MessageCache.php
17eba67ef329master

MessageCache.php
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			<?php
			/**
			* Localisation messages cache.
			*
			* This program is free software; you can redistribute it and/or modify
			* it under the terms of the GNU General Public License as published by
			* the Free Software Foundation; either version 2 of the License, or
			* (at your option) any later version.
			*
			* This program is distributed in the hope that it will be useful,
			* but WITHOUT ANY WARRANTY; without even the implied warranty of
			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
			* GNU General Public License for more details.
			*
			* You should have received a copy of the GNU General Public License along
			* with this program; if not, write to the Free Software Foundation, Inc.,
			* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
			* http://www.gnu.org/copyleft/gpl.html
			*
			* @file
			* @ingroup Cache
			*/
			use MediaWiki\MediaWikiServices;
			use Wikimedia\ScopedCallback;
			use MediaWiki\Logger\LoggerFactory;

			/**
			* MediaWiki message cache structure version.
			* Bump this whenever the message cache format has changed.
			*/
			define( 'MSG_CACHE_VERSION', 2 );

			/**
			* Message cache
			* Performs various MediaWiki namespace-related functions
			* @ingroup Cache
			*/
			class MessageCache {
			const FOR_UPDATE = 1; // force message reload

			/** How long to wait for memcached locks */
			const WAIT_SEC = 15;
			/** How long memcached locks last */
			const LOCK_TTL = 30;

			/**
			* Process local cache of loaded messages that are defined in
			* MediaWiki namespace. First array level is a language code,
			* second level is message key and the values are either message
			* content prefixed with space, or !NONEXISTENT for negative
			* caching.
			* @var array $mCache
			*/
			protected $mCache;

			/**
			* @var bool[] Map of (language code => boolean)
			*/
			protected $mCacheVolatile = [];

			/**
			* Should mean that database cannot be used, but check
			* @var bool $mDisable
			*/
			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
			*/
			protected $mParserOptions;
			/** @var Parser */
			protected $mParser;

			/**
			* Variable for tracking which variables are already loaded
			* @var array $mLoadedLanguages
			*/
			protected $mLoadedLanguages = [];

			/**
			* @var bool $mInParser
			*/
			protected $mInParser = false;

			/** @var WANObjectCache */
			protected $wanCache;
			/** @var BagOStuff */
			protected $clusterCache;
			/** @var BagOStuff */
			protected $srvCache;

			/**
			* Singleton instance
			*
			* @var MessageCache $instance
			*/
			private static $instance;

			/**
			* Get the signleton instance of this class
			*
			* @since 1.18
			* @return MessageCache
			*/
			public static function singleton() {
			if ( self::$instance === null ) {
			global $wgUseDatabaseMessages, $wgMsgCacheExpiry, $wgUseLocalMessageCache;
			self::$instance = new self(
			MediaWikiServices::getInstance()->getMainWANObjectCache(),
			wfGetMessageCacheStorage(),
			$wgUseLocalMessageCache
			? MediaWikiServices::getInstance()->getLocalServerObjectCache()
			: new EmptyBagOStuff(),
			$wgUseDatabaseMessages,
			$wgMsgCacheExpiry
			);
			}

			return self::$instance;
			}

			/**
			* Destroy the singleton instance
			*
			* @since 1.18
			*/
			public static function destroyInstance() {
			self::$instance = null;
			}

			/**
			* Normalize message key input
			*
			* @param string $key Input message key to be normalized
			* @return string Normalized message key
			*/
			public static function normalizeKey( $key ) {
			global $wgContLang;

			$lckey = strtr( $key, ' ', '_' );
			if ( ord( $lckey ) < 128 ) {
			$lckey[0] = strtolower( $lckey[0] );
			} else {
			$lckey = $wgContLang->lcfirst( $lckey );
			}

			return $lckey;
			}

			/**
			* @param WANObjectCache $wanCache WAN cache instance
			* @param BagOStuff $clusterCache Cluster cache instance
			* @param BagOStuff $srvCache Server cache instance
			* @param bool $useDB Whether to look for message overrides (e.g. MediaWiki: pages)
			* @param int $expiry Lifetime for cache. @see $mExpiry.
			*/
			public function __construct(
			WANObjectCache $wanCache,
			BagOStuff $clusterCache,
			BagOStuff $srvCache,
			$useDB,
			$expiry
			) {
			$this->wanCache = $wanCache;
			$this->clusterCache = $clusterCache;
			$this->srvCache = $srvCache;

			$this->mDisable = !$useDB;
			$this->mExpiry = $expiry;
			}

			/**
			* ParserOptions is lazy initialised.
			*
			* @return ParserOptions
			*/
			function getParserOptions() {
			global $wgUser;

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

			$this->mParserOptions = new ParserOptions;
			$this->mParserOptions->setEditSection( false );
			}

			return $this->mParserOptions;
			}

			/**
			* Try to load the cache from APC.
			*
			* @param string $code Optional language code, see documenation of load().
			* @return array\|bool The cache array, or false if not in cache.
			*/
			protected function getLocalCache( $code ) {
			$cacheKey = wfMemcKey( __CLASS__, $code );

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

			/**
			* Save the cache to APC.
			*
			* @param string $code
			* @param array $cache The cache array
			*/
			protected function saveToLocalCache( $code, $cache ) {
			$cacheKey = wfMemcKey( __CLASS__, $code );
			$this->srvCache->set( $cacheKey, $cache );
			}

			/**
			* Loads messages from caches or from database in this order:
			* (1) local message cache (if $wgUseLocalMessageCache is enabled)
			* (2) memcached
			* (3) from the database.
			*
			* When succesfully loading from (2) or (3), all higher level caches are
			* updated for the newest version.
			*
			* Nothing is loaded if member variable mDisable is true, either manually
			* set by calling code or if message loading fails (is this possible?).
			*
			* Returns true if cache is already populated or it was succesfully populated,
			* or false if populating empty cache fails. Also returns true if MessageCache
			* is disabled.
			*
			* @param string $code Language to which load messages
			* @param integer $mode Use MessageCache::FOR_UPDATE to skip process cache [optional]
			* @throws MWException
			* @return bool
			*/
			protected function load( $code, $mode = null ) {
			if ( !is_string( $code ) ) {
			throw new InvalidArgumentException( "Missing language code" );
			}

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

			# 8 lines of code just to say (once) that message cache is disabled
			if ( $this->mDisable ) {
			static $shownDisabled = false;
			if ( !$shownDisabled ) {
			wfDebug( __METHOD__ . ": disabled\n" );
			$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 );
			$this->mCacheVolatile[$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';
			$success = true;
			$this->mCache[$code] = $cache;
			}

			if ( !$success ) {
			$cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages
			# 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 renerates the cache while others use old values.
			$where[] = 'global cache is expired/volatile';
			$staleCache = $cache;
			} else {
			$where[] = 'got from global cache';
			$this->mCache[$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';
			$this->mCache[$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 yeild 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->mCache = false;
			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
			$this->mLoadedLanguages[$code] = true;
			}

			$info = implode( ', ', $where );
			wfDebugLog( 'MessageCache', __METHOD__ . ": Loading $code... $info\n" );

			return $success;
			}

			/**
			* @param string $code
			* @param array $where List of wfDebug() comments
			* @param integer $mode Use MessageCache::FOR_UPDATE to use DB_MASTER
			* @return bool\|string True on success or one of ("cantacquire", "disabled")
			*/
			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 = wfMemcKey( '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 = wfMemcKey( 'messages', $code );
			$scopedLock = $this->getReentrantScopedLock( $cacheKey, 0 );
			if ( !$scopedLock ) {
			$where[] = 'could not acquire main lock';
			return 'cantacquire';
			}

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

			if ( !$saveSuccess ) {
			/**
			* Cache save has failed.
			*
			* There are two main scenarios where this could be a problem:
			* - The cache is more than the maximum size (typically 1MB compressed).
			* - Memcached has no space remaining in the relevant slab class. This is
			* unlikely with recent versions of memcached.
			*
			* Either way, if there is a local cache, nothing bad will happen. If there
			* is no local cache, disabling the message cache for all requests avoids
			* incurring a loadFromDB() overhead on every request, and thus saves the
			* wiki from complete downtime under moderate traffic conditions.
			*/
			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;
			}

			/**
			* Loads cacheable messages from the database. Messages bigger than
			* $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
			* on-demand from the database later.
			*
			* @param string $code Language code
			* @param integer $mode Use MessageCache::FOR_UPDATE to skip process cache
			* @return array Loaded messages for storing in caches
			*/
			protected function loadFromDB( $code, $mode = null ) {
			global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;

			$dbr = wfGetDB( ( $mode == self::FOR_UPDATE ) ? DB_MASTER : DB_REPLICA );

			$cache = [];

			# Common conditions
			$conds = [
			'page_is_redirect' => 0,
			'page_namespace' => NS_MEDIAWIKI,
			];

			$mostused = [];
			if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
			if ( !isset( $this->mCache[$wgLanguageCode] ) ) {
			$this->load( $wgLanguageCode );
			}
			$mostused = array_keys( $this->mCache[$wgLanguageCode] );
			foreach ( $mostused as $key => $value ) {
			$mostused[$key] = "$value/$code";
			}
			}

			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() );
			}

			# Conditions to fetch oversized pages to ignore them
			$bigConds = $conds;
			$bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );

			# Load titles for all oversized pages in the MediaWiki namespace
			$res = $dbr->select(
			'page',
			[ 'page_title', 'page_latest' ],
			$bigConds,
			__METHOD__ . "($code)-big"
			);
			foreach ( $res as $row ) {
			$cache[$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;
			}

			# Conditions to load the remaining pages with their contents
			$smallConds = $conds;
			$smallConds[] = 'page_latest=rev_id';
			$smallConds[] = 'rev_text_id=old_id';
			$smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );

			$res = $dbr->select(
			[ 'page', 'revision', 'text' ],
			[ 'page_title', 'old_id', 'old_text', 'old_flags' ],
			$smallConds,
			__METHOD__ . "($code)-small"
			);

			foreach ( $res as $row ) {
			$text = Revision::getRevisionText( $row );
			if ( $text === false ) {
			// Failed to fetch data; possible ES errors?
			// Store a marker to fetch on-demand as a workaround...
			// TODO Use a differnt marker
			$entry = '!TOO BIG';
			wfDebugLog(
			'MessageCache',
			__METHOD__
			. ": failed to load message page text for {$row->page_title} ($code)"
			);
			} else {
			$entry = ' ' . $text;
			}
			$cache[$row->page_title] = $entry;
			}

			$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() + $this->mExpiry );

			return $cache;
			}

			/**
			* Updates cache as necessary when message page is changed
			*
			* @param string $title Message cache key with initial uppercase letter.
			* @param string\|bool $text New contents of the page (false if deleted)
			*/
			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
			$this->mCache[$code][$title] = '!NONEXISTENT';
			} else {
			// Ignore $wgMaxMsgCacheEntrySize so the process cache is up to date
			$this->mCache[$code][$title] = ' ' . $text;
			}

			// (b) Update the shared caches in a deferred update with a fresh DB snapshot
			DeferredUpdates::addCallableUpdate(
			function () use ( $title, $msg, $code ) {
			global $wgContLang, $wgMaxMsgCacheEntrySize;
			// Allow one caller at a time to avoid race conditions
			$scopedLock = $this->getReentrantScopedLock( wfMemcKey( 'messages', $code ) );
			if ( !$scopedLock ) {
			LoggerFactory::getInstance( 'MessageCache' )->error(
			__METHOD__ . ': could not acquire lock to update {title} ({code})',
			[ 'title' => $title, 'code' => $code ] );
			return;
			}
			// Load the messages from the master DB to avoid race conditions
			$cache = $this->loadFromDB( $code, self::FOR_UPDATE );
			$this->mCache[$code] = $cache;
			// Load the process cache values and set the per-title cache keys
			$page = WikiPage::factory( Title::makeTitle( NS_MEDIAWIKI, $title ) );
			$page->loadPageData( $page::READ_LATEST );
			$text = $this->getMessageTextFromContent( $page->getContent() );
			// Check if an individual cache key should exist and update cache accordingly
			$titleKey = $this->wanCache->makeKey(
			'messages-big', $this->mCache[$code]['HASH'], $title );
			if ( is_string( $text ) && strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
			$this->wanCache->set( $titleKey, ' ' . $text, $this->mExpiry );
			}
			// Mark this cache as definitely being "latest" (non-volatile) so
			// load() calls do try to refresh the cache with replica DB data
			$this->mCache[$code]['LATEST'] = time();
			// Pre-emptively update the local datacenter cache so things like edit filter and
			// blacklist changes are reflect immediately, as these often use MediaWiki: pages.
			// The datacenter handling replace() calls should be the same one handling edits
			// as they require HTTP POST.
			$this->saveToCaches( $this->mCache[$code], '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( wfMemcKey( 'messages', $code ) );
			// Also delete cached sidebar... just in case it is affected
			// @TODO: shouldn't this be $code === $wgLanguageCode?
			if ( $code === 'en' ) {
			// Purge all language sidebars, e.g. on ?action=purge to the sidebar messages
			$codes = array_keys( Language::fetchLanguageNames() );
			} else {
			// Purge only the sidebar for this language
			$codes = [ $code ];
			}
			foreach ( $codes as $code ) {
			$this->wanCache->delete( wfMemcKey( 'sidebar', $code ) );
			}

			// Purge the message in the message blob store
			$resourceloader = RequestContext::getMain()->getOutput()->getResourceLoader();
			$blobStore = $resourceloader->getMessageBlobStore();
			$blobStore->updateMessage( $wgContLang->lcfirst( $msg ) );

			Hooks::run( 'MessageCacheReplace', [ $title, $text ] );
			},
			DeferredUpdates::PRESEND
			);
			}

			/**
			* Is the given cache array expired due to time passing or a version change?
			*
			* @param array $cache
			* @return bool
			*/
			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;
			}

			/**
			* Shortcut to update caches.
			*
			* @param array $cache Cached messages with a version.
			* @param string $dest Either "local-only" to save to local caches only
			* or "all" to save to all caches.
			* @param string\|bool $code Language code (default: false)
			* @return bool
			*/
			protected function saveToCaches( array $cache, $dest, $code = false ) {
			if ( $dest === 'all' ) {
			$cacheKey = wfMemcKey( 'messages', $code );
			$success = $this->clusterCache->set( $cacheKey, $cache );
			$this->setValidationHash( $code, $cache );
			} else {
			$success = true;
			}

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

			return $success;
			}

			/**
			* Get the md5 used to validate the local APC cache
			*
			* @param string $code
			* @return array (hash or false, bool expiry/volatility status)
			*/
			protected function getValidationHash( $code ) {
			$curTTL = null;
			$value = $this->wanCache->get(
			$this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
			$curTTL,
			[ wfMemcKey( 'messages', $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 ];
			}

			/**
			* Set the md5 used to validate the local disk cache
			*
			* If $cache has a 'LATEST' UNIX timestamp key, then the hash will not
			* be treated as "volatile" by getValidationHash() for the next few seconds.
			* This is triggered when $cache is generated using FOR_UPDATE mode.
			*
			* @param string $code
			* @param array $cache Cached messages with a version
			*/
			protected function setValidationHash( $code, array $cache ) {
			$this->wanCache->set(
			$this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
			[
			'hash' => $cache['HASH'],
			'latest' => isset( $cache['LATEST'] ) ? $cache['LATEST'] : 0
			],
			WANObjectCache::TTL_INDEFINITE
			);
			}

			/**
			* @param string $key A language message cache key that stores blobs
			* @param integer $timeout Wait timeout in seconds
			* @return null\|ScopedCallback
			*/
			protected function getReentrantScopedLock( $key, $timeout = self::WAIT_SEC ) {
			return $this->clusterCache->getScopedLock( $key, $timeout, self::LOCK_TTL, __METHOD__ );
			}

			/**
			* Get a message from either the content language or the user language.
			*
			* First, assemble a list of languages to attempt getting the message from. This
			* chain begins with the requested language and its fallbacks and then continues with
			* the content language and its fallbacks. For each language in the chain, the following
			* process will occur (in this order):
			* 1. If a language-specific override, i.e., [[MW:msg/lang]], is available, use that.
			* Note: for the content language, there is no /lang subpage.
			* 2. Fetch from the static CDB cache.
			* 3. If available, check the database for fallback language overrides.
			*
			* This process provides a number of guarantees. When changing this code, make sure all
			* of these guarantees are preserved.
			* * If the requested language is not the content language, then the CDB cache for that
			* specific language will take precedence over the root database page ([[MW:msg]]).
			* * Fallbacks will be just that: fallbacks. A fallback language will never be reached if
			* the message is available anywhere in the language for which it is a fallback.
			*
			* @param string $key The message key
			* @param bool $useDB If true, look for the message in the DB, false
			* to use only the compiled l10n cache.
			* @param bool\|string\|object $langcode Code of the language to get the message for.
			* - If string and a valid code, will create a standard language object
			* - If string but not a valid code, will create a basic language object
			* - If boolean and false, create object from the current users language
			* - If boolean and true, create object from the wikis content language
			* - If language object, use it as given
			* @param bool $isFullKey Specifies whether $key is a two part key "msg/lang".
			*
			* @throws MWException When given an invalid key
			* @return string\|bool False if the message doesn't exist, otherwise the
			* message (which can be empty)
			*/
			function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
			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;
			}

			// For full keys, get the language code from the key
			$pos = strrpos( $key, '/' );
			if ( $isFullKey && $pos !== false ) {
			$langcode = substr( $key, $pos + 1 );
			$key = substr( $key, 0, $pos );
			}

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

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

			// Loop through each language in the fallback list until we find something useful
			$lang = wfGetLangObj( $langcode );
			$message = $this->getMessageFromFallbackChain(
			$lang,
			$lckey,
			!$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
			' ',
			# Fix for NBSP, converted to space by firefox
			' ',
			' ',
			''
			],
			[
			' ',
			"\xc2\xa0",
			"\xc2\xa0",
			"\xc2\xad"
			],
			$message
			);
			}

			return $message;
			}

			/**
			* Given a language, try and fetch messages from that language.
			*
			* Will also consider fallbacks of that language, the site language, and fallbacks for
			* the site language.
			*
			* @see MessageCache::get
			* @param Language\|StubObject $lang Preferred language
			* @param string $lckey Lowercase key for the message (as for localisation cache)
			* @param bool $useDB Whether to include messages from the wiki database
			* @return string\|bool The message, or false if not found
			*/
			protected function getMessageFromFallbackChain( $lang, $lckey, $useDB ) {
			global $wgContLang;

			$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( $wgContLang, $lckey, $useDB, $alreadyTried );
			return $message;
			}

			/**
			* Given a language, try and fetch messages from that language and its fallbacks.
			*
			* @see MessageCache::get
			* @param Language\|StubObject $lang Preferred language
			* @param string $lckey Lowercase key for the message (as for localisation cache)
			* @param bool $useDB Whether to include messages from the wiki database
			* @param bool[] $alreadyTried Contains true for each language that has been tried already
			* @return string\|bool The message, or false if not found
			*/
			private function getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried ) {
			global $wgContLang;

			$langcode = $lang->getCode();

			// Try checking the database for the requested language
			if ( $useDB ) {
			$uckey = $wgContLang->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;
			}

			/**
			* Get the message page name for a given language
			*
			* @param string $langcode
			* @param string $uckey Uppercase key for the message
			* @return string The page name
			*/
			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";
			}
			}

			/**
			* Get a message from the MediaWiki namespace, with caching. The key must
			* first be converted to two-part lang/msg form if necessary.
			*
			* Unlike self::get(), this function doesn't resolve fallback chains, and
			* some callers require this behavior. LanguageConverter::parseCachedTable()
			* and self::get() are some examples in core.
			*
			* @param string $title Message cache key with initial uppercase letter.
			* @param string $code Code denoting the language to try.
			* @return string\|bool The message, or false if it does not exist or on error
			*/
			public function getMsgFromNamespace( $title, $code ) {
			$this->load( $code );

			if ( isset( $this->mCache[$code][$title] ) ) {
			$entry = $this->mCache[$code][$title];
			if ( substr( $entry, 0, 1 ) === ' ' ) {
			// The message exists, so make sure a string is returned.
			return (string)substr( $entry, 1 );
			} elseif ( $entry === '!NONEXISTENT' ) {
			return false;
			} elseif ( $entry === '!TOO BIG' ) {
			// Fall through and try invididual message cache below
			}
			} else {
			// XXX: This is not cached in process cache, should it?
			$message = false;
			Hooks::run( 'MessagesPreLoad', [ $title, &$message, $code ] );
			if ( $message !== false ) {
			return $message;
			}

			return false;
			}

			// Try the individual message cache
			$titleKey = $this->wanCache->makeKey( 'messages-big', $this->mCache[$code]['HASH'], $title );

			if ( $this->mCacheVolatile[$code] ) {
			$entry = false;
			// Make sure that individual keys respect the WAN cache holdoff period too
			LoggerFactory::getInstance( 'MessageCache' )->debug(
			__METHOD__ . ': loading volatile key \'{titleKey}\'',
			[ 'titleKey' => $titleKey, 'code' => $code ] );
			} else {
			$entry = $this->wanCache->get( $titleKey );
			}

			if ( $entry !== false ) {
			if ( substr( $entry, 0, 1 ) === ' ' ) {
			$this->mCache[$code][$title] = $entry;
			// The message exists, so make sure a string is returned
			return (string)substr( $entry, 1 );
			} elseif ( $entry === '!NONEXISTENT' ) {
			$this->mCache[$code][$title] = '!NONEXISTENT';

			return false;
			} else {
			// Corrupt/obsolete entry, delete it
			$this->wanCache->delete( $titleKey );
			}
			}

			// Try loading the message from the database
			$dbr = wfGetDB( DB_REPLICA );
			$cacheOpts = Database::getCacheSetOptions( $dbr );
			// Use newKnownCurrent() to avoid querying revision/user tables
			$titleObj = Title::makeTitle( NS_MEDIAWIKI, $title );
			if ( $titleObj->getLatestRevID() ) {
			$revision = Revision::newKnownCurrent(
			$dbr,
			$titleObj->getArticleID(),
			$titleObj->getLatestRevID()
			);
			} else {
			$revision = false;
			}

			if ( $revision ) {
			$content = $revision->getContent();
			if ( $content ) {
			$message = $this->getMessageTextFromContent( $content );
			if ( is_string( $message ) ) {
			$this->mCache[$code][$title] = ' ' . $message;
			$this->wanCache->set( $titleKey, ' ' . $message, $this->mExpiry, $cacheOpts );
			}
			} else {
			// A possibly temporary loading failure
			LoggerFactory::getInstance( 'MessageCache' )->warning(
			__METHOD__ . ': failed to load message page text for \'{titleKey}\'',
			[ 'titleKey' => $titleKey, 'code' => $code ] );
			$message = null; // no negative caching
			}
			} else {
			$message = false; // negative caching
			}

			if ( $message === false ) { // negative caching
			$this->mCache[$code][$title] = '!NONEXISTENT';
			$this->wanCache->set( $titleKey, '!NONEXISTENT', $this->mExpiry, $cacheOpts );
			}

			return $message;
			}

			/**
			* @param string $message
			* @param bool $interface
			* @param string $language Language code
			* @param Title $title
			* @return string
			*/
			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;
			}

			/**
			* @return Parser
			*/
			function getParser() {
			global $wgParser, $wgParserConf;

			if ( !$this->mParser && isset( $wgParser ) ) {
			# Do some initialisation so that we don't have to do it twice
			$wgParser->firstCallInit();
			# Clone it and store it
			$class = $wgParserConf['class'];
			if ( $class == 'ParserDiffTest' ) {
			# Uncloneable
			$this->mParser = new $class( $wgParserConf );
			} else {
			$this->mParser = clone $wgParser;
			}
			}

			return $this->mParser;
			}

			/**
			* @param string $text
			* @param Title $title
			* @param bool $linestart Whether or not this is at the start of a line
			* @param bool $interface Whether this is an interface message
			* @param Language\|string $language Language code
			* @return ParserOutput\|string
			*/
			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;
			}

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

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

			/**
			* Whether DB/cache usage is disabled for determining messages
			*
			* If so, this typically indicates either:
			* - a) load() failed to find a cached copy nor query the DB
			* - b) we are in a special context or error mode that cannot use the DB
			* If the DB is ignored, any derived HTML output or cached objects may be wrong.
			* To avoid long-term cache pollution, TTLs can be adjusted accordingly.
			*
			* @return bool
			* @since 1.27
			*/
			public function isDisabled() {
			return $this->mDisable;
			}

			/**
			* Clear all stored messages. Mainly used after a mass rebuild.
			*/
			function clear() {
			$langs = Language::fetchLanguageNames( null, 'mw' );
			foreach ( array_keys( $langs ) as $code ) {
			# Global and local caches
			$this->wanCache->touchCheckKey( wfMemcKey( 'messages', $code ) );
			}

			$this->mLoadedLanguages = [];
			}

			/**
			* @param string $key
			* @return array
			*/
			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 ];
			}

			/**
			* Get all message keys stored in the message cache for a given language.
			* If $code is the content language code, this will return all message keys
			* for which MediaWiki:msgkey exists. If $code is another language code, this
			* will ONLY return message keys for which MediaWiki:msgkey/$code exists.
			* @param string $code Language code
			* @return array Array of message keys (strings)
			*/
			public function getAllMessageKeys( $code ) {
			global $wgContLang;

			$this->load( $code );
			if ( !isset( $this->mCache[$code] ) ) {
			// Apparently load() failed
			return null;
			}
			// Remove administrative keys
			$cache = $this->mCache[$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( [ $wgContLang, 'lcfirst' ], array_keys( $cache ) );
			}

			/**
			* Purge message caches when a MediaWiki: page is created, updated, or deleted
			*
			* @param Title $title Message page title
			* @param Content\|null $content New content for edit/create, null on deletion
			* @since 1.29
			*/
			public function updateMessageOverride( Title $title, Content $content = null ) {
			global $wgContLang;

			$msgText = $this->getMessageTextFromContent( $content );
			if ( $msgText === null ) {
			$msgText = false; // treat as not existing
			}

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

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

			/**
			* @param Content\|null $content Content or null if the message page does not exist
			* @return string\|bool\|null Returns false if $content is null and null on error
			*/
			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;
			LoggerFactory::getInstance( 'MessageCache' )->warning(
			__METHOD__ . ": message content doesn't provide wikitext "
			. "(content model: " . $content->getModel() . ")" );
			}
			} else {
			// Message page does not exist...
			$msgText = false;
			}

			return $msgText;
			}
			}

mediawiki/includes/cache/MessageCache.php17eba67ef329master

MessageCache.phpView Options

mediawiki/includes/cache/MessageCache.php
17eba67ef329master

MessageCache.php
View Options