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  * @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
  35         protected $mDb;            //!< Database connection reference
  36         protected $mOptions;       //!< SELECT options to be used (array)
  37
  38         private   $mHasTransaction; //!< bool whether a transaction is open on this object (internal use only!)
  39
  40         /**
  41          * Constructor
  42         **/
  43         public function __construct( ) {
  44                 global $wgAntiLockFlags;
  45
  46                 parent::__construct( );
  47
  48                 if ( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) {
  49                         $this->mOptions = array();
  50                 } else {
  51                         $this->mOptions = array( 'FOR UPDATE' );
  52                 }
  53
  54                 // @todo: get connection only when it's needed? make sure that doesn't break anything, especially transactions!
  55                 $this->mDb = wfGetDB( DB_MASTER );
  56                 $this->mHasTransaction = false;
  57         }
  58
  59         /**
  60          * Begin a database transaction.
  61          *
  62          * Because nested transactions are not supportred by the Database class, this implementation
  63          * checkes Database::trxLevel() and only opens a transaction if none is yet active.
  64          */
  65         public function beginTransaction() {
  66                 // NOTE: nested transactions are not supported, only start a transaction if none is open
  67                 if ( $this->mDb->trxLevel() === 0 ) {
  68                         $this->mDb->begin( get_class( $this ) . '::beginTransaction'  );
  69                         $this->mHasTransaction = true;
  70                 }
  71         }
  72
  73         /**
  74          * Commit the database transaction started via beginTransaction (if any).
  75          */
  76         public function commitTransaction() {
  77                 if ( $this->mHasTransaction ) {
  78                         $this->mDb->commit( get_class( $this ) . '::commitTransaction' );
  79                 }
  80         }
  81
  82         /**
  83          * Abort the database transaction started via beginTransaction (if any).
  84          */
  85         public function abortTransaction() {
  86                 if ( $this->mHasTransaction ) {
  87                         $this->mDb->rollback( get_class( $this ) . '::abortTransaction' );
  88                 }
  89         }
  90
  91         /**
  92          * Invalidate the cache of a list of pages from a single namespace.
  93          * This is intended for use by subclasses.
  94          *
  95          * @param $namespace Integer
  96          * @param $dbkeys Array
  97          */
  98         protected function invalidatePages( $namespace, Array $dbkeys ) {
  99                 if ( !count( $dbkeys ) ) {
 100                         return;
 101                 }
 102
 103                 /**
 104                  * Determine which pages need to be updated
 105                  * This is necessary to prevent the job queue from smashing the DB with
 106                  * large numbers of concurrent invalidations of the same page
 107                  */
 108                 $now = $this->mDb->timestamp();
 109                 $ids = array();
 110                 $res = $this->mDb->select( 'page', array( 'page_id' ),
 111                         array(
 112                                 'page_namespace' => $namespace,
 113                                 'page_title' => $dbkeys,
 114                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 115                         ), __METHOD__
 116                 );
 117                 foreach ( $res as $row ) {
 118                         $ids[] = $row->page_id;
 119                 }
 120                 if ( !count( $ids ) ) {
 121                         return;
 122                 }
 123
 124                 /**
 125                  * Do the update
 126                  * We still need the page_touched condition, in case the row has changed since
 127                  * the non-locking select above.
 128                  */
 129                 $this->mDb->update( 'page', array( 'page_touched' => $now ),
 130                         array(
 131                                 'page_id' => $ids,
 132                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 133                         ), __METHOD__
 134                 );
 135         }
 136
 137 }