includes/SqlDataUpdate.php

   1 <?php
   2 /**
   3  * See docs/deferred.txt
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * Abstract base class for update jobs that put some secondary data extracted
  21  * from article content into the database.
  22  */
  23 abstract class SqlDataUpdate extends DataUpdate {
  24
  25         protected $mDb;            //!< Database connection reference
  26         protected $mOptions;       //!< SELECT options to be used (array)
  27
  28         private   $mHasTransaction; //!< bool whether a transaction is open on this object (internal use only!)
  29
  30         /**
  31          * Constructor
  32         **/
  33         public function __construct( ) {
  34                 global $wgAntiLockFlags;
  35
  36                 parent::__construct( );
  37
  38                 if ( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) {
  39                         $this->mOptions = array();
  40                 } else {
  41                         $this->mOptions = array( 'FOR UPDATE' );
  42                 }
  43
  44                 // @todo: get connection only when it's needed? make sure that doesn't break anything, especially transactions!
  45                 $this->mDb = wfGetDB( DB_MASTER );
  46                 $this->mHasTransaction = false;
  47         }
  48
  49         /**
  50          * Begin a database transaction.
  51          *
  52          * Because nested transactions are not supportred by the Database class, this implementation
  53          * checkes Database::trxLevel() and only opens a transaction if none is yet active.
  54          */
  55         public function beginTransaction() {
  56                 // NOTE: nested transactions are not supported, only start a transaction if none is open
  57                 if ( $this->mDb->trxLevel() === 0 ) {
  58                         $this->mDb->begin( get_class( $this ) . '::beginTransaction'  );
  59                         $this->mHasTransaction = true;
  60                 }
  61         }
  62
  63         /**
  64          * Commit the database transaction started via beginTransaction (if any).
  65          */
  66         public function commitTransaction() {
  67                 if ( $this->mHasTransaction ) {
  68                         $this->mDb->commit( get_class( $this ) . '::commitTransaction' );
  69                 }
  70         }
  71
  72         /**
  73          * Abort the database transaction started via beginTransaction (if any).
  74          */
  75         public function abortTransaction() {
  76                 if ( $this->mHasTransaction ) {
  77                         $this->mDb->rollback( get_class( $this ) . '::abortTransaction' );
  78                 }
  79         }
  80
  81         /**
  82          * Invalidate the cache of a list of pages from a single namespace.
  83          * This is intended for use by subclasses.
  84          *
  85          * @param $namespace Integer
  86          * @param $dbkeys Array
  87          */
  88         protected function invalidatePages( $namespace, Array $dbkeys ) {
  89                 if ( !count( $dbkeys ) ) {
  90                         return;
  91                 }
  92
  93                 /**
  94                  * Determine which pages need to be updated
  95                  * This is necessary to prevent the job queue from smashing the DB with
  96                  * large numbers of concurrent invalidations of the same page
  97                  */
  98                 $now = $this->mDb->timestamp();
  99                 $ids = array();
 100                 $res = $this->mDb->select( 'page', array( 'page_id' ),
 101                         array(
 102                                 'page_namespace' => $namespace,
 103                                 'page_title' => $dbkeys,
 104                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 105                         ), __METHOD__
 106                 );
 107                 foreach ( $res as $row ) {
 108                         $ids[] = $row->page_id;
 109                 }
 110                 if ( !count( $ids ) ) {
 111                         return;
 112                 }
 113
 114                 /**
 115                  * Do the update
 116                  * We still need the page_touched condition, in case the row has changed since
 117                  * the non-locking select above.
 118                  */
 119                 $this->mDb->update( 'page', array( 'page_touched' => $now ),
 120                         array(
 121                                 'page_id' => $ids,
 122                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 123                         ), __METHOD__
 124                 );
 125         }
 126
 127 }