includes/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 abstract class SqlDataUpdate extends DataUpdate {
  29
  30         protected $mDb;            //!< Database connection reference
  31         protected $mOptions;       //!< SELECT options to be used (array)
  32
  33         private   $mHasTransaction; //!< bool whether a transaction is open on this object (internal use only!)
  34
  35         /**
  36          * Constructor
  37         **/
  38         public function __construct( ) {
  39                 global $wgAntiLockFlags;
  40
  41                 parent::__construct( );
  42
  43                 if ( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) {
  44                         $this->mOptions = array();
  45                 } else {
  46                         $this->mOptions = array( 'FOR UPDATE' );
  47                 }
  48
  49                 // @todo: get connection only when it's needed? make sure that doesn't break anything, especially transactions!
  50                 $this->mDb = wfGetDB( DB_MASTER );
  51                 $this->mHasTransaction = false;
  52         }
  53
  54         /**
  55          * Begin a database transaction.
  56          *
  57          * Because nested transactions are not supportred by the Database class, this implementation
  58          * checkes Database::trxLevel() and only opens a transaction if none is yet active.
  59          */
  60         public function beginTransaction() {
  61                 // NOTE: nested transactions are not supported, only start a transaction if none is open
  62                 if ( $this->mDb->trxLevel() === 0 ) {
  63                         $this->mDb->begin( get_class( $this ) . '::beginTransaction'  );
  64                         $this->mHasTransaction = true;
  65                 }
  66         }
  67
  68         /**
  69          * Commit the database transaction started via beginTransaction (if any).
  70          */
  71         public function commitTransaction() {
  72                 if ( $this->mHasTransaction ) {
  73                         $this->mDb->commit( get_class( $this ) . '::commitTransaction' );
  74                 }
  75         }
  76
  77         /**
  78          * Abort the database transaction started via beginTransaction (if any).
  79          */
  80         public function abortTransaction() {
  81                 if ( $this->mHasTransaction ) {
  82                         $this->mDb->rollback( get_class( $this ) . '::abortTransaction' );
  83                 }
  84         }
  85
  86         /**
  87          * Invalidate the cache of a list of pages from a single namespace.
  88          * This is intended for use by subclasses.
  89          *
  90          * @param $namespace Integer
  91          * @param $dbkeys Array
  92          */
  93         protected function invalidatePages( $namespace, Array $dbkeys ) {
  94                 if ( !count( $dbkeys ) ) {
  95                         return;
  96                 }
  97
  98                 /**
  99                  * Determine which pages need to be updated
 100                  * This is necessary to prevent the job queue from smashing the DB with
 101                  * large numbers of concurrent invalidations of the same page
 102                  */
 103                 $now = $this->mDb->timestamp();
 104                 $ids = array();
 105                 $res = $this->mDb->select( 'page', array( 'page_id' ),
 106                         array(
 107                                 'page_namespace' => $namespace,
 108                                 'page_title' => $dbkeys,
 109                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 110                         ), __METHOD__
 111                 );
 112                 foreach ( $res as $row ) {
 113                         $ids[] = $row->page_id;
 114                 }
 115                 if ( !count( $ids ) ) {
 116                         return;
 117                 }
 118
 119                 /**
 120                  * Do the update
 121                  * We still need the page_touched condition, in case the row has changed since
 122                  * the non-locking select above.
 123                  */
 124                 $this->mDb->update( 'page', array( 'page_touched' => $now ),
 125                         array(
 126                                 'page_id' => $ids,
 127                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 128                         ), __METHOD__
 129                 );
 130         }
 131
 132 }