diff options
Diffstat (limited to 'includes/db/LoadMonitor.php')
-rw-r--r-- | includes/db/LoadMonitor.php | 87 |
1 files changed, 0 insertions, 87 deletions
diff --git a/includes/db/LoadMonitor.php b/includes/db/LoadMonitor.php index 91840dd9..4975ea19 100644 --- a/includes/db/LoadMonitor.php +++ b/includes/db/LoadMonitor.php @@ -64,90 +64,3 @@ class LoadMonitorNull implements LoadMonitor { return array_fill_keys( $serverIndexes, 0 ); } } - -/** - * Basic MySQL load monitor with no external dependencies - * Uses memcached to cache the replication lag for a short time - * - * @ingroup Database - */ -class LoadMonitorMySQL implements LoadMonitor { - /** @var LoadBalancer */ - public $parent; - /** @var BagOStuff */ - protected $cache; - - public function __construct( $parent ) { - global $wgMemc; - - $this->parent = $parent; - $this->cache = $wgMemc ?: wfGetMainCache(); - } - - public function scaleLoads( &$loads, $group = false, $wiki = false ) { - } - - public function getLagTimes( $serverIndexes, $wiki ) { - if ( count( $serverIndexes ) == 1 && reset( $serverIndexes ) == 0 ) { - // Single server only, just return zero without caching - return array( 0 => 0 ); - } - - $expiry = 5; - $requestRate = 10; - - $cache = $this->cache; - $masterName = $this->parent->getServerName( 0 ); - $memcKey = wfMemcKey( 'lag_times', $masterName ); - $times = $cache->get( $memcKey ); - if ( is_array( $times ) ) { - # Randomly recache with probability rising over $expiry - $elapsed = time() - $times['timestamp']; - $chance = max( 0, ( $expiry - $elapsed ) * $requestRate ); - if ( mt_rand( 0, $chance ) != 0 ) { - unset( $times['timestamp'] ); // hide from caller - - return $times; - } - wfIncrStats( 'lag_cache_miss_expired' ); - } else { - wfIncrStats( 'lag_cache_miss_absent' ); - } - - # Cache key missing or expired - if ( $cache->add( "$memcKey:lock", 1, 10 ) ) { - # Let this process alone update the cache value - $unlocker = new ScopedCallback( function () use ( $cache, $memcKey ) { - $cache->delete( $memcKey ); - } ); - } elseif ( is_array( $times ) ) { - # Could not acquire lock but an old cache exists, so use it - unset( $times['timestamp'] ); // hide from caller - - return $times; - } - - $times = array(); - foreach ( $serverIndexes as $i ) { - if ( $i == 0 ) { # Master - $times[$i] = 0; - } elseif ( false !== ( $conn = $this->parent->getAnyOpenConnection( $i ) ) ) { - $times[$i] = $conn->getLag(); - } elseif ( false !== ( $conn = $this->parent->openConnection( $i, $wiki ) ) ) { - $times[$i] = $conn->getLag(); - // Close the connection to avoid sleeper connections piling up. - // Note that the caller will pick one of these DBs and reconnect, - // which is slightly inefficient, but this only matters for the lag - // time cache miss cache, which is far less common that cache hits. - $this->parent->closeConnection( $conn ); - } - } - - # Add a timestamp key so we know when it was cached - $times['timestamp'] = time(); - $cache->set( $memcKey, $times, $expiry + 10 ); - unset( $times['timestamp'] ); // hide from caller - - return $times; - } -} |