages'] ) ) {
+				unset( $info['namespace'] );
+				unset( $info['title'] );
+			}
+		}
+
+		return $info;
+	}
+
+	public function workItemCount() {
+		return isset( $this->params['pages'] ) ? count( $this->params['pages'] ) : 1;
+	}
+}
diff --git a/includes/jobqueue/jobs/RefreshLinksJob2.php b/includes/jobqueue/jobs/RefreshLinksJob2.php
new file mode 100644
index 00000000..97405aeb
--- /dev/null
+++ b/includes/jobqueue/jobs/RefreshLinksJob2.php
@@ -0,0 +1,141 @@
+<?php
+/**
+ * Job to update links for a given title.
+ *
+ * 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 JobQueue
+ */
+
+/**
+ * Background job to update links for titles in certain backlink range by page ID.
+ * Newer version for high use templates. This is deprecated by RefreshLinksPartitionJob.
+ *
+ * @ingroup JobQueue
+ * @deprecated since 1.23
+ */
+class RefreshLinksJob2 extends Job {
+	function __construct( $title, $params ) {
+		parent::__construct( 'refreshLinks2', $title, $params );
+		// Base jobs for large templates can easily be de-duplicated
+		$this->removeDuplicates = !isset( $params['start'] ) && !isset( $params['end'] );
+	}
+
+	/**
+	 * Run a refreshLinks2 job
+	 * @return bool Success
+	 */
+	function run() {
+		global $wgUpdateRowsPerJob;
+
+		$linkCache = LinkCache::singleton();
+		$linkCache->clear();
+
+		if ( is_null( $this->title ) ) {
+			$this->error = "refreshLinks2: Invalid title";
+			return false;
+		}
+
+		// Back compat for pre-r94435 jobs
+		$table = isset( $this->params['table'] ) ? $this->params['table'] : 'templatelinks';
+
+		// Avoid slave lag when fetching templates.
+		// When the outermost job is run, we know that the caller that enqueued it must have
+		// committed the relevant changes to the DB by now. At that point, record the master
+		// position and pass it along as the job recursively breaks into smaller range jobs.
+		// Hopefully, when leaf jobs are popped, the slaves will have reached that position.
+		if ( isset( $this->params['masterPos'] ) ) {
+			$masterPos = $this->params['masterPos'];
+		} elseif ( wfGetLB()->getServerCount() > 1 ) {
+			$masterPos = wfGetLB()->getMasterPos();
+		} else {
+			$masterPos = false;
+		}
+
+		$tbc = $this->title->getBacklinkCache();
+
+		$jobs = array(); // jobs to insert
+		if ( isset( $this->params['start'] ) && isset( $this->params['end'] ) ) {
+			# This is a partition job to trigger the insertion of leaf jobs...
+			$jobs = array_merge( $jobs, $this->getSingleTitleJobs( $table, $masterPos ) );
+		} else {
+			# This is a base job to trigger the insertion of partitioned jobs...
+			if ( $tbc->getNumLinks( $table, $wgUpdateRowsPerJob + 1 ) <= $wgUpdateRowsPerJob ) {
+				# Just directly insert the single per-title jobs
+				$jobs = array_merge( $jobs, $this->getSingleTitleJobs( $table, $masterPos ) );
+			} else {
+				# Insert the partition jobs to make per-title jobs
+				foreach ( $tbc->partition( $table, $wgUpdateRowsPerJob ) as $batch ) {
+					list( $start, $end ) = $batch;
+					$jobs[] = new RefreshLinksJob2( $this->title,
+						array(
+							'table' => $table,
+							'start' => $start,
+							'end' => $end,
+							'masterPos' => $masterPos,
+						) + $this->getRootJobParams() // carry over information for de-duplication
+					);
+				}
+			}
+		}
+
+		if ( count( $jobs ) ) {
+			JobQueueGroup::singleton()->push( $jobs );
+		}
+
+		return true;
+	}
+
+	/**
+	 * @param string $table
+	 * @param mixed $masterPos
+	 * @return array
+	 */
+	protected function getSingleTitleJobs( $table, $masterPos ) {
+		# The "start"/"end" fields are not set for the base jobs
+		$start = isset( $this->params['start'] ) ? $this->params['start'] : false;
+		$end = isset( $this->params['end'] ) ? $this->params['end'] : false;
+		$titles = $this->title->getBacklinkCache()->getLinks( $table, $start, $end );
+		# Convert into single page refresh links jobs.
+		# This handles well when in sapi mode and is useful in any case for job
+		# de-duplication. If many pages use template A, and that template itself
+		# uses template B, then an edit to both will create many duplicate jobs.
+		# Roughly speaking, for each page, one of the "RefreshLinksJob" jobs will
+		# get run first, and when it does, it will remove the duplicates. Of course,
+		# one page could have its job popped when the other page's job is still
+		# buried within the logic of a refreshLinks2 job.
+		$jobs = array();
+		foreach ( $titles as $title ) {
+			$jobs[] = new RefreshLinksJob( $title,
+				array( 'masterPos' => $masterPos ) + $this->getRootJobParams()
+			); // carry over information for de-duplication
+		}
+		return $jobs;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getDeduplicationInfo() {
+		$info = parent::getDeduplicationInfo();
+		// Don't let highly unique "masterPos" values ruin duplicate detection
+		if ( is_array( $info['params'] ) ) {
+			unset( $info['params']['masterPos'] );
+		}
+		return $info;
+	}
+}
diff --git a/includes/jobqueue/jobs/UploadFromUrlJob.php b/includes/jobqueue/jobs/UploadFromUrlJob.php
new file mode 100644
index 00000000..a09db15a
--- /dev/null
+++ b/includes/jobqueue/jobs/UploadFromUrlJob.php
@@ -0,0 +1,187 @@
+<?php
+/**
+ * Job for asynchronous upload-by-url.
+ *
+ * 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 JobQueue
+ */
+
+/**
+ * Job for asynchronous upload-by-url.
+ *
+ * This job is in fact an interface to UploadFromUrl, which is designed such
+ * that it does not require any globals. If it does, fix it elsewhere, do not
+ * add globals in here.
+ *
+ * @ingroup JobQueue
+ */
+class UploadFromUrlJob extends Job {
+	const SESSION_KEYNAME = 'wsUploadFromUrlJobData';
+
+	/** @var UploadFromUrl */
+	public $upload;
+
+	/** @var User */
+	protected $user;
+
+	public function __construct( $title, $params ) {
+		parent::__construct( 'uploadFromUrl', $title, $params );
+	}
+
+	public function run() {
+		global $wgCopyUploadAsyncTimeout;
+		# Initialize this object and the upload object
+		$this->upload = new UploadFromUrl();
+		$this->upload->initialize(
+			$this->title->getText(),
+			$this->params['url'],
+			false
+		);
+		$this->user = User::newFromName( $this->params['userName'] );
+
+		# Fetch the file
+		$opts = array();
+		if ( $wgCopyUploadAsyncTimeout ) {
+			$opts['timeout'] = $wgCopyUploadAsyncTimeout;
+		}
+		$status = $this->upload->fetchFile( $opts );
+		if ( !$status->isOk() ) {
+			$this->leaveMessage( $status );
+
+			return true;
+		}
+
+		# Verify upload
+		$result = $this->upload->verifyUpload();
+		if ( $result['status'] != UploadBase::OK ) {
+			$status = $this->upload->convertVerifyErrorToStatus( $result );
+			$this->leaveMessage( $status );
+
+			return true;
+		}
+
+		# Check warnings
+		if ( !$this->params['ignoreWarnings'] ) {
+			$warnings = $this->upload->checkWarnings();
+			if ( $warnings ) {
+
+				# Stash the upload
+				$key = $this->upload->stashFile();
+
+				// @todo FIXME: This has been broken for a while.
+				// User::leaveUserMessage() does not exist.
+				if ( $this->params['leaveMessage'] ) {
+					$this->user->leaveUserMessage(
+						wfMessage( 'upload-warning-subj' )->text(),
+						wfMessage( 'upload-warning-msg',
+							$key,
+							$this->params['url'] )->text()
+					);
+				} else {
+					wfSetupSession( $this->params['sessionId'] );
+					$this->storeResultInSession( 'Warning',
+						'warnings', $warnings );
+					session_write_close();
+				}
+
+				return true;
+			}
+		}
+
+		# Perform the upload
+		$status = $this->upload->performUpload(
+			$this->params['comment'],
+			$this->params['pageText'],
+			$this->params['watch'],
+			$this->user
+		);
+		$this->leaveMessage( $status );
+
+		return true;
+	}
+
+	/**
+	 * Leave a message on the user talk page or in the session according to
+	 * $params['leaveMessage'].
+	 *
+	 * @param Status $status
+	 */
+	protected function leaveMessage( $status ) {
+		if ( $this->params['leaveMessage'] ) {
+			if ( $status->isGood() ) {
+				// @todo FIXME: user->leaveUserMessage does not exist.
+				$this->user->leaveUserMessage( wfMessage( 'upload-success-subj' )->text(),
+					wfMessage( 'upload-success-msg',
+						$this->upload->getTitle()->getText(),
+						$this->params['url']
+					)->text() );
+			} else {
+				// @todo FIXME: user->leaveUserMessage does not exist.
+				$this->user->leaveUserMessage( wfMessage( 'upload-failure-subj' )->text(),
+					wfMessage( 'upload-failure-msg',
+						$status->getWikiText(),
+						$this->params['url']
+					)->text() );
+			}
+		} else {
+			wfSetupSession( $this->params['sessionId'] );
+			if ( $status->isOk() ) {
+				$this->storeResultInSession( 'Success',
+					'filename', $this->upload->getLocalFile()->getName() );
+			} else {
+				$this->storeResultInSession( 'Failure',
+					'errors', $status->getErrorsArray() );
+			}
+			session_write_close();
+		}
+	}
+
+	/**
+	 * Store a result in the session data. Note that the caller is responsible
+	 * for appropriate session_start and session_write_close calls.
+	 *
+	 * @param string $result The result (Success|Warning|Failure)
+	 * @param string $dataKey The key of the extra data
+	 * @param mixed $dataValue The extra data itself
+	 */
+	protected function storeResultInSession( $result, $dataKey, $dataValue ) {
+		$session =& self::getSessionData( $this->params['sessionKey'] );
+		$session['result'] = $result;
+		$session[$dataKey] = $dataValue;
+	}
+
+	/**
+	 * Initialize the session data. Sets the intial result to queued.
+	 */
+	public function initializeSessionData() {
+		$session =& self::getSessionData( $this->params['sessionKey'] );
+		$$session['result'] = 'Queued';
+	}
+
+	/**
+	 * @param string $key
+	 * @return mixed
+	 */
+	public static function &getSessionData( $key ) {
+		if ( !isset( $_SESSION[self::SESSION_KEYNAME][$key] ) ) {
+			$_SESSION[self::SESSION_KEYNAME][$key] = array();
+		}
+
+		return $_SESSION[self::SESSION_KEYNAME][$key];
+	}
+}
diff --git a/includes/jobqueue/utils/BacklinkJobUtils.php b/includes/jobqueue/utils/BacklinkJobUtils.php
new file mode 100644
index 00000000..c8e5df66
--- /dev/null
+++ b/includes/jobqueue/utils/BacklinkJobUtils.php
@@ -0,0 +1,122 @@
+<?php
+/**
+ * Job to update links for a given title.
+ *
+ * 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 JobQueue
+ * @author Aaron Schulz
+ */
+
+/**
+ * Class with Backlink related Job helper methods
+ *
+ * @ingroup JobQueue
+ * @since 1.23
+ */
+class BacklinkJobUtils {
+	/**
+	 * Break down $job into approximately ($bSize/$cSize) leaf jobs and a single partition
+	 * job that covers the remaining backlink range (if needed). Jobs for the first $bSize
+	 * titles are collated ($cSize per job) into leaf jobs to do actual work. All the
+	 * resulting jobs are of the same class as $job. No partition job is returned if the
+	 * range covered by $job was less than $bSize, as the leaf jobs have full coverage.
+	 *
+	 * The leaf jobs have the 'pages' param set to a (<page ID>:(<namespace>,<DB key>),...)
+	 * map so that the run() function knows what pages to act on. The leaf jobs will keep
+	 * the same job title as the parent job (e.g. $job).
+	 *
+	 * The partition jobs have the 'range' parameter set to a map of the format
+	 * (start:<integer>, end:<integer>, batchSize:<integer>, subranges:((<start>,<end>),...)),
+	 * the 'table' parameter set to that of $job, and the 'recursive' parameter set to true.
+	 * This method can be called on the resulting job to repeat the process again.
+	 *
+	 * The job provided ($job) must have the 'recursive' parameter set to true and the 'table'
+	 * parameter must be set to a backlink table. The job title will be used as the title to
+	 * find backlinks for. Any 'range' parameter must follow the same format as mentioned above.
+	 * This should be managed by recursive calls to this method.
+	 *
+	 * The first jobs return are always the leaf jobs. This lets the caller use push() to
+	 * put them directly into the queue and works well if the queue is FIFO. In such a queue,
+	 * the leaf jobs have to get finished first before anything can resolve the next partition
+	 * job, which keeps the queue very small.
+	 *
+	 * $opts includes:
+	 *   - params : extra job parameters to include in each job
+	 *
+	 * @param Job $job
+	 * @param int $bSize BacklinkCache partition size; usually $wgUpdateRowsPerJob
+	 * @param int $cSize Max titles per leaf job; Usually 1 or a modest value
+	 * @param array $opts Optional parameter map
+	 * @return Job[] List of Job objects
+	 */
+	public static function partitionBacklinkJob( Job $job, $bSize, $cSize, $opts = array() ) {
+		$class = get_class( $job );
+		$title = $job->getTitle();
+		$params = $job->getParams();
+
+		if ( isset( $params['pages'] ) || empty( $params['recursive'] ) ) {
+			$ranges = array(); // sanity; this is a leaf node
+			wfWarn( __METHOD__ . " called on {$job->getType()} leaf job (explosive recursion)." );
+		} elseif ( isset( $params['range'] ) ) {
+			// This is a range job to trigger the insertion of partitioned/title jobs...
+			$ranges = $params['range']['subranges'];
+			$realBSize = $params['range']['batchSize'];
+		} else {
+			// This is a base job to trigger the insertion of partitioned jobs...
+			$ranges = $title->getBacklinkCache()->partition( $params['table'], $bSize );
+			$realBSize = $bSize;
+		}
+
+		$extraParams = isset( $opts['params'] ) ? $opts['params'] : array();
+
+		$jobs = array();
+		// Combine the first range (of size $bSize) backlinks into leaf jobs
+		if ( isset( $ranges[0] ) ) {
+			list( $start, $end ) = $ranges[0];
+			$titles = $title->getBacklinkCache()->getLinks( $params['table'], $start, $end );
+			foreach ( array_chunk( iterator_to_array( $titles ), $cSize ) as $titleBatch ) {
+				$pages = array();
+				foreach ( $titleBatch as $tl ) {
+					$pages[$tl->getArticleId()] = array( $tl->getNamespace(), $tl->getDBKey() );
+				}
+				$jobs[] = new $class(
+					$title, // maintain parent job title
+					array( 'pages' => $pages ) + $extraParams
+				);
+			}
+		}
+		// Take all of the remaining ranges and build a partition job from it
+		if ( isset( $ranges[1] ) ) {
+			$jobs[] = new $class(
+				$title, // maintain parent job title
+				array(
+					'recursive'     => true,
+					'table'         => $params['table'],
+					'range'         => array(
+						'start'     => $ranges[1][0],
+						'end'	    => $ranges[count( $ranges ) - 1][1],
+						'batchSize' => $realBSize,
+						'subranges' => array_slice( $ranges, 1 )
+					),
+				) + $extraParams
+			);
+		}
+
+		return $jobs;
+	}
+}