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<?php
/**
* Job queue aggregator code that uses BagOStuff.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @author Aaron Schulz
*/
/**
* Class to handle tracking information about all queues using BagOStuff
*
* @ingroup JobQueue
* @since 1.21
*/
class JobQueueAggregatorMemc extends JobQueueAggregator {
/** @var BagOStuff */
protected $cache;
protected $cacheTTL; // integer; seconds
/**
* @params include:
* - objectCache : Name of an object cache registered in $wgObjectCaches.
* This defaults to the one specified by $wgMainCacheType.
* - cacheTTL : Seconds to cache the aggregate data before regenerating.
* @param array $params
*/
protected function __construct( array $params ) {
parent::__construct( $params );
$this->cache = isset( $params['objectCache'] )
? wfGetCache( $params['objectCache'] )
: wfGetMainCache();
$this->cacheTTL = isset( $params['cacheTTL'] ) ? $params['cacheTTL'] : 180; // 3 min
}
/**
* @see JobQueueAggregator::doNotifyQueueEmpty()
*/
protected function doNotifyQueueEmpty( $wiki, $type ) {
$key = $this->getReadyQueueCacheKey();
// Delist the queue from the "ready queue" list
if ( $this->cache->add( "$key:lock", 1, 60 ) ) { // lock
$curInfo = $this->cache->get( $key );
if ( is_array( $curInfo ) && isset( $curInfo['pendingDBs'][$type] ) ) {
if ( in_array( $wiki, $curInfo['pendingDBs'][$type] ) ) {
$curInfo['pendingDBs'][$type] = array_diff(
$curInfo['pendingDBs'][$type], array( $wiki ) );
$this->cache->set( $key, $curInfo );
}
}
$this->cache->delete( "$key:lock" ); // unlock
}
return true;
}
/**
* @see JobQueueAggregator::doNotifyQueueNonEmpty()
*/
protected function doNotifyQueueNonEmpty( $wiki, $type ) {
return true; // updated periodically
}
/**
* @see JobQueueAggregator::doAllGetReadyWikiQueues()
*/
protected function doGetAllReadyWikiQueues() {
$key = $this->getReadyQueueCacheKey();
// If the cache entry wasn't present, is stale, or in .1% of cases otherwise,
// regenerate the cache. Use any available stale cache if another process is
// currently regenerating the pending DB information.
$pendingDbInfo = $this->cache->get( $key );
if ( !is_array( $pendingDbInfo )
|| ( time() - $pendingDbInfo['timestamp'] ) > $this->cacheTTL
|| mt_rand( 0, 999 ) == 0
) {
if ( $this->cache->add( "$key:rebuild", 1, 1800 ) ) { // lock
$pendingDbInfo = array(
'pendingDBs' => $this->findPendingWikiQueues(),
'timestamp' => time()
);
for ( $attempts=1; $attempts <= 25; ++$attempts ) {
if ( $this->cache->add( "$key:lock", 1, 60 ) ) { // lock
$this->cache->set( $key, $pendingDbInfo );
$this->cache->delete( "$key:lock" ); // unlock
break;
}
}
$this->cache->delete( "$key:rebuild" ); // unlock
}
}
return is_array( $pendingDbInfo )
? $pendingDbInfo['pendingDBs']
: array(); // cache is both empty and locked
}
/**
* @return string
*/
private function getReadyQueueCacheKey() {
return "jobqueue:aggregator:ready-queues:v1"; // global
}
}
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