From 5c57d228945c92b17df04ce6778889b34cf7c3d8 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Fri, 25 Apr 2014 11:25:51 -0700
Subject: [PATCH] Randomize thumbnail failure key TTL a bit to avoid stampedes

Change-Id: Ibf268b646a9eb2acfaa649d634c5278133091158
---
 thumb.php | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/thumb.php b/thumb.php
index 707f1e26cb..a5bdc5bb25 100644
--- a/thumb.php
+++ b/thumb.php
@@ -374,7 +374,8 @@ function wfGenerateThumbnail( File $file, array $params, $thumbName ) {
 	register_shutdown_function( function() use ( &$done, $key ) {
 		if ( !$done ) { // transform() gave a fatal
 			global $wgMemc;
-			$wgMemc->incrWithInit( $key, 3600 );
+			// Randomize TTL to reduce stampedes
+			$wgMemc->incrWithInit( $key, 3600 + mt_rand( 0, 300 ) );
 		}
 	} );
 
@@ -412,7 +413,8 @@ function wfGenerateThumbnail( File $file, array $params, $thumbName ) {
 	$done = true; // no PHP fatal occured
 
 	if ( !$thumb || $thumb->isError() ) {
-		$wgMemc->incrWithInit( $key, 3600 );
+		// Randomize TTL to reduce stampedes
+		$wgMemc->incrWithInit( $key, 3600 + mt_rand( 0, 300 ) );
 	}
 
 	return array( $thumb, $errorHtml );
-- 
2.20.1