includes/deferred/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 DeferrableUpdate $update 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 $title
  60          * @param string $table
  61          */
  62         public static function addHTMLCacheUpdate( $title, $table ) {
  63                 self::addUpdate( new HTMLCacheUpdate( $title, $table ) );
  64         }
  65
  66         /**
  67          * Add a callable update.  In a lot of cases, we just need a callback/closure,
  68          * defining a new DeferrableUpdate object is not necessary
  69          * @see MWCallableUpdate::__construct()
  70          * @param callable $callable
  71          */
  72         public static function addCallableUpdate( $callable ) {
  73                 self::addUpdate( new MWCallableUpdate( $callable ) );
  74         }
  75
  76         /**
  77          * Do any deferred updates and clear the list
  78          *
  79          * @param string $commit Set to 'commit' to commit after every update to
  80          *   prevent lock contention
  81          */
  82         public static function doUpdates( $commit = '' ) {
  83                 global $wgDeferredUpdateList;
  84
  85                 $updates = array_merge( $wgDeferredUpdateList, self::$updates );
  86
  87                 // No need to get master connections in case of empty updates array
  88                 if ( !count( $updates ) ) {
  89
  90                         return;
  91                 }
  92
  93                 $dbw = false;
  94                 $doCommit = $commit == 'commit';
  95                 if ( $doCommit ) {
  96                         $dbw = wfGetDB( DB_MASTER );
  97                 }
  98
  99                 while ( $updates ) {
 100                         self::clearPendingUpdates();
 101
 102                         /** @var DeferrableUpdate $update */
 103                         foreach ( $updates as $update ) {
 104                                 try {
 105                                         $update->doUpdate();
 106
 107                                         if ( $doCommit && $dbw->trxLevel() ) {
 108                                                 $dbw->commit( __METHOD__, 'flush' );
 109                                         }
 110                                 } catch ( Exception $e ) {
 111                                         // We don't want exceptions thrown during deferred updates to
 112                                         // be reported to the user since the output is already sent.
 113                                         // Instead we just log them.
 114                                         if ( !$e instanceof ErrorPageError ) {
 115                                                 MWExceptionHandler::logException( $e );
 116                                         }
 117                                 }
 118                         }
 119                         $updates = array_merge( $wgDeferredUpdateList, self::$updates );
 120                 }
 121
 122         }
 123
 124         /**
 125          * Clear all pending updates without performing them. Generally, you don't
 126          * want or need to call this. Unit tests need it though.
 127          */
 128         public static function clearPendingUpdates() {
 129                 global $wgDeferredUpdateList;
 130                 $wgDeferredUpdateList = self::$updates = array();
 131         }
 132 }