includes/DeferredUpdates.php

   1 <?php
   2 /**
   3  * Interface and manager for deferred updates.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 /**
  24  * Interface that deferrable updates should implement. Basically required so we
  25  * can validate input on DeferredUpdates::addUpdate()
  26  *
  27  * @since 1.19
  28  */
  29 interface DeferrableUpdate {
  30         /**
  31          * Perform the actual work
  32          */
  33         function doUpdate();
  34 }
  35
  36 /**
  37  * Class for managing the deferred updates.
  38  *
  39  * @since 1.19
  40  */
  41 class DeferredUpdates {
  42         /**
  43          * Store of updates to be deferred until the end of the request.
  44          */
  45         private static $updates = array();
  46
  47         /**
  48          * Add an update to the deferred list
  49          * @param $update DeferrableUpdate Some object that implements doUpdate()
  50          */
  51         public static function addUpdate( DeferrableUpdate $update ) {
  52                 array_push( self::$updates, $update );
  53         }
  54
  55         /**
  56          * HTMLCacheUpdates are the most common deferred update people use. This
  57          * is a shortcut method for that.
  58          * @see HTMLCacheUpdate::__construct()
  59          * @param $title
  60          * @param $table
  61          */
  62         public static function addHTMLCacheUpdate( $title, $table ) {
  63                 self::addUpdate( new HTMLCacheUpdate( $title, $table ) );
  64         }
  65
  66         /**
  67          * Do any deferred updates and clear the list
  68          *
  69          * @param string $commit set to 'commit' to commit after every update to
  70          *                prevent lock contention
  71          */
  72         public static function doUpdates( $commit = '' ) {
  73                 global $wgDeferredUpdateList;
  74
  75                 wfProfileIn( __METHOD__ );
  76
  77                 $updates = array_merge( $wgDeferredUpdateList, self::$updates );
  78
  79                 // No need to get master connections in case of empty updates array
  80                 if ( !count( $updates ) ) {
  81                         wfProfileOut( __METHOD__ );
  82                         return;
  83                 }
  84
  85                 $doCommit = $commit == 'commit';
  86                 if ( $doCommit ) {
  87                         $dbw = wfGetDB( DB_MASTER );
  88                 }
  89
  90                 foreach ( $updates as $update ) {
  91                         try {
  92                                 $update->doUpdate();
  93
  94                                 if ( $doCommit && $dbw->trxLevel() ) {
  95                                         $dbw->commit( __METHOD__, 'flush' );
  96                                 }
  97                         } catch ( MWException $e ) {
  98                                 // We don't want exceptions thrown during deferred updates to
  99                                 // be reported to the user since the output is already sent.
 100                                 // Instead we just log them.
 101                                 if ( !$e instanceof ErrorPageError ) {
 102                                         wfDebugLog( 'exception', $e->getLogMessage() );
 103                                 }
 104                         }
 105                 }
 106
 107                 self::clearPendingUpdates();
 108                 wfProfileOut( __METHOD__ );
 109         }
 110
 111         /**
 112          * Clear all pending updates without performing them. Generally, you don't
 113          * want or need to call this. Unit tests need it though.
 114          */
 115         public static function clearPendingUpdates() {
 116                 global $wgDeferredUpdateList;
 117                 $wgDeferredUpdateList = self::$updates = array();
 118         }
 119 }