master/php/MessageCache_8php_source.html

 <?php
 use MediaWiki\MediaWikiServices;
 use Wikimedia\ScopedCallback;
 use Wikimedia\Rdbms\Database;
 use Psr\Log\LoggerAwareInterface;
 use Psr\Log\LoggerInterface;

 define( 'MSG_CACHE_VERSION', 2 );

 class MessageCache implements LoggerAwareInterface {
     const FOR_UPDATE = 1; // force message reload

     const WAIT_SEC = 15;
     const LOCK_TTL = 30;

     const WAN_TTL = IExpiringStore::TTL_DAY;

     private $logger;

     protected $cache;

     protected $overridable;

     protected $cacheVolatile = [];

     protected $mDisable;

     protected $mParserOptions;
     protected $mParser;

     protected $mInParser = false;

     protected $wanCache;
     protected $clusterCache;
     protected $srvCache;
     protected $contLang;

     public static function singleton() {
         return MediaWikiServices::getInstance()->getMessageCache();
     }

     public static function normalizeKey( $key ) {
         $lckey = strtr( $key, ' ', '_' );
         if ( ord( $lckey ) < 128 ) {
             $lckey[0] = strtolower( $lckey[0] );
         } else {
             $lckey = MediaWikiServices::getInstance()->getContentLanguage()->lcfirst( $lckey );
         }

         return $lckey;
     }

     public function __construct(
         WANObjectCache $wanCache,
         BagOStuff $clusterCache,
         BagOStuff $serverCache,
         Language $contLang,
         LoggerInterface $logger,
         array $options
     ) {
         $this->wanCache = $wanCache;
         $this->clusterCache = $clusterCache;
         $this->srvCache = $serverCache;
         $this->contLang = $contLang;
         $this->logger = $logger;

         $this->cache = new MapCacheLRU( 5 ); // limit size for sanity

         $this->mDisable = !( $options['useDB'] ?? true );
     }

     public function setLogger( LoggerInterface $logger ) {
         $this->logger = $logger;
     }

     function getParserOptions() {
         global $wgUser;

         if ( !$this->mParserOptions ) {
             if ( !$wgUser || !$wgUser->isSafeToLoad() ) {
                 // $wgUser isn't available yet, so don't try to get a
                 // ParserOptions for it. And don't cache this ParserOptions
                 // either.
                 $po = ParserOptions::newFromAnon();
                 $po->setAllowUnsafeRawHtml( false );
                 $po->setTidy( true );
                 return $po;
             }

             $this->mParserOptions = new ParserOptions;
             // Messages may take parameters that could come
             // from malicious sources. As a precaution, disable
             // the <html> parser tag when parsing messages.
             $this->mParserOptions->setAllowUnsafeRawHtml( false );
             // For the same reason, tidy the output!
             $this->mParserOptions->setTidy( true );
         }

         return $this->mParserOptions;
     }

     protected function getLocalCache( $code ) {
         $cacheKey = $this->srvCache->makeKey( __CLASS__, $code );

         return $this->srvCache->get( $cacheKey );
     }

     protected function saveToLocalCache( $code, $cache ) {
         $cacheKey = $this->srvCache->makeKey( __CLASS__, $code );
         $this->srvCache->set( $cacheKey, $cache );
     }

     protected function load( $code, $mode = null ) {
         if ( !is_string( $code ) ) {
             throw new InvalidArgumentException( "Missing language code" );
         }

         # Don't do double loading...
         if ( $this->isLanguageLoaded( $code ) && $mode != self::FOR_UPDATE ) {
             return true;
         }

         $this->overridable = array_flip( Language::getMessageKeysFor( $code ) );

         # 8 lines of code just to say (once) that message cache is disabled
         if ( $this->mDisable ) {
             static $shownDisabled = false;
             if ( !$shownDisabled ) {
                 $this->logger->debug( __METHOD__ . ': disabled' );
                 $shownDisabled = true;
             }

             return true;
         }

         # Loading code starts
         $success = false; # Keep track of success
         $staleCache = false; # a cache array with expired data, or false if none has been loaded
         $where = []; # Debug info, delayed to avoid spamming debug log too much

         # Hash of the contents is stored in memcache, to detect if data-center cache
         # or local cache goes out of date (e.g. due to replace() on some other server)
         list( $hash, $hashVolatile ) = $this->getValidationHash( $code );
         $this->cacheVolatile[$code] = $hashVolatile;

         # Try the local cache and check against the cluster hash key...
         $cache = $this->getLocalCache( $code );
         if ( !$cache ) {
             $where[] = 'local cache is empty';
         } elseif ( !isset( $cache['HASH'] ) || $cache['HASH'] !== $hash ) {
             $where[] = 'local cache has the wrong hash';
             $staleCache = $cache;
         } elseif ( $this->isCacheExpired( $cache ) ) {
             $where[] = 'local cache is expired';
             $staleCache = $cache;
         } elseif ( $hashVolatile ) {
             $where[] = 'local cache validation key is expired/volatile';
             $staleCache = $cache;
         } else {
             $where[] = 'got from local cache';
             $this->cache->set( $code, $cache );
             $success = true;
         }

         if ( !$success ) {
             $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
             # Try the global cache. If it is empty, try to acquire a lock. If
             # the lock can't be acquired, wait for the other thread to finish
             # and then try the global cache a second time.
             for ( $failedAttempts = 0; $failedAttempts <= 1; $failedAttempts++ ) {
                 if ( $hashVolatile && $staleCache ) {
                     # Do not bother fetching the whole cache blob to avoid I/O.
                     # Instead, just try to get the non-blocking $statusKey lock
                     # below, and use the local stale value if it was not acquired.
                     $where[] = 'global cache is presumed expired';
                 } else {
                     $cache = $this->clusterCache->get( $cacheKey );
                     if ( !$cache ) {
                         $where[] = 'global cache is empty';
                     } elseif ( $this->isCacheExpired( $cache ) ) {
                         $where[] = 'global cache is expired';
                         $staleCache = $cache;
                     } elseif ( $hashVolatile ) {
                         # DB results are replica DB lag prone until the holdoff TTL passes.
                         # By then, updates should be reflected in loadFromDBWithLock().
                         # One thread regenerates the cache while others use old values.
                         $where[] = 'global cache is expired/volatile';
                         $staleCache = $cache;
                     } else {
                         $where[] = 'got from global cache';
                         $this->cache->set( $code, $cache );
                         $this->saveToCaches( $cache, 'local-only', $code );
                         $success = true;
                     }
                 }

                 if ( $success ) {
                     # Done, no need to retry
                     break;
                 }

                 # We need to call loadFromDB. Limit the concurrency to one process.
                 # This prevents the site from going down when the cache expires.
                 # Note that the DB slam protection lock here is non-blocking.
                 $loadStatus = $this->loadFromDBWithLock( $code, $where, $mode );
                 if ( $loadStatus === true ) {
                     $success = true;
                     break;
                 } elseif ( $staleCache ) {
                     # Use the stale cache while some other thread constructs the new one
                     $where[] = 'using stale cache';
                     $this->cache->set( $code, $staleCache );
                     $success = true;
                     break;
                 } elseif ( $failedAttempts > 0 ) {
                     # Already blocked once, so avoid another lock/unlock cycle.
                     # This case will typically be hit if memcached is down, or if
                     # loadFromDB() takes longer than LOCK_WAIT.
                     $where[] = "could not acquire status key.";
                     break;
                 } elseif ( $loadStatus === 'cantacquire' ) {
                     # Wait for the other thread to finish, then retry. Normally,
                     # the memcached get() will then yield the other thread's result.
                     $where[] = 'waited for other thread to complete';
                     $this->getReentrantScopedLock( $cacheKey );
                 } else {
                     # Disable cache; $loadStatus is 'disabled'
                     break;
                 }
             }
         }

         if ( !$success ) {
             $where[] = 'loading FAILED - cache is disabled';
             $this->mDisable = true;
             $this->cache->set( $code, [] );
             $this->logger->error( __METHOD__ . ": Failed to load $code" );
             # 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
         }

         if ( !$this->isLanguageLoaded( $code ) ) { // sanity
             throw new LogicException( "Process cache for '$code' should be set by now." );
         }

         $info = implode( ', ', $where );
         $this->logger->debug( __METHOD__ . ": Loading $code... $info" );

         return $success;
     }

     protected function loadFromDBWithLock( $code, array &$where, $mode = null ) {
         # If cache updates on all levels fail, give up on message overrides.
         # This is to avoid easy site outages; see $saveSuccess comments below.
         $statusKey = $this->clusterCache->makeKey( 'messages', $code, 'status' );
         $status = $this->clusterCache->get( $statusKey );
         if ( $status === 'error' ) {
             $where[] = "could not load; method is still globally disabled";
             return 'disabled';
         }

         # Now let's regenerate
         $where[] = 'loading from database';

         # Lock the cache to prevent conflicting writes.
         # This lock is non-blocking so stale cache can quickly be used.
         # Note that load() will call a blocking getReentrantScopedLock()
         # after this if it really need to wait for any current thread.
         $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
         $scopedLock = $this->getReentrantScopedLock( $cacheKey, 0 );
         if ( !$scopedLock ) {
             $where[] = 'could not acquire main lock';
             return 'cantacquire';
         }

         $cache = $this->loadFromDB( $code, $mode );
         $this->cache->set( $code, $cache );
         $saveSuccess = $this->saveToCaches( $cache, 'all', $code );

         if ( !$saveSuccess ) {
             if ( $this->srvCache instanceof EmptyBagOStuff ) {
                 $this->clusterCache->set( $statusKey, 'error', 60 * 5 );
                 $where[] = 'could not save cache, disabled globally for 5 minutes';
             } else {
                 $where[] = "could not save global cache";
             }
         }

         return true;
     }

     protected function loadFromDB( $code, $mode = null ) {
         global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;

         // (T164666) The query here performs really poorly on WMF's
         // contributions replicas. We don't have a way to say "any group except
         // contributions", so for the moment let's specify 'api'.
         // @todo: Get rid of this hack.
         $dbr = wfGetDB( ( $mode == self::FOR_UPDATE ) ? DB_MASTER : DB_REPLICA, 'api' );

         $cache = [];

         $mostused = []; // list of "<cased message key>/<code>"
         if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
             if ( !$this->cache->has( $wgLanguageCode ) ) {
                 $this->load( $wgLanguageCode );
             }
             $mostused = array_keys( $this->cache->get( $wgLanguageCode ) );
             foreach ( $mostused as $key => $value ) {
                 $mostused[$key] = "$value/$code";
             }
         }

         // Get the list of software-defined messages in core/extensions
         $overridable = array_flip( Language::getMessageKeysFor( $wgLanguageCode ) );

         // Common conditions
         $conds = [
             'page_is_redirect' => 0,
             'page_namespace' => NS_MEDIAWIKI,
         ];
         if ( count( $mostused ) ) {
             $conds['page_title'] = $mostused;
         } elseif ( $code !== $wgLanguageCode ) {
             $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
         } else {
             # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
             # other than language code.
             $conds[] = 'page_title NOT' .
                 $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
         }

         // Set the stubs for oversized software-defined messages in the main cache map
         $res = $dbr->select(
             'page',
             [ 'page_title', 'page_latest' ],
             array_merge( $conds, [ 'page_len > ' . intval( $wgMaxMsgCacheEntrySize ) ] ),
             __METHOD__ . "($code)-big"
         );
         foreach ( $res as $row ) {
             // Include entries/stubs for all keys in $mostused in adaptive mode
             if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $row->page_title, $overridable ) ) {
                 $cache[$row->page_title] = '!TOO BIG';
             }
             // At least include revision ID so page changes are reflected in the hash
             $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
         }

         // Set the text for small software-defined messages in the main cache map
         $revisionStore = MediaWikiServices::getInstance()->getRevisionStore();
         $revQuery = $revisionStore->getQueryInfo( [ 'page', 'user' ] );

         // T231196: MySQL/MariaDB (10.1.37) can sometimes irrationally decide that querying `actor` then
         // `revision` then `page` is somehow better than starting with `page`. Tell it not to reorder the
         // query (and also reorder it ourselves because as generated by RevisionStore it'll have
         // `revision` first rather than `page`).
         $revQuery['joins']['revision'] = $revQuery['joins']['page'];
         unset( $revQuery['joins']['page'] );
         // It isn't actually necesssary to reorder $revQuery['tables'] as Database does the right thing
         // when join conditions are given for all joins, but Gergő is wary of relying on that so pull
         // `page` to the start.
         $revQuery['tables'] = array_merge(
             [ 'page' ],
             array_diff( $revQuery['tables'], [ 'page' ] )
         );

         $res = $dbr->select(
             $revQuery['tables'],
             $revQuery['fields'],
             array_merge( $conds, [
                 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize ),
                 'page_latest = rev_id' // get the latest revision only
             ] ),
             __METHOD__ . "($code)-small",
             [ 'STRAIGHT_JOIN' ],
             $revQuery['joins']
         );
         foreach ( $res as $row ) {
             // Include entries/stubs for all keys in $mostused in adaptive mode
             if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $row->page_title, $overridable ) ) {
                 try {
                     $rev = $revisionStore->newRevisionFromRow( $row );
                     $content = $rev->getContent( MediaWiki\Revision\SlotRecord::MAIN );
                     $text = $this->getMessageTextFromContent( $content );
                 } catch ( Exception $ex ) {
                     $text = false;
                 }

                 if ( !is_string( $text ) ) {
                     $entry = '!ERROR';
                     $this->logger->error(
                         __METHOD__
                         . ": failed to load message page text for {$row->page_title} ($code)"
                     );
                 } else {
                     $entry = ' ' . $text;
                 }
                 $cache[$row->page_title] = $entry;
             } else {
                 // T193271: cache object gets too big and slow to generate.
                 // At least include revision ID so page changes are reflected in the hash.
                 $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
             }
         }

         $cache['VERSION'] = MSG_CACHE_VERSION;
         ksort( $cache );

         # Hash for validating local cache (APC). No need to take into account
         # messages larger than $wgMaxMsgCacheEntrySize, since those are only
         # stored and fetched from memcache.
         $cache['HASH'] = md5( serialize( $cache ) );
         $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + self::WAN_TTL );
         unset( $cache['EXCESSIVE'] ); // only needed for hash

         return $cache;
     }

     private function isLanguageLoaded( $lang ) {
         // It is important that this only returns true if the cache was fully
         // populated by load(), so that callers can assume all cache keys exist.
         // It is possible for $this->cache to be only patially populated through
         // methods like MessageCache::replace(), which must not make this method
         // return true (T208897). And this method must cease to return true
         // if the language was evicted by MapCacheLRU (T230690).
         return $this->cache->hasField( $lang, 'VERSION' );
     }

     private function isMainCacheable( $name, array $overridable ) {
         // Convert first letter to lowercase, and strip /code suffix
         $name = $this->contLang->lcfirst( $name );
         $msg = preg_replace( '/\/[a-z0-9-]{2,}$/', '', $name );
         // Include common conversion table pages. This also avoids problems with
         // Installer::parse() bailing out due to disallowed DB queries (T207979).
         return ( isset( $overridable[$msg] ) || strpos( $name, 'conversiontable/' ) === 0 );
     }

     public function replace( $title, $text ) {
         global $wgLanguageCode;

         if ( $this->mDisable ) {
             return;
         }

         list( $msg, $code ) = $this->figureMessage( $title );
         if ( strpos( $title, '/' ) !== false && $code === $wgLanguageCode ) {
             // Content language overrides do not use the /<code> suffix
             return;
         }

         // (a) Update the process cache with the new message text
         if ( $text === false ) {
             // Page deleted
             $this->cache->setField( $code, $title, '!NONEXISTENT' );
         } else {
             // Ignore $wgMaxMsgCacheEntrySize so the process cache is up to date
             $this->cache->setField( $code, $title, ' ' . $text );
         }

         // (b) Update the shared caches in a deferred update with a fresh DB snapshot
         DeferredUpdates::addUpdate(
             new MessageCacheUpdate( $code, $title, $msg ),
             DeferredUpdates::PRESEND
         );
     }

     public function refreshAndReplaceInternal( $code, array $replacements ) {
         global $wgMaxMsgCacheEntrySize;

         // Allow one caller at a time to avoid race conditions
         $scopedLock = $this->getReentrantScopedLock(
             $this->clusterCache->makeKey( 'messages', $code )
         );
         if ( !$scopedLock ) {
             foreach ( $replacements as list( $title ) ) {
                 $this->logger->error(
                     __METHOD__ . ': could not acquire lock to update {title} ({code})',
                     [ 'title' => $title, 'code' => $code ] );
             }

             return;
         }

         // Load the existing cache to update it in the local DC cache.
         // The other DCs will see a hash mismatch.
         if ( $this->load( $code, self::FOR_UPDATE ) ) {
             $cache = $this->cache->get( $code );
         } else {
             // Err? Fall back to loading from the database.
             $cache = $this->loadFromDB( $code, self::FOR_UPDATE );
         }
         // Check if individual cache keys should exist and update cache accordingly
         $newTextByTitle = []; // map of (title => content)
         $newBigTitles = []; // map of (title => latest revision ID), like EXCESSIVE in loadFromDB()
         foreach ( $replacements as list( $title ) ) {
             $page = WikiPage::factory( Title::makeTitle( NS_MEDIAWIKI, $title ) );
             $page->loadPageData( $page::READ_LATEST );
             $text = $this->getMessageTextFromContent( $page->getContent() );
             // Remember the text for the blob store update later on
             $newTextByTitle[$title] = $text;
             // Note that if $text is false, then $cache should have a !NONEXISTANT entry
             if ( !is_string( $text ) ) {
                 $cache[$title] = '!NONEXISTENT';
             } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
                 $cache[$title] = '!TOO BIG';
                 $newBigTitles[$title] = $page->getLatest();
             } else {
                 $cache[$title] = ' ' . $text;
             }
         }
         // Update HASH for the new key. Incorporates various administrative keys,
         // including the old HASH (and thereby the EXCESSIVE value from loadFromDB()
         // and previous replace() calls), but that doesn't really matter since we
         // only ever compare it for equality with a copy saved by saveToCaches().
         $cache['HASH'] = md5( serialize( $cache + [ 'EXCESSIVE' => $newBigTitles ] ) );
         // Update the too-big WAN cache entries now that we have the new HASH
         foreach ( $newBigTitles as $title => $id ) {
             // Match logic of loadCachedMessagePageEntry()
             $this->wanCache->set(
                 $this->bigMessageCacheKey( $cache['HASH'], $title ),
                 ' ' . $newTextByTitle[$title],
                 self::WAN_TTL
             );
         }
         // Mark this cache as definitely being "latest" (non-volatile) so
         // load() calls do not try to refresh the cache with replica DB data
         $cache['LATEST'] = time();
         // Update the process cache
         $this->cache->set( $code, $cache );
         // Pre-emptively update the local datacenter cache so things like edit filter and
         // blacklist changes are reflected immediately; these often use MediaWiki: pages.
         // The datacenter handling replace() calls should be the same one handling edits
         // as they require HTTP POST.
         $this->saveToCaches( $cache, 'all', $code );
         // Release the lock now that the cache is saved
         ScopedCallback::consume( $scopedLock );

         // Relay the purge. Touching this check key expires cache contents
         // and local cache (APC) validation hash across all datacenters.
         $this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );

         // Purge the messages in the message blob store and fire any hook handlers
         $blobStore = MediaWikiServices::getInstance()->getResourceLoader()->getMessageBlobStore();
         foreach ( $replacements as list( $title, $msg ) ) {
             $blobStore->updateMessage( $this->contLang->lcfirst( $msg ) );
             Hooks::run( 'MessageCacheReplace', [ $title, $newTextByTitle[$title] ] );
         }
     }

     protected function isCacheExpired( $cache ) {
         if ( !isset( $cache['VERSION'] ) || !isset( $cache['EXPIRY'] ) ) {
             return true;
         }
         if ( $cache['VERSION'] != MSG_CACHE_VERSION ) {
             return true;
         }
         if ( wfTimestampNow() >= $cache['EXPIRY'] ) {
             return true;
         }

         return false;
     }

     protected function saveToCaches( array $cache, $dest, $code = false ) {
         if ( $dest === 'all' ) {
             $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
             $success = $this->clusterCache->set( $cacheKey, $cache );
             $this->setValidationHash( $code, $cache );
         } else {
             $success = true;
         }

         $this->saveToLocalCache( $code, $cache );

         return $success;
     }

     protected function getValidationHash( $code ) {
         $curTTL = null;
         $value = $this->wanCache->get(
             $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
             $curTTL,
             [ $this->getCheckKey( $code ) ]
         );

         if ( $value ) {
             $hash = $value['hash'];
             if ( ( time() - $value['latest'] ) < WANObjectCache::TTL_MINUTE ) {
                 // Cache was recently updated via replace() and should be up-to-date.
                 // That method is only called in the primary datacenter and uses FOR_UPDATE.
                 // Also, it is unlikely that the current datacenter is *now* secondary one.
                 $expired = false;
             } else {
                 // See if the "check" key was bumped after the hash was generated
                 $expired = ( $curTTL < 0 );
             }
         } else {
             // No hash found at all; cache must regenerate to be safe
             $hash = false;
             $expired = true;
         }

         return [ $hash, $expired ];
     }

     protected function setValidationHash( $code, array $cache ) {
         $this->wanCache->set(
             $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
             [
                 'hash' => $cache['HASH'],
                 'latest' => $cache['LATEST'] ?? 0
             ],
             WANObjectCache::TTL_INDEFINITE
         );
     }

     protected function getReentrantScopedLock( $key, $timeout = self::WAIT_SEC ) {
         return $this->clusterCache->getScopedLock( $key, $timeout, self::LOCK_TTL, __METHOD__ );
     }

     function get( $key, $useDB = true, $langcode = true ) {
         if ( is_int( $key ) ) {
             // Fix numerical strings that somehow become ints
             // on their way here
             $key = (string)$key;
         } elseif ( !is_string( $key ) ) {
             throw new MWException( 'Non-string key given' );
         } elseif ( $key === '' ) {
             // Shortcut: the empty key is always missing
             return false;
         }

         // Normalise title-case input (with some inlining)
         $lckey = self::normalizeKey( $key );

         Hooks::run( 'MessageCache::get', [ &$lckey ] );

         // Loop through each language in the fallback list until we find something useful
         $message = $this->getMessageFromFallbackChain(
             wfGetLangObj( $langcode ),
             $lckey,
             !$this->mDisable && $useDB
         );

         // If we still have no message, maybe the key was in fact a full key so try that
         if ( $message === false ) {
             $parts = explode( '/', $lckey );
             // We may get calls for things that are http-urls from sidebar
             // Let's not load nonexistent languages for those
             // They usually have more than one slash.
             if ( count( $parts ) == 2 && $parts[1] !== '' ) {
                 $message = Language::getMessageFor( $parts[0], $parts[1] );
                 if ( $message === null ) {
                     $message = false;
                 }
             }
         }

         // Post-processing if the message exists
         if ( $message !== false ) {
             // Fix whitespace
             $message = str_replace(
                 [
                     # Fix for trailing whitespace, removed by textarea
                     '&#32;',
                     # Fix for NBSP, converted to space by firefox
                     '&nbsp;',
                     '&#160;',
                     '&shy;'
                 ],
                 [
                     ' ',
                     "\u{00A0}",
                     "\u{00A0}",
                     "\u{00AD}"
                 ],
                 $message
             );
         }

         return $message;
     }

     protected function getMessageFromFallbackChain( $lang, $lckey, $useDB ) {
         $alreadyTried = [];

         // First try the requested language.
         $message = $this->getMessageForLang( $lang, $lckey, $useDB, $alreadyTried );
         if ( $message !== false ) {
             return $message;
         }

         // Now try checking the site language.
         $message = $this->getMessageForLang( $this->contLang, $lckey, $useDB, $alreadyTried );
         return $message;
     }

     private function getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried ) {
         $langcode = $lang->getCode();

         // Try checking the database for the requested language
         if ( $useDB ) {
             $uckey = $this->contLang->ucfirst( $lckey );

             if ( !isset( $alreadyTried[$langcode] ) ) {
                 $message = $this->getMsgFromNamespace(
                     $this->getMessagePageName( $langcode, $uckey ),
                     $langcode
                 );
                 if ( $message !== false ) {
                     return $message;
                 }
                 $alreadyTried[$langcode] = true;
             }
         } else {
             $uckey = null;
         }

         // Check the CDB cache
         $message = $lang->getMessage( $lckey );
         if ( $message !== null ) {
             return $message;
         }

         // Try checking the database for all of the fallback languages
         if ( $useDB ) {
             $fallbackChain = Language::getFallbacksFor( $langcode );

             foreach ( $fallbackChain as $code ) {
                 if ( isset( $alreadyTried[$code] ) ) {
                     continue;
                 }

                 $message = $this->getMsgFromNamespace(
                     $this->getMessagePageName( $code, $uckey ), $code );

                 if ( $message !== false ) {
                     return $message;
                 }
                 $alreadyTried[$code] = true;
             }
         }

         return false;
     }

     private function getMessagePageName( $langcode, $uckey ) {
         global $wgLanguageCode;

         if ( $langcode === $wgLanguageCode ) {
             // Messages created in the content language will not have the /lang extension
             return $uckey;
         } else {
             return "$uckey/$langcode";
         }
     }

     public function getMsgFromNamespace( $title, $code ) {
         // Load all MediaWiki page definitions into cache. Note that individual keys
         // already loaded into cache during this request remain in the cache, which
         // includes the value of hook-defined messages.
         $this->load( $code );

         $entry = $this->cache->getField( $code, $title );

         if ( $entry !== null ) {
             // Message page exists as an override of a software messages
             if ( substr( $entry, 0, 1 ) === ' ' ) {
                 // The message exists and is not '!TOO BIG' or '!ERROR'
                 return (string)substr( $entry, 1 );
             } elseif ( $entry === '!NONEXISTENT' ) {
                 // The text might be '-' or missing due to some data loss
                 return false;
             }
             // Load the message page, utilizing the individual message cache.
             // If the page does not exist, there will be no hook handler fallbacks.
             $entry = $this->loadCachedMessagePageEntry(
                 $title,
                 $code,
                 $this->cache->getField( $code, 'HASH' )
             );
         } else {
             // Message page either does not exist or does not override a software message
             if ( !$this->isMainCacheable( $title, $this->overridable ) ) {
                 // Message page does not override any software-defined message. A custom
                 // message might be defined to have content or settings specific to the wiki.
                 // Load the message page, utilizing the individual message cache as needed.
                 $entry = $this->loadCachedMessagePageEntry(
                     $title,
                     $code,
                     $this->cache->getField( $code, 'HASH' )
                 );
             }
             if ( $entry === null || substr( $entry, 0, 1 ) !== ' ' ) {
                 // Message does not have a MediaWiki page definition; try hook handlers
                 $message = false;
                 Hooks::run( 'MessagesPreLoad', [ $title, &$message, $code ] );
                 if ( $message !== false ) {
                     $this->cache->setField( $code, $title, ' ' . $message );
                 } else {
                     $this->cache->setField( $code, $title, '!NONEXISTENT' );
                 }

                 return $message;
             }
         }

         if ( $entry !== false && substr( $entry, 0, 1 ) === ' ' ) {
             if ( $this->cacheVolatile[$code] ) {
                 // Make sure that individual keys respect the WAN cache holdoff period too
                 $this->logger->debug(
                     __METHOD__ . ': loading volatile key \'{titleKey}\'',
                     [ 'titleKey' => $title, 'code' => $code ] );
             } else {
                 $this->cache->setField( $code, $title, $entry );
             }
             // The message exists, so make sure a string is returned
             return (string)substr( $entry, 1 );
         }

         $this->cache->setField( $code, $title, '!NONEXISTENT' );

         return false;
     }

     private function loadCachedMessagePageEntry( $dbKey, $code, $hash ) {
         $fname = __METHOD__;
         return $this->srvCache->getWithSetCallback(
             $this->srvCache->makeKey( 'messages-big', $hash, $dbKey ),
             BagOStuff::TTL_HOUR,
             function () use ( $code, $dbKey, $hash, $fname ) {
                 return $this->wanCache->getWithSetCallback(
                     $this->bigMessageCacheKey( $hash, $dbKey ),
                     self::WAN_TTL,
                     function ( $oldValue, &$ttl, &$setOpts ) use ( $dbKey, $code, $fname ) {
                         // Try loading the message from the database
                         $dbr = wfGetDB( DB_REPLICA );
                         $setOpts += Database::getCacheSetOptions( $dbr );
                         // Use newKnownCurrent() to avoid querying revision/user tables
                         $title = Title::makeTitle( NS_MEDIAWIKI, $dbKey );
                         $revision = Revision::newKnownCurrent( $dbr, $title );
                         if ( !$revision ) {
                             // The wiki doesn't have a local override page. Cache absence with normal TTL.
                             // When overrides are created, self::replace() takes care of the cache.
                             return '!NONEXISTENT';
                         }
                         $content = $revision->getContent();
                         if ( $content ) {
                             $message = $this->getMessageTextFromContent( $content );
                         } else {
                             $this->logger->warning(
                                 $fname . ': failed to load page text for \'{titleKey}\'',
                                 [ 'titleKey' => $dbKey, 'code' => $code ]
                             );
                             $message = null;
                         }

                         if ( !is_string( $message ) ) {
                             // Revision failed to load Content, or Content is incompatible with wikitext.
                             // Possibly a temporary loading failure.
                             $ttl = 5;

                             return '!NONEXISTENT';
                         }

                         return ' ' . $message;
                     }
                 );
             }
         );
     }

     public function transform( $message, $interface = false, $language = null, $title = null ) {
         // Avoid creating parser if nothing to transform
         if ( strpos( $message, '{{' ) === false ) {
             return $message;
         }

         if ( $this->mInParser ) {
             return $message;
         }

         $parser = $this->getParser();
         if ( $parser ) {
             $popts = $this->getParserOptions();
             $popts->setInterfaceMessage( $interface );
             $popts->setTargetLanguage( $language );

             $userlang = $popts->setUserLang( $language );
             $this->mInParser = true;
             $message = $parser->transformMsg( $message, $popts, $title );
             $this->mInParser = false;
             $popts->setUserLang( $userlang );
         }

         return $message;
     }

     public function getParser() {
         global $wgParserConf;
         if ( !$this->mParser ) {
             $parser = MediaWikiServices::getInstance()->getParser();
             # Do some initialisation so that we don't have to do it twice
             $parser->firstCallInit();
             # Clone it and store it
             $class = $wgParserConf['class'];
             if ( $class == ParserDiffTest::class ) {
                 # Uncloneable
                 // @phan-suppress-next-line PhanTypeMismatchProperty
                 $this->mParser = new $class( $wgParserConf );
             } else {
                 $this->mParser = clone $parser;
             }
         }

         return $this->mParser;
     }

     public function parse( $text, $title = null, $linestart = true,
         $interface = false, $language = null
     ) {
         global $wgTitle;

         if ( $this->mInParser ) {
             return htmlspecialchars( $text );
         }

         $parser = $this->getParser();
         $popts = $this->getParserOptions();
         $popts->setInterfaceMessage( $interface );

         if ( is_string( $language ) ) {
             $language = Language::factory( $language );
         }
         $popts->setTargetLanguage( $language );

         if ( !$title || !$title instanceof Title ) {
             wfDebugLog( 'GlobalTitleFail', __METHOD__ . ' called by ' .
                 wfGetAllCallers( 6 ) . ' with no title set.' );
             $title = $wgTitle;
         }
         // Sometimes $wgTitle isn't set either...
         if ( !$title ) {
             # It's not uncommon having a null $wgTitle in scripts. See r80898
             # Create a ghost title in such case
             $title = Title::makeTitle( NS_SPECIAL, 'Badtitle/title not set in ' . __METHOD__ );
         }

         $this->mInParser = true;
         $res = $parser->parse( $text, $title, $popts, $linestart );
         $this->mInParser = false;

         return $res;
     }

     public function disable() {
         $this->mDisable = true;
     }

     public function enable() {
         $this->mDisable = false;
     }

     public function isDisabled() {
         return $this->mDisable;
     }

     public function clear() {
         $langs = Language::fetchLanguageNames( null, 'mw' );
         foreach ( array_keys( $langs ) as $code ) {
             $this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
         }
         $this->cache->clear();
     }

     public function figureMessage( $key ) {
         global $wgLanguageCode;

         $pieces = explode( '/', $key );
         if ( count( $pieces ) < 2 ) {
             return [ $key, $wgLanguageCode ];
         }

         $lang = array_pop( $pieces );
         if ( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
             return [ $key, $wgLanguageCode ];
         }

         $message = implode( '/', $pieces );

         return [ $message, $lang ];
     }

     public function getAllMessageKeys( $code ) {
         $this->load( $code );
         if ( !$this->cache->has( $code ) ) {
             // Apparently load() failed
             return null;
         }
         // Remove administrative keys
         $cache = $this->cache->get( $code );
         unset( $cache['VERSION'] );
         unset( $cache['EXPIRY'] );
         unset( $cache['EXCESSIVE'] );
         // Remove any !NONEXISTENT keys
         $cache = array_diff( $cache, [ '!NONEXISTENT' ] );

         // Keys may appear with a capital first letter. lcfirst them.
         return array_map( [ $this->contLang, 'lcfirst' ], array_keys( $cache ) );
     }

     public function updateMessageOverride( Title $title, Content $content = null ) {
         $msgText = $this->getMessageTextFromContent( $content );
         if ( $msgText === null ) {
             $msgText = false; // treat as not existing
         }

         $this->replace( $title->getDBkey(), $msgText );

         if ( $this->contLang->hasVariants() ) {
             $this->contLang->updateConversionTable( $title );
         }
     }

     public function getCheckKey( $code ) {
         return $this->wanCache->makeKey( 'messages', $code );
     }

     private function getMessageTextFromContent( Content $content = null ) {
         // @TODO: could skip pseudo-messages like js/css here, based on content model
         if ( $content ) {
             // Message page exists...
             // XXX: Is this the right way to turn a Content object into a message?
             // NOTE: $content is typically either WikitextContent, JavaScriptContent or
             //       CssContent. MessageContent is *not* used for storing messages, it's
             //       only used for wrapping them when needed.
             $msgText = $content->getWikitextForTransclusion();
             if ( $msgText === false || $msgText === null ) {
                 // This might be due to some kind of misconfiguration...
                 $msgText = null;
                 $this->logger->warning(
                     __METHOD__ . ": message content doesn't provide wikitext "
                     . "(content model: " . $content->getModel() . ")" );
             }
         } else {
             // Message page does not exist...
             $msgText = false;
         }

         return $msgText;
     }

     private function bigMessageCacheKey( $hash, $title ) {
         return $this->wanCache->makeKey( 'messages-big', $hash, $title );
     }
 }
MessageCache\load
load( $code, $mode=null)
Loads messages from caches or from database in this order: (1) local message cache (if $wgUseLocalMes...
Definition: MessageCache.php:242

WikiPage\factory
static factory(Title $title)
Create a WikiPage object of the appropriate class for the given title.
Definition: WikiPage.php:142

MessageCache\saveToCaches
saveToCaches(array $cache, $dest, $code=false)
Shortcut to update caches.
Definition: MessageCache.php:758

$title
$title
Definition: testCompression.php:34

LogicException

MessageCache\$mInParser
$mInParser
Definition: MessageCache.php:94

MessageCache\loadFromDBWithLock
loadFromDBWithLock( $code, array &$where, $mode=null)
Definition: MessageCache.php:387

MSG_CACHE_VERSION
const MSG_CACHE_VERSION
MediaWiki message cache structure version.
Definition: MessageCache.php:33

Language\fetchLanguageNames
static fetchLanguageNames( $inLanguage=self::AS_AUTONYMS, $include='mw')
Get an array of language names, indexed by code.
Definition: Language.php:814

MediaWikiServices

WANObjectCache

IExpiringStore\TTL_INDEFINITE
const TTL_INDEFINITE
Definition: IExpiringStore.php:44

MapCacheLRU\get
get( $key, $maxAge=INF, $default=null)
Get the value for a key.
Definition: MapCacheLRU.php:168

MessageCache\figureMessage
figureMessage( $key)
Definition: MessageCache.php:1310

MessageCache\disable
disable()
Definition: MessageCache.php:1269

MapCacheLRU

$success
$success
Definition: NoLocalSettings.php:42

serialize
serialize()
Definition: ApiMessageTrait.php:138

MessageCache\transform
transform( $message, $interface=false, $language=null, $title=null)
Definition: MessageCache.php:1175

MessageCache\setValidationHash
setValidationHash( $code, array $cache)
Set the md5 used to validate the local disk cache.
Definition: MessageCache.php:816

$lang
if(!isset( $args[0])) $lang
Definition: testCompression.php:33

EmptyBagOStuff

MessageCache\getAllMessageKeys
getAllMessageKeys( $code)
Get all message keys stored in the message cache for a given language.
Definition: MessageCache.php:1336

wfGetDB
wfGetDB( $db, $groups=[], $wiki=false)
Get a Database object.
Definition: GlobalFunctions.php:2578

IExpiringStore\TTL_DAY
const TTL_DAY
Definition: IExpiringStore.php:35

MessageCache\bigMessageCacheKey
bigMessageCacheKey( $hash, $title)
Definition: MessageCache.php:1415

MessageCache\saveToLocalCache
saveToLocalCache( $code, $cache)
Save the cache to APC.
Definition: MessageCache.php:216

MessageCache\getMessageTextFromContent
getMessageTextFromContent(Content $content=null)
Definition: MessageCache.php:1386

NS_SPECIAL
const NS_SPECIAL
Definition: Defines.php:49

MessageCache\isMainCacheable
isMainCacheable( $name, array $overridable)
Definition: MessageCache.php:597

MessageCache\$clusterCache
BagOStuff $clusterCache
Definition: MessageCache.php:99

IExpiringStore\TTL_HOUR
const TTL_HOUR
Definition: IExpiringStore.php:34

$res
$res
Definition: testCompression.php:52

MessageCacheUpdate
Message cache purging and in-place update handler for specific message page changes.
Definition: MessageCacheUpdate.php:31

MediaWiki
A helper class for throttling authentication attempts.

MessageCache\loadFromDB
loadFromDB( $code, $mode=null)
Loads cacheable messages from the database.
Definition: MessageCache.php:449

IExpiringStore\TTL_MINUTE
const TTL_MINUTE
Definition: IExpiringStore.php:33

LoggerInterface

MessageCache\$mParser
Parser $mParser
Definition: MessageCache.php:89

DB_MASTER
const DB_MASTER
Definition: defines.php:26

MessageCache\normalizeKey
static normalizeKey( $key)
Normalize message key input.
Definition: MessageCache.php:122

wfGetLangObj
wfGetLangObj( $langcode=false)
Return a Language object from $langcode.
Definition: GlobalFunctions.php:1215

ScopedCallback

MessageCache\getParserOptions
getParserOptions()
ParserOptions is lazy initialised.
Definition: MessageCache.php:172

$dbr
$dbr
Definition: testCompression.php:50

ParserOptions

MessageCache\refreshAndReplaceInternal
refreshAndReplaceInternal( $code, array $replacements)
Definition: MessageCache.php:646

Content

MessageCache\getMsgFromNamespace
getMsgFromNamespace( $title, $code)
Get a message from the MediaWiki namespace, with caching.
Definition: MessageCache.php:1047

wfGetAllCallers
wfGetAllCallers( $limit=3)
Return a string consisting of callers in the stack.
Definition: GlobalFunctions.php:1470

$wgLanguageCode
$wgLanguageCode
Site language code.
Definition: DefaultSettings.php:2955

wfTimestamp
wfTimestamp( $outputtype=TS_UNIX, $ts=0)
Get a timestamp string in one of various formats.
Definition: GlobalFunctions.php:1872

Language\getMessageFor
static getMessageFor( $key, $code)
Get a message for a given language.
Definition: Language.php:4426

MessageCache\$cache
MapCacheLRU $cache
Process cache of loaded messages that are defined in MediaWiki namespace.
Definition: MessageCache.php:63

$wgMaxMsgCacheEntrySize
$wgMaxMsgCacheEntrySize
Maximum entry size in the message cache, in bytes.
Definition: DefaultSettings.php:3118

MessageCache\loadCachedMessagePageEntry
loadCachedMessagePageEntry( $dbKey, $code, $hash)
Definition: MessageCache.php:1121

BagOStuff

MessageCache

MapCacheLRU\set
set( $key, $value, $rank=self::RANK_TOP)
Set a key/value pair.
Definition: MapCacheLRU.php:110

MessageCache\replace
replace( $title, $text)
Updates cache as necessary when message page is changed.
Definition: MessageCache.php:612

Language\getMessageKeysFor
static getMessageKeysFor( $code)
Get all message keys for a given language.
Definition: Language.php:4438

Language

Title\getDBkey
getDBkey()
Get the main part with underscores.
Definition: Title.php:1016

Revision\newKnownCurrent
static newKnownCurrent(IDatabase $db, $pageIdOrTitle, $revId=0)
Load a revision based on a known page ID and current revision ID from the DB.
Definition: Revision.php:1123

MessageCache\getValidationHash
getValidationHash( $code)
Get the md5 used to validate the local APC cache.
Definition: MessageCache.php:778

MessageCache\$logger
LoggerInterface $logger
Definition: MessageCache.php:49

$wgAdaptiveMessageCache
$wgAdaptiveMessageCache
Instead of caching everything, only cache those messages which have been customised in the site conte...
Definition: DefaultSettings.php:2589

MessageCache\$overridable
array $overridable
Map of (lowercase message key => index) for all software defined messages.
Definition: MessageCache.php:70

wfTimestampNow
wfTimestampNow()
Convenience function; returns MediaWiki timestamp for the present time.
Definition: GlobalFunctions.php:1901

MessageCache\getParser
getParser()
Definition: MessageCache.php:1204

MessageCache\getLocalCache
getLocalCache( $code)
Try to load the cache from APC.
Definition: MessageCache.php:204

Language\factory
static factory( $code)
Get a cached or new language object for a given language code.
Definition: Language.php:212

MessageCache\$cacheVolatile
bool [] $cacheVolatile
Map of (language code => boolean)
Definition: MessageCache.php:75

$wgParserConf
$wgParserConf
Parser configuration.
Definition: DefaultSettings.php:4142

NS_MEDIAWIKI
const NS_MEDIAWIKI
Definition: Defines.php:68

ParserOptions\newFromAnon
static newFromAnon()
Get a ParserOptions object for an anonymous user.
Definition: ParserOptions.php:1013

MessageCache\getReentrantScopedLock
getReentrantScopedLock( $key, $timeout=self::WAIT_SEC)
Definition: MessageCache.php:832

MessageCache\WAIT_SEC
const WAIT_SEC
How long to wait for memcached locks.
Definition: MessageCache.php:45

Title\makeTitle
static makeTitle( $ns, $title, $fragment='', $interwiki='')
Create a new Title from a namespace index and a DB key.
Definition: Title.php:586

Language\fetchLanguageName
static fetchLanguageName( $code, $inLanguage=self::AS_AUTONYMS, $include=self::ALL)
Definition: Language.php:828

MessageCache\getMessagePageName
getMessagePageName( $langcode, $uckey)
Get the message page name for a given language.
Definition: MessageCache.php:1024

MessageCache\getMessageFromFallbackChain
getMessageFromFallbackChain( $lang, $lckey, $useDB)
Given a language, try and fetch messages from that language.
Definition: MessageCache.php:944

MessageCache\FOR_UPDATE
const FOR_UPDATE
Definition: MessageCache.php:42

MessageCache\__construct
__construct(WANObjectCache $wanCache, BagOStuff $clusterCache, BagOStuff $serverCache, Language $contLang, LoggerInterface $logger, array $options)
Definition: MessageCache.php:144

MessageCache\isDisabled
isDisabled()
Whether DB/cache usage is disabled for determining messages.
Definition: MessageCache.php:1289

MessageCache\updateMessageOverride
updateMessageOverride(Title $title, Content $content=null)
Purge message caches when a MediaWiki: page is created, updated, or deleted.
Definition: MessageCache.php:1361

MessageCache\parse
parse( $text, $title=null, $linestart=true, $interface=false, $language=null)
Definition: MessageCache.php:1232

MessageCache\$mParserOptions
ParserOptions $mParserOptions
Message cache has its own parser which it uses to transform messages.
Definition: MessageCache.php:87

DeferredUpdates\addUpdate
static addUpdate(DeferrableUpdate $update, $stage=self::POSTSEND)
Add an update to the deferred list to be run later by execute()
Definition: DeferredUpdates.php:85

MessageCache\$srvCache
BagOStuff $srvCache
Definition: MessageCache.php:101

wfDebugLog
wfDebugLog( $logGroup, $text, $dest='all', array $context=[])
Send a line to a supplementary debug log file, if configured, or main debug log if not...
Definition: GlobalFunctions.php:1007

MessageCache\getMessageForLang
getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried)
Given a language, try and fetch messages from that language and its fallbacks.
Definition: MessageCache.php:968

Language\getFallbacksFor
static getFallbacksFor( $code, $mode=self::MESSAGES_FALLBACKS)
Get the ordered list of fallback languages.
Definition: Language.php:4386

$revQuery
$revQuery
Definition: testCompression.php:51

MessageCache\$contLang
Language $contLang
Definition: MessageCache.php:103

MessageCache\clear
clear()
Clear all stored messages in global and local cache.
Definition: MessageCache.php:1298

MessageCache\getCheckKey
getCheckKey( $code)
Definition: MessageCache.php:1378

LoggerAwareInterface

DB_REPLICA
const DB_REPLICA
Definition: defines.php:25

$content
$content
Definition: router.php:78

InvalidArgumentException

$wgTitle
if(! $wgRequest->checkUrlExtension()) if(isset( $_SERVER['PATH_INFO']) && $_SERVER['PATH_INFO'] !='') $wgTitle
Definition: api.php:58

MessageCache\$mDisable
$mDisable
Should mean that database cannot be used, but check.
Definition: MessageCache.php:81

Title

Database

DeferredUpdates\PRESEND
const PRESEND
Definition: DeferredUpdates.php:69

Revision
Definition: Revision.php:40

MessageCache\isLanguageLoaded
isLanguageLoaded( $lang)
Whether the language was loaded and its data is still in the process cache.
Definition: MessageCache.php:582

MessageCache\$wanCache
WANObjectCache $wanCache
Definition: MessageCache.php:97

MWException

true
return true
Definition: router.php:92

MessageCache\LOCK_TTL
const LOCK_TTL
How long memcached locks last.
Definition: MessageCache.php:47

MessageCache\singleton
static singleton()
Get the singleton instance of this class.
Definition: MessageCache.php:112

MessageCache\isCacheExpired
isCacheExpired( $cache)
Is the given cache array expired due to time passing or a version change?
Definition: MessageCache.php:735

Hooks\run
static run( $event, array $args=[], $deprecatedVersion=null)
Call hook functions defined in Hooks::register and $wgHooks.
Definition: Hooks.php:200

MessageCache\enable
enable()
Definition: MessageCache.php:1273

MessageCache\setLogger
setLogger(LoggerInterface $logger)
Definition: MessageCache.php:163

Exception