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+<?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();
+ }
+}