Update to MediaWiki 1.24.1

10 files changed, 2431 insertions, 0 deletions

diff --git a/includes/deferred/CallableUpdate.php b/includes/deferred/CallableUpdate.php
new file mode 100644
index 00000000..808626d0
--- /dev/null
+++ b/includes/deferred/CallableUpdate.php
@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * Deferrable Update for closure/callback
+ */
+class MWCallableUpdate implements DeferrableUpdate {
+	/**
+	 * @var Closure|callable
+	 */
+	private $callback;
+
+	/**
+	 * @param callable $callback
+	 * @throws MWException
+	 */
+	public function __construct( $callback ) {
+		if ( !is_callable( $callback ) ) {
+			throw new MWException( 'Not a valid callback/closure!' );
+		}
+		$this->callback = $callback;
+	}
+
+	/**
+	 * Run the update
+	 */
+	public function doUpdate() {
+		call_user_func( $this->callback );
+	}
+}
diff --git a/includes/deferred/DataUpdate.php b/includes/deferred/DataUpdate.php
new file mode 100644
index 00000000..ed12c601
--- /dev/null
+++ b/includes/deferred/DataUpdate.php
@@ -0,0 +1,125 @@
+<?php
+/**
+ * Base code for update jobs that do something with some secondary
+ * data extracted from article.
+ *
+ * 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
+ */
+
+/**
+ * Abstract base class for update jobs that do something with some secondary
+ * data extracted from article.
+ *
+ * @note subclasses should NOT start or commit transactions in their doUpdate() method,
+ *       a transaction will automatically be wrapped around the update. If need be,
+ *       subclasses can override the beginTransaction() and commitTransaction() methods.
+ */
+abstract class DataUpdate implements DeferrableUpdate {
+	/**
+	 * Constructor
+	 */
+	public function __construct() {
+		# noop
+	}
+
+	/**
+	 * Begin an appropriate transaction, if any.
+	 * This default implementation does nothing.
+	 */
+	public function beginTransaction() {
+		//noop
+	}
+
+	/**
+	 * Commit the transaction started via beginTransaction, if any.
+	 * This default implementation does nothing.
+	 */
+	public function commitTransaction() {
+		//noop
+	}
+
+	/**
+	 * Abort / roll back the transaction started via beginTransaction, if any.
+	 * This default implementation does nothing.
+	 */
+	public function rollbackTransaction() {
+		//noop
+	}
+
+	/**
+	 * Convenience method, calls doUpdate() on every DataUpdate in the array.
+	 *
+	 * This methods supports transactions logic by first calling beginTransaction()
+	 * on all updates in the array, then calling doUpdate() on each, and, if all goes well,
+	 * then calling commitTransaction() on each update. If an error occurs,
+	 * rollbackTransaction() will be called on any update object that had beginTransaction()
+	 * called but not yet commitTransaction().
+	 *
+	 * This allows for limited transactional logic across multiple backends for storing
+	 * secondary data.
+	 *
+	 * @param array $updates A list of DataUpdate instances
+	 * @throws Exception|null
+	 */
+	public static function runUpdates( $updates ) {
+		if ( empty( $updates ) ) {
+			return; # nothing to do
+		}
+
+		$open_transactions = array();
+		$exception = null;
+
+		/**
+		 * @var $update DataUpdate
+		 * @var $trans DataUpdate
+		 */
+
+		try {
+			// begin transactions
+			foreach ( $updates as $update ) {
+				$update->beginTransaction();
+				$open_transactions[] = $update;
+			}
+
+			// do work
+			foreach ( $updates as $update ) {
+				$update->doUpdate();
+			}
+
+			// commit transactions
+			while ( count( $open_transactions ) > 0 ) {
+				$trans = array_pop( $open_transactions );
+				$trans->commitTransaction();
+			}
+		} catch ( Exception $ex ) {
+			$exception = $ex;
+			wfDebug( "Caught exception, will rethrow after rollback: " .
+				$ex->getMessage() . "\n" );
+		}
+
+		// rollback remaining transactions
+		while ( count( $open_transactions ) > 0 ) {
+			$trans = array_pop( $open_transactions );
+			$trans->rollbackTransaction();
+		}
+
+		if ( $exception ) {
+			throw $exception; // rethrow after cleanup
+		}
+	}
+}
diff --git a/includes/deferred/DeferredUpdates.php b/includes/deferred/DeferredUpdates.php
new file mode 100644
index 00000000..b0c1899f
--- /dev/null
+++ b/includes/deferred/DeferredUpdates.php
@@ -0,0 +1,136 @@
+<?php
+/**
+ * Interface and manager for deferred updates.
+ *
+ * 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
+ */
+
+/**
+ * Interface that deferrable updates should implement. Basically required so we
+ * can validate input on DeferredUpdates::addUpdate()
+ *
+ * @since 1.19
+ */
+interface DeferrableUpdate {
+	/**
+	 * Perform the actual work
+	 */
+	function doUpdate();
+}
+
+/**
+ * Class for managing the deferred updates.
+ *
+ * @since 1.19
+ */
+class DeferredUpdates {
+	/**
+	 * Store of updates to be deferred until the end of the request.
+	 */
+	private static $updates = array();
+
+	/**
+	 * Add an update to the deferred list
+	 * @param DeferrableUpdate $update Some object that implements doUpdate()
+	 */
+	public static function addUpdate( DeferrableUpdate $update ) {
+		array_push( self::$updates, $update );
+	}
+
+	/**
+	 * HTMLCacheUpdates are the most common deferred update people use. This
+	 * is a shortcut method for that.
+	 * @see HTMLCacheUpdate::__construct()
+	 * @param Title $title
+	 * @param string $table
+	 */
+	public static function addHTMLCacheUpdate( $title, $table ) {
+		self::addUpdate( new HTMLCacheUpdate( $title, $table ) );
+	}
+
+	/**
+	 * Add a callable update.  In a lot of cases, we just need a callback/closure,
+	 * defining a new DeferrableUpdate object is not necessary
+	 * @see MWCallableUpdate::__construct()
+	 * @param callable $callable
+	 */
+	public static function addCallableUpdate( $callable ) {
+		self::addUpdate( new MWCallableUpdate( $callable ) );
+	}
+
+	/**
+	 * Do any deferred updates and clear the list
+	 *
+	 * @param string $commit Set to 'commit' to commit after every update to
+	 *   prevent lock contention
+	 */
+	public static function doUpdates( $commit = '' ) {
+		global $wgDeferredUpdateList;
+
+		wfProfileIn( __METHOD__ );
+
+		$updates = array_merge( $wgDeferredUpdateList, self::$updates );
+
+		// No need to get master connections in case of empty updates array
+		if ( !count( $updates ) ) {
+			wfProfileOut( __METHOD__ );
+
+			return;
+		}
+
+		$dbw = false;
+		$doCommit = $commit == 'commit';
+		if ( $doCommit ) {
+			$dbw = wfGetDB( DB_MASTER );
+		}
+
+		while ( $updates ) {
+			self::clearPendingUpdates();
+
+			/** @var DeferrableUpdate $update */
+			foreach ( $updates as $update ) {
+				try {
+					$update->doUpdate();
+
+					if ( $doCommit && $dbw->trxLevel() ) {
+						$dbw->commit( __METHOD__, 'flush' );
+					}
+				} catch ( MWException $e ) {
+					// We don't want exceptions thrown during deferred updates to
+					// be reported to the user since the output is already sent.
+					// Instead we just log them.
+					if ( !$e instanceof ErrorPageError ) {
+						MWExceptionHandler::logException( $e );
+					}
+				}
+			}
+			$updates = array_merge( $wgDeferredUpdateList, self::$updates );
+		}
+
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * Clear all pending updates without performing them. Generally, you don't
+	 * want or need to call this. Unit tests need it though.
+	 */
+	public static function clearPendingUpdates() {
+		global $wgDeferredUpdateList;
+		$wgDeferredUpdateList = self::$updates = array();
+	}
+}
diff --git a/includes/deferred/HTMLCacheUpdate.php b/includes/deferred/HTMLCacheUpdate.php
new file mode 100644
index 00000000..54fa5943
--- /dev/null
+++ b/includes/deferred/HTMLCacheUpdate.php
@@ -0,0 +1,70 @@
+<?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
+ */
+
+/**
+ * Class to invalidate the HTML cache of all the pages linking to a given title.
+ *
+ * @ingroup Cache
+ */
+class HTMLCacheUpdate implements DeferrableUpdate {
+	/** @var Title */
+	public $mTitle;
+
+	/** @var string */
+	public $mTable;
+
+	/**
+	 * @param Title $titleTo
+	 * @param string $table
+	 */
+	function __construct( Title $titleTo, $table ) {
+		$this->mTitle = $titleTo;
+		$this->mTable = $table;
+	}
+
+	public function doUpdate() {
+		wfProfileIn( __METHOD__ );
+
+		$job = new HTMLCacheUpdateJob(
+			$this->mTitle,
+			array(
+				'table' => $this->mTable,
+			) + Job::newRootJobParams( // "overall" refresh links job info
+				"htmlCacheUpdate:{$this->mTable}:{$this->mTitle->getPrefixedText()}"
+			)
+		);
+
+		$count = $this->mTitle->getBacklinkCache()->getNumLinks( $this->mTable, 100 );
+		if ( $count >= 100 ) { // many backlinks
+			JobQueueGroup::singleton()->push( $job );
+			JobQueueGroup::singleton()->deduplicateRootJob( $job );
+		} else { // few backlinks ($count might be off even if 0)
+			$dbw = wfGetDB( DB_MASTER );
+			$dbw->onTransactionIdle( function () use ( $job ) {
+				$job->run(); // just do the purge query now
+			} );
+		}
+
+		wfProfileOut( __METHOD__ );
+	}
+}
diff --git a/includes/deferred/LinksUpdate.php b/includes/deferred/LinksUpdate.php
new file mode 100644
index 00000000..45d26648
--- /dev/null
+++ b/includes/deferred/LinksUpdate.php
@@ -0,0 +1,1019 @@
+<?php
+/**
+ * Updater for link tracking tables after a page edit.
+ *
+ * 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
+ */
+
+/**
+ * See docs/deferred.txt
+ *
+ * @todo document (e.g. one-sentence top-level class description).
+ */
+class LinksUpdate extends SqlDataUpdate {
+	// @todo make members protected, but make sure extensions don't break
+
+	/** @var int Page ID of the article linked from */
+	public $mId;
+
+	/** @var Title Title object of the article linked from */
+	public $mTitle;
+
+	/** @var ParserOutput */
+	public $mParserOutput;
+
+	/** @var array Map of title strings to IDs for the links in the document */
+	public $mLinks;
+
+	/** @var array DB keys of the images used, in the array key only */
+	public $mImages;
+
+	/** @var array Map of title strings to IDs for the template references, including broken ones */
+	public $mTemplates;
+
+	/** @var array URLs of external links, array key only */
+	public $mExternals;
+
+	/** @var array Map of category names to sort keys */
+	public $mCategories;
+
+	/** @var array Map of language codes to titles */
+	public $mInterlangs;
+
+	/** @var array Map of arbitrary name to value */
+	public $mProperties;
+
+	/** @var DatabaseBase Database connection reference */
+	public $mDb;
+
+	/** @var array SELECT options to be used */
+	public $mOptions;
+
+	/** @var bool Whether to queue jobs for recursive updates */
+	public $mRecursive;
+
+	/**
+	 * @var null|array Added links if calculated.
+	 */
+	private $linkInsertions = null;
+
+	/**
+	 * @var null|array Deleted links if calculated.
+	 */
+	private $linkDeletions = null;
+
+	/**
+	 * Constructor
+	 *
+	 * @param Title $title Title of the page we're updating
+	 * @param ParserOutput $parserOutput Output from a full parse of this page
+	 * @param bool $recursive Queue jobs for recursive updates?
+	 * @throws MWException
+	 */
+	function __construct( $title, $parserOutput, $recursive = true ) {
+		parent::__construct( false ); // no implicit transaction
+
+		if ( !( $title instanceof Title ) ) {
+			throw new MWException( "The calling convention to LinksUpdate::LinksUpdate() has changed. " .
+				"Please see Article::editUpdates() for an invocation example.\n" );
+		}
+
+		if ( !( $parserOutput instanceof ParserOutput ) ) {
+			throw new MWException( "The calling convention to LinksUpdate::__construct() has changed. " .
+				"Please see WikiPage::doEditUpdates() for an invocation example.\n" );
+		}
+
+		$this->mTitle = $title;
+		$this->mId = $title->getArticleID();
+
+		if ( !$this->mId ) {
+			throw new MWException( "The Title object did not provide an article " .
+				"ID. Perhaps the page doesn't exist?" );
+		}
+
+		$this->mParserOutput = $parserOutput;
+
+		$this->mLinks = $parserOutput->getLinks();
+		$this->mImages = $parserOutput->getImages();
+		$this->mTemplates = $parserOutput->getTemplates();
+		$this->mExternals = $parserOutput->getExternalLinks();
+		$this->mCategories = $parserOutput->getCategories();
+		$this->mProperties = $parserOutput->getProperties();
+		$this->mInterwikis = $parserOutput->getInterwikiLinks();
+
+		# Convert the format of the interlanguage links
+		# I didn't want to change it in the ParserOutput, because that array is passed all
+		# the way back to the skin, so either a skin API break would be required, or an
+		# inefficient back-conversion.
+		$ill = $parserOutput->getLanguageLinks();
+		$this->mInterlangs = array();
+		foreach ( $ill as $link ) {
+			list( $key, $title ) = explode( ':', $link, 2 );
+			$this->mInterlangs[$key] = $title;
+		}
+
+		foreach ( $this->mCategories as &$sortkey ) {
+			# If the sortkey is longer then 255 bytes,
+			# it truncated by DB, and then doesn't get
+			# matched when comparing existing vs current
+			# categories, causing bug 25254.
+			# Also. substr behaves weird when given "".
+			if ( $sortkey !== '' ) {
+				$sortkey = substr( $sortkey, 0, 255 );
+			}
+		}
+
+		$this->mRecursive = $recursive;
+
+		wfRunHooks( 'LinksUpdateConstructed', array( &$this ) );
+	}
+
+	/**
+	 * Update link tables with outgoing links from an updated article
+	 */
+	public function doUpdate() {
+		wfRunHooks( 'LinksUpdate', array( &$this ) );
+		$this->doIncrementalUpdate();
+		wfRunHooks( 'LinksUpdateComplete', array( &$this ) );
+	}
+
+	protected function doIncrementalUpdate() {
+		wfProfileIn( __METHOD__ );
+
+		# Page links
+		$existing = $this->getExistingLinks();
+		$this->linkDeletions = $this->getLinkDeletions( $existing );
+		$this->linkInsertions = $this->getLinkInsertions( $existing );
+		$this->incrTableUpdate( 'pagelinks', 'pl', $this->linkDeletions, $this->linkInsertions );
+
+		# Image links
+		$existing = $this->getExistingImages();
+
+		$imageDeletes = $this->getImageDeletions( $existing );
+		$this->incrTableUpdate( 'imagelinks', 'il', $imageDeletes,
+			$this->getImageInsertions( $existing ) );
+
+		# Invalidate all image description pages which had links added or removed
+		$imageUpdates = $imageDeletes + array_diff_key( $this->mImages, $existing );
+		$this->invalidateImageDescriptions( $imageUpdates );
+
+		# External links
+		$existing = $this->getExistingExternals();
+		$this->incrTableUpdate( 'externallinks', 'el', $this->getExternalDeletions( $existing ),
+			$this->getExternalInsertions( $existing ) );
+
+		# Language links
+		$existing = $this->getExistingInterlangs();
+		$this->incrTableUpdate( 'langlinks', 'll', $this->getInterlangDeletions( $existing ),
+			$this->getInterlangInsertions( $existing ) );
+
+		# Inline interwiki links
+		$existing = $this->getExistingInterwikis();
+		$this->incrTableUpdate( 'iwlinks', 'iwl', $this->getInterwikiDeletions( $existing ),
+			$this->getInterwikiInsertions( $existing ) );
+
+		# Template links
+		$existing = $this->getExistingTemplates();
+		$this->incrTableUpdate( 'templatelinks', 'tl', $this->getTemplateDeletions( $existing ),
+			$this->getTemplateInsertions( $existing ) );
+
+		# Category links
+		$existing = $this->getExistingCategories();
+
+		$categoryDeletes = $this->getCategoryDeletions( $existing );
+
+		$this->incrTableUpdate( 'categorylinks', 'cl', $categoryDeletes,
+			$this->getCategoryInsertions( $existing ) );
+
+		# Invalidate all categories which were added, deleted or changed (set symmetric difference)
+		$categoryInserts = array_diff_assoc( $this->mCategories, $existing );
+		$categoryUpdates = $categoryInserts + $categoryDeletes;
+		$this->invalidateCategories( $categoryUpdates );
+		$this->updateCategoryCounts( $categoryInserts, $categoryDeletes );
+
+		# Page properties
+		$existing = $this->getExistingProperties();
+
+		$propertiesDeletes = $this->getPropertyDeletions( $existing );
+
+		$this->incrTableUpdate( 'page_props', 'pp', $propertiesDeletes,
+			$this->getPropertyInsertions( $existing ) );
+
+		# Invalidate the necessary pages
+		$changed = $propertiesDeletes + array_diff_assoc( $this->mProperties, $existing );
+		$this->invalidateProperties( $changed );
+
+		# Update the links table freshness for this title
+		$this->updateLinksTimestamp();
+
+		# Refresh links of all pages including this page
+		# This will be in a separate transaction
+		if ( $this->mRecursive ) {
+			$this->queueRecursiveJobs();
+		}
+
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * Queue recursive jobs for this page
+	 *
+	 * Which means do LinksUpdate on all pages that include the current page,
+	 * using the job queue.
+	 */
+	function queueRecursiveJobs() {
+		self::queueRecursiveJobsForTable( $this->mTitle, 'templatelinks' );
+		if ( $this->mTitle->getNamespace() == NS_FILE ) {
+			// Process imagelinks in case the title is or was a redirect
+			self::queueRecursiveJobsForTable( $this->mTitle, 'imagelinks' );
+		}
+	}
+
+	/**
+	 * Queue a RefreshLinks job for any table.
+	 *
+	 * @param Title $title Title to do job for
+	 * @param string $table Table to use (e.g. 'templatelinks')
+	 */
+	public static function queueRecursiveJobsForTable( Title $title, $table ) {
+		wfProfileIn( __METHOD__ );
+		if ( $title->getBacklinkCache()->hasLinks( $table ) ) {
+			$job = new RefreshLinksJob(
+				$title,
+				array(
+					'table' => $table,
+					'recursive' => true,
+				) + Job::newRootJobParams( // "overall" refresh links job info
+					"refreshlinks:{$table}:{$title->getPrefixedText()}"
+				)
+			);
+			JobQueueGroup::singleton()->push( $job );
+			JobQueueGroup::singleton()->deduplicateRootJob( $job );
+		}
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * @param array $cats
+	 */
+	function invalidateCategories( $cats ) {
+		$this->invalidatePages( NS_CATEGORY, array_keys( $cats ) );
+	}
+
+	/**
+	 * Update all the appropriate counts in the category table.
+	 * @param array $added Associative array of category name => sort key
+	 * @param array $deleted Associative array of category name => sort key
+	 */
+	function updateCategoryCounts( $added, $deleted ) {
+		$a = WikiPage::factory( $this->mTitle );
+		$a->updateCategoryCounts(
+			array_keys( $added ), array_keys( $deleted )
+		);
+	}
+
+	/**
+	 * @param array $images
+	 */
+	function invalidateImageDescriptions( $images ) {
+		$this->invalidatePages( NS_FILE, array_keys( $images ) );
+	}
+
+	/**
+	 * Update a table by doing a delete query then an insert query
+	 * @param string $table Table name
+	 * @param string $prefix Field name prefix
+	 * @param array $deletions
+	 * @param array $insertions Rows to insert
+	 */
+	function incrTableUpdate( $table, $prefix, $deletions, $insertions ) {
+		if ( $table == 'page_props' ) {
+			$fromField = 'pp_page';
+		} else {
+			$fromField = "{$prefix}_from";
+		}
+		$where = array( $fromField => $this->mId );
+		if ( $table == 'pagelinks' || $table == 'templatelinks' || $table == 'iwlinks' ) {
+			if ( $table == 'iwlinks' ) {
+				$baseKey = 'iwl_prefix';
+			} else {
+				$baseKey = "{$prefix}_namespace";
+			}
+			$clause = $this->mDb->makeWhereFrom2d( $deletions, $baseKey, "{$prefix}_title" );
+			if ( $clause ) {
+				$where[] = $clause;
+			} else {
+				$where = false;
+			}
+		} else {
+			if ( $table == 'langlinks' ) {
+				$toField = 'll_lang';
+			} elseif ( $table == 'page_props' ) {
+				$toField = 'pp_propname';
+			} else {
+				$toField = $prefix . '_to';
+			}
+			if ( count( $deletions ) ) {
+				$where[$toField] = array_keys( $deletions );
+			} else {
+				$where = false;
+			}
+		}
+		if ( $where ) {
+			$this->mDb->delete( $table, $where, __METHOD__ );
+		}
+		if ( count( $insertions ) ) {
+			$this->mDb->insert( $table, $insertions, __METHOD__, 'IGNORE' );
+			wfRunHooks( 'LinksUpdateAfterInsert', array( $this, $table, $insertions ) );
+		}
+	}
+
+	/**
+	 * Get an array of pagelinks insertions for passing to the DB
+	 * Skips the titles specified by the 2-D array $existing
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getLinkInsertions( $existing = array() ) {
+		$arr = array();
+		foreach ( $this->mLinks as $ns => $dbkeys ) {
+			$diffs = isset( $existing[$ns] )
+				? array_diff_key( $dbkeys, $existing[$ns] )
+				: $dbkeys;
+			foreach ( $diffs as $dbk => $id ) {
+				$arr[] = array(
+					'pl_from' => $this->mId,
+					'pl_from_namespace' => $this->mTitle->getNamespace(),
+					'pl_namespace' => $ns,
+					'pl_title' => $dbk
+				);
+			}
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of template insertions. Like getLinkInsertions()
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getTemplateInsertions( $existing = array() ) {
+		$arr = array();
+		foreach ( $this->mTemplates as $ns => $dbkeys ) {
+			$diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
+			foreach ( $diffs as $dbk => $id ) {
+				$arr[] = array(
+					'tl_from' => $this->mId,
+					'tl_from_namespace' => $this->mTitle->getNamespace(),
+					'tl_namespace' => $ns,
+					'tl_title' => $dbk
+				);
+			}
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of image insertions
+	 * Skips the names specified in $existing
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getImageInsertions( $existing = array() ) {
+		$arr = array();
+		$diffs = array_diff_key( $this->mImages, $existing );
+		foreach ( $diffs as $iname => $dummy ) {
+			$arr[] = array(
+				'il_from' => $this->mId,
+				'il_from_namespace' => $this->mTitle->getNamespace(),
+				'il_to' => $iname
+			);
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of externallinks insertions. Skips the names specified in $existing
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getExternalInsertions( $existing = array() ) {
+		$arr = array();
+		$diffs = array_diff_key( $this->mExternals, $existing );
+		foreach ( $diffs as $url => $dummy ) {
+			foreach ( wfMakeUrlIndexes( $url ) as $index ) {
+				$arr[] = array(
+					'el_id' => $this->mDb->nextSequenceValue( 'externallinks_el_id_seq' ),
+					'el_from' => $this->mId,
+					'el_to' => $url,
+					'el_index' => $index,
+				);
+			}
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of category insertions
+	 *
+	 * @param array $existing Mapping existing category names to sort keys. If both
+	 * match a link in $this, the link will be omitted from the output
+	 *
+	 * @return array
+	 */
+	private function getCategoryInsertions( $existing = array() ) {
+		global $wgContLang, $wgCategoryCollation;
+		$diffs = array_diff_assoc( $this->mCategories, $existing );
+		$arr = array();
+		foreach ( $diffs as $name => $prefix ) {
+			$nt = Title::makeTitleSafe( NS_CATEGORY, $name );
+			$wgContLang->findVariantLink( $name, $nt, true );
+
+			if ( $this->mTitle->getNamespace() == NS_CATEGORY ) {
+				$type = 'subcat';
+			} elseif ( $this->mTitle->getNamespace() == NS_FILE ) {
+				$type = 'file';
+			} else {
+				$type = 'page';
+			}
+
+			# Treat custom sortkeys as a prefix, so that if multiple
+			# things are forced to sort as '*' or something, they'll
+			# sort properly in the category rather than in page_id
+			# order or such.
+			$sortkey = Collation::singleton()->getSortKey(
+				$this->mTitle->getCategorySortkey( $prefix ) );
+
+			$arr[] = array(
+				'cl_from' => $this->mId,
+				'cl_to' => $name,
+				'cl_sortkey' => $sortkey,
+				'cl_timestamp' => $this->mDb->timestamp(),
+				'cl_sortkey_prefix' => $prefix,
+				'cl_collation' => $wgCategoryCollation,
+				'cl_type' => $type,
+			);
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of interlanguage link insertions
+	 *
+	 * @param array $existing Mapping existing language codes to titles
+	 *
+	 * @return array
+	 */
+	private function getInterlangInsertions( $existing = array() ) {
+		$diffs = array_diff_assoc( $this->mInterlangs, $existing );
+		$arr = array();
+		foreach ( $diffs as $lang => $title ) {
+			$arr[] = array(
+				'll_from' => $this->mId,
+				'll_lang' => $lang,
+				'll_title' => $title
+			);
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of page property insertions
+	 * @param array $existing
+	 * @return array
+	 */
+	function getPropertyInsertions( $existing = array() ) {
+		$diffs = array_diff_assoc( $this->mProperties, $existing );
+
+		$arr = array();
+		foreach ( array_keys( $diffs ) as $name ) {
+			$arr[] = $this->getPagePropRowData( $name );
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Returns an associative array to be used for inserting a row into
+	 * the page_props table. Besides the given property name, this will
+	 * include the page id from $this->mId and any property value from
+	 * $this->mProperties.
+	 *
+	 * The array returned will include the pp_sortkey field if this
+	 * is present in the database (as indicated by $wgPagePropsHaveSortkey).
+	 * The sortkey value is currently determined by getPropertySortKeyValue().
+	 *
+	 * @note this assumes that $this->mProperties[$prop] is defined.
+	 *
+	 * @param string $prop The name of the property.
+	 *
+	 * @return array
+	 */
+	private function getPagePropRowData( $prop ) {
+		global $wgPagePropsHaveSortkey;
+
+		$value = $this->mProperties[$prop];
+
+		$row = array(
+			'pp_page' => $this->mId,
+			'pp_propname' => $prop,
+			'pp_value' => $value,
+		);
+
+		if ( $wgPagePropsHaveSortkey ) {
+			$row['pp_sortkey'] = $this->getPropertySortKeyValue( $value );
+		}
+
+		return $row;
+	}
+
+	/**
+	 * Determines the sort key for the given property value.
+	 * This will return $value if it is a float or int,
+	 * 1 or resp. 0 if it is a bool, and null otherwise.
+	 *
+	 * @note In the future, we may allow the sortkey to be specified explicitly
+	 *       in ParserOutput::setProperty.
+	 *
+	 * @param mixed $value
+	 *
+	 * @return float|null
+	 */
+	private function getPropertySortKeyValue( $value ) {
+		if ( is_int( $value ) || is_float( $value ) || is_bool( $value ) ) {
+			return floatval( $value );
+		}
+
+		return null;
+	}
+
+	/**
+	 * Get an array of interwiki insertions for passing to the DB
+	 * Skips the titles specified by the 2-D array $existing
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getInterwikiInsertions( $existing = array() ) {
+		$arr = array();
+		foreach ( $this->mInterwikis as $prefix => $dbkeys ) {
+			$diffs = isset( $existing[$prefix] )
+				? array_diff_key( $dbkeys, $existing[$prefix] )
+				: $dbkeys;
+
+			foreach ( $diffs as $dbk => $id ) {
+				$arr[] = array(
+					'iwl_from' => $this->mId,
+					'iwl_prefix' => $prefix,
+					'iwl_title' => $dbk
+				);
+			}
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Given an array of existing links, returns those links which are not in $this
+	 * and thus should be deleted.
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getLinkDeletions( $existing ) {
+		$del = array();
+		foreach ( $existing as $ns => $dbkeys ) {
+			if ( isset( $this->mLinks[$ns] ) ) {
+				$del[$ns] = array_diff_key( $existing[$ns], $this->mLinks[$ns] );
+			} else {
+				$del[$ns] = $existing[$ns];
+			}
+		}
+
+		return $del;
+	}
+
+	/**
+	 * Given an array of existing templates, returns those templates which are not in $this
+	 * and thus should be deleted.
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getTemplateDeletions( $existing ) {
+		$del = array();
+		foreach ( $existing as $ns => $dbkeys ) {
+			if ( isset( $this->mTemplates[$ns] ) ) {
+				$del[$ns] = array_diff_key( $existing[$ns], $this->mTemplates[$ns] );
+			} else {
+				$del[$ns] = $existing[$ns];
+			}
+		}
+
+		return $del;
+	}
+
+	/**
+	 * Given an array of existing images, returns those images which are not in $this
+	 * and thus should be deleted.
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getImageDeletions( $existing ) {
+		return array_diff_key( $existing, $this->mImages );
+	}
+
+	/**
+	 * Given an array of existing external links, returns those links which are not
+	 * in $this and thus should be deleted.
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getExternalDeletions( $existing ) {
+		return array_diff_key( $existing, $this->mExternals );
+	}
+
+	/**
+	 * Given an array of existing categories, returns those categories which are not in $this
+	 * and thus should be deleted.
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getCategoryDeletions( $existing ) {
+		return array_diff_assoc( $existing, $this->mCategories );
+	}
+
+	/**
+	 * Given an array of existing interlanguage links, returns those links which are not
+	 * in $this and thus should be deleted.
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getInterlangDeletions( $existing ) {
+		return array_diff_assoc( $existing, $this->mInterlangs );
+	}
+
+	/**
+	 * Get array of properties which should be deleted.
+	 * @param array $existing
+	 * @return array
+	 */
+	function getPropertyDeletions( $existing ) {
+		return array_diff_assoc( $existing, $this->mProperties );
+	}
+
+	/**
+	 * Given an array of existing interwiki links, returns those links which are not in $this
+	 * and thus should be deleted.
+	 * @param array $existing
+	 * @return array
+	 */
+	private function getInterwikiDeletions( $existing ) {
+		$del = array();
+		foreach ( $existing as $prefix => $dbkeys ) {
+			if ( isset( $this->mInterwikis[$prefix] ) ) {
+				$del[$prefix] = array_diff_key( $existing[$prefix], $this->mInterwikis[$prefix] );
+			} else {
+				$del[$prefix] = $existing[$prefix];
+			}
+		}
+
+		return $del;
+	}
+
+	/**
+	 * Get an array of existing links, as a 2-D array
+	 *
+	 * @return array
+	 */
+	private function getExistingLinks() {
+		$res = $this->mDb->select( 'pagelinks', array( 'pl_namespace', 'pl_title' ),
+			array( 'pl_from' => $this->mId ), __METHOD__, $this->mOptions );
+		$arr = array();
+		foreach ( $res as $row ) {
+			if ( !isset( $arr[$row->pl_namespace] ) ) {
+				$arr[$row->pl_namespace] = array();
+			}
+			$arr[$row->pl_namespace][$row->pl_title] = 1;
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of existing templates, as a 2-D array
+	 *
+	 * @return array
+	 */
+	private function getExistingTemplates() {
+		$res = $this->mDb->select( 'templatelinks', array( 'tl_namespace', 'tl_title' ),
+			array( 'tl_from' => $this->mId ), __METHOD__, $this->mOptions );
+		$arr = array();
+		foreach ( $res as $row ) {
+			if ( !isset( $arr[$row->tl_namespace] ) ) {
+				$arr[$row->tl_namespace] = array();
+			}
+			$arr[$row->tl_namespace][$row->tl_title] = 1;
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of existing images, image names in the keys
+	 *
+	 * @return array
+	 */
+	private function getExistingImages() {
+		$res = $this->mDb->select( 'imagelinks', array( 'il_to' ),
+			array( 'il_from' => $this->mId ), __METHOD__, $this->mOptions );
+		$arr = array();
+		foreach ( $res as $row ) {
+			$arr[$row->il_to] = 1;
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of existing external links, URLs in the keys
+	 *
+	 * @return array
+	 */
+	private function getExistingExternals() {
+		$res = $this->mDb->select( 'externallinks', array( 'el_to' ),
+			array( 'el_from' => $this->mId ), __METHOD__, $this->mOptions );
+		$arr = array();
+		foreach ( $res as $row ) {
+			$arr[$row->el_to] = 1;
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of existing categories, with the name in the key and sort key in the value.
+	 *
+	 * @return array
+	 */
+	private function getExistingCategories() {
+		$res = $this->mDb->select( 'categorylinks', array( 'cl_to', 'cl_sortkey_prefix' ),
+			array( 'cl_from' => $this->mId ), __METHOD__, $this->mOptions );
+		$arr = array();
+		foreach ( $res as $row ) {
+			$arr[$row->cl_to] = $row->cl_sortkey_prefix;
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of existing interlanguage links, with the language code in the key and the
+	 * title in the value.
+	 *
+	 * @return array
+	 */
+	private function getExistingInterlangs() {
+		$res = $this->mDb->select( 'langlinks', array( 'll_lang', 'll_title' ),
+			array( 'll_from' => $this->mId ), __METHOD__, $this->mOptions );
+		$arr = array();
+		foreach ( $res as $row ) {
+			$arr[$row->ll_lang] = $row->ll_title;
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of existing inline interwiki links, as a 2-D array
+	 * @return array (prefix => array(dbkey => 1))
+	 */
+	protected function getExistingInterwikis() {
+		$res = $this->mDb->select( 'iwlinks', array( 'iwl_prefix', 'iwl_title' ),
+			array( 'iwl_from' => $this->mId ), __METHOD__, $this->mOptions );
+		$arr = array();
+		foreach ( $res as $row ) {
+			if ( !isset( $arr[$row->iwl_prefix] ) ) {
+				$arr[$row->iwl_prefix] = array();
+			}
+			$arr[$row->iwl_prefix][$row->iwl_title] = 1;
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Get an array of existing categories, with the name in the key and sort key in the value.
+	 *
+	 * @return array Array of property names and values
+	 */
+	private function getExistingProperties() {
+		$res = $this->mDb->select( 'page_props', array( 'pp_propname', 'pp_value' ),
+			array( 'pp_page' => $this->mId ), __METHOD__, $this->mOptions );
+		$arr = array();
+		foreach ( $res as $row ) {
+			$arr[$row->pp_propname] = $row->pp_value;
+		}
+
+		return $arr;
+	}
+
+	/**
+	 * Return the title object of the page being updated
+	 * @return Title
+	 */
+	public function getTitle() {
+		return $this->mTitle;
+	}
+
+	/**
+	 * Returns parser output
+	 * @since 1.19
+	 * @return ParserOutput
+	 */
+	public function getParserOutput() {
+		return $this->mParserOutput;
+	}
+
+	/**
+	 * Return the list of images used as generated by the parser
+	 * @return array
+	 */
+	public function getImages() {
+		return $this->mImages;
+	}
+
+	/**
+	 * Invalidate any necessary link lists related to page property changes
+	 * @param array $changed
+	 */
+	private function invalidateProperties( $changed ) {
+		global $wgPagePropLinkInvalidations;
+
+		foreach ( $changed as $name => $value ) {
+			if ( isset( $wgPagePropLinkInvalidations[$name] ) ) {
+				$inv = $wgPagePropLinkInvalidations[$name];
+				if ( !is_array( $inv ) ) {
+					$inv = array( $inv );
+				}
+				foreach ( $inv as $table ) {
+					$update = new HTMLCacheUpdate( $this->mTitle, $table );
+					$update->doUpdate();
+				}
+			}
+		}
+	}
+
+	/**
+	 * Fetch page links added by this LinksUpdate.  Only available after the update is complete.
+	 * @since 1.22
+	 * @return null|array Array of Titles
+	 */
+	public function getAddedLinks() {
+		if ( $this->linkInsertions === null ) {
+			return null;
+		}
+		$result = array();
+		foreach ( $this->linkInsertions as $insertion ) {
+			$result[] = Title::makeTitle( $insertion['pl_namespace'], $insertion['pl_title'] );
+		}
+
+		return $result;
+	}
+
+	/**
+	 * Fetch page links removed by this LinksUpdate.  Only available after the update is complete.
+	 * @since 1.22
+	 * @return null|array Array of Titles
+	 */
+	public function getRemovedLinks() {
+		if ( $this->linkDeletions === null ) {
+			return null;
+		}
+		$result = array();
+		foreach ( $this->linkDeletions as $ns => $titles ) {
+			foreach ( $titles as $title => $unused ) {
+				$result[] = Title::makeTitle( $ns, $title );
+			}
+		}
+
+		return $result;
+	}
+
+	/**
+	 * Update links table freshness
+	 */
+	protected function updateLinksTimestamp() {
+		if ( $this->mId ) {
+			// The link updates made here only reflect the freshness of the parser output
+			$timestamp = $this->mParserOutput->getCacheTime();
+			$this->mDb->update( 'page',
+				array( 'page_links_updated' => $this->mDb->timestamp( $timestamp ) ),
+				array( 'page_id' => $this->mId ),
+				__METHOD__
+			);
+		}
+	}
+}
+
+/**
+ * Update object handling the cleanup of links tables after a page was deleted.
+ **/
+class LinksDeletionUpdate extends SqlDataUpdate {
+	/** @var WikiPage The WikiPage that was deleted */
+	protected $mPage;
+
+	/**
+	 * Constructor
+	 *
+	 * @param WikiPage $page Page we are updating
+	 * @throws MWException
+	 */
+	function __construct( WikiPage $page ) {
+		parent::__construct( false ); // no implicit transaction
+
+		$this->mPage = $page;
+
+		if ( !$page->exists() ) {
+			throw new MWException( "Page ID not known, perhaps the page doesn't exist?" );
+		}
+	}
+
+	/**
+	 * Do some database updates after deletion
+	 */
+	public function doUpdate() {
+		$title = $this->mPage->getTitle();
+		$id = $this->mPage->getId();
+
+		# Delete restrictions for it
+		$this->mDb->delete( 'page_restrictions', array( 'pr_page' => $id ), __METHOD__ );
+
+		# Fix category table counts
+		$cats = array();
+		$res = $this->mDb->select( 'categorylinks', 'cl_to', array( 'cl_from' => $id ), __METHOD__ );
+
+		foreach ( $res as $row ) {
+			$cats[] = $row->cl_to;
+		}
+
+		$this->mPage->updateCategoryCounts( array(), $cats );
+
+		# If using cascading deletes, we can skip some explicit deletes
+		if ( !$this->mDb->cascadingDeletes() ) {
+			# Delete outgoing links
+			$this->mDb->delete( 'pagelinks', array( 'pl_from' => $id ), __METHOD__ );
+			$this->mDb->delete( 'imagelinks', array( 'il_from' => $id ), __METHOD__ );
+			$this->mDb->delete( 'categorylinks', array( 'cl_from' => $id ), __METHOD__ );
+			$this->mDb->delete( 'templatelinks', array( 'tl_from' => $id ), __METHOD__ );
+			$this->mDb->delete( 'externallinks', array( 'el_from' => $id ), __METHOD__ );
+			$this->mDb->delete( 'langlinks', array( 'll_from' => $id ), __METHOD__ );
+			$this->mDb->delete( 'iwlinks', array( 'iwl_from' => $id ), __METHOD__ );
+			$this->mDb->delete( 'redirect', array( 'rd_from' => $id ), __METHOD__ );
+			$this->mDb->delete( 'page_props', array( 'pp_page' => $id ), __METHOD__ );
+		}
+
+		# If using cleanup triggers, we can skip some manual deletes
+		if ( !$this->mDb->cleanupTriggers() ) {
+			# Clean up recentchanges entries...
+			$this->mDb->delete( 'recentchanges',
+				array( 'rc_type != ' . RC_LOG,
+					'rc_namespace' => $title->getNamespace(),
+					'rc_title' => $title->getDBkey() ),
+				__METHOD__ );
+			$this->mDb->delete( 'recentchanges',
+				array( 'rc_type != ' . RC_LOG, 'rc_cur_id' => $id ),
+				__METHOD__ );
+		}
+	}
+
+	/**
+	 * Update all the appropriate counts in the category table.
+	 * @param array $added Associative array of category name => sort key
+	 * @param array $deleted Associative array of category name => sort key
+	 */
+	function updateCategoryCounts( $added, $deleted ) {
+		$a = WikiPage::factory( $this->mTitle );
+		$a->updateCategoryCounts(
+			array_keys( $added ), array_keys( $deleted )
+		);
+	}
+}
diff --git a/includes/deferred/SearchUpdate.php b/includes/deferred/SearchUpdate.php
new file mode 100644
index 00000000..5d084afd
--- /dev/null
+++ b/includes/deferred/SearchUpdate.php
@@ -0,0 +1,209 @@
+<?php
+/**
+ * Search index updater
+ *
+ * See deferred.txt
+ *
+ * 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 Search
+ */
+
+/**
+ * Database independant search index updater
+ *
+ * @ingroup Search
+ */
+class SearchUpdate implements DeferrableUpdate {
+	/** @var int Page id being updated */
+	private $id = 0;
+
+	/** @var Title Title we're updating */
+	private $title;
+
+	/** @var Content|bool Content of the page (not text) */
+	private $content;
+
+	/**
+	 * Constructor
+	 *
+	 * @param int $id Page id to update
+	 * @param Title|string $title Title of page to update
+	 * @param Content|string|bool $c Content of the page to update. Default: false.
+	 *  If a Content object, text will be gotten from it. String is for back-compat.
+	 *  Passing false tells the backend to just update the title, not the content
+	 */
+	public function __construct( $id, $title, $c = false ) {
+		if ( is_string( $title ) ) {
+			$nt = Title::newFromText( $title );
+		} else {
+			$nt = $title;
+		}
+
+		if ( $nt ) {
+			$this->id = $id;
+			// is_string() check is back-compat for ApprovedRevs
+			if ( is_string( $c ) ) {
+				$this->content = new TextContent( $c );
+			} else {
+				$this->content = $c ?: false;
+			}
+			$this->title = $nt;
+		} else {
+			wfDebug( "SearchUpdate object created with invalid title '$title'\n" );
+		}
+	}
+
+	/**
+	 * Perform actual update for the entry
+	 */
+	public function doUpdate() {
+		global $wgDisableSearchUpdate;
+
+		if ( $wgDisableSearchUpdate || !$this->id ) {
+			return;
+		}
+
+		wfProfileIn( __METHOD__ );
+
+		$page = WikiPage::newFromId( $this->id, WikiPage::READ_LATEST );
+
+		foreach ( SearchEngine::getSearchTypes() as $type ) {
+			$search = SearchEngine::create( $type );
+			$indexTitle = $this->indexTitle( $search );
+			if ( !$search->supports( 'search-update' ) ) {
+				continue;
+			}
+
+			$normalTitle = $search->normalizeText( $indexTitle );
+
+			if ( $page === null ) {
+				$search->delete( $this->id, $normalTitle );
+				continue;
+			} elseif ( $this->content === false ) {
+				$search->updateTitle( $this->id, $normalTitle );
+				continue;
+			}
+
+			$text = $search->getTextFromContent( $this->title, $this->content );
+			if ( !$search->textAlreadyUpdatedForIndex() ) {
+				$text = self::updateText( $text );
+			}
+
+			# Perform the actual update
+			$search->update( $this->id, $normalTitle, $search->normalizeText( $text ) );
+		}
+
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * Clean text for indexing. Only really suitable for indexing in databases.
+	 * If you're using a real search engine, you'll probably want to override
+	 * this behavior and do something nicer with the original wikitext.
+	 * @param string $text
+	 * @return string
+	 */
+	public static function updateText( $text ) {
+		global $wgContLang;
+
+		# Language-specific strip/conversion
+		$text = $wgContLang->normalizeForSearch( $text );
+		$lc = SearchEngine::legalSearchChars() . '&#;';
+
+		wfProfileIn( __METHOD__ . '-regexps' );
+		$text = preg_replace( "/<\\/?\\s*[A-Za-z][^>]*?>/",
+			' ', $wgContLang->lc( " " . $text . " " ) ); # Strip HTML markup
+		$text = preg_replace( "/(^|\\n)==\\s*([^\\n]+)\\s*==(\\s)/sD",
+			"\\1\\2 \\2 \\2\\3", $text ); # Emphasize headings
+
+		# Strip external URLs
+		$uc = "A-Za-z0-9_\\/:.,~%\\-+&;#?!=()@\\x80-\\xFF";
+		$protos = "http|https|ftp|mailto|news|gopher";
+		$pat = "/(^|[^\\[])({$protos}):[{$uc}]+([^{$uc}]|$)/";
+		$text = preg_replace( $pat, "\\1 \\3", $text );
+
+		$p1 = "/([^\\[])\\[({$protos}):[{$uc}]+]/";
+		$p2 = "/([^\\[])\\[({$protos}):[{$uc}]+\\s+([^\\]]+)]/";
+		$text = preg_replace( $p1, "\\1 ", $text );
+		$text = preg_replace( $p2, "\\1 \\3 ", $text );
+
+		# Internal image links
+		$pat2 = "/\\[\\[image:([{$uc}]+)\\.(gif|png|jpg|jpeg)([^{$uc}])/i";
+		$text = preg_replace( $pat2, " \\1 \\3", $text );
+
+		$text = preg_replace( "/([^{$lc}])([{$lc}]+)]]([a-z]+)/",
+			"\\1\\2 \\2\\3", $text ); # Handle [[game]]s
+
+		# Strip all remaining non-search characters
+		$text = preg_replace( "/[^{$lc}]+/", " ", $text );
+
+		# Handle 's, s'
+		#
+		#   $text = preg_replace( "/([{$lc}]+)'s /", "\\1 \\1's ", $text );
+		#   $text = preg_replace( "/([{$lc}]+)s' /", "\\1s ", $text );
+		#
+		# These tail-anchored regexps are insanely slow. The worst case comes
+		# when Japanese or Chinese text (ie, no word spacing) is written on
+		# a wiki configured for Western UTF-8 mode. The Unicode characters are
+		# expanded to hex codes and the "words" are very long paragraph-length
+		# monstrosities. On a large page the above regexps may take over 20
+		# seconds *each* on a 1GHz-level processor.
+		#
+		# Following are reversed versions which are consistently fast
+		# (about 3 milliseconds on 1GHz-level processor).
+		#
+		$text = strrev( preg_replace( "/ s'([{$lc}]+)/", " s'\\1 \\1", strrev( $text ) ) );
+		$text = strrev( preg_replace( "/ 's([{$lc}]+)/", " s\\1", strrev( $text ) ) );
+
+		# Strip wiki '' and '''
+		$text = preg_replace( "/''[']*/", " ", $text );
+		wfProfileOut( __METHOD__ . '-regexps' );
+
+		return $text;
+	}
+
+	/**
+	 * Get a string representation of a title suitable for
+	 * including in a search index
+	 *
+	 * @param SearchEngine $search
+	 * @return string A stripped-down title string ready for the search index
+	 */
+	private function indexTitle( SearchEngine $search ) {
+		global $wgContLang;
+
+		$ns = $this->title->getNamespace();
+		$title = $this->title->getText();
+
+		$lc = $search->legalSearchChars() . '&#;';
+		$t = $wgContLang->normalizeForSearch( $title );
+		$t = preg_replace( "/[^{$lc}]+/", ' ', $t );
+		$t = $wgContLang->lc( $t );
+
+		# Handle 's, s'
+		$t = preg_replace( "/([{$lc}]+)'s( |$)/", "\\1 \\1's ", $t );
+		$t = preg_replace( "/([{$lc}]+)s'( |$)/", "\\1s ", $t );
+
+		$t = preg_replace( "/\\s+/", ' ', $t );
+
+		if ( $ns == NS_FILE ) {
+			$t = preg_replace( "/ (png|gif|jpg|jpeg|ogg)$/", "", $t );
+		}
+		return trim( $t );
+	}
+}
diff --git a/includes/deferred/SiteStatsUpdate.php b/includes/deferred/SiteStatsUpdate.php
new file mode 100644
index 00000000..7bfafee8
--- /dev/null
+++ b/includes/deferred/SiteStatsUpdate.php
@@ -0,0 +1,254 @@
+<?php
+/**
+ * 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
+ */
+
+/**
+ * Class for handling updates to the site_stats table
+ */
+class SiteStatsUpdate implements DeferrableUpdate {
+	/** @var int */
+	protected $views = 0;
+
+	/** @var int */
+	protected $edits = 0;
+
+	/** @var int */
+	protected $pages = 0;
+
+	/** @var int */
+	protected $articles = 0;
+
+	/** @var int */
+	protected $users = 0;
+
+	/** @var int */
+	protected $images = 0;
+
+	// @todo deprecate this constructor
+	function __construct( $views, $edits, $good, $pages = 0, $users = 0 ) {
+		$this->views = $views;
+		$this->edits = $edits;
+		$this->articles = $good;
+		$this->pages = $pages;
+		$this->users = $users;
+	}
+
+	/**
+	 * @param array $deltas
+	 * @return SiteStatsUpdate
+	 */
+	public static function factory( array $deltas ) {
+		$update = new self( 0, 0, 0 );
+
+		$fields = array( 'views', 'edits', 'pages', 'articles', 'users', 'images' );
+		foreach ( $fields as $field ) {
+			if ( isset( $deltas[$field] ) && $deltas[$field] ) {
+				$update->$field = $deltas[$field];
+			}
+		}
+
+		return $update;
+	}
+
+	public function doUpdate() {
+		global $wgSiteStatsAsyncFactor;
+
+		$rate = $wgSiteStatsAsyncFactor; // convenience
+		// If set to do so, only do actual DB updates 1 every $rate times.
+		// The other times, just update "pending delta" values in memcached.
+		if ( $rate && ( $rate < 0 || mt_rand( 0, $rate - 1 ) != 0 ) ) {
+			$this->doUpdatePendingDeltas();
+		} else {
+			// Need a separate transaction because this a global lock
+			wfGetDB( DB_MASTER )->onTransactionIdle( array( $this, 'tryDBUpdateInternal' ) );
+		}
+	}
+
+	/**
+	 * Do not call this outside of SiteStatsUpdate
+	 */
+	public function tryDBUpdateInternal() {
+		global $wgSiteStatsAsyncFactor;
+
+		$dbw = wfGetDB( DB_MASTER );
+		$lockKey = wfMemcKey( 'site_stats' ); // prepend wiki ID
+		$pd = array();
+		if ( $wgSiteStatsAsyncFactor ) {
+			// Lock the table so we don't have double DB/memcached updates
+			if ( !$dbw->lockIsFree( $lockKey, __METHOD__ )
+				|| !$dbw->lock( $lockKey, __METHOD__, 1 ) // 1 sec timeout
+			) {
+				$this->doUpdatePendingDeltas();
+
+				return;
+			}
+			$pd = $this->getPendingDeltas();
+			// Piggy-back the async deltas onto those of this stats update....
+			$this->views += ( $pd['ss_total_views']['+'] - $pd['ss_total_views']['-'] );
+			$this->edits += ( $pd['ss_total_edits']['+'] - $pd['ss_total_edits']['-'] );
+			$this->articles += ( $pd['ss_good_articles']['+'] - $pd['ss_good_articles']['-'] );
+			$this->pages += ( $pd['ss_total_pages']['+'] - $pd['ss_total_pages']['-'] );
+			$this->users += ( $pd['ss_users']['+'] - $pd['ss_users']['-'] );
+			$this->images += ( $pd['ss_images']['+'] - $pd['ss_images']['-'] );
+		}
+
+		// Build up an SQL query of deltas and apply them...
+		$updates = '';
+		$this->appendUpdate( $updates, 'ss_total_views', $this->views );
+		$this->appendUpdate( $updates, 'ss_total_edits', $this->edits );
+		$this->appendUpdate( $updates, 'ss_good_articles', $this->articles );
+		$this->appendUpdate( $updates, 'ss_total_pages', $this->pages );
+		$this->appendUpdate( $updates, 'ss_users', $this->users );
+		$this->appendUpdate( $updates, 'ss_images', $this->images );
+		if ( $updates != '' ) {
+			$dbw->update( 'site_stats', array( $updates ), array(), __METHOD__ );
+		}
+
+		if ( $wgSiteStatsAsyncFactor ) {
+			// Decrement the async deltas now that we applied them
+			$this->removePendingDeltas( $pd );
+			// Commit the updates and unlock the table
+			$dbw->unlock( $lockKey, __METHOD__ );
+		}
+	}
+
+	/**
+	 * @param DatabaseBase $dbw
+	 * @return bool|mixed
+	 */
+	public static function cacheUpdate( $dbw ) {
+		global $wgActiveUserDays;
+		$dbr = wfGetDB( DB_SLAVE, array( 'SpecialStatistics', 'vslow' ) );
+		# Get non-bot users than did some recent action other than making accounts.
+		# If account creation is included, the number gets inflated ~20+ fold on enwiki.
+		$activeUsers = $dbr->selectField(
+			'recentchanges',
+			'COUNT( DISTINCT rc_user_text )',
+			array(
+				'rc_user != 0',
+				'rc_bot' => 0,
+				'rc_log_type != ' . $dbr->addQuotes( 'newusers' ) . ' OR rc_log_type IS NULL',
+				'rc_timestamp >= ' . $dbr->addQuotes( $dbr->timestamp( wfTimestamp( TS_UNIX )
+					- $wgActiveUserDays * 24 * 3600 ) ),
+			),
+			__METHOD__
+		);
+		$dbw->update(
+			'site_stats',
+			array( 'ss_active_users' => intval( $activeUsers ) ),
+			array( 'ss_row_id' => 1 ),
+			__METHOD__
+		);
+
+		return $activeUsers;
+	}
+
+	protected function doUpdatePendingDeltas() {
+		$this->adjustPending( 'ss_total_views', $this->views );
+		$this->adjustPending( 'ss_total_edits', $this->edits );
+		$this->adjustPending( 'ss_good_articles', $this->articles );
+		$this->adjustPending( 'ss_total_pages', $this->pages );
+		$this->adjustPending( 'ss_users', $this->users );
+		$this->adjustPending( 'ss_images', $this->images );
+	}
+
+	/**
+	 * @param string $sql
+	 * @param string $field
+	 * @param int $delta
+	 */
+	protected function appendUpdate( &$sql, $field, $delta ) {
+		if ( $delta ) {
+			if ( $sql ) {
+				$sql .= ',';
+			}
+			if ( $delta < 0 ) {
+				$sql .= "$field=$field-" . abs( $delta );
+			} else {
+				$sql .= "$field=$field+" . abs( $delta );
+			}
+		}
+	}
+
+	/**
+	 * @param string $type
+	 * @param string $sign ('+' or '-')
+	 * @return string
+	 */
+	private function getTypeCacheKey( $type, $sign ) {
+		return wfMemcKey( 'sitestatsupdate', 'pendingdelta', $type, $sign );
+	}
+
+	/**
+	 * Adjust the pending deltas for a stat type.
+	 * Each stat type has two pending counters, one for increments and decrements
+	 * @param string $type
+	 * @param int $delta Delta (positive or negative)
+	 */
+	protected function adjustPending( $type, $delta ) {
+		global $wgMemc;
+
+		if ( $delta < 0 ) { // decrement
+			$key = $this->getTypeCacheKey( $type, '-' );
+		} else { // increment
+			$key = $this->getTypeCacheKey( $type, '+' );
+		}
+
+		$magnitude = abs( $delta );
+		if ( !$wgMemc->incr( $key, $magnitude ) ) { // not there?
+			if ( !$wgMemc->add( $key, $magnitude ) ) { // race?
+				$wgMemc->incr( $key, $magnitude );
+			}
+		}
+	}
+
+	/**
+	 * Get pending delta counters for each stat type
+	 * @return array Positive and negative deltas for each type
+	 */
+	protected function getPendingDeltas() {
+		global $wgMemc;
+
+		$pending = array();
+		foreach ( array( 'ss_total_views', 'ss_total_edits',
+			'ss_good_articles', 'ss_total_pages', 'ss_users', 'ss_images' ) as $type
+		) {
+			// Get pending increments and pending decrements
+			$pending[$type]['+'] = (int)$wgMemc->get( $this->getTypeCacheKey( $type, '+' ) );
+			$pending[$type]['-'] = (int)$wgMemc->get( $this->getTypeCacheKey( $type, '-' ) );
+		}
+
+		return $pending;
+	}
+
+	/**
+	 * Reduce pending delta counters after updates have been applied
+	 * @param array $pd Result of getPendingDeltas(), used for DB update
+	 */
+	protected function removePendingDeltas( array $pd ) {
+		global $wgMemc;
+
+		foreach ( $pd as $type => $deltas ) {
+			foreach ( $deltas as $sign => $magnitude ) {
+				// Lower the pending counter now that we applied these changes
+				$wgMemc->decr( $this->getTypeCacheKey( $type, $sign ), $magnitude );
+			}
+		}
+	}
+}
diff --git a/includes/deferred/SqlDataUpdate.php b/includes/deferred/SqlDataUpdate.php
new file mode 100644
index 00000000..9c58503f
--- /dev/null
+++ b/includes/deferred/SqlDataUpdate.php
@@ -0,0 +1,159 @@
+<?php
+/**
+ * Base code for update jobs that put some secondary data extracted
+ * from article content into the database.
+ *
+ * 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
+ */
+
+/**
+ * Abstract base class for update jobs that put some secondary data extracted
+ * from article content into the database.
+ *
+ * @note subclasses should NOT start or commit transactions in their doUpdate() method,
+ *       a transaction will automatically be wrapped around the update. Starting another
+ *       one would break the outer transaction bracket. If need be, subclasses can override
+ *       the beginTransaction() and commitTransaction() methods.
+ */
+abstract class SqlDataUpdate extends DataUpdate {
+	/** @var DatabaseBase Database connection reference */
+	protected $mDb;
+
+	/** @var array SELECT options to be used (array) */
+	protected $mOptions;
+
+	/** @var bool Whether a transaction is open on this object (internal use only!) */
+	private $mHasTransaction;
+
+	/** @var bool Whether this update should be wrapped in a transaction */
+	protected $mUseTransaction;
+
+	/**
+	 * Constructor
+	 *
+	 * @param bool $withTransaction Whether this update should be wrapped in a
+	 *   transaction (default: true). A transaction is only started if no
+	 *   transaction is already in progress, see beginTransaction() for details.
+	 */
+	public function __construct( $withTransaction = true ) {
+		global $wgAntiLockFlags;
+
+		parent::__construct();
+
+		if ( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) {
+			$this->mOptions = array();
+		} else {
+			$this->mOptions = array( 'FOR UPDATE' );
+		}
+
+		// @todo Get connection only when it's needed? Make sure that doesn't
+		// break anything, especially transactions!
+		$this->mDb = wfGetDB( DB_MASTER );
+
+		$this->mWithTransaction = $withTransaction;
+		$this->mHasTransaction = false;
+	}
+
+	/**
+	 * Begin a database transaction, if $withTransaction was given as true in
+	 * the constructor for this SqlDataUpdate.
+	 *
+	 * Because nested transactions are not supported by the Database class,
+	 * this implementation checks Database::trxLevel() and only opens a
+	 * transaction if none is already active.
+	 */
+	public function beginTransaction() {
+		if ( !$this->mWithTransaction ) {
+			return;
+		}
+
+		// NOTE: nested transactions are not supported, only start a transaction if none is open
+		if ( $this->mDb->trxLevel() === 0 ) {
+			$this->mDb->begin( get_class( $this ) . '::beginTransaction' );
+			$this->mHasTransaction = true;
+		}
+	}
+
+	/**
+	 * Commit the database transaction started via beginTransaction (if any).
+	 */
+	public function commitTransaction() {
+		if ( $this->mHasTransaction ) {
+			$this->mDb->commit( get_class( $this ) . '::commitTransaction' );
+			$this->mHasTransaction = false;
+		}
+	}
+
+	/**
+	 * Abort the database transaction started via beginTransaction (if any).
+	 */
+	public function abortTransaction() {
+		if ( $this->mHasTransaction ) { //XXX: actually... maybe always?
+			$this->mDb->rollback( get_class( $this ) . '::abortTransaction' );
+			$this->mHasTransaction = false;
+		}
+	}
+
+	/**
+	 * Invalidate the cache of a list of pages from a single namespace.
+	 * This is intended for use by subclasses.
+	 *
+	 * @param int $namespace Namespace number
+	 * @param array $dbkeys
+	 */
+	protected function invalidatePages( $namespace, array $dbkeys ) {
+		if ( $dbkeys === array() ) {
+			return;
+		}
+
+		/**
+		 * Determine which pages need to be updated
+		 * This is necessary to prevent the job queue from smashing the DB with
+		 * large numbers of concurrent invalidations of the same page
+		 */
+		$now = $this->mDb->timestamp();
+		$ids = array();
+		$res = $this->mDb->select( 'page', array( 'page_id' ),
+			array(
+				'page_namespace' => $namespace,
+				'page_title' => $dbkeys,
+				'page_touched < ' . $this->mDb->addQuotes( $now )
+			), __METHOD__
+		);
+
+		foreach ( $res as $row ) {
+			$ids[] = $row->page_id;
+		}
+
+		if ( $ids === array() ) {
+			return;
+		}
+
+		/**
+		 * Do the update
+		 * We still need the page_touched condition, in case the row has changed since
+		 * the non-locking select above.
+		 */
+		$this->mDb->update( 'page', array( 'page_touched' => $now ),
+			array(
+				'page_id' => $ids,
+				'page_touched < ' . $this->mDb->addQuotes( $now )
+			), __METHOD__
+		);
+	}
+}
diff --git a/includes/deferred/SquidUpdate.php b/includes/deferred/SquidUpdate.php
new file mode 100644
index 00000000..0dcff44a
--- /dev/null
+++ b/includes/deferred/SquidUpdate.php
@@ -0,0 +1,311 @@
+<?php
+/**
+ * Squid cache purging.
+ *
+ * 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
+ */
+
+/**
+ * Handles purging appropriate Squid URLs given a title (or titles)
+ * @ingroup Cache
+ */
+class SquidUpdate {
+	/**
+	 * Collection of URLs to purge.
+	 * @var array
+	 */
+	protected $urlArr;
+
+	/**
+	 * @param array $urlArr Collection of URLs to purge
+	 * @param bool|int $maxTitles Maximum number of unique URLs to purge
+	 */
+	public function __construct( $urlArr = array(), $maxTitles = false ) {
+		global $wgMaxSquidPurgeTitles;
+		if ( $maxTitles === false ) {
+			$maxTitles = $wgMaxSquidPurgeTitles;
+		}
+
+		// Remove duplicate URLs from list
+		$urlArr = array_unique( $urlArr );
+		if ( count( $urlArr ) > $maxTitles ) {
+			// Truncate to desired maximum URL count
+			$urlArr = array_slice( $urlArr, 0, $maxTitles );
+		}
+		$this->urlArr = $urlArr;
+	}
+
+	/**
+	 * Create a SquidUpdate from the given Title object.
+	 *
+	 * The resulting SquidUpdate will purge the given Title's URLs as well as
+	 * the pages that link to it. Capped at $wgMaxSquidPurgeTitles total URLs.
+	 *
+	 * @param Title $title
+	 * @return SquidUpdate
+	 */
+	public static function newFromLinksTo( Title $title ) {
+		global $wgMaxSquidPurgeTitles;
+		wfProfileIn( __METHOD__ );
+
+		# Get a list of URLs linking to this page
+		$dbr = wfGetDB( DB_SLAVE );
+		$res = $dbr->select( array( 'links', 'page' ),
+			array( 'page_namespace', 'page_title' ),
+			array(
+				'pl_namespace' => $title->getNamespace(),
+				'pl_title' => $title->getDBkey(),
+				'pl_from=page_id' ),
+			__METHOD__ );
+		$blurlArr = $title->getSquidURLs();
+		if ( $res->numRows() <= $wgMaxSquidPurgeTitles ) {
+			foreach ( $res as $BL ) {
+				$tobj = Title::makeTitle( $BL->page_namespace, $BL->page_title );
+				$blurlArr[] = $tobj->getInternalURL();
+			}
+		}
+
+		wfProfileOut( __METHOD__ );
+
+		return new SquidUpdate( $blurlArr );
+	}
+
+	/**
+	 * Create a SquidUpdate from an array of Title objects, or a TitleArray object
+	 *
+	 * @param array $titles
+	 * @param array $urlArr
+	 * @return SquidUpdate
+	 */
+	public static function newFromTitles( $titles, $urlArr = array() ) {
+		global $wgMaxSquidPurgeTitles;
+		$i = 0;
+		/** @var Title $title */
+		foreach ( $titles as $title ) {
+			$urlArr[] = $title->getInternalURL();
+			if ( $i++ > $wgMaxSquidPurgeTitles ) {
+				break;
+			}
+		}
+
+		return new SquidUpdate( $urlArr );
+	}
+
+	/**
+	 * @param Title $title
+	 * @return SquidUpdate
+	 */
+	public static function newSimplePurge( Title $title ) {
+		$urlArr = $title->getSquidURLs();
+
+		return new SquidUpdate( $urlArr );
+	}
+
+	/**
+	 * Purges the list of URLs passed to the constructor.
+	 */
+	public function doUpdate() {
+		self::purge( $this->urlArr );
+	}
+
+	/**
+	 * Purges a list of Squids defined in $wgSquidServers.
+	 * $urlArr should contain the full URLs to purge as values
+	 * (example: $urlArr[] = 'http://my.host/something')
+	 * XXX report broken Squids per mail or log
+	 *
+	 * @param array $urlArr List of full URLs to purge
+	 */
+	public static function purge( $urlArr ) {
+		global $wgSquidServers, $wgHTCPRouting;
+
+		if ( !$urlArr ) {
+			return;
+		}
+
+		wfDebugLog( 'squid', __METHOD__ . ': ' . implode( ' ', $urlArr ) );
+
+		if ( $wgHTCPRouting ) {
+			self::HTCPPurge( $urlArr );
+		}
+
+		wfProfileIn( __METHOD__ );
+
+		// Remove duplicate URLs
+		$urlArr = array_unique( $urlArr );
+		// Maximum number of parallel connections per squid
+		$maxSocketsPerSquid = 8;
+		// Number of requests to send per socket
+		// 400 seems to be a good tradeoff, opening a socket takes a while
+		$urlsPerSocket = 400;
+		$socketsPerSquid = ceil( count( $urlArr ) / $urlsPerSocket );
+		if ( $socketsPerSquid > $maxSocketsPerSquid ) {
+			$socketsPerSquid = $maxSocketsPerSquid;
+		}
+
+		$pool = new SquidPurgeClientPool;
+		$chunks = array_chunk( $urlArr, ceil( count( $urlArr ) / $socketsPerSquid ) );
+		foreach ( $wgSquidServers as $server ) {
+			foreach ( $chunks as $chunk ) {
+				$client = new SquidPurgeClient( $server );
+				foreach ( $chunk as $url ) {
+					$client->queuePurge( $url );
+				}
+				$pool->addClient( $client );
+			}
+		}
+		$pool->run();
+
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * Send Hyper Text Caching Protocol (HTCP) CLR requests.
+	 *
+	 * @throws MWException
+	 * @param array $urlArr Collection of URLs to purge
+	 */
+	public static function HTCPPurge( $urlArr ) {
+		global $wgHTCPRouting, $wgHTCPMulticastTTL;
+		wfProfileIn( __METHOD__ );
+
+		// HTCP CLR operation
+		$htcpOpCLR = 4;
+
+		// @todo FIXME: PHP doesn't support these socket constants (include/linux/in.h)
+		if ( !defined( "IPPROTO_IP" ) ) {
+			define( "IPPROTO_IP", 0 );
+			define( "IP_MULTICAST_LOOP", 34 );
+			define( "IP_MULTICAST_TTL", 33 );
+		}
+
+		// pfsockopen doesn't work because we need set_sock_opt
+		$conn = socket_create( AF_INET, SOCK_DGRAM, SOL_UDP );
+		if ( !$conn ) {
+			$errstr = socket_strerror( socket_last_error() );
+			wfDebugLog( 'squid', __METHOD__ .
+				": Error opening UDP socket: $errstr" );
+			wfProfileOut( __METHOD__ );
+
+			return;
+		}
+
+		// Set socket options
+		socket_set_option( $conn, IPPROTO_IP, IP_MULTICAST_LOOP, 0 );
+		if ( $wgHTCPMulticastTTL != 1 ) {
+			// Set multicast time to live (hop count) option on socket
+			socket_set_option( $conn, IPPROTO_IP, IP_MULTICAST_TTL,
+				$wgHTCPMulticastTTL );
+		}
+
+		// Remove duplicate URLs from collection
+		$urlArr = array_unique( $urlArr );
+		// Get sequential trx IDs for packet loss counting
+		$ids = UIDGenerator::newSequentialPerNodeIDs(
+			'squidhtcppurge', 32, count( $urlArr ), UIDGenerator::QUICK_VOLATILE
+		);
+
+		foreach ( $urlArr as $url ) {
+			if ( !is_string( $url ) ) {
+				wfProfileOut( __METHOD__ );
+				throw new MWException( 'Bad purge URL' );
+			}
+			$url = self::expand( $url );
+			$conf = self::getRuleForURL( $url, $wgHTCPRouting );
+			if ( !$conf ) {
+				wfDebugLog( 'squid', __METHOD__ .
+					"No HTCP rule configured for URL {$url} , skipping" );
+				continue;
+			}
+
+			if ( isset( $conf['host'] ) && isset( $conf['port'] ) ) {
+				// Normalize single entries
+				$conf = array( $conf );
+			}
+			foreach ( $conf as $subconf ) {
+				if ( !isset( $subconf['host'] ) || !isset( $subconf['port'] ) ) {
+					wfProfileOut( __METHOD__ );
+					throw new MWException( "Invalid HTCP rule for URL $url\n" );
+				}
+			}
+
+			// Construct a minimal HTCP request diagram
+			// as per RFC 2756
+			// Opcode 'CLR', no response desired, no auth
+			$htcpTransID = current( $ids );
+			next( $ids );
+
+			$htcpSpecifier = pack( 'na4na*na8n',
+				4, 'HEAD', strlen( $url ), $url,
+				8, 'HTTP/1.0', 0 );
+
+			$htcpDataLen = 8 + 2 + strlen( $htcpSpecifier );
+			$htcpLen = 4 + $htcpDataLen + 2;
+
+			// Note! Squid gets the bit order of the first
+			// word wrong, wrt the RFC. Apparently no other
+			// implementation exists, so adapt to Squid
+			$htcpPacket = pack( 'nxxnCxNxxa*n',
+				$htcpLen, $htcpDataLen, $htcpOpCLR,
+				$htcpTransID, $htcpSpecifier, 2 );
+
+			wfDebugLog( 'squid', __METHOD__ .
+				"Purging URL $url via HTCP" );
+			foreach ( $conf as $subconf ) {
+				socket_sendto( $conn, $htcpPacket, $htcpLen, 0,
+					$subconf['host'], $subconf['port'] );
+			}
+		}
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * Expand local URLs to fully-qualified URLs using the internal protocol
+	 * and host defined in $wgInternalServer. Input that's already fully-
+	 * qualified will be passed through unchanged.
+	 *
+	 * This is used to generate purge URLs that may be either local to the
+	 * main wiki or include a non-native host, such as images hosted on a
+	 * second internal server.
+	 *
+	 * Client functions should not need to call this.
+	 *
+	 * @param string $url
+	 * @return string
+	 */
+	public static function expand( $url ) {
+		return wfExpandUrl( $url, PROTO_INTERNAL );
+	}
+
+	/**
+	 * Find the HTCP routing rule to use for a given URL.
+	 * @param string $url URL to match
+	 * @param array $rules Array of rules, see $wgHTCPRouting for format and behavior
+	 * @return mixed Element of $rules that matched, or false if nothing matched
+	 */
+	private static function getRuleForURL( $url, $rules ) {
+		foreach ( $rules as $regex => $routing ) {
+			if ( $regex === '' || preg_match( $regex, $url ) ) {
+				return $routing;
+			}
+		}
+
+		return false;
+	}
+}
diff --git a/includes/deferred/ViewCountUpdate.php b/includes/deferred/ViewCountUpdate.php
new file mode 100644
index 00000000..8282295b
--- /dev/null
+++ b/includes/deferred/ViewCountUpdate.php
@@ -0,0 +1,119 @@
+<?php
+/**
+ * Update for the 'page_counter' field
+ *
+ * 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
+ */
+
+/**
+ * Update for the 'page_counter' field, when $wgDisableCounters is false.
+ *
+ * Depending on $wgHitcounterUpdateFreq, this will directly increment the
+ * 'page_counter' field or use the 'hitcounter' table and then collect the data
+ * from that table to update the 'page_counter' field in a batch operation.
+ */
+class ViewCountUpdate implements DeferrableUpdate {
+	/** @var int Page ID to increment the view count */
+	protected $id;
+
+	/**
+	 * Constructor
+	 *
+	 * @param int $id Page ID to increment the view count
+	 */
+	public function __construct( $id ) {
+		$this->id = intval( $id );
+	}
+
+	/**
+	 * Run the update
+	 */
+	public function doUpdate() {
+		global $wgHitcounterUpdateFreq;
+
+		$dbw = wfGetDB( DB_MASTER );
+
+		if ( $wgHitcounterUpdateFreq <= 1 || $dbw->getType() == 'sqlite' ) {
+			$id = $this->id;
+			$method = __METHOD__;
+			$dbw->onTransactionIdle( function () use ( $dbw, $id, $method ) {
+				try {
+					$dbw->update( 'page',
+						array( 'page_counter = page_counter + 1' ),
+						array( 'page_id' => $id ),
+						$method
+					);
+				} catch ( DBError $e ) {
+					MWExceptionHandler::logException( $e );
+				}
+			} );
+			return;
+		}
+
+		# Not important enough to warrant an error page in case of failure
+		try {
+			// Since `hitcounter` is non-transactional, the contention is minimal
+			$dbw->insert( 'hitcounter', array( 'hc_id' => $this->id ), __METHOD__ );
+			$checkfreq = intval( $wgHitcounterUpdateFreq / 25 + 1 );
+			if ( rand() % $checkfreq == 0 && $dbw->lastErrno() == 0 ) {
+				$this->collect();
+			}
+		} catch ( DBError $e ) {
+			MWExceptionHandler::logException( $e );
+		}
+	}
+
+	protected function collect() {
+		global $wgHitcounterUpdateFreq;
+
+		$dbw = wfGetDB( DB_MASTER );
+
+		$rown = $dbw->selectField( 'hitcounter', 'COUNT(*)', array(), __METHOD__ );
+		if ( $rown < $wgHitcounterUpdateFreq ) {
+			return;
+		}
+
+		wfProfileIn( __METHOD__ . '-collect' );
+		$old_user_abort = ignore_user_abort( true );
+
+		$dbType = $dbw->getType();
+		$tabletype = $dbType == 'mysql' ? "ENGINE=HEAP " : '';
+		$hitcounterTable = $dbw->tableName( 'hitcounter' );
+		$acchitsTable = $dbw->tableName( 'acchits' );
+		$pageTable = $dbw->tableName( 'page' );
+
+		$dbw->lockTables( array(), array( 'hitcounter' ), __METHOD__, false );
+		$dbw->query( "CREATE TEMPORARY TABLE $acchitsTable $tabletype AS " .
+			"SELECT hc_id,COUNT(*) AS hc_n FROM $hitcounterTable " .
+			'GROUP BY hc_id', __METHOD__ );
+		$dbw->delete( 'hitcounter', '*', __METHOD__ );
+		$dbw->unlockTables( __METHOD__ );
+
+		if ( $dbType == 'mysql' ) {
+			$dbw->query( "UPDATE $pageTable,$acchitsTable SET page_counter=page_counter + hc_n " .
+				'WHERE page_id = hc_id', __METHOD__ );
+		} else {
+			$dbw->query( "UPDATE $pageTable SET page_counter=page_counter + hc_n " .
+				"FROM $acchitsTable WHERE page_id = hc_id", __METHOD__ );
+		}
+		$dbw->query( "DROP TABLE $acchitsTable", __METHOD__ );
+
+		ignore_user_abort( $old_user_abort );
+		wfProfileOut( __METHOD__ . '-collect' );
+	}
+}