Added pt-heartbeat support to DatabaseMysqlBase

Bug: T111266
Bug: T19179
Change-Id: I04c93d5c7389fbb8fba633d955591b30a9504f31

diff --git a/includes/db/DatabaseMysqlBase.php b/includes/db/DatabaseMysqlBase.php
index 61a0565..ac7ce10 100644 (file)
--- a/includes/db/DatabaseMysqlBase.php
+++ b/includes/db/DatabaseMysqlBase.php
@@ -32,10 +32,33 @@
 abstract class DatabaseMysqlBase extends DatabaseBase {
        /** @var MysqlMasterPos */
        protected $lastKnownSlavePos;
+       /** @var string Method to detect slave lag */
+       protected $lagDetectionMethod;
+
+       /** @var BagOStuff APC cache */
+       protected $srvCache;
 
        /** @var string|null */
        private $serverVersion = null;
 
+       /**
+        * Additional $params include:
+        *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
+        *                          pt-heartbeat assumes the table is at heartbeat.heartbeat
+        *                          and uses UTC timestamps in the heartbeat.ts column.
+        *                          (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
+        * @param array $params
+        */
+       function __construct( array $params ) {
+               parent::__construct( $params );
+
+               $this->lagDetectionMethod = isset( $params['lagDetectionMethod'] )
+                       ? $params['lagDetectionMethod']
+                       : 'Seconds_Behind_Master';
+
+               $this->srvCache = ObjectCache::newAccelerator( 'hash' );
+       }
+
        /**
         * @return string
         */
@@ -604,26 +627,55 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
         * @return int
         */
        function getLag() {
-               return $this->getLagFromSlaveStatus();
+               if ( $this->lagDetectionMethod === 'pt-heartbeat' ) {
+                       return $this->getLagFromPtHeartbeat();
+               } else {
+                       return $this->getLagFromSlaveStatus();
+               }
        }
 
        /**
         * @return bool|int
         */
-       function getLagFromSlaveStatus() {
+       protected function getLagFromSlaveStatus() {
                $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
-               if ( !$res ) {
-                       return false;
+               $row = $res ? $res->fetchObject() : false;
+               if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
+                       return intval( $row->Seconds_Behind_Master );
                }
-               $row = $res->fetchObject();
-               if ( !$row ) {
-                       return false;
+
+               return false;
+       }
+
+       /**
+        * @return bool|float
+        */
+       protected function getLagFromPtHeartbeat() {
+               $key = wfMemcKey( 'mysql', 'master-server-id', $this->getServer() );
+               $masterId = intval( $this->srvCache->get( $key ) );
+               if ( !$masterId ) {
+                       $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
+                       $row = $res ? $res->fetchObject() : false;
+                       if ( $row && strval( $row->Master_Server_Id ) !== '' ) {
+                               $masterId = intval( $row->Master_Server_Id );
+                               $this->srvCache->set( $key, $masterId, 30 );
+                       }
                }
-               if ( strval( $row->Seconds_Behind_Master ) === '' ) {
+
+               if ( !$masterId ) {
                        return false;
-               } else {
-                       return intval( $row->Seconds_Behind_Master );
                }
+
+               $res = $this->query(
+                       "SELECT TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6)) AS Lag " .
+                       "FROM heartbeat.heartbeat WHERE server_id = $masterId"
+               );
+               $row = $res ? $res->fetchObject() : false;
+               if ( $row ) {
+                       return max( floatval( $row->Lag ) / 1e6, 0.0 );
+               }
+
+               return false;
        }
 
        /**