From b6d8421ab62231c6de53ac71a1bfc0937695ecb3 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Thu, 6 Oct 2016 09:52:17 -0700
Subject: [PATCH] Minor LoadBalancer cleanups

* Close the master connection in safeWaitForMasterPos() if created.
* Remove unnecessary reuseConnection() calls.
* Add DOMAIN_ANY constant for readability.

Change-Id: I9e64a7405e0eedc50e7b93d05d65cf00d5544a77
---
 .../libs/rdbms/loadbalancer/ILoadBalancer.php |  3 +++
 .../libs/rdbms/loadbalancer/LoadBalancer.php  | 22 ++++++++++---------
 includes/site/DBSiteStore.php                 |  6 -----
 3 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/includes/libs/rdbms/loadbalancer/ILoadBalancer.php b/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
index e5ed2f1e84..8854479a63 100644
--- a/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
+++ b/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
@@ -78,6 +78,9 @@ interface ILoadBalancer {
 	/** @var integer Request a master DB connection */
 	const DB_MASTER = -2;
 
+	/** @var string Domain specifier when no specific database needs to be selected */
+	const DOMAIN_ANY = '';
+
 	/**
 	 * Construct a manager of IDatabase connection objects
 	 *
diff --git a/includes/libs/rdbms/loadbalancer/LoadBalancer.php b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
index 73aa23c683..33f3561557 100644
--- a/includes/libs/rdbms/loadbalancer/LoadBalancer.php
+++ b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
@@ -105,10 +105,9 @@ class LoadBalancer implements ILoadBalancer {
 
 	/** @var integer Warn when this many connection are held */
 	const CONN_HELD_WARN_THRESHOLD = 10;
+
 	/** @var integer Default 'max lag' when unspecified */
 	const MAX_LAG_DEFAULT = 10;
-	/** @var integer Max time to wait for a replica DB to catch up (e.g. ChronologyProtector) */
-	const POS_WAIT_TIMEOUT = 10;
 	/** @var integer Seconds to cache master server read-only status */
 	const TTL_CACHE_READONLY = 5;
 
@@ -130,9 +129,7 @@ class LoadBalancer implements ILoadBalancer {
 			$this->localDomainIdAlias = $this->localDomain->getDatabase();
 		}
 
-		$this->mWaitTimeout = isset( $params['waitTimeout'] )
-			? $params['waitTimeout']
-			: self::POS_WAIT_TIMEOUT;
+		$this->mWaitTimeout = isset( $params['waitTimeout'] ) ? $params['waitTimeout'] : 10;
 
 		$this->mReadIndex = -1;
 		$this->mConns = [
@@ -477,7 +474,7 @@ class LoadBalancer implements ILoadBalancer {
 
 				return false;
 			} else {
-				$conn = $this->openConnection( $index, '' );
+				$conn = $this->openConnection( $index, self::DOMAIN_ANY );
 				if ( !$conn ) {
 					$this->replLogger->warning( __METHOD__ . ": failed to connect to $server" );
 
@@ -1454,10 +1451,15 @@ class LoadBalancer implements ILoadBalancer {
 		}
 
 		if ( !$pos ) {
-			// Get the current master position
-			$dbw = $this->getConnection( self::DB_MASTER );
-			$pos = $dbw->getMasterPos();
-			$this->reuseConnection( $dbw );
+			// Get the current master position, opening a connection if needed
+			$masterConn = $this->getAnyOpenConnection( $this->getWriterIndex() );
+			if ( $masterConn ) {
+				$pos = $masterConn->getMasterPos();
+			} else {
+				$masterConn = $this->openConnection( $this->getWriterIndex(), self::DOMAIN_ANY );
+				$pos = $masterConn->getMasterPos();
+				$this->closeConnection( $masterConn );
+			}
 		}
 
 		if ( $pos instanceof DBMasterPos ) {
diff --git a/includes/site/DBSiteStore.php b/includes/site/DBSiteStore.php
index 432d5ce1da..e5247f2fc1 100644
--- a/includes/site/DBSiteStore.php
+++ b/includes/site/DBSiteStore.php
@@ -130,8 +130,6 @@ class DBSiteStore implements SiteStore {
 				$this->sites->setSite( $site );
 			}
 		}
-
-		$this->dbLoadBalancer->reuseConnection( $dbr );
 	}
 
 	/**
@@ -249,8 +247,6 @@ class DBSiteStore implements SiteStore {
 
 		$dbw->endAtomic( __METHOD__ );
 
-		$this->dbLoadBalancer->reuseConnection( $dbw );
-
 		$this->reset();
 
 		return $success;
@@ -280,8 +276,6 @@ class DBSiteStore implements SiteStore {
 		$ok = $dbw->delete( 'site_identifiers', '*', __METHOD__ ) && $ok;
 		$dbw->endAtomic( __METHOD__ );
 
-		$this->dbLoadBalancer->reuseConnection( $dbw );
-
 		$this->reset();
 
 		return $ok;
-- 
2.20.1