From: Aaron <aschulz@wikimedia.org>
Date: Thu, 10 May 2012 22:42:59 +0000 (-0700)
Subject: [SiteStatsUpdate] Reduced contention by using a new lockIsFree() DB function.
X-Git-Tag: 1.31.0-rc.0~23648^2
X-Git-Url: https://git.cyclocoop.org/%7B%7B%20url_for%28%27votes%27%2C%20votes=%27waiting%27%29%20%7D%7D?a=commitdiff_plain;h=ff187ea7cc0afe9b4ccc87209c2dda6cab62f6f1;p=lhc%2Fweb%2Fwiklou.git

[SiteStatsUpdate] Reduced contention by using a new lockIsFree() DB function.

* Note: follows up a4b3979160c3ae895d4763967c485380448ce8c0
* Cleanup up transaction statements a bit; transactions don't effect the lock calls
* Also made DatabaseMysql::unlock() actually return a bool

Change-Id: Iade2efa94165b6918eae0863716cc163f36a07b8
---

diff --git a/includes/SiteStats.php b/includes/SiteStats.php
index fec24e910c..10aed9cc9a 100644
--- a/includes/SiteStats.php
+++ b/includes/SiteStats.php
@@ -286,14 +286,13 @@ class SiteStatsUpdate implements DeferrableUpdate {
 			$this->doUpdatePendingDeltas();
 		} else {
 			$dbw = wfGetDB( DB_MASTER );
-			// Need a separate transaction because this a global lock
-			$dbw->begin( __METHOD__ );
 
 			$lockKey = wfMemcKey( 'site_stats' ); // prepend wiki ID
 			if ( $rate ) {
 				// Lock the table so we don't have double DB/memcached updates
-				if ( !$dbw->lock( $lockKey, __METHOD__, 1 ) ) {
-					$dbw->commit( __METHOD__ );
+				if ( !$dbw->lockIsFree( $lockKey, __METHOD__ )
+					|| !$dbw->lock( $lockKey, __METHOD__, 1 ) // 1 sec timeout
+				) {
 					$this->doUpdatePendingDeltas();
 					return;
 				}
@@ -307,6 +306,9 @@ class SiteStatsUpdate implements DeferrableUpdate {
 				$this->images   += ( $pd['ss_images']['+'] - $pd['ss_images']['-'] );
 			}
 
+			// Need a separate transaction because this a global lock
+			$dbw->begin( __METHOD__ );
+
 			// Build up an SQL query of deltas and apply them...
 			$updates = '';
 			$this->appendUpdate( $updates, 'ss_total_views', $this->views );
diff --git a/includes/db/Database.php b/includes/db/Database.php
index 6eb51afc75..b972f3b140 100644
--- a/includes/db/Database.php
+++ b/includes/db/Database.php
@@ -3364,6 +3364,18 @@ abstract class DatabaseBase implements DatabaseType {
 		return 'CONCAT(' . implode( ',', $stringList ) . ')';
 	}
 
+	/**
+	 * Check to see if a named lock is available. This is non-blocking.
+	 *
+	 * @param $lockName String: name of lock to poll
+	 * @param $method String: name of method calling us
+	 * @return Boolean
+	 * @since 1.20
+	 */
+	public function lockIsFree( $lockName, $method ) {
+		return true;
+	}
+
 	/**
 	 * Acquire a named lock
 	 *
diff --git a/includes/db/DatabaseMysql.php b/includes/db/DatabaseMysql.php
index c334c388d8..8550635a39 100644
--- a/includes/db/DatabaseMysql.php
+++ b/includes/db/DatabaseMysql.php
@@ -686,6 +686,21 @@ class DatabaseMysql extends DatabaseBase {
 		return parent::streamStatementEnd( $sql, $newLine );
 	}
 
+	/**
+	 * Check to see if a named lock is available. This is non-blocking.
+	 *
+	 * @param $lockName String: name of lock to poll
+	 * @param $method String: name of method calling us
+	 * @return Boolean
+	 * @since 1.20
+	 */
+	public function lockIsFree( $lockName, $method ) {
+		$lockName = $this->addQuotes( $lockName );
+		$result = $this->query( "SELECT IS_FREE_LOCK($lockName) AS lockstatus", $method );
+		$row = $this->fetchObject( $result );
+		return ( $row->lockstatus == 1 );
+	}
+
 	/**
 	 * @param $lockName string
 	 * @param $method string
@@ -715,7 +730,7 @@ class DatabaseMysql extends DatabaseBase {
 		$lockName = $this->addQuotes( $lockName );
 		$result = $this->query( "SELECT RELEASE_LOCK($lockName) as lockstatus", $method );
 		$row = $this->fetchObject( $result );
-		return $row->lockstatus;
+		return ( $row->lockstatus == 1 );
 	}
 
 	/**