From: Timo Tijhof <krinklemail@gmail.com>
Date: Mon, 29 Jul 2019 18:22:10 +0000 (+0100)
Subject: MessageCache: Restore 'loadedLanguages' tracking for load()
X-Git-Tag: 1.34.0-rc.0~846^2
X-Git-Url: https://git.heureux-cyclage.org/?p=lhc%2Fweb%2Fwiklou.git;a=commitdiff_plain;h=a5c984cc5978f869516e8a0c4892e8113d1c139f

MessageCache: Restore 'loadedLanguages' tracking for load()

This was removed in 97e86d934b3 in 2018 in favour of using
`$this->cache->has($code)`. This is a problem because there
are cases where only a narrow subset of that structure is
populated (by MessageCache->replace) without things like
$this->overridable (or anything else that MessageCache->load does)
having ocurred yet.

The assumption that keys are only added to $this->cache by
MessageCache->load (or after that method has been called) was
actually true at some point. But, this changed in 2017 when
commit c962b480568e optimised MessageCache->replace to not call
MessageCache->load.

Bug: T208897
Change-Id: Ie8bb4a4793675e5f1454e65c427f3100035c8b4d
---

diff --git a/includes/cache/MessageCache.php b/includes/cache/MessageCache.php
index a8bcfc6b44..57454516f3 100644
--- a/includes/cache/MessageCache.php
+++ b/includes/cache/MessageCache.php
@@ -98,6 +98,12 @@ class MessageCache {
 	/** @var Language */
 	protected $contLang;
 
+	/**
+	 * Track which languages have been loaded by load().
+	 * @var array
+	 */
+	private $loadedLanguages = [];
+
 	/**
 	 * Singleton instance
 	 *
@@ -264,23 +270,12 @@ class MessageCache {
 		}
 
 		# Don't do double loading...
-		if ( $this->cache->has( $code ) && $mode != self::FOR_UPDATE ) {
+		if ( isset( $this->loadedLanguages[$code] ) && $mode != self::FOR_UPDATE ) {
 			return true;
 		}
 
 		$this->overridable = array_flip( Language::getMessageKeysFor( $code ) );
 
-		// T208897 array_flip can fail and return null
-		if ( is_null( $this->overridable ) ) {
-			LoggerFactory::getInstance( 'MessageCache' )->error(
-				__METHOD__ . ': $this->overridable is null',
-				[
-					'message_keys' => Language::getMessageKeysFor( $code ),
-					'code' => $code
-				]
-			);
-		}
-
 		# 8 lines of code just to say (once) that message cache is disabled
 		if ( $this->mDisable ) {
 			static $shownDisabled = false;
@@ -396,6 +391,9 @@ class MessageCache {
 			wfDebugLog( 'MessageCacheError', __METHOD__ . ": Failed to load $code\n" );
 			# This used to throw an exception, but that led to nasty side effects like
 			# the whole wiki being instantly down if the memcached server died
+		} else {
+			# All good, just record the success
+			$this->loadedLanguages[$code] = true;
 		}
 
 		if ( !$this->cache->has( $code ) ) { // sanity
@@ -1300,6 +1298,7 @@ class MessageCache {
 			$this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
 		}
 		$this->cache->clear();
+		$this->loadedLanguages = [];
 	}
 
 	/**