MessageCache: Remove $wgMsgCacheExpiry configuration var

This variable has never been set to anything other than the default value of
24 hours as introduced in 2003 (r2203, r2204; or 036ff960ce, edf6b38626).

The variable has never changed in core, it's not overridden at WMF,
and MessageCache is not constructed anywhere other than ServiceWiring.php
anywhere in repos on Wikimedia Gerrit, indexed by MediaWiki Codesearch,
or any GitHub-hosted repository (incl Wikia repos and WikiHow mirrors).

I've also checked all GitHub-hosted repos for boilerplates and/or public
settings files from devs or prod, and couldn't find any example of
this being overridden (after filtering out copies of the core files
themselves). Rather than having to support potentially hard-to-predict
interactions betweeen caching layers by checking its state, make it
a constant so we can code reason about it more easily.

Change-Id: Ie2e139001aae3ac54b509d94a3d917bb408eaca0

diff --git a/RELEASE-NOTES-1.34 b/RELEASE-NOTES-1.34
index df25d30..7cf1c02 100644 (file)
--- a/RELEASE-NOTES-1.34
+++ b/RELEASE-NOTES-1.34
@@ -75,6 +75,8 @@ For notes on 1.33.x and older releases, see HISTORY.
 * $wgDebugPrintHttpHeaders - The default of including HTTP headers in the
   debug log channel is no longer configurable. The debug log itself remains
   configurable via $wgDebugLogFile.
+* $wgMsgCacheExpiry - The MessageCache uses 24 hours as the expiry for values
+  stored in WANObjectCache. This is no longer configurable.
 * $wgPasswordSalt – This setting, used for migrating exceptionally old, insecure
   password setups and deprecated since 1.24, is now removed.
 * $wgDBOracleDRCP - If you must use persistent connections, set DBO_PERSISTENT

diff --git a/docs/memcached.txt b/docs/memcached.txt
index ba325fe..d0a6e3d 100644 (file)
--- a/docs/memcached.txt
+++ b/docs/memcached.txt
@@ -131,13 +131,7 @@ Localisation:
        cleared by: Language::loadLocalisation()
 
 Message Cache:
-       backend: $wgMessageCacheType
-       key: $wgDBname:messages, $wgDBname:messages-hash, $wgDBname:messages-status
-       ex: wikidb:messages, wikidb:messages-hash, wikidb:messages-status
-       stores: an array where the keys are DB keys and the values are messages
-       set in: wfMessage(), Article::editUpdates() and Title::moveTo()
-       expiry: $wgMsgCacheExpiry
-       cleared by: nothing
+       See MessageCache.php.
 
 Newtalk:
        key: $wgDBname:newtalk:ip:$ip

diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 554a2d5..b1d7b3a 100644 (file)
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -3120,13 +3120,6 @@ $wgTranslateNumerals = true;
  */
 $wgUseDatabaseMessages = true;
 
-/**
- * Expiry time for the message cache key, in seconds.
- *
- * @var int Defaults to 24 hours.
- */
-$wgMsgCacheExpiry = 86400;
-
 /**
  * Maximum entry size in the message cache, in bytes
  */

diff --git a/includes/ServiceWiring.php b/includes/ServiceWiring.php
index 21a66cd..78609e5 100644 (file)
--- a/includes/ServiceWiring.php
+++ b/includes/ServiceWiring.php
@@ -403,7 +403,6 @@ return [
                                ? $services->getLocalServerObjectCache()
                                : new EmptyBagOStuff(),
                        $mainConfig->get( 'UseDatabaseMessages' ),
-                       $mainConfig->get( 'MsgCacheExpiry' ),
                        $services->getContentLanguage()
                );
        },

diff --git a/includes/cache/MessageCache.php b/includes/cache/MessageCache.php
index c2913e5..661ab87 100644 (file)
--- a/includes/cache/MessageCache.php
+++ b/includes/cache/MessageCache.php
@@ -45,6 +45,12 @@ class MessageCache {
        /** How long memcached locks last */
        const LOCK_TTL = 30;
 
+       /**
+        * Lifetime for cache, for keys stored in $wanCache, in seconds.
+        * @var int
+        */
+       const WAN_TTL = IExpiringStore::TTL_DAY;
+
        /**
         * Process cache of loaded messages that are defined in MediaWiki namespace
         *
@@ -70,12 +76,6 @@ class MessageCache {
         */
        protected $mDisable;
 
-       /**
-        * Lifetime for cache, used by object caching.
-        * Set on construction, see __construct().
-        */
-       protected $mExpiry;
-
        /**
         * Message cache has its own parser which it uses to transform messages
         * @var ParserOptions
@@ -137,7 +137,6 @@ class MessageCache {
         * @param BagOStuff $clusterCache
         * @param BagOStuff $serverCache
         * @param bool $useDB Whether to look for message overrides (e.g. MediaWiki: pages)
-        * @param int $expiry Lifetime for cache. @see $mExpiry.
         * @param Language|null $contLang Content language of site
         */
        public function __construct(
@@ -145,7 +144,6 @@ class MessageCache {
                BagOStuff $clusterCache,
                BagOStuff $serverCache,
                $useDB,
-               $expiry,
                Language $contLang = null
        ) {
                $this->wanCache = $wanCache;
@@ -155,7 +153,6 @@ class MessageCache {
                $this->cache = new MapCacheLRU( 5 ); // limit size for sanity
 
                $this->mDisable = !$useDB;
-               $this->mExpiry = $expiry;
                $this->contLang = $contLang ?? MediaWikiServices::getInstance()->getContentLanguage();
        }
 
@@ -551,7 +548,7 @@ class MessageCache {
                # messages larger than $wgMaxMsgCacheEntrySize, since those are only
                # stored and fetched from memcache.
                $cache['HASH'] = md5( serialize( $cache ) );
-               $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );
+               $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + self::WAN_TTL );
                unset( $cache['EXCESSIVE'] ); // only needed for hash
 
                return $cache;
@@ -666,7 +663,7 @@ class MessageCache {
                        $this->wanCache->set(
                                $this->bigMessageCacheKey( $cache['HASH'], $title ),
                                ' ' . $newTextByTitle[$title],
-                               $this->mExpiry
+                               self::WAN_TTL
                        );
                }
                // Mark this cache as definitely being "latest" (non-volatile) so
@@ -1094,7 +1091,7 @@ class MessageCache {
                        function () use ( $code, $dbKey, $hash, $fname ) {
                                return $this->wanCache->getWithSetCallback(
                                        $this->bigMessageCacheKey( $hash, $dbKey ),
-                                       $this->mExpiry,
+                                       self::WAN_TTL,
                                        function ( $oldValue, &$ttl, &$setOpts ) use ( $dbKey, $code, $fname ) {
                                                // Try loading the message from the database
                                                $dbr = wfGetDB( DB_REPLICA );