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diff --git a/includes/job/JobQueueAggregator.php b/includes/job/JobQueueAggregator.php
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+<?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 ) {}
+
+	/**
+	 * @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();
+
+	/**
+	 * 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;
+	}
+}