From 7480b9250cbb561f1f3e9b65fe048f4a96afc88c Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Tue, 10 Mar 2015 20:33:52 -0700
Subject: [PATCH] Avoid excess master queries in getTimestampFromId

Bug: T92357
Change-Id: Id5cf7a5620daeee12abfa778f9be19435f3e5e84
---
 includes/Revision.php                        | 18 ++++++++----------
 includes/api/ApiSetNotificationTimestamp.php |  6 ++++--
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/includes/Revision.php b/includes/Revision.php
index d535028a92..cc00f9f152 100644
--- a/includes/Revision.php
+++ b/includes/Revision.php
@@ -1684,23 +1684,21 @@ class Revision implements IDBAccessObject {
 	 *
 	 * @param Title $title
 	 * @param int $id
-	 * @return string
+	 * @return string|bool False if not found
 	 */
-	static function getTimestampFromId( $title, $id ) {
-		$dbr = wfGetDB( DB_SLAVE );
+	static function getTimestampFromId( $title, $id, $flags = 0 ) {
+		$db = ( $flags & self::READ_LATEST )
+			? wfGetDB( DB_MASTER )
+			: wfGetDB( DB_SLAVE );
 		// Casting fix for databases that can't take '' for rev_id
 		if ( $id == '' ) {
 			$id = 0;
 		}
 		$conds = array( 'rev_id' => $id );
 		$conds['rev_page'] = $title->getArticleID();
-		$timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
-		if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
-			# Not in slave, try master
-			$dbw = wfGetDB( DB_MASTER );
-			$timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
-		}
-		return wfTimestamp( TS_MW, $timestamp );
+		$timestamp = $db->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
+
+		return ( $timestamp !== false ) ? wfTimestamp( TS_MW, $timestamp ) : false;
 	}
 
 	/**
diff --git a/includes/api/ApiSetNotificationTimestamp.php b/includes/api/ApiSetNotificationTimestamp.php
index 5d37e20dc5..dec64cc746 100644
--- a/includes/api/ApiSetNotificationTimestamp.php
+++ b/includes/api/ApiSetNotificationTimestamp.php
@@ -73,7 +73,8 @@ class ApiSetNotificationTimestamp extends ApiBase {
 			}
 			$title = reset( $pageSet->getGoodTitles() );
 			if ( $title ) {
-				$timestamp = Revision::getTimestampFromId( $title, $params['torevid'] );
+				$timestamp = Revision::getTimestampFromId(
+					$title, $params['torevid'], Revision::READ_LATEST );
 				if ( $timestamp ) {
 					$timestamp = $dbw->timestamp( $timestamp );
 				} else {
@@ -86,7 +87,8 @@ class ApiSetNotificationTimestamp extends ApiBase {
 			}
 			$title = reset( $pageSet->getGoodTitles() );
 			if ( $title ) {
-				$revid = $title->getNextRevisionID( $params['newerthanrevid'] );
+				$revid = $title->getNextRevisionID(
+					$params['newerthanrevid'], Title::GAID_FOR_UPDATE );
 				if ( $revid ) {
 					$timestamp = $dbw->timestamp( Revision::getTimestampFromId( $title, $revid ) );
 				} else {
-- 
2.20.1