includes/deferred/SqlDataUpdate.php

   1 <?php
   2 /**
   3  * Base code for update jobs that put some secondary data extracted
   4  * from article content into the database.
   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 put some secondary data extracted
  26  * from article content into the database.
  27  *
  28  * @note subclasses should NOT start or commit transactions in their doUpdate() method,
  29  *       a transaction will automatically be wrapped around the update. Starting another
  30  *       one would break the outer transaction bracket. If need be, subclasses can override
  31  *       the beginTransaction() and commitTransaction() methods.
  32  */
  33 abstract class SqlDataUpdate extends DataUpdate {
  34         /** @var IDatabase Database connection reference */
  35         protected $mDb;
  36
  37         /** @var array SELECT options to be used (array) */
  38         protected $mOptions = array();
  39
  40         /** @var bool Whether a transaction is open on this object (internal use only!) */
  41         private $mHasTransaction;
  42
  43         /** @var bool Whether this update should be wrapped in a transaction */
  44         protected $mUseTransaction;
  45
  46         /**
  47          * Constructor
  48          *
  49          * @param bool $withTransaction Whether this update should be wrapped in a
  50          *   transaction (default: true). A transaction is only started if no
  51          *   transaction is already in progress, see beginTransaction() for details.
  52          */
  53         public function __construct( $withTransaction = true ) {
  54                 parent::__construct();
  55
  56                 $this->mDb = wfGetLB()->getLazyConnectionRef( DB_MASTER );
  57
  58                 $this->mWithTransaction = $withTransaction;
  59                 $this->mHasTransaction = false;
  60         }
  61
  62         /**
  63          * Begin a database transaction, if $withTransaction was given as true in
  64          * the constructor for this SqlDataUpdate.
  65          *
  66          * Because nested transactions are not supported by the Database class,
  67          * this implementation checks Database::trxLevel() and only opens a
  68          * transaction if none is already active.
  69          */
  70         public function beginTransaction() {
  71                 if ( !$this->mWithTransaction ) {
  72                         return;
  73                 }
  74
  75                 // NOTE: nested transactions are not supported, only start a transaction if none is open
  76                 if ( $this->mDb->trxLevel() === 0 ) {
  77                         $this->mDb->begin( get_class( $this ) . '::beginTransaction' );
  78                         $this->mHasTransaction = true;
  79                 }
  80         }
  81
  82         /**
  83          * Commit the database transaction started via beginTransaction (if any).
  84          */
  85         public function commitTransaction() {
  86                 if ( $this->mHasTransaction ) {
  87                         $this->mDb->commit( get_class( $this ) . '::commitTransaction' );
  88                         $this->mHasTransaction = false;
  89                 }
  90         }
  91
  92         /**
  93          * Abort the database transaction started via beginTransaction (if any).
  94          */
  95         public function abortTransaction() {
  96                 if ( $this->mHasTransaction ) { // XXX: actually... maybe always?
  97                         $this->mDb->rollback( get_class( $this ) . '::abortTransaction' );
  98                         $this->mHasTransaction = false;
  99                 }
 100         }
 101
 102         /**
 103          * Invalidate the cache of a list of pages from a single namespace.
 104          * This is intended for use by subclasses.
 105          *
 106          * @param int $namespace Namespace number
 107          * @param array $dbkeys
 108          */
 109         protected function invalidatePages( $namespace, array $dbkeys ) {
 110                 if ( $dbkeys === array() ) {
 111                         return;
 112                 }
 113
 114                 $dbw = $this->mDb;
 115                 $dbw->onTransactionPreCommitOrIdle( function() use ( $dbw, $namespace, $dbkeys ) {
 116                         /**
 117                          * Determine which pages need to be updated
 118                          * This is necessary to prevent the job queue from smashing the DB with
 119                          * large numbers of concurrent invalidations of the same page
 120                          */
 121                         $now = $dbw->timestamp();
 122                         $ids = $dbw->selectFieldValues( 'page',
 123                                 'page_id',
 124                                 array(
 125                                         'page_namespace' => $namespace,
 126                                         'page_title' => $dbkeys,
 127                                         'page_touched < ' . $dbw->addQuotes( $now )
 128                                 ),
 129                                 __METHOD__
 130                         );
 131
 132                         if ( $ids === array() ) {
 133                                 return;
 134                         }
 135
 136                         /**
 137                          * Do the update
 138                          * We still need the page_touched condition, in case the row has changed since
 139                          * the non-locking select above.
 140                          */
 141                         $dbw->update( 'page',
 142                                 array( 'page_touched' => $now ),
 143                                 array(
 144                                         'page_id' => $ids,
 145                                         'page_touched < ' . $dbw->addQuotes( $now )
 146                                 ), __METHOD__
 147                         );
 148                 } );
 149         }
 150 }