From 8ecde9b038143ff8370965c8ff8908097737f7d8 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aaron@users.mediawiki.org>
Date: Mon, 26 Sep 2011 03:37:20 +0000
Subject: [PATCH] Cache negative results for interwiki prefix checks. Also
 helps filecache fail-over mode if DB is down.

---
 includes/interwiki/Interwiki.php | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/includes/interwiki/Interwiki.php b/includes/interwiki/Interwiki.php
index ac9bee7657..f19919fbc2 100644
--- a/includes/interwiki/Interwiki.php
+++ b/includes/interwiki/Interwiki.php
@@ -151,6 +151,9 @@ class Interwiki {
 		if ( !$iwData ) {
 			$key = wfMemcKey( 'interwiki', $prefix );
 			$iwData = $wgMemc->get( $key );
+			if ( $iwData === '!EMPTY' ) {
+				return false; // negative cache hit
+			}
 		}
 
 		if( $iwData && is_array( $iwData ) ) { // is_array is hack for old keys
@@ -175,6 +178,8 @@ class Interwiki {
 			);
 			$wgMemc->add( $key, $mc, $wgInterwikiExpiry );
 			return $iw;
+		} else {
+			$wgMemc->add( $key, '!EMPTY', $wgInterwikiExpiry ); // negative cache hit
 		}
 
 		return false;
-- 
2.20.1