Merge "Add support for PHP7 random_bytes in favor of mcrypt_create_iv"

[lhc/web/wiklou.git] / includes / libs / rdbms / loadmonitor / LoadMonitorMySQL.php

diff --git a/includes/libs/rdbms/loadmonitor/LoadMonitorMySQL.php b/includes/libs/rdbms/loadmonitor/LoadMonitorMySQL.php
index 7286417..c0db68c 100644 (file)
--- a/includes/libs/rdbms/loadmonitor/LoadMonitorMySQL.php
+++ b/includes/libs/rdbms/loadmonitor/LoadMonitorMySQL.php
@@ -19,6 +19,11 @@
  * @ingroup Database
  */
 
+namespace Wikimedia\Rdbms;
+
+use IDatabase;
+use BagOStuff;
+
 /**
  * Basic MySQL load monitor with no external dependencies
  * Uses memcached to cache the replication lag for a short time
@@ -26,8 +31,43 @@
  * @ingroup Database
  */
 class LoadMonitorMySQL extends LoadMonitor {
-       public function scaleLoads( &$loads, $group = false, $domain = false ) {
-               // @TODO: maybe use Threads_running/Threads_created ratio to guess load
-               // and Queries/Uptime to guess if a server is warming up the buffer pool
+       /** @var float What buffer pool use ratio counts as "warm" (e.g. 0.5 for 50% usage) */
+       private $warmCacheRatio;
+
+       public function __construct(
+               ILoadBalancer $lb, BagOStuff $srvCache, BagOStuff $cache, array $options = []
+       ) {
+               parent::__construct( $lb, $srvCache, $cache, $options );
+
+               $this->warmCacheRatio = isset( $options['warmCacheRatio'] )
+                       ? $options['warmCacheRatio']
+                       : 0.0;
+       }
+
+       protected function getWeightScale( $index, IDatabase $conn = null ) {
+               if ( !$conn ) {
+                       return 0.0;
+               }
+
+               $weight = 1.0;
+               if ( $this->warmCacheRatio > 0 ) {
+                       $res = $conn->query( 'SHOW STATUS', false );
+                       $s = $res ? $conn->fetchObject( $res ) : false;
+                       if ( $s === false ) {
+                               $host = $this->parent->getServerName( $index );
+                               $this->replLogger->error( __METHOD__ . ": could not get status for $host" );
+                       } else {
+                               // https://dev.mysql.com/doc/refman/5.7/en/server-status-variables.html
+                               if ( $s->Innodb_buffer_pool_pages_total > 0 ) {
+                                       $ratio = $s->Innodb_buffer_pool_pages_data / $s->Innodb_buffer_pool_pages_total;
+                               } else {
+                                       $ratio = 1.0;
+                               }
+                               // Stop caring once $ratio >= $this->warmCacheRatio
+                               $weight *= min( $ratio / $this->warmCacheRatio, 1.0 );
+                       }
+               }
+
+               return $weight;
        }
 }