From: Ori Livneh <ori@wikimedia.org>
Date: Thu, 13 Aug 2015 04:40:49 +0000 (-0700)
Subject: MessageCache: derive the hash from the cache contents
X-Git-Tag: 1.31.0-rc.0~10420
X-Git-Url: http://git.cyclocoop.org/%28%5B%5E/404?a=commitdiff_plain;h=6147de1182101903cf24259d61ec6ea34b907bf3;p=lhc%2Fweb%2Fwiklou.git

MessageCache: derive the hash from the cache contents

Follow-up for I020617d, where I got this wrong. It is probable that multiple
application servers will try to build a local cache at the same time, in which
case they will cause the cache key to thrash. It is necessary that two
application servers building a local cache from the database generate the same
hash for a given set of messages.

Change-Id: Ieeefc2094a83be9401c466bec859c1588ddfbcdf
---

diff --git a/includes/cache/MessageCache.php b/includes/cache/MessageCache.php
index 304c4f2192..3f60d8c0c5 100644
--- a/includes/cache/MessageCache.php
+++ b/includes/cache/MessageCache.php
@@ -530,7 +530,8 @@ class MessageCache {
 		}
 
 		$cache['VERSION'] = MSG_CACHE_VERSION;
-		$cache['HASH'] = wfRandomString( 8 );
+		ksort( $cache );
+		$cache['HASH'] = md5( serialize( $cache ) );
 		$cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );
 
 		return $cache;