includes/cache/MessageCache.php

   1 <?php
   2 /**
   3  * Localisation messages cache.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Cache
  22  */
  23 use MediaWiki\MediaWikiServices;
  24 use Wikimedia\ScopedCallback;
  25 use MediaWiki\Logger\LoggerFactory;
  26 use Wikimedia\Rdbms\Database;
  27
  28 /**
  29  * MediaWiki message cache structure version.
  30  * Bump this whenever the message cache format has changed.
  31  */
  32 define( 'MSG_CACHE_VERSION', 2 );
  33
  34 /**
  35  * Cache of messages that are defined by MediaWiki namespace pages or by hooks
  36  *
  37  * Performs various MediaWiki namespace-related functions
  38  * @ingroup Cache
  39  */
  40 class MessageCache {
  41         const FOR_UPDATE = 1; // force message reload
  42
  43         /** How long to wait for memcached locks */
  44         const WAIT_SEC = 15;
  45         /** How long memcached locks last */
  46         const LOCK_TTL = 30;
  47
  48         /**
  49          * Process cache of loaded messages that are defined in MediaWiki namespace
  50          *
  51          * @var MapCacheLRU Map of (language code => key => " <MESSAGE>" or "!TOO BIG" or "!ERROR")
  52          */
  53         protected $cache;
  54
  55         /**
  56          * Map of (lowercase message key => index) for all software defined messages
  57          *
  58          * @var array
  59          */
  60         protected $overridable;
  61
  62         /**
  63          * @var bool[] Map of (language code => boolean)
  64          */
  65         protected $cacheVolatile = [];
  66
  67         /**
  68          * Should mean that database cannot be used, but check
  69          * @var bool $mDisable
  70          */
  71         protected $mDisable;
  72
  73         /**
  74          * Lifetime for cache, used by object caching.
  75          * Set on construction, see __construct().
  76          */
  77         protected $mExpiry;
  78
  79         /**
  80          * Message cache has its own parser which it uses to transform messages
  81          * @var ParserOptions
  82          */
  83         protected $mParserOptions;
  84         /** @var Parser */
  85         protected $mParser;
  86
  87         /**
  88          * @var bool $mInParser
  89          */
  90         protected $mInParser = false;
  91
  92         /** @var WANObjectCache */
  93         protected $wanCache;
  94         /** @var BagOStuff */
  95         protected $clusterCache;
  96         /** @var BagOStuff */
  97         protected $srvCache;
  98         /** @var Language */
  99         protected $contLang;
 100
 101         /**
 102          * Track which languages have been loaded by load().
 103          * @var array
 104          */
 105         private $loadedLanguages = [];
 106
 107         /**
 108          * Singleton instance
 109          *
 110          * @var MessageCache $instance
 111          */
 112         private static $instance;
 113
 114         /**
 115          * Get the signleton instance of this class
 116          *
 117          * @since 1.18
 118          * @return MessageCache
 119          */
 120         public static function singleton() {
 121                 if ( self::$instance === null ) {
 122                         global $wgUseDatabaseMessages, $wgMsgCacheExpiry, $wgUseLocalMessageCache;
 123                         $services = MediaWikiServices::getInstance();
 124                         self::$instance = new self(
 125                                 $services->getMainWANObjectCache(),
 126                                 wfGetMessageCacheStorage(),
 127                                 $wgUseLocalMessageCache
 128                                         ? $services->getLocalServerObjectCache()
 129                                         : new EmptyBagOStuff(),
 130                                 $wgUseDatabaseMessages,
 131                                 $wgMsgCacheExpiry,
 132                                 $services->getContentLanguage()
 133                         );
 134                 }
 135
 136                 return self::$instance;
 137         }
 138
 139         /**
 140          * Destroy the singleton instance
 141          *
 142          * @since 1.18
 143          */
 144         public static function destroyInstance() {
 145                 self::$instance = null;
 146         }
 147
 148         /**
 149          * Normalize message key input
 150          *
 151          * @param string $key Input message key to be normalized
 152          * @return string Normalized message key
 153          */
 154         public static function normalizeKey( $key ) {
 155                 $lckey = strtr( $key, ' ', '_' );
 156                 if ( ord( $lckey ) < 128 ) {
 157                         $lckey[0] = strtolower( $lckey[0] );
 158                 } else {
 159                         $lckey = MediaWikiServices::getInstance()->getContentLanguage()->lcfirst( $lckey );
 160                 }
 161
 162                 return $lckey;
 163         }
 164
 165         /**
 166          * @param WANObjectCache $wanCache
 167          * @param BagOStuff $clusterCache
 168          * @param BagOStuff $serverCache
 169          * @param bool $useDB Whether to look for message overrides (e.g. MediaWiki: pages)
 170          * @param int $expiry Lifetime for cache. @see $mExpiry.
 171          * @param Language|null $contLang Content language of site
 172          */
 173         public function __construct(
 174                 WANObjectCache $wanCache,
 175                 BagOStuff $clusterCache,
 176                 BagOStuff $serverCache,
 177                 $useDB,
 178                 $expiry,
 179                 Language $contLang = null
 180         ) {
 181                 $this->wanCache = $wanCache;
 182                 $this->clusterCache = $clusterCache;
 183                 $this->srvCache = $serverCache;
 184
 185                 $this->cache = new MapCacheLRU( 5 ); // limit size for sanity
 186
 187                 $this->mDisable = !$useDB;
 188                 $this->mExpiry = $expiry;
 189                 $this->contLang = $contLang ?? MediaWikiServices::getInstance()->getContentLanguage();
 190         }
 191
 192         /**
 193          * ParserOptions is lazy initialised.
 194          *
 195          * @return ParserOptions
 196          */
 197         function getParserOptions() {
 198                 global $wgUser;
 199
 200                 if ( !$this->mParserOptions ) {
 201                         if ( !$wgUser->isSafeToLoad() ) {
 202                                 // $wgUser isn't unstubbable yet, so don't try to get a
 203                                 // ParserOptions for it. And don't cache this ParserOptions
 204                                 // either.
 205                                 $po = ParserOptions::newFromAnon();
 206                                 $po->setAllowUnsafeRawHtml( false );
 207                                 $po->setTidy( true );
 208                                 return $po;
 209                         }
 210
 211                         $this->mParserOptions = new ParserOptions;
 212                         // Messages may take parameters that could come
 213                         // from malicious sources. As a precaution, disable
 214                         // the <html> parser tag when parsing messages.
 215                         $this->mParserOptions->setAllowUnsafeRawHtml( false );
 216                         // For the same reason, tidy the output!
 217                         $this->mParserOptions->setTidy( true );
 218                 }
 219
 220                 return $this->mParserOptions;
 221         }
 222
 223         /**
 224          * Try to load the cache from APC.
 225          *
 226          * @param string $code Optional language code, see documentation of load().
 227          * @return array|bool The cache array, or false if not in cache.
 228          */
 229         protected function getLocalCache( $code ) {
 230                 $cacheKey = $this->srvCache->makeKey( __CLASS__, $code );
 231
 232                 return $this->srvCache->get( $cacheKey );
 233         }
 234
 235         /**
 236          * Save the cache to APC.
 237          *
 238          * @param string $code
 239          * @param array $cache The cache array
 240          */
 241         protected function saveToLocalCache( $code, $cache ) {
 242                 $cacheKey = $this->srvCache->makeKey( __CLASS__, $code );
 243                 $this->srvCache->set( $cacheKey, $cache );
 244         }
 245
 246         /**
 247          * Loads messages from caches or from database in this order:
 248          * (1) local message cache (if $wgUseLocalMessageCache is enabled)
 249          * (2) memcached
 250          * (3) from the database.
 251          *
 252          * When successfully loading from (2) or (3), all higher level caches are
 253          * updated for the newest version.
 254          *
 255          * Nothing is loaded if member variable mDisable is true, either manually
 256          * set by calling code or if message loading fails (is this possible?).
 257          *
 258          * Returns true if cache is already populated or it was successfully populated,
 259          * or false if populating empty cache fails. Also returns true if MessageCache
 260          * is disabled.
 261          *
 262          * @param string $code Language to which load messages
 263          * @param int|null $mode Use MessageCache::FOR_UPDATE to skip process cache [optional]
 264          * @throws InvalidArgumentException
 265          * @return bool
 266          */
 267         protected function load( $code, $mode = null ) {
 268                 if ( !is_string( $code ) ) {
 269                         throw new InvalidArgumentException( "Missing language code" );
 270                 }
 271
 272                 # Don't do double loading...
 273                 if ( isset( $this->loadedLanguages[$code] ) && $mode != self::FOR_UPDATE ) {
 274                         return true;
 275                 }
 276
 277                 $this->overridable = array_flip( Language::getMessageKeysFor( $code ) );
 278
 279                 # 8 lines of code just to say (once) that message cache is disabled
 280                 if ( $this->mDisable ) {
 281                         static $shownDisabled = false;
 282                         if ( !$shownDisabled ) {
 283                                 wfDebug( __METHOD__ . ": disabled\n" );
 284                                 $shownDisabled = true;
 285                         }
 286
 287                         return true;
 288                 }
 289
 290                 # Loading code starts
 291                 $success = false; # Keep track of success
 292                 $staleCache = false; # a cache array with expired data, or false if none has been loaded
 293                 $where = []; # Debug info, delayed to avoid spamming debug log too much
 294
 295                 # Hash of the contents is stored in memcache, to detect if data-center cache
 296                 # or local cache goes out of date (e.g. due to replace() on some other server)
 297                 list( $hash, $hashVolatile ) = $this->getValidationHash( $code );
 298                 $this->cacheVolatile[$code] = $hashVolatile;
 299
 300                 # Try the local cache and check against the cluster hash key...
 301                 $cache = $this->getLocalCache( $code );
 302                 if ( !$cache ) {
 303                         $where[] = 'local cache is empty';
 304                 } elseif ( !isset( $cache['HASH'] ) || $cache['HASH'] !== $hash ) {
 305                         $where[] = 'local cache has the wrong hash';
 306                         $staleCache = $cache;
 307                 } elseif ( $this->isCacheExpired( $cache ) ) {
 308                         $where[] = 'local cache is expired';
 309                         $staleCache = $cache;
 310                 } elseif ( $hashVolatile ) {
 311                         $where[] = 'local cache validation key is expired/volatile';
 312                         $staleCache = $cache;
 313                 } else {
 314                         $where[] = 'got from local cache';
 315                         $this->cache->set( $code, $cache );
 316                         $success = true;
 317                 }
 318
 319                 if ( !$success ) {
 320                         $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
 321                         # Try the global cache. If it is empty, try to acquire a lock. If
 322                         # the lock can't be acquired, wait for the other thread to finish
 323                         # and then try the global cache a second time.
 324                         for ( $failedAttempts = 0; $failedAttempts <= 1; $failedAttempts++ ) {
 325                                 if ( $hashVolatile && $staleCache ) {
 326                                         # Do not bother fetching the whole cache blob to avoid I/O.
 327                                         # Instead, just try to get the non-blocking $statusKey lock
 328                                         # below, and use the local stale value if it was not acquired.
 329                                         $where[] = 'global cache is presumed expired';
 330                                 } else {
 331                                         $cache = $this->clusterCache->get( $cacheKey );
 332                                         if ( !$cache ) {
 333                                                 $where[] = 'global cache is empty';
 334                                         } elseif ( $this->isCacheExpired( $cache ) ) {
 335                                                 $where[] = 'global cache is expired';
 336                                                 $staleCache = $cache;
 337                                         } elseif ( $hashVolatile ) {
 338                                                 # DB results are replica DB lag prone until the holdoff TTL passes.
 339                                                 # By then, updates should be reflected in loadFromDBWithLock().
 340                                                 # One thread regenerates the cache while others use old values.
 341                                                 $where[] = 'global cache is expired/volatile';
 342                                                 $staleCache = $cache;
 343                                         } else {
 344                                                 $where[] = 'got from global cache';
 345                                                 $this->cache->set( $code, $cache );
 346                                                 $this->saveToCaches( $cache, 'local-only', $code );
 347                                                 $success = true;
 348                                         }
 349                                 }
 350
 351                                 if ( $success ) {
 352                                         # Done, no need to retry
 353                                         break;
 354                                 }
 355
 356                                 # We need to call loadFromDB. Limit the concurrency to one process.
 357                                 # This prevents the site from going down when the cache expires.
 358                                 # Note that the DB slam protection lock here is non-blocking.
 359                                 $loadStatus = $this->loadFromDBWithLock( $code, $where, $mode );
 360                                 if ( $loadStatus === true ) {
 361                                         $success = true;
 362                                         break;
 363                                 } elseif ( $staleCache ) {
 364                                         # Use the stale cache while some other thread constructs the new one
 365                                         $where[] = 'using stale cache';
 366                                         $this->cache->set( $code, $staleCache );
 367                                         $success = true;
 368                                         break;
 369                                 } elseif ( $failedAttempts > 0 ) {
 370                                         # Already blocked once, so avoid another lock/unlock cycle.
 371                                         # This case will typically be hit if memcached is down, or if
 372                                         # loadFromDB() takes longer than LOCK_WAIT.
 373                                         $where[] = "could not acquire status key.";
 374                                         break;
 375                                 } elseif ( $loadStatus === 'cantacquire' ) {
 376                                         # Wait for the other thread to finish, then retry. Normally,
 377                                         # the memcached get() will then yield the other thread's result.
 378                                         $where[] = 'waited for other thread to complete';
 379                                         $this->getReentrantScopedLock( $cacheKey );
 380                                 } else {
 381                                         # Disable cache; $loadStatus is 'disabled'
 382                                         break;
 383                                 }
 384                         }
 385                 }
 386
 387                 if ( !$success ) {
 388                         $where[] = 'loading FAILED - cache is disabled';
 389                         $this->mDisable = true;
 390                         $this->cache->set( $code, [] );
 391                         wfDebugLog( 'MessageCacheError', __METHOD__ . ": Failed to load $code\n" );
 392                         # This used to throw an exception, but that led to nasty side effects like
 393                         # the whole wiki being instantly down if the memcached server died
 394                 } else {
 395                         # All good, just record the success
 396                         $this->loadedLanguages[$code] = true;
 397                 }
 398
 399                 if ( !$this->cache->has( $code ) ) { // sanity
 400                         throw new LogicException( "Process cache for '$code' should be set by now." );
 401                 }
 402
 403                 $info = implode( ', ', $where );
 404                 wfDebugLog( 'MessageCache', __METHOD__ . ": Loading $code... $info\n" );
 405
 406                 return $success;
 407         }
 408
 409         /**
 410          * @param string $code
 411          * @param array &$where List of wfDebug() comments
 412          * @param int|null $mode Use MessageCache::FOR_UPDATE to use DB_MASTER
 413          * @return bool|string True on success or one of ("cantacquire", "disabled")
 414          */
 415         protected function loadFromDBWithLock( $code, array &$where, $mode = null ) {
 416                 # If cache updates on all levels fail, give up on message overrides.
 417                 # This is to avoid easy site outages; see $saveSuccess comments below.
 418                 $statusKey = $this->clusterCache->makeKey( 'messages', $code, 'status' );
 419                 $status = $this->clusterCache->get( $statusKey );
 420                 if ( $status === 'error' ) {
 421                         $where[] = "could not load; method is still globally disabled";
 422                         return 'disabled';
 423                 }
 424
 425                 # Now let's regenerate
 426                 $where[] = 'loading from database';
 427
 428                 # Lock the cache to prevent conflicting writes.
 429                 # This lock is non-blocking so stale cache can quickly be used.
 430                 # Note that load() will call a blocking getReentrantScopedLock()
 431                 # after this if it really need to wait for any current thread.
 432                 $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
 433                 $scopedLock = $this->getReentrantScopedLock( $cacheKey, 0 );
 434                 if ( !$scopedLock ) {
 435                         $where[] = 'could not acquire main lock';
 436                         return 'cantacquire';
 437                 }
 438
 439                 $cache = $this->loadFromDB( $code, $mode );
 440                 $this->cache->set( $code, $cache );
 441                 $saveSuccess = $this->saveToCaches( $cache, 'all', $code );
 442
 443                 if ( !$saveSuccess ) {
 444                         /**
 445                          * Cache save has failed.
 446                          *
 447                          * There are two main scenarios where this could be a problem:
 448                          * - The cache is more than the maximum size (typically 1MB compressed).
 449                          * - Memcached has no space remaining in the relevant slab class. This is
 450                          *   unlikely with recent versions of memcached.
 451                          *
 452                          * Either way, if there is a local cache, nothing bad will happen. If there
 453                          * is no local cache, disabling the message cache for all requests avoids
 454                          * incurring a loadFromDB() overhead on every request, and thus saves the
 455                          * wiki from complete downtime under moderate traffic conditions.
 456                          */
 457                         if ( $this->srvCache instanceof EmptyBagOStuff ) {
 458                                 $this->clusterCache->set( $statusKey, 'error', 60 * 5 );
 459                                 $where[] = 'could not save cache, disabled globally for 5 minutes';
 460                         } else {
 461                                 $where[] = "could not save global cache";
 462                         }
 463                 }
 464
 465                 return true;
 466         }
 467
 468         /**
 469          * Loads cacheable messages from the database. Messages bigger than
 470          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 471          * on-demand from the database later.
 472          *
 473          * @param string $code Language code
 474          * @param int|null $mode Use MessageCache::FOR_UPDATE to skip process cache
 475          * @return array Loaded messages for storing in caches
 476          */
 477         protected function loadFromDB( $code, $mode = null ) {
 478                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 479
 480                 // (T164666) The query here performs really poorly on WMF's
 481                 // contributions replicas. We don't have a way to say "any group except
 482                 // contributions", so for the moment let's specify 'api'.
 483                 // @todo: Get rid of this hack.
 484                 $dbr = wfGetDB( ( $mode == self::FOR_UPDATE ) ? DB_MASTER : DB_REPLICA, 'api' );
 485
 486                 $cache = [];
 487
 488                 $mostused = []; // list of "<cased message key>/<code>"
 489                 if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
 490                         if ( !$this->cache->has( $wgLanguageCode ) ) {
 491                                 $this->load( $wgLanguageCode );
 492                         }
 493                         $mostused = array_keys( $this->cache->get( $wgLanguageCode ) );
 494                         foreach ( $mostused as $key => $value ) {
 495                                 $mostused[$key] = "$value/$code";
 496                         }
 497                 }
 498
 499                 // Get the list of software-defined messages in core/extensions
 500                 $overridable = array_flip( Language::getMessageKeysFor( $wgLanguageCode ) );
 501
 502                 // Common conditions
 503                 $conds = [
 504                         'page_is_redirect' => 0,
 505                         'page_namespace' => NS_MEDIAWIKI,
 506                 ];
 507                 if ( count( $mostused ) ) {
 508                         $conds['page_title'] = $mostused;
 509                 } elseif ( $code !== $wgLanguageCode ) {
 510                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
 511                 } else {
 512                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 513                         # other than language code.
 514                         $conds[] = 'page_title NOT' .
 515                                 $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 516                 }
 517
 518                 // Set the stubs for oversized software-defined messages in the main cache map
 519                 $res = $dbr->select(
 520                         'page',
 521                         [ 'page_title', 'page_latest' ],
 522                         array_merge( $conds, [ 'page_len > ' . intval( $wgMaxMsgCacheEntrySize ) ] ),
 523                         __METHOD__ . "($code)-big"
 524                 );
 525                 foreach ( $res as $row ) {
 526                         // Include entries/stubs for all keys in $mostused in adaptive mode
 527                         if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $row->page_title, $overridable ) ) {
 528                                 $cache[$row->page_title] = '!TOO BIG';
 529                         }
 530                         // At least include revision ID so page changes are reflected in the hash
 531                         $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
 532                 }
 533
 534                 // Set the text for small software-defined messages in the main cache map
 535                 $revisionStore = MediaWikiServices::getInstance()->getRevisionStore();
 536                 $revQuery = $revisionStore->getQueryInfo( [ 'page', 'user' ] );
 537                 $res = $dbr->select(
 538                         $revQuery['tables'],
 539                         $revQuery['fields'],
 540                         array_merge( $conds, [
 541                                 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize ),
 542                                 'page_latest = rev_id' // get the latest revision only
 543                         ] ),
 544                         __METHOD__ . "($code)-small",
 545                         [],
 546                         $revQuery['joins']
 547                 );
 548                 foreach ( $res as $row ) {
 549                         // Include entries/stubs for all keys in $mostused in adaptive mode
 550                         if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $row->page_title, $overridable ) ) {
 551                                 try {
 552                                         $rev = $revisionStore->newRevisionFromRow( $row );
 553                                         $content = $rev->getContent( MediaWiki\Revision\SlotRecord::MAIN );
 554                                         $text = $this->getMessageTextFromContent( $content );
 555                                 } catch ( Exception $ex ) {
 556                                         $text = false;
 557                                 }
 558
 559                                 if ( !is_string( $text ) ) {
 560                                         $entry = '!ERROR';
 561                                         wfDebugLog(
 562                                                 'MessageCache',
 563                                                 __METHOD__
 564                                                 . ": failed to load message page text for {$row->page_title} ($code)"
 565                                         );
 566                                 } else {
 567                                         $entry = ' ' . $text;
 568                                 }
 569                                 $cache[$row->page_title] = $entry;
 570                         } else {
 571                                 // T193271: cache object gets too big and slow to generate.
 572                                 // At least include revision ID so page changes are reflected in the hash.
 573                                 $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
 574                         }
 575                 }
 576
 577                 $cache['VERSION'] = MSG_CACHE_VERSION;
 578                 ksort( $cache );
 579
 580                 # Hash for validating local cache (APC). No need to take into account
 581                 # messages larger than $wgMaxMsgCacheEntrySize, since those are only
 582                 # stored and fetched from memcache.
 583                 $cache['HASH'] = md5( serialize( $cache ) );
 584                 $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );
 585                 unset( $cache['EXCESSIVE'] ); // only needed for hash
 586
 587                 return $cache;
 588         }
 589
 590         /**
 591          * @param string $name Message name (possibly with /code suffix)
 592          * @param array $overridable Map of (key => unused) for software-defined messages
 593          * @return bool
 594          */
 595         private function isMainCacheable( $name, array $overridable ) {
 596                 // Convert first letter to lowercase, and strip /code suffix
 597                 $name = $this->contLang->lcfirst( $name );
 598                 $msg = preg_replace( '/\/[a-z0-9-]{2,}$/', '', $name );
 599                 // Include common conversion table pages. This also avoids problems with
 600                 // Installer::parse() bailing out due to disallowed DB queries (T207979).
 601                 return ( isset( $overridable[$msg] ) || strpos( $name, 'conversiontable/' ) === 0 );
 602         }
 603
 604         /**
 605          * Updates cache as necessary when message page is changed
 606          *
 607          * @param string $title Message cache key with initial uppercase letter
 608          * @param string|bool $text New contents of the page (false if deleted)
 609          */
 610         public function replace( $title, $text ) {
 611                 global $wgLanguageCode;
 612
 613                 if ( $this->mDisable ) {
 614                         return;
 615                 }
 616
 617                 list( $msg, $code ) = $this->figureMessage( $title );
 618                 if ( strpos( $title, '/' ) !== false && $code === $wgLanguageCode ) {
 619                         // Content language overrides do not use the /<code> suffix
 620                         return;
 621                 }
 622
 623                 // (a) Update the process cache with the new message text
 624                 if ( $text === false ) {
 625                         // Page deleted
 626                         $this->cache->setField( $code, $title, '!NONEXISTENT' );
 627                 } else {
 628                         // Ignore $wgMaxMsgCacheEntrySize so the process cache is up to date
 629                         $this->cache->setField( $code, $title, ' ' . $text );
 630                 }
 631
 632                 // (b) Update the shared caches in a deferred update with a fresh DB snapshot
 633                 DeferredUpdates::addUpdate(
 634                         new MessageCacheUpdate( $code, $title, $msg ),
 635                         DeferredUpdates::PRESEND
 636                 );
 637         }
 638
 639         /**
 640          * @param string $code
 641          * @param array[] $replacements List of (title, message key) pairs
 642          * @throws MWException
 643          */
 644         public function refreshAndReplaceInternal( $code, array $replacements ) {
 645                 global $wgMaxMsgCacheEntrySize;
 646
 647                 // Allow one caller at a time to avoid race conditions
 648                 $scopedLock = $this->getReentrantScopedLock(
 649                         $this->clusterCache->makeKey( 'messages', $code )
 650                 );
 651                 if ( !$scopedLock ) {
 652                         foreach ( $replacements as list( $title ) ) {
 653                                 LoggerFactory::getInstance( 'MessageCache' )->error(
 654                                         __METHOD__ . ': could not acquire lock to update {title} ({code})',
 655                                         [ 'title' => $title, 'code' => $code ] );
 656                         }
 657
 658                         return;
 659                 }
 660
 661                 // Load the existing cache to update it in the local DC cache.
 662                 // The other DCs will see a hash mismatch.
 663                 if ( $this->load( $code, self::FOR_UPDATE ) ) {
 664                         $cache = $this->cache->get( $code );
 665                 } else {
 666                         // Err? Fall back to loading from the database.
 667                         $cache = $this->loadFromDB( $code, self::FOR_UPDATE );
 668                 }
 669                 // Check if individual cache keys should exist and update cache accordingly
 670                 $newTextByTitle = []; // map of (title => content)
 671                 $newBigTitles = []; // map of (title => latest revision ID), like EXCESSIVE in loadFromDB()
 672                 foreach ( $replacements as list( $title ) ) {
 673                         $page = WikiPage::factory( Title::makeTitle( NS_MEDIAWIKI, $title ) );
 674                         $page->loadPageData( $page::READ_LATEST );
 675                         $text = $this->getMessageTextFromContent( $page->getContent() );
 676                         // Remember the text for the blob store update later on
 677                         $newTextByTitle[$title] = $text;
 678                         // Note that if $text is false, then $cache should have a !NONEXISTANT entry
 679                         if ( !is_string( $text ) ) {
 680                                 $cache[$title] = '!NONEXISTENT';
 681                         } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 682                                 $cache[$title] = '!TOO BIG';
 683                                 $newBigTitles[$title] = $page->getLatest();
 684                         } else {
 685                                 $cache[$title] = ' ' . $text;
 686                         }
 687                 }
 688                 // Update HASH for the new key. Incorporates various administrative keys,
 689                 // including the old HASH (and thereby the EXCESSIVE value from loadFromDB()
 690                 // and previous replace() calls), but that doesn't really matter since we
 691                 // only ever compare it for equality with a copy saved by saveToCaches().
 692                 $cache['HASH'] = md5( serialize( $cache + [ 'EXCESSIVE' => $newBigTitles ] ) );
 693                 // Update the too-big WAN cache entries now that we have the new HASH
 694                 foreach ( $newBigTitles as $title => $id ) {
 695                         // Match logic of loadCachedMessagePageEntry()
 696                         $this->wanCache->set(
 697                                 $this->bigMessageCacheKey( $cache['HASH'], $title ),
 698                                 ' ' . $newTextByTitle[$title],
 699                                 $this->mExpiry
 700                         );
 701                 }
 702                 // Mark this cache as definitely being "latest" (non-volatile) so
 703                 // load() calls do not try to refresh the cache with replica DB data
 704                 $cache['LATEST'] = time();
 705                 // Update the process cache
 706                 $this->cache->set( $code, $cache );
 707                 // Pre-emptively update the local datacenter cache so things like edit filter and
 708                 // blacklist changes are reflected immediately; these often use MediaWiki: pages.
 709                 // The datacenter handling replace() calls should be the same one handling edits
 710                 // as they require HTTP POST.
 711                 $this->saveToCaches( $cache, 'all', $code );
 712                 // Release the lock now that the cache is saved
 713                 ScopedCallback::consume( $scopedLock );
 714
 715                 // Relay the purge. Touching this check key expires cache contents
 716                 // and local cache (APC) validation hash across all datacenters.
 717                 $this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
 718
 719                 // Purge the messages in the message blob store and fire any hook handlers
 720                 $blobStore = MediaWikiServices::getInstance()->getResourceLoader()->getMessageBlobStore();
 721                 foreach ( $replacements as list( $title, $msg ) ) {
 722                         $blobStore->updateMessage( $this->contLang->lcfirst( $msg ) );
 723                         Hooks::run( 'MessageCacheReplace', [ $title, $newTextByTitle[$title] ] );
 724                 }
 725         }
 726
 727         /**
 728          * Is the given cache array expired due to time passing or a version change?
 729          *
 730          * @param array $cache
 731          * @return bool
 732          */
 733         protected function isCacheExpired( $cache ) {
 734                 if ( !isset( $cache['VERSION'] ) || !isset( $cache['EXPIRY'] ) ) {
 735                         return true;
 736                 }
 737                 if ( $cache['VERSION'] != MSG_CACHE_VERSION ) {
 738                         return true;
 739                 }
 740                 if ( wfTimestampNow() >= $cache['EXPIRY'] ) {
 741                         return true;
 742                 }
 743
 744                 return false;
 745         }
 746
 747         /**
 748          * Shortcut to update caches.
 749          *
 750          * @param array $cache Cached messages with a version.
 751          * @param string $dest Either "local-only" to save to local caches only
 752          *   or "all" to save to all caches.
 753          * @param string|bool $code Language code (default: false)
 754          * @return bool
 755          */
 756         protected function saveToCaches( array $cache, $dest, $code = false ) {
 757                 if ( $dest === 'all' ) {
 758                         $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
 759                         $success = $this->clusterCache->set( $cacheKey, $cache );
 760                         $this->setValidationHash( $code, $cache );
 761                 } else {
 762                         $success = true;
 763                 }
 764
 765                 $this->saveToLocalCache( $code, $cache );
 766
 767                 return $success;
 768         }
 769
 770         /**
 771          * Get the md5 used to validate the local APC cache
 772          *
 773          * @param string $code
 774          * @return array (hash or false, bool expiry/volatility status)
 775          */
 776         protected function getValidationHash( $code ) {
 777                 $curTTL = null;
 778                 $value = $this->wanCache->get(
 779                         $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
 780                         $curTTL,
 781                         [ $this->getCheckKey( $code ) ]
 782                 );
 783
 784                 if ( $value ) {
 785                         $hash = $value['hash'];
 786                         if ( ( time() - $value['latest'] ) < WANObjectCache::TTL_MINUTE ) {
 787                                 // Cache was recently updated via replace() and should be up-to-date.
 788                                 // That method is only called in the primary datacenter and uses FOR_UPDATE.
 789                                 // Also, it is unlikely that the current datacenter is *now* secondary one.
 790                                 $expired = false;
 791                         } else {
 792                                 // See if the "check" key was bumped after the hash was generated
 793                                 $expired = ( $curTTL < 0 );
 794                         }
 795                 } else {
 796                         // No hash found at all; cache must regenerate to be safe
 797                         $hash = false;
 798                         $expired = true;
 799                 }
 800
 801                 return [ $hash, $expired ];
 802         }
 803
 804         /**
 805          * Set the md5 used to validate the local disk cache
 806          *
 807          * If $cache has a 'LATEST' UNIX timestamp key, then the hash will not
 808          * be treated as "volatile" by getValidationHash() for the next few seconds.
 809          * This is triggered when $cache is generated using FOR_UPDATE mode.
 810          *
 811          * @param string $code
 812          * @param array $cache Cached messages with a version
 813          */
 814         protected function setValidationHash( $code, array $cache ) {
 815                 $this->wanCache->set(
 816                         $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
 817                         [
 818                                 'hash' => $cache['HASH'],
 819                                 'latest' => $cache['LATEST'] ?? 0
 820                         ],
 821                         WANObjectCache::TTL_INDEFINITE
 822                 );
 823         }
 824
 825         /**
 826          * @param string $key A language message cache key that stores blobs
 827          * @param int $timeout Wait timeout in seconds
 828          * @return null|ScopedCallback
 829          */
 830         protected function getReentrantScopedLock( $key, $timeout = self::WAIT_SEC ) {
 831                 return $this->clusterCache->getScopedLock( $key, $timeout, self::LOCK_TTL, __METHOD__ );
 832         }
 833
 834         /**
 835          * Get a message from either the content language or the user language.
 836          *
 837          * First, assemble a list of languages to attempt getting the message from. This
 838          * chain begins with the requested language and its fallbacks and then continues with
 839          * the content language and its fallbacks. For each language in the chain, the following
 840          * process will occur (in this order):
 841          *  1. If a language-specific override, i.e., [[MW:msg/lang]], is available, use that.
 842          *     Note: for the content language, there is no /lang subpage.
 843          *  2. Fetch from the static CDB cache.
 844          *  3. If available, check the database for fallback language overrides.
 845          *
 846          * This process provides a number of guarantees. When changing this code, make sure all
 847          * of these guarantees are preserved.
 848          *  * If the requested language is *not* the content language, then the CDB cache for that
 849          *    specific language will take precedence over the root database page ([[MW:msg]]).
 850          *  * Fallbacks will be just that: fallbacks. A fallback language will never be reached if
 851          *    the message is available *anywhere* in the language for which it is a fallback.
 852          *
 853          * @param string $key The message key
 854          * @param bool $useDB If true, look for the message in the DB, false
 855          *   to use only the compiled l10n cache.
 856          * @param bool|string|object $langcode Code of the language to get the message for.
 857          *   - If string and a valid code, will create a standard language object
 858          *   - If string but not a valid code, will create a basic language object
 859          *   - If boolean and false, create object from the current users language
 860          *   - If boolean and true, create object from the wikis content language
 861          *   - If language object, use it as given
 862          *
 863          * @throws MWException When given an invalid key
 864          * @return string|bool False if the message doesn't exist, otherwise the
 865          *   message (which can be empty)
 866          */
 867         function get( $key, $useDB = true, $langcode = true ) {
 868                 if ( is_int( $key ) ) {
 869                         // Fix numerical strings that somehow become ints
 870                         // on their way here
 871                         $key = (string)$key;
 872                 } elseif ( !is_string( $key ) ) {
 873                         throw new MWException( 'Non-string key given' );
 874                 } elseif ( $key === '' ) {
 875                         // Shortcut: the empty key is always missing
 876                         return false;
 877                 }
 878
 879                 // Normalise title-case input (with some inlining)
 880                 $lckey = self::normalizeKey( $key );
 881
 882                 Hooks::run( 'MessageCache::get', [ &$lckey ] );
 883
 884                 // Loop through each language in the fallback list until we find something useful
 885                 $message = $this->getMessageFromFallbackChain(
 886                         wfGetLangObj( $langcode ),
 887                         $lckey,
 888                         !$this->mDisable && $useDB
 889                 );
 890
 891                 // If we still have no message, maybe the key was in fact a full key so try that
 892                 if ( $message === false ) {
 893                         $parts = explode( '/', $lckey );
 894                         // We may get calls for things that are http-urls from sidebar
 895                         // Let's not load nonexistent languages for those
 896                         // They usually have more than one slash.
 897                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 898                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 899                                 if ( $message === null ) {
 900                                         $message = false;
 901                                 }
 902                         }
 903                 }
 904
 905                 // Post-processing if the message exists
 906                 if ( $message !== false ) {
 907                         // Fix whitespace
 908                         $message = str_replace(
 909                                 [
 910                                         # Fix for trailing whitespace, removed by textarea
 911                                         '&#32;',
 912                                         # Fix for NBSP, converted to space by firefox
 913                                         '&nbsp;',
 914                                         '&#160;',
 915                                         '&shy;'
 916                                 ],
 917                                 [
 918                                         ' ',
 919                                         "\u{00A0}",
 920                                         "\u{00A0}",
 921                                         "\u{00AD}"
 922                                 ],
 923                                 $message
 924                         );
 925                 }
 926
 927                 return $message;
 928         }
 929
 930         /**
 931          * Given a language, try and fetch messages from that language.
 932          *
 933          * Will also consider fallbacks of that language, the site language, and fallbacks for
 934          * the site language.
 935          *
 936          * @see MessageCache::get
 937          * @param Language|StubObject $lang Preferred language
 938          * @param string $lckey Lowercase key for the message (as for localisation cache)
 939          * @param bool $useDB Whether to include messages from the wiki database
 940          * @return string|bool The message, or false if not found
 941          */
 942         protected function getMessageFromFallbackChain( $lang, $lckey, $useDB ) {
 943                 $alreadyTried = [];
 944
 945                 // First try the requested language.
 946                 $message = $this->getMessageForLang( $lang, $lckey, $useDB, $alreadyTried );
 947                 if ( $message !== false ) {
 948                         return $message;
 949                 }
 950
 951                 // Now try checking the site language.
 952                 $message = $this->getMessageForLang( $this->contLang, $lckey, $useDB, $alreadyTried );
 953                 return $message;
 954         }
 955
 956         /**
 957          * Given a language, try and fetch messages from that language and its fallbacks.
 958          *
 959          * @see MessageCache::get
 960          * @param Language|StubObject $lang Preferred language
 961          * @param string $lckey Lowercase key for the message (as for localisation cache)
 962          * @param bool $useDB Whether to include messages from the wiki database
 963          * @param bool[] $alreadyTried Contains true for each language that has been tried already
 964          * @return string|bool The message, or false if not found
 965          */
 966         private function getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried ) {
 967                 $langcode = $lang->getCode();
 968
 969                 // Try checking the database for the requested language
 970                 if ( $useDB ) {
 971                         $uckey = $this->contLang->ucfirst( $lckey );
 972
 973                         if ( !isset( $alreadyTried[$langcode] ) ) {
 974                                 $message = $this->getMsgFromNamespace(
 975                                         $this->getMessagePageName( $langcode, $uckey ),
 976                                         $langcode
 977                                 );
 978                                 if ( $message !== false ) {
 979                                         return $message;
 980                                 }
 981                                 $alreadyTried[$langcode] = true;
 982                         }
 983                 } else {
 984                         $uckey = null;
 985                 }
 986
 987                 // Check the CDB cache
 988                 $message = $lang->getMessage( $lckey );
 989                 if ( $message !== null ) {
 990                         return $message;
 991                 }
 992
 993                 // Try checking the database for all of the fallback languages
 994                 if ( $useDB ) {
 995                         $fallbackChain = Language::getFallbacksFor( $langcode );
 996
 997                         foreach ( $fallbackChain as $code ) {
 998                                 if ( isset( $alreadyTried[$code] ) ) {
 999                                         continue;
1000                                 }
1001
1002                                 $message = $this->getMsgFromNamespace(
1003                                         $this->getMessagePageName( $code, $uckey ), $code );
1004
1005                                 if ( $message !== false ) {
1006                                         return $message;
1007                                 }
1008                                 $alreadyTried[$code] = true;
1009                         }
1010                 }
1011
1012                 return false;
1013         }
1014
1015         /**
1016          * Get the message page name for a given language
1017          *
1018          * @param string $langcode
1019          * @param string $uckey Uppercase key for the message
1020          * @return string The page name
1021          */
1022         private function getMessagePageName( $langcode, $uckey ) {
1023                 global $wgLanguageCode;
1024
1025                 if ( $langcode === $wgLanguageCode ) {
1026                         // Messages created in the content language will not have the /lang extension
1027                         return $uckey;
1028                 } else {
1029                         return "$uckey/$langcode";
1030                 }
1031         }
1032
1033         /**
1034          * Get a message from the MediaWiki namespace, with caching. The key must
1035          * first be converted to two-part lang/msg form if necessary.
1036          *
1037          * Unlike self::get(), this function doesn't resolve fallback chains, and
1038          * some callers require this behavior. LanguageConverter::parseCachedTable()
1039          * and self::get() are some examples in core.
1040          *
1041          * @param string $title Message cache key with initial uppercase letter
1042          * @param string $code Code denoting the language to try
1043          * @return string|bool The message, or false if it does not exist or on error
1044          */
1045         public function getMsgFromNamespace( $title, $code ) {
1046                 // Load all MediaWiki page definitions into cache. Note that individual keys
1047                 // already loaded into cache during this request remain in the cache, which
1048                 // includes the value of hook-defined messages.
1049                 $this->load( $code );
1050
1051                 $entry = $this->cache->getField( $code, $title );
1052
1053                 if ( $entry !== null ) {
1054                         // Message page exists as an override of a software messages
1055                         if ( substr( $entry, 0, 1 ) === ' ' ) {
1056                                 // The message exists and is not '!TOO BIG' or '!ERROR'
1057                                 return (string)substr( $entry, 1 );
1058                         } elseif ( $entry === '!NONEXISTENT' ) {
1059                                 // The text might be '-' or missing due to some data loss
1060                                 return false;
1061                         }
1062                         // Load the message page, utilizing the individual message cache.
1063                         // If the page does not exist, there will be no hook handler fallbacks.
1064                         $entry = $this->loadCachedMessagePageEntry(
1065                                 $title,
1066                                 $code,
1067                                 $this->cache->getField( $code, 'HASH' )
1068                         );
1069                 } else {
1070                         // Message page either does not exist or does not override a software message
1071                         if ( !$this->isMainCacheable( $title, $this->overridable ) ) {
1072                                 // Message page does not override any software-defined message. A custom
1073                                 // message might be defined to have content or settings specific to the wiki.
1074                                 // Load the message page, utilizing the individual message cache as needed.
1075                                 $entry = $this->loadCachedMessagePageEntry(
1076                                         $title,
1077                                         $code,
1078                                         $this->cache->getField( $code, 'HASH' )
1079                                 );
1080                         }
1081                         if ( $entry === null || substr( $entry, 0, 1 ) !== ' ' ) {
1082                                 // Message does not have a MediaWiki page definition; try hook handlers
1083                                 $message = false;
1084                                 Hooks::run( 'MessagesPreLoad', [ $title, &$message, $code ] );
1085                                 if ( $message !== false ) {
1086                                         $this->cache->setField( $code, $title, ' ' . $message );
1087                                 } else {
1088                                         $this->cache->setField( $code, $title, '!NONEXISTENT' );
1089                                 }
1090
1091                                 return $message;
1092                         }
1093                 }
1094
1095                 if ( $entry !== false && substr( $entry, 0, 1 ) === ' ' ) {
1096                         if ( $this->cacheVolatile[$code] ) {
1097                                 // Make sure that individual keys respect the WAN cache holdoff period too
1098                                 LoggerFactory::getInstance( 'MessageCache' )->debug(
1099                                         __METHOD__ . ': loading volatile key \'{titleKey}\'',
1100                                         [ 'titleKey' => $title, 'code' => $code ] );
1101                         } else {
1102                                 $this->cache->setField( $code, $title, $entry );
1103                         }
1104                         // The message exists, so make sure a string is returned
1105                         return (string)substr( $entry, 1 );
1106                 }
1107
1108                 $this->cache->setField( $code, $title, '!NONEXISTENT' );
1109
1110                 return false;
1111         }
1112
1113         /**
1114          * @param string $dbKey
1115          * @param string $code
1116          * @param string $hash
1117          * @return string Either " <MESSAGE>" or "!NONEXISTANT"
1118          */
1119         private function loadCachedMessagePageEntry( $dbKey, $code, $hash ) {
1120                 $fname = __METHOD__;
1121                 return $this->srvCache->getWithSetCallback(
1122                         $this->srvCache->makeKey( 'messages-big', $hash, $dbKey ),
1123                         IExpiringStore::TTL_MINUTE,
1124                         function () use ( $code, $dbKey, $hash, $fname ) {
1125                                 return $this->wanCache->getWithSetCallback(
1126                                         $this->bigMessageCacheKey( $hash, $dbKey ),
1127                                         $this->mExpiry,
1128                                         function ( $oldValue, &$ttl, &$setOpts ) use ( $dbKey, $code, $fname ) {
1129                                                 // Try loading the message from the database
1130                                                 $dbr = wfGetDB( DB_REPLICA );
1131                                                 $setOpts += Database::getCacheSetOptions( $dbr );
1132                                                 // Use newKnownCurrent() to avoid querying revision/user tables
1133                                                 $title = Title::makeTitle( NS_MEDIAWIKI, $dbKey );
1134                                                 $revision = Revision::newKnownCurrent( $dbr, $title );
1135                                                 if ( !$revision ) {
1136                                                         // The wiki doesn't have a local override page. Cache absence with normal TTL.
1137                                                         // When overrides are created, self::replace() takes care of the cache.
1138                                                         return '!NONEXISTENT';
1139                                                 }
1140                                                 $content = $revision->getContent();
1141                                                 if ( $content ) {
1142                                                         $message = $this->getMessageTextFromContent( $content );
1143                                                 } else {
1144                                                         LoggerFactory::getInstance( 'MessageCache' )->warning(
1145                                                                 $fname . ': failed to load page text for \'{titleKey}\'',
1146                                                                 [ 'titleKey' => $dbKey, 'code' => $code ]
1147                                                         );
1148                                                         $message = null;
1149                                                 }
1150
1151                                                 if ( !is_string( $message ) ) {
1152                                                         // Revision failed to load Content, or Content is incompatible with wikitext.
1153                                                         // Possibly a temporary loading failure.
1154                                                         $ttl = 5;
1155
1156                                                         return '!NONEXISTENT';
1157                                                 }
1158
1159                                                 return ' ' . $message;
1160                                         }
1161                                 );
1162                         }
1163                 );
1164         }
1165
1166         /**
1167          * @param string $message
1168          * @param bool $interface
1169          * @param Language|null $language
1170          * @param Title|null $title
1171          * @return string
1172          */
1173         public function transform( $message, $interface = false, $language = null, $title = null ) {
1174                 // Avoid creating parser if nothing to transform
1175                 if ( strpos( $message, '{{' ) === false ) {
1176                         return $message;
1177                 }
1178
1179                 if ( $this->mInParser ) {
1180                         return $message;
1181                 }
1182
1183                 $parser = $this->getParser();
1184                 if ( $parser ) {
1185                         $popts = $this->getParserOptions();
1186                         $popts->setInterfaceMessage( $interface );
1187                         $popts->setTargetLanguage( $language );
1188
1189                         $userlang = $popts->setUserLang( $language );
1190                         $this->mInParser = true;
1191                         $message = $parser->transformMsg( $message, $popts, $title );
1192                         $this->mInParser = false;
1193                         $popts->setUserLang( $userlang );
1194                 }
1195
1196                 return $message;
1197         }
1198
1199         /**
1200          * @return Parser
1201          */
1202         public function getParser() {
1203                 global $wgParserConf;
1204                 if ( !$this->mParser ) {
1205                         $parser = MediaWikiServices::getInstance()->getParser();
1206                         # Do some initialisation so that we don't have to do it twice
1207                         $parser->firstCallInit();
1208                         # Clone it and store it
1209                         $class = $wgParserConf['class'];
1210                         if ( $class == ParserDiffTest::class ) {
1211                                 # Uncloneable
1212                                 $this->mParser = new $class( $wgParserConf );
1213                         } else {
1214                                 $this->mParser = clone $parser;
1215                         }
1216                 }
1217
1218                 return $this->mParser;
1219         }
1220
1221         /**
1222          * @param string $text
1223          * @param Title|null $title
1224          * @param bool $linestart Whether or not this is at the start of a line
1225          * @param bool $interface Whether this is an interface message
1226          * @param Language|string|null $language Language code
1227          * @return ParserOutput|string
1228          */
1229         public function parse( $text, $title = null, $linestart = true,
1230                 $interface = false, $language = null
1231         ) {
1232                 global $wgTitle;
1233
1234                 if ( $this->mInParser ) {
1235                         return htmlspecialchars( $text );
1236                 }
1237
1238                 $parser = $this->getParser();
1239                 $popts = $this->getParserOptions();
1240                 $popts->setInterfaceMessage( $interface );
1241
1242                 if ( is_string( $language ) ) {
1243                         $language = Language::factory( $language );
1244                 }
1245                 $popts->setTargetLanguage( $language );
1246
1247                 if ( !$title || !$title instanceof Title ) {
1248                         wfDebugLog( 'GlobalTitleFail', __METHOD__ . ' called by ' .
1249                                 wfGetAllCallers( 6 ) . ' with no title set.' );
1250                         $title = $wgTitle;
1251                 }
1252                 // Sometimes $wgTitle isn't set either...
1253                 if ( !$title ) {
1254                         # It's not uncommon having a null $wgTitle in scripts. See r80898
1255                         # Create a ghost title in such case
1256                         $title = Title::makeTitle( NS_SPECIAL, 'Badtitle/title not set in ' . __METHOD__ );
1257                 }
1258
1259                 $this->mInParser = true;
1260                 $res = $parser->parse( $text, $title, $popts, $linestart );
1261                 $this->mInParser = false;
1262
1263                 return $res;
1264         }
1265
1266         public function disable() {
1267                 $this->mDisable = true;
1268         }
1269
1270         public function enable() {
1271                 $this->mDisable = false;
1272         }
1273
1274         /**
1275          * Whether DB/cache usage is disabled for determining messages
1276          *
1277          * If so, this typically indicates either:
1278          *   - a) load() failed to find a cached copy nor query the DB
1279          *   - b) we are in a special context or error mode that cannot use the DB
1280          * If the DB is ignored, any derived HTML output or cached objects may be wrong.
1281          * To avoid long-term cache pollution, TTLs can be adjusted accordingly.
1282          *
1283          * @return bool
1284          * @since 1.27
1285          */
1286         public function isDisabled() {
1287                 return $this->mDisable;
1288         }
1289
1290         /**
1291          * Clear all stored messages in global and local cache
1292          *
1293          * Mainly used after a mass rebuild
1294          */
1295         public function clear() {
1296                 $langs = Language::fetchLanguageNames( null, 'mw' );
1297                 foreach ( array_keys( $langs ) as $code ) {
1298                         $this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
1299                 }
1300                 $this->cache->clear();
1301                 $this->loadedLanguages = [];
1302         }
1303
1304         /**
1305          * @param string $key
1306          * @return array
1307          */
1308         public function figureMessage( $key ) {
1309                 global $wgLanguageCode;
1310
1311                 $pieces = explode( '/', $key );
1312                 if ( count( $pieces ) < 2 ) {
1313                         return [ $key, $wgLanguageCode ];
1314                 }
1315
1316                 $lang = array_pop( $pieces );
1317                 if ( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
1318                         return [ $key, $wgLanguageCode ];
1319                 }
1320
1321                 $message = implode( '/', $pieces );
1322
1323                 return [ $message, $lang ];
1324         }
1325
1326         /**
1327          * Get all message keys stored in the message cache for a given language.
1328          * If $code is the content language code, this will return all message keys
1329          * for which MediaWiki:msgkey exists. If $code is another language code, this
1330          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
1331          * @param string $code Language code
1332          * @return array Array of message keys (strings)
1333          */
1334         public function getAllMessageKeys( $code ) {
1335                 $this->load( $code );
1336                 if ( !$this->cache->has( $code ) ) {
1337                         // Apparently load() failed
1338                         return null;
1339                 }
1340                 // Remove administrative keys
1341                 $cache = $this->cache->get( $code );
1342                 unset( $cache['VERSION'] );
1343                 unset( $cache['EXPIRY'] );
1344                 unset( $cache['EXCESSIVE'] );
1345                 // Remove any !NONEXISTENT keys
1346                 $cache = array_diff( $cache, [ '!NONEXISTENT' ] );
1347
1348                 // Keys may appear with a capital first letter. lcfirst them.
1349                 return array_map( [ $this->contLang, 'lcfirst' ], array_keys( $cache ) );
1350         }
1351
1352         /**
1353          * Purge message caches when a MediaWiki: page is created, updated, or deleted
1354          *
1355          * @param Title $title Message page title
1356          * @param Content|null $content New content for edit/create, null on deletion
1357          * @since 1.29
1358          */
1359         public function updateMessageOverride( Title $title, Content $content = null ) {
1360                 $msgText = $this->getMessageTextFromContent( $content );
1361                 if ( $msgText === null ) {
1362                         $msgText = false; // treat as not existing
1363                 }
1364
1365                 $this->replace( $title->getDBkey(), $msgText );
1366
1367                 if ( $this->contLang->hasVariants() ) {
1368                         $this->contLang->updateConversionTable( $title );
1369                 }
1370         }
1371
1372         /**
1373          * @param string $code Language code
1374          * @return string WAN cache key usable as a "check key" against language page edits
1375          */
1376         public function getCheckKey( $code ) {
1377                 return $this->wanCache->makeKey( 'messages', $code );
1378         }
1379
1380         /**
1381          * @param Content|null $content Content or null if the message page does not exist
1382          * @return string|bool|null Returns false if $content is null and null on error
1383          */
1384         private function getMessageTextFromContent( Content $content = null ) {
1385                 // @TODO: could skip pseudo-messages like js/css here, based on content model
1386                 if ( $content ) {
1387                         // Message page exists...
1388                         // XXX: Is this the right way to turn a Content object into a message?
1389                         // NOTE: $content is typically either WikitextContent, JavaScriptContent or
1390                         //       CssContent. MessageContent is *not* used for storing messages, it's
1391                         //       only used for wrapping them when needed.
1392                         $msgText = $content->getWikitextForTransclusion();
1393                         if ( $msgText === false || $msgText === null ) {
1394                                 // This might be due to some kind of misconfiguration...
1395                                 $msgText = null;
1396                                 LoggerFactory::getInstance( 'MessageCache' )->warning(
1397                                         __METHOD__ . ": message content doesn't provide wikitext "
1398                                         . "(content model: " . $content->getModel() . ")" );
1399                         }
1400                 } else {
1401                         // Message page does not exist...
1402                         $msgText = false;
1403                 }
1404
1405                 return $msgText;
1406         }
1407
1408         /**
1409          * @param string $hash Hash for this version of the entire key/value overrides map
1410          * @param string $title Message cache key with initial uppercase letter
1411          * @return string
1412          */
1413         private function bigMessageCacheKey( $hash, $title ) {
1414                 return $this->wanCache->makeKey( 'messages-big', $hash, $title );
1415         }
1416 }