From ac174f80ac4468d3767d1afec6e7afc1cd0e1cf8 Mon Sep 17 00:00:00 2001
From: Brian Wolff <bawolff+wn@gmail.com>
Date: Wed, 7 Aug 2013 17:26:52 -0300
Subject: [PATCH] More rigorous clearing of image redirect cache

Instead of deleting the cache key, set a temporary
value, so that the key stays "deleted" long enough
so that replag won't cause the key to be repopulated with
an incorrect value from a slave db.

Bug: 52200
Change-Id: I0941c93b76fb0aa8eedb883a3ed1167c6e14d0c0
---
 includes/filerepo/LocalRepo.php       | 14 +++++++++-----
 includes/specials/SpecialMovepage.php |  7 -------
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/includes/filerepo/LocalRepo.php b/includes/filerepo/LocalRepo.php
index 549be40807..9b62243b7c 100644
--- a/includes/filerepo/LocalRepo.php
+++ b/includes/filerepo/LocalRepo.php
@@ -171,13 +171,13 @@ class LocalRepo extends FileRepo {
 		if ( $cachedValue === ' ' || $cachedValue === '' ) {
 			// Does not exist
 			return false;
-		} elseif ( strval( $cachedValue ) !== '' ) {
+		} elseif ( strval( $cachedValue ) !== '' && $cachedValue !== ' PURGED' ) {
 			return Title::newFromText( $cachedValue, NS_FILE );
 		} // else $cachedValue is false or null: cache miss
 
 		$id = $this->getArticleID( $title );
 		if ( !$id ) {
-			$wgMemc->set( $memcKey, " ", $expiry );
+			$wgMemc->add( $memcKey, " ", $expiry );
 			return false;
 		}
 		$dbr = $this->getSlaveDB();
@@ -190,10 +190,10 @@ class LocalRepo extends FileRepo {
 
 		if ( $row && $row->rd_namespace == NS_FILE ) {
 			$targetTitle = Title::makeTitle( $row->rd_namespace, $row->rd_title );
-			$wgMemc->set( $memcKey, $targetTitle->getDBkey(), $expiry );
+			$wgMemc->add( $memcKey, $targetTitle->getDBkey(), $expiry );
 			return $targetTitle;
 		} else {
-			$wgMemc->set( $memcKey, '', $expiry );
+			$wgMemc->add( $memcKey, '', $expiry );
 			return false;
 		}
 	}
@@ -347,7 +347,11 @@ class LocalRepo extends FileRepo {
 		global $wgMemc;
 		$memcKey = $this->getSharedCacheKey( 'image_redirect', md5( $title->getDBkey() ) );
 		if ( $memcKey ) {
-			$wgMemc->delete( $memcKey );
+			// Set a temporary value for the cache key, to ensure
+			// that this value stays purged long enough so that
+			// it isn't refreshed with a stale value due to a
+			// lagged slave.
+			$wgMemc->set( $memcKey, ' PURGED', 12 );
 		}
 	}
 }
diff --git a/includes/specials/SpecialMovepage.php b/includes/specials/SpecialMovepage.php
index 0e342cc0bb..1dc4244eb8 100644
--- a/includes/specials/SpecialMovepage.php
+++ b/includes/specials/SpecialMovepage.php
@@ -692,13 +692,6 @@ class MovePageForm extends UnlistedSpecialPage {
 		# Deal with watches (we don't watch subpages)
 		WatchAction::doWatchOrUnwatch( $this->watch, $ot, $user );
 		WatchAction::doWatchOrUnwatch( $this->watch, $nt, $user );
-
-		# Re-clear the file redirect cache, which may have been polluted by
-		# parsing in messages above. See CR r56745.
-		# @todo FIXME: Needs a more robust solution inside FileRepo.
-		if ( $ot->getNamespace() == NS_FILE ) {
-			RepoGroup::singleton()->getLocalRepo()->invalidateImageRedirect( $ot );
-		}
 	}
 
 	function showLogFragment( $title ) {
-- 
2.20.1