includes/DataUpdate.php

   1 <?php
   2 /**
   3  * Base code for update jobs that do something with some secondary
   4  * data extracted from article.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  19  * http://www.gnu.org/copyleft/gpl.html
  20  *
  21  * @file
  22  */
  23
  24 /**
  25  * Abstract base class for update jobs that do something with some secondary
  26  * data extracted from article.
  27  */
  28 abstract class DataUpdate implements DeferrableUpdate {
  29
  30         /**
  31          * Constructor
  32          */
  33         public function __construct( ) {
  34                 # noop
  35         }
  36
  37         /**
  38          * Begin an appropriate transaction, if any.
  39          * This default implementation does nothing.
  40          */
  41         public function beginTransaction() {
  42                 //noop
  43         }
  44
  45         /**
  46          * Commit the transaction started via beginTransaction, if any.
  47          * This default implementation does nothing.
  48          */
  49         public function commitTransaction() {
  50                 //noop
  51         }
  52
  53         /**
  54          * Abort / roll back the transaction started via beginTransaction, if any.
  55          * This default implementation does nothing.
  56          */
  57         public function rollbackTransaction() {
  58                 //noop
  59         }
  60
  61         /**
  62          * Convenience method, calls doUpdate() on every DataUpdate in the array.
  63          *
  64          * This methods supports transactions logic by first calling beginTransaction()
  65          * on all updates in the array, then calling doUpdate() on each, and, if all goes well,
  66          * then calling commitTransaction() on each update. If an error occurrs,
  67          * rollbackTransaction() will be called on any update object that had beginTranscation()
  68          * called but not yet commitTransaction().
  69          *
  70          * This allows for limited transactional logic across multiple backends for storing
  71          * secondary data.
  72          *
  73          * @static
  74          * @param $updates array a list of DataUpdate instances
  75          */
  76         public static function runUpdates( $updates ) {
  77                 if ( empty( $updates ) ) return; # nothing to do
  78
  79                 $open_transactions = array();
  80                 $exception = null;
  81
  82                 /**
  83                  * @var $update StorageUpdate
  84                  * @var $trans StorageUpdate
  85                  */
  86
  87                 try {
  88                         // begin transactions
  89                         foreach ( $updates as $update ) {
  90                                 $update->beginTransaction();
  91                                 $open_transactions[] = $update;
  92                         }
  93
  94                         // do work
  95                         foreach ( $updates as $update ) {
  96                                 $update->doUpdate();
  97                         }
  98
  99                         // commit transactions
 100                         while ( count( $open_transactions ) > 0 ) {
 101                                 $trans = array_pop( $open_transactions );
 102                                 $trans->commitTransaction();
 103                         }
 104                 } catch ( Exception $ex ) {
 105                         $exception = $ex;
 106                         wfDebug( "Caught exception, will rethrow after rollback: " . $ex->getMessage() );
 107                 }
 108
 109                 // rollback remaining transactions
 110                 while ( count( $open_transactions ) > 0 ) {
 111                         $trans = array_pop( $open_transactions );
 112                         $trans->rollbackTransaction();
 113                 }
 114
 115                 if ( $exception ) {
 116                         throw $exception; // rethrow after cleanup
 117                 }
 118         }
 119
 120 }