From faac856f213639fce78a02eaf7a67e490b7b70cb Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Thu, 15 Sep 2016 04:50:25 -0700
Subject: [PATCH] Fix broken wincache merge() implementation

Bug: T145664
Change-Id: I2f841779108df281e24003c586775b71aa176909
---
 includes/libs/objectcache/WinCacheBagOStuff.php | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/includes/libs/objectcache/WinCacheBagOStuff.php b/includes/libs/objectcache/WinCacheBagOStuff.php
index 19cc66a8ba..6996ce54c3 100644
--- a/includes/libs/objectcache/WinCacheBagOStuff.php
+++ b/includes/libs/objectcache/WinCacheBagOStuff.php
@@ -65,6 +65,13 @@ class WinCacheBagOStuff extends BagOStuff {
 	}
 
 	public function merge( $key, callable $callback, $exptime = 0, $attempts = 10, $flags = 0 ) {
-		return $this->mergeViaCas( $key, $callback, $exptime, $attempts );
+		if ( wincache_lock( $key ) ) { // optimize with FIFO lock
+			$ok = $this->mergeViaLock( $key, $callback, $exptime, $attempts, $flags );
+			wincache_unlock( $key );
+		} else {
+			$ok = false;
+		}
+
+		return $ok;
 	}
 }
-- 
2.20.1