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LoadMonitorMySQL.php
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1 <?php
22 namespace Wikimedia\Rdbms;
23 
24 use BagOStuff;
25 use WANObjectCache;
26 
35  private $warmCacheRatio;
36 
37  public function __construct(
38  ILoadBalancer $lb, BagOStuff $srvCache, WANObjectCache $wCache, array $options = []
39  ) {
40  parent::__construct( $lb, $srvCache, $wCache, $options );
41 
42  $this->warmCacheRatio = $options['warmCacheRatio'] ?? 0.0;
43  }
44 
45  protected function getWeightScale( $index, IDatabase $conn = null ) {
46  if ( $conn === null ) {
47  return parent::getWeightScale( $index, $conn );
48  }
49 
50  $weight = 1.0;
51  if ( $this->warmCacheRatio > 0 ) {
52  $res = $conn->query( 'SHOW STATUS', __METHOD__ );
53  $s = $res ? $conn->fetchObject( $res ) : false;
54  if ( $s === false ) {
55  $host = $this->lb->getServerName( $index );
56  $this->replLogger->error( __METHOD__ . ": could not get status for $host" );
57  } else {
58  // https://dev.mysql.com/doc/refman/5.7/en/server-status-variables.html
59  if ( $s->Innodb_buffer_pool_pages_total > 0 ) {
60  $ratio = $s->Innodb_buffer_pool_pages_data / $s->Innodb_buffer_pool_pages_total;
61  } else {
62  $ratio = 1.0;
63  }
64  // Stop caring once $ratio >= $this->warmCacheRatio
65  $weight *= min( $ratio / $this->warmCacheRatio, 1.0 );
66  }
67  }
68 
69  return $weight;
70  }
71 }
Wikimedia\Rdbms\LoadMonitor
Basic DB load monitor with no external dependencies.
Definition: LoadMonitor.php:41
Wikimedia\Rdbms\LoadMonitor\$srvCache
BagOStuff $srvCache
Definition: LoadMonitor.php:45
Wikimedia\Rdbms\LoadMonitorMySQL\getWeightScale
getWeightScale( $index, IDatabase $conn=null)
Definition: LoadMonitorMySQL.php:45
Wikimedia\Rdbms
Definition: ChronologyProtector.php:24
BagOStuff
Class representing a cache/ephemeral data store.
Definition: BagOStuff.php:71
$s
$s
Definition: mergeMessageFileList.php:185
$res
$res
Definition: testCompression.php:57
Wikimedia\Rdbms\IDatabase
Basic database interface for live and lazy-loaded relation database handles.
Definition: IDatabase.php:38
Wikimedia\Rdbms\LoadMonitor\$lb
ILoadBalancer $lb
Definition: LoadMonitor.php:43
Wikimedia\Rdbms\LoadMonitorMySQL
Basic MySQL load monitor with no external dependencies Uses memcached to cache the replication lag fo...
Definition: LoadMonitorMySQL.php:33
WANObjectCache
Multi-datacenter aware caching interface.
Definition: WANObjectCache.php:125
Wikimedia\Rdbms\LoadMonitorMySQL\$warmCacheRatio
float $warmCacheRatio
What buffer pool use ratio counts as "warm" (e.g.
Definition: LoadMonitorMySQL.php:35
Wikimedia\Rdbms\LoadMonitorMySQL\__construct
__construct(ILoadBalancer $lb, BagOStuff $srvCache, WANObjectCache $wCache, array $options=[])
Definition: LoadMonitorMySQL.php:37
Wikimedia\Rdbms\ILoadBalancer
Database cluster connection, tracking, load balancing, and transaction manager interface.
Definition: ILoadBalancer.php:81