From ece85dd20f7e3a69f56ec9d9af25bcaf6762aed2 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Thu, 24 Sep 2015 23:19:06 -0700
Subject: [PATCH] Avoid CAS errors on double post to ApiOptions

Bug: T95839
Change-Id: I62f8eea31164be1ab0eacf31c494f0b296b367f2
---
 includes/User.php           | 9 +++------
 includes/api/ApiOptions.php | 2 +-
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/includes/User.php b/includes/User.php
index d57dfaac15..31d3a99976 100644
--- a/includes/User.php
+++ b/includes/User.php
@@ -1203,18 +1203,15 @@ class User implements IDBAccessObject {
 			return false;
 		}
 
-		$db = ( $flags & self::READ_LATEST )
-			? wfGetDB( DB_MASTER )
-			: wfGetDB( DB_SLAVE );
+		list( $index, $options ) = DBAccessObjectUtils::getDBOptions( $flags );
+		$db = wfGetDB( $index );
 
 		$s = $db->selectRow(
 			'user',
 			self::selectFields(),
 			array( 'user_id' => $this->mId ),
 			__METHOD__,
-			( ( $flags & self::READ_LOCKING ) == self::READ_LOCKING )
-				? array( 'LOCK IN SHARE MODE' )
-				: array()
+			$options
 		);
 
 		$this->queryFlagsUsed = $flags;
diff --git a/includes/api/ApiOptions.php b/includes/api/ApiOptions.php
index a62bcb6d56..74ce0539d5 100644
--- a/includes/api/ApiOptions.php
+++ b/includes/api/ApiOptions.php
@@ -55,7 +55,7 @@ class ApiOptions extends ApiBase {
 		// Load the user from the master to reduce CAS errors on double post (T95839)
 		if ( wfGetLB()->getServerCount() > 1 ) {
 			$user = User::newFromId( $user->getId() );
-			if ( !$user->loadFromId( User::READ_LATEST ) ) {
+			if ( !$user->loadFromId( User::READ_EXCLUSIVE ) ) {
 				$this->dieUsage( 'Anonymous users cannot change preferences', 'notloggedin' );
 			}
 		}
-- 
2.20.1