From 4028bcb506c022f620b7702e1033b64c68d95bbc Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Tue, 19 May 2015 19:34:20 -0700
Subject: [PATCH] Fixed race condition in MessageCache::replace

* The cache has to reload and *after* locking to avoid
  losing any concurrent changes.
* Also fixed incorrect assumption in MessageCacheTest.
  Message overrides for the content language do not use
  the language suffix.

Change-Id: I98ff158a1575330bc59efe6badb27f8de8717951
---
 includes/cache/MessageCache.php                   | 15 ++++++++-------
 tests/phpunit/includes/cache/MessageCacheTest.php |  7 +++----
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/includes/cache/MessageCache.php b/includes/cache/MessageCache.php
index 31ee487504..86b073c75e 100644
--- a/includes/cache/MessageCache.php
+++ b/includes/cache/MessageCache.php
@@ -50,6 +50,8 @@ define( 'MSG_WAIT_TIMEOUT', 30 );
  * @ingroup Cache
  */
 class MessageCache {
+	const FOR_UPDATE = 1; // force message reload
+
 	/**
 	 * Process local cache of loaded messages that are defined in
 	 * MediaWiki namespace. First array level is a language code,
@@ -236,10 +238,11 @@ class MessageCache {
 	 * is disabled.
 	 *
 	 * @param bool|string $code Language to which load messages
+	 * @param integer $mode Use MessageCache::FOR_UPDATE to skip process cache
 	 * @throws MWException
 	 * @return bool
 	 */
-	function load( $code = false ) {
+	function load( $code = false, $mode = null ) {
 		global $wgUseLocalMessageCache;
 
 		if ( !is_string( $code ) ) {
@@ -250,7 +253,7 @@ class MessageCache {
 		}
 
 		# Don't do double loading...
-		if ( isset( $this->mLoadedLanguages[$code] ) ) {
+		if ( isset( $this->mLoadedLanguages[$code] ) && $mode != self::FOR_UPDATE ) {
 			return true;
 		}
 
@@ -275,7 +278,6 @@ class MessageCache {
 		# Hash of the contents is stored in memcache, to detect if local cache goes
 		# out of date (e.g. due to replace() on some other server)
 		if ( $wgUseLocalMessageCache ) {
-
 			$hash = $this->mMemc->get( wfMemcKey( 'messages', $code, 'hash' ) );
 			if ( $hash ) {
 				$cache = $this->getLocalCache( $hash, $code );
@@ -431,6 +433,7 @@ class MessageCache {
 	 */
 	function loadFromDB( $code ) {
 		global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
+
 		$dbr = wfGetDB( DB_SLAVE );
 		$cache = array();
 
@@ -514,18 +517,17 @@ class MessageCache {
 	 * @param mixed $text New contents of the page.
 	 */
 	public function replace( $title, $text ) {
-		global $wgMaxMsgCacheEntrySize;
+		global $wgMaxMsgCacheEntrySize, $wgContLang;
 
 		if ( $this->mDisable ) {
-
 			return;
 		}
 
 		list( $msg, $code ) = $this->figureMessage( $title );
 
 		$cacheKey = wfMemcKey( 'messages', $code );
-		$this->load( $code );
 		$this->lock( $cacheKey );
+		$this->load( $code, self::FOR_UPDATE );
 
 		$titleKey = wfMemcKey( 'messages', 'individual', $title );
 
@@ -561,7 +563,6 @@ class MessageCache {
 		}
 
 		// Update the message in the message blob store
-		global $wgContLang;
 		$blobStore = new MessageBlobStore();
 		$blobStore->updateMessage( $wgContLang->lcfirst( $msg ) );
 
diff --git a/tests/phpunit/includes/cache/MessageCacheTest.php b/tests/phpunit/includes/cache/MessageCacheTest.php
index 442e9f9f66..9c59e659f9 100644
--- a/tests/phpunit/includes/cache/MessageCacheTest.php
+++ b/tests/phpunit/includes/cache/MessageCacheTest.php
@@ -52,7 +52,7 @@ class MessageCacheTest extends MediaWikiLangTestCase {
 		$this->makePage( 'MessageCacheTest-FullKeyTest', 'ru' );
 
 		// In content language -- get base if no derivative
-		$this->makePage( 'FallbackLanguageTest-NoDervContLang', 'de', 'de/none', false );
+		$this->makePage( 'FallbackLanguageTest-NoDervContLang', 'de', 'de/none' );
 	}
 
 	/**
@@ -61,15 +61,14 @@ class MessageCacheTest extends MediaWikiLangTestCase {
 	 * @param string $title Title of page to be created
 	 * @param string $lang Language and content of the created page
 	 * @param string|null $content Content of the created page, or null for a generic string
-	 * @param bool $createSubPage Set to false if a root page should be created
 	 */
-	protected function makePage( $title, $lang, $content = null, $createSubPage = true ) {
+	protected function makePage( $title, $lang, $content = null ) {
 		global $wgContLang;
 
 		if ( $content === null ) {
 			$content = $lang;
 		}
-		if ( $lang !== $wgContLang->getCode() || $createSubPage ) {
+		if ( $lang !== $wgContLang->getCode() ) {
 			$title = "$title/$lang";
 		}
 
-- 
2.20.1