includes/job/JobQueueAggregatorMemc.php

   1 <?php
   2 /**
   3  * Job queue aggregator code that uses BagOStuff.
   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  * @file
  21  * @author Aaron Schulz
  22  */
  23
  24 /**
  25  * Class to handle tracking information about all queues using BagOStuff
  26  *
  27  * @ingroup JobQueue
  28  * @since 1.21
  29  */
  30 class JobQueueAggregatorMemc extends JobQueueAggregator {
  31         /** @var BagOStuff */
  32         protected $cache;
  33
  34         protected $cacheTTL; // integer; seconds
  35
  36         /**
  37          * @params include:
  38          *   - objectCache : Name of an object cache registered in $wgObjectCaches.
  39          *                   This defaults to the one specified by $wgMainCacheType.
  40          *   - cacheTTL    : Seconds to cache the aggregate data before regenerating.
  41          * @param array $params
  42          */
  43         protected function __construct( array $params ) {
  44                 parent::__construct( $params );
  45                 $this->cache = isset( $params['objectCache'] )
  46                         ? wfGetCache( $params['objectCache'] )
  47                         : wfGetMainCache();
  48                 $this->cacheTTL = isset( $params['cacheTTL'] ) ? $params['cacheTTL'] : 180; // 3 min
  49         }
  50
  51         /**
  52          * @see JobQueueAggregator::doNotifyQueueEmpty()
  53          */
  54         protected function doNotifyQueueEmpty( $wiki, $type ) {
  55                 $key = $this->getReadyQueueCacheKey();
  56                 // Delist the queue from the "ready queue" list
  57                 if ( $this->cache->add( "$key:lock", 1, 60 ) ) { // lock
  58                         $curInfo = $this->cache->get( $key );
  59                         if ( is_array( $curInfo ) && isset( $curInfo['pendingDBs'][$type] ) ) {
  60                                 if ( in_array( $wiki, $curInfo['pendingDBs'][$type] ) ) {
  61                                         $curInfo['pendingDBs'][$type] = array_diff(
  62                                                 $curInfo['pendingDBs'][$type], array( $wiki ) );
  63                                         $this->cache->set( $key, $curInfo );
  64                                 }
  65                         }
  66                         $this->cache->delete( "$key:lock" ); // unlock
  67                 }
  68                 return true;
  69         }
  70
  71         /**
  72          * @see JobQueueAggregator::doNotifyQueueNonEmpty()
  73          */
  74         protected function doNotifyQueueNonEmpty( $wiki, $type ) {
  75                 return true; // updated periodically
  76         }
  77
  78         /**
  79          * @see JobQueueAggregator::doAllGetReadyWikiQueues()
  80          */
  81         protected function doGetAllReadyWikiQueues() {
  82                 $key = $this->getReadyQueueCacheKey();
  83                 // If the cache entry wasn't present, is stale, or in .1% of cases otherwise,
  84                 // regenerate the cache. Use any available stale cache if another process is
  85                 // currently regenerating the pending DB information.
  86                 $pendingDbInfo = $this->cache->get( $key );
  87                 if ( !is_array( $pendingDbInfo )
  88                         || ( time() - $pendingDbInfo['timestamp'] ) > $this->cacheTTL
  89                         || mt_rand( 0, 999 ) == 0
  90                 ) {
  91                         if ( $this->cache->add( "$key:rebuild", 1, 1800 ) ) { // lock
  92                                 $pendingDbInfo = array(
  93                                         'pendingDBs' => $this->findPendingWikiQueues(),
  94                                         'timestamp'  => time()
  95                                 );
  96                                 for ( $attempts=1; $attempts <= 25; ++$attempts ) {
  97                                         if ( $this->cache->add( "$key:lock", 1, 60 ) ) { // lock
  98                                                 $this->cache->set( $key, $pendingDbInfo );
  99                                                 $this->cache->delete( "$key:lock" ); // unlock
 100                                                 break;
 101                                         }
 102                                 }
 103                                 $this->cache->delete( "$key:rebuild" ); // unlock
 104                         }
 105                 }
 106                 return is_array( $pendingDbInfo )
 107                         ? $pendingDbInfo['pendingDBs']
 108                         : array(); // cache is both empty and locked
 109         }
 110
 111         /**
 112          * @see JobQueueAggregator::doPurge()
 113          */
 114         protected function doPurge() {
 115                 return $this->cache->delete( $this->getReadyQueueCacheKey() );
 116         }
 117
 118         /**
 119          * @return string
 120          */
 121         private function getReadyQueueCacheKey() {
 122                 return "jobqueue:aggregator:ready-queues:v1"; // global
 123         }
 124 }