includes/deferred/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  * @note subclasses should NOT start or commit transactions in their doUpdate() method,
  29  *       a transaction will automatically be wrapped around the update. If need be,
  30  *       subclasses can override the beginTransaction() and commitTransaction() methods.
  31  */
  32 abstract class DataUpdate implements DeferrableUpdate {
  33         /** @var mixed Result from LBFactory::getEmptyTransactionTicket() */
  34         protected $ticket;
  35
  36         public function __construct() {
  37                 // noop
  38         }
  39
  40         /**
  41          * @param mixed $ticket Result of getEmptyTransactionTicket()
  42          * @since 1.28
  43          */
  44         public function setTransactionTicket( $ticket ) {
  45                 $this->ticket = $ticket;
  46         }
  47
  48         /**
  49          * Begin an appropriate transaction, if any.
  50          * This default implementation does nothing.
  51          */
  52         public function beginTransaction() {
  53                 // noop
  54         }
  55
  56         /**
  57          * Commit the transaction started via beginTransaction, if any.
  58          * This default implementation does nothing.
  59          */
  60         public function commitTransaction() {
  61                 // noop
  62         }
  63
  64         /**
  65          * Abort / roll back the transaction started via beginTransaction, if any.
  66          * This default implementation does nothing.
  67          */
  68         public function rollbackTransaction() {
  69                 // noop
  70         }
  71
  72         /**
  73          * Convenience method, calls doUpdate() on every DataUpdate in the array.
  74          *
  75          * This methods supports transactions logic by first calling beginTransaction()
  76          * on all updates in the array, then calling doUpdate() on each, and, if all goes well,
  77          * then calling commitTransaction() on each update. If an error occurs,
  78          * rollbackTransaction() will be called on any update object that had beginTransaction()
  79          * called but not yet commitTransaction().
  80          *
  81          * This allows for limited transactional logic across multiple backends for storing
  82          * secondary data.
  83          *
  84          * @param DataUpdate[] $updates A list of DataUpdate instances
  85          * @param string $mode Use "enqueue" to use the job queue when possible [Default: run]
  86          * @throws Exception|null
  87          */
  88         public static function runUpdates( array $updates, $mode = 'run' ) {
  89                 if ( $mode === 'enqueue' ) {
  90                         // When possible, push updates as jobs instead of calling doUpdate()
  91                         $updates = self::enqueueUpdates( $updates );
  92                 }
  93
  94                 if ( !count( $updates ) ) {
  95                         return; // nothing to do
  96                 }
  97
  98                 $open_transactions = [];
  99                 $exception = null;
 100
 101                 try {
 102                         // begin transactions
 103                         foreach ( $updates as $update ) {
 104                                 $update->beginTransaction();
 105                                 $open_transactions[] = $update;
 106                         }
 107
 108                         // do work
 109                         foreach ( $updates as $update ) {
 110                                 $update->doUpdate();
 111                         }
 112
 113                         // commit transactions
 114                         while ( count( $open_transactions ) > 0 ) {
 115                                 $trans = array_pop( $open_transactions );
 116                                 $trans->commitTransaction();
 117                         }
 118                 } catch ( Exception $ex ) {
 119                         $exception = $ex;
 120                         wfDebug( "Caught exception, will rethrow after rollback: " .
 121                                 $ex->getMessage() . "\n" );
 122                 }
 123
 124                 // rollback remaining transactions
 125                 while ( count( $open_transactions ) > 0 ) {
 126                         $trans = array_pop( $open_transactions );
 127                         $trans->rollbackTransaction();
 128                 }
 129
 130                 if ( $exception ) {
 131                         throw $exception; // rethrow after cleanup
 132                 }
 133         }
 134
 135         /**
 136          * Enqueue jobs for every DataUpdate that support enqueueUpdate()
 137          * and return the remaining DataUpdate objects (those that do not)
 138          *
 139          * @param DataUpdate[] $updates A list of DataUpdate instances
 140          * @return DataUpdate[]
 141          * @since 1.27
 142          */
 143         protected static function enqueueUpdates( array $updates ) {
 144                 $remaining = [];
 145
 146                 foreach ( $updates as $update ) {
 147                         if ( $update instanceof EnqueueableDataUpdate ) {
 148                                 $spec = $update->getAsJobSpecification();
 149                                 JobQueueGroup::singleton( $spec['wiki'] )->push( $spec['job'] );
 150                         } else {
 151                                 $remaining[] = $update;
 152                         }
 153                 }
 154
 155                 return $remaining;
 156         }
 157 }