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          * Lifetime for cache, for keys stored in $wanCache, in seconds.
  50          * @var int
  51          */
  52         const WAN_TTL = IExpiringStore::TTL_DAY;
  53
  54         /**
  55          * Process cache of loaded messages that are defined in MediaWiki namespace
  56          *
  57          * @var MapCacheLRU Map of (language code => key => " <MESSAGE>" or "!TOO BIG" or "!ERROR")
  58          */
  59         protected $cache;
  60
  61         /**
  62          * Map of (lowercase message key => index) for all software defined messages
  63          *
  64          * @var array
  65          */
  66         protected $overridable;
  67
  68         /**
  69          * @var bool[] Map of (language code => boolean)
  70          */
  71         protected $cacheVolatile = [];
  72
  73         /**
  74          * Should mean that database cannot be used, but check
  75          * @var bool $mDisable
  76          */
  77         protected $mDisable;
  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          * Get the singleton instance of this class
 109          *
 110          * @deprecated in 1.34 inject an instance of this class instead of using global state
 111          * @since 1.18
 112          * @return MessageCache
 113          */
 114         public static function singleton() {
 115                 return MediaWikiServices::getInstance()->getMessageCache();
 116         }
 117
 118         /**
 119          * Normalize message key input
 120          *
 121          * @param string $key Input message key to be normalized
 122          * @return string Normalized message key
 123          */
 124         public static function normalizeKey( $key ) {
 125                 $lckey = strtr( $key, ' ', '_' );
 126                 if ( ord( $lckey ) < 128 ) {
 127                         $lckey[0] = strtolower( $lckey[0] );
 128                 } else {
 129                         $lckey = MediaWikiServices::getInstance()->getContentLanguage()->lcfirst( $lckey );
 130                 }
 131
 132                 return $lckey;
 133         }
 134
 135         /**
 136          * @param WANObjectCache $wanCache
 137          * @param BagOStuff $clusterCache
 138          * @param BagOStuff $serverCache
 139          * @param bool $useDB Whether to look for message overrides (e.g. MediaWiki: pages)
 140          * @param Language|null $contLang Content language of site
 141          */
 142         public function __construct(
 143                 WANObjectCache $wanCache,
 144                 BagOStuff $clusterCache,
 145                 BagOStuff $serverCache,
 146                 $useDB,
 147                 Language $contLang = null
 148         ) {
 149                 $this->wanCache = $wanCache;
 150                 $this->clusterCache = $clusterCache;
 151                 $this->srvCache = $serverCache;
 152
 153                 $this->cache = new MapCacheLRU( 5 ); // limit size for sanity
 154
 155                 $this->mDisable = !$useDB;
 156                 $this->contLang = $contLang ?? MediaWikiServices::getInstance()->getContentLanguage();
 157         }
 158
 159         /**
 160          * ParserOptions is lazy initialised.
 161          *
 162          * @return ParserOptions
 163          */
 164         function getParserOptions() {
 165                 global $wgUser;
 166
 167                 if ( !$this->mParserOptions ) {
 168                         if ( !$wgUser || !$wgUser->isSafeToLoad() ) {
 169                                 // $wgUser isn't available yet, so don't try to get a
 170                                 // ParserOptions for it. And don't cache this ParserOptions
 171                                 // either.
 172                                 $po = ParserOptions::newFromAnon();
 173                                 $po->setAllowUnsafeRawHtml( false );
 174                                 $po->setTidy( true );
 175                                 return $po;
 176                         }
 177
 178                         $this->mParserOptions = new ParserOptions;
 179                         // Messages may take parameters that could come
 180                         // from malicious sources. As a precaution, disable
 181                         // the <html> parser tag when parsing messages.
 182                         $this->mParserOptions->setAllowUnsafeRawHtml( false );
 183                         // For the same reason, tidy the output!
 184                         $this->mParserOptions->setTidy( true );
 185                 }
 186
 187                 return $this->mParserOptions;
 188         }
 189
 190         /**
 191          * Try to load the cache from APC.
 192          *
 193          * @param string $code Optional language code, see documentation of load().
 194          * @return array|bool The cache array, or false if not in cache.
 195          */
 196         protected function getLocalCache( $code ) {
 197                 $cacheKey = $this->srvCache->makeKey( __CLASS__, $code );
 198
 199                 return $this->srvCache->get( $cacheKey );
 200         }
 201
 202         /**
 203          * Save the cache to APC.
 204          *
 205          * @param string $code
 206          * @param array $cache The cache array
 207          */
 208         protected function saveToLocalCache( $code, $cache ) {
 209                 $cacheKey = $this->srvCache->makeKey( __CLASS__, $code );
 210                 $this->srvCache->set( $cacheKey, $cache );
 211         }
 212
 213         /**
 214          * Loads messages from caches or from database in this order:
 215          * (1) local message cache (if $wgUseLocalMessageCache is enabled)
 216          * (2) memcached
 217          * (3) from the database.
 218          *
 219          * When successfully loading from (2) or (3), all higher level caches are
 220          * updated for the newest version.
 221          *
 222          * Nothing is loaded if member variable mDisable is true, either manually
 223          * set by calling code or if message loading fails (is this possible?).
 224          *
 225          * Returns true if cache is already populated or it was successfully populated,
 226          * or false if populating empty cache fails. Also returns true if MessageCache
 227          * is disabled.
 228          *
 229          * @param string $code Language to which load messages
 230          * @param int|null $mode Use MessageCache::FOR_UPDATE to skip process cache [optional]
 231          * @throws InvalidArgumentException
 232          * @return bool
 233          */
 234         protected function load( $code, $mode = null ) {
 235                 if ( !is_string( $code ) ) {
 236                         throw new InvalidArgumentException( "Missing language code" );
 237                 }
 238
 239                 # Don't do double loading...
 240                 if ( isset( $this->loadedLanguages[$code] ) && $mode != self::FOR_UPDATE ) {
 241                         return true;
 242                 }
 243
 244                 $this->overridable = array_flip( Language::getMessageKeysFor( $code ) );
 245
 246                 # 8 lines of code just to say (once) that message cache is disabled
 247                 if ( $this->mDisable ) {
 248                         static $shownDisabled = false;
 249                         if ( !$shownDisabled ) {
 250                                 wfDebug( __METHOD__ . ": disabled\n" );
 251                                 $shownDisabled = true;
 252                         }
 253
 254                         return true;
 255                 }
 256
 257                 # Loading code starts
 258                 $success = false; # Keep track of success
 259                 $staleCache = false; # a cache array with expired data, or false if none has been loaded
 260                 $where = []; # Debug info, delayed to avoid spamming debug log too much
 261
 262                 # Hash of the contents is stored in memcache, to detect if data-center cache
 263                 # or local cache goes out of date (e.g. due to replace() on some other server)
 264                 list( $hash, $hashVolatile ) = $this->getValidationHash( $code );
 265                 $this->cacheVolatile[$code] = $hashVolatile;
 266
 267                 # Try the local cache and check against the cluster hash key...
 268                 $cache = $this->getLocalCache( $code );
 269                 if ( !$cache ) {
 270                         $where[] = 'local cache is empty';
 271                 } elseif ( !isset( $cache['HASH'] ) || $cache['HASH'] !== $hash ) {
 272                         $where[] = 'local cache has the wrong hash';
 273                         $staleCache = $cache;
 274                 } elseif ( $this->isCacheExpired( $cache ) ) {
 275                         $where[] = 'local cache is expired';
 276                         $staleCache = $cache;
 277                 } elseif ( $hashVolatile ) {
 278                         $where[] = 'local cache validation key is expired/volatile';
 279                         $staleCache = $cache;
 280                 } else {
 281                         $where[] = 'got from local cache';
 282                         $this->cache->set( $code, $cache );
 283                         $success = true;
 284                 }
 285
 286                 if ( !$success ) {
 287                         $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
 288                         # Try the global cache. If it is empty, try to acquire a lock. If
 289                         # the lock can't be acquired, wait for the other thread to finish
 290                         # and then try the global cache a second time.
 291                         for ( $failedAttempts = 0; $failedAttempts <= 1; $failedAttempts++ ) {
 292                                 if ( $hashVolatile && $staleCache ) {
 293                                         # Do not bother fetching the whole cache blob to avoid I/O.
 294                                         # Instead, just try to get the non-blocking $statusKey lock
 295                                         # below, and use the local stale value if it was not acquired.
 296                                         $where[] = 'global cache is presumed expired';
 297                                 } else {
 298                                         $cache = $this->clusterCache->get( $cacheKey );
 299                                         if ( !$cache ) {
 300                                                 $where[] = 'global cache is empty';
 301                                         } elseif ( $this->isCacheExpired( $cache ) ) {
 302                                                 $where[] = 'global cache is expired';
 303                                                 $staleCache = $cache;
 304                                         } elseif ( $hashVolatile ) {
 305                                                 # DB results are replica DB lag prone until the holdoff TTL passes.
 306                                                 # By then, updates should be reflected in loadFromDBWithLock().
 307                                                 # One thread regenerates the cache while others use old values.
 308                                                 $where[] = 'global cache is expired/volatile';
 309                                                 $staleCache = $cache;
 310                                         } else {
 311                                                 $where[] = 'got from global cache';
 312                                                 $this->cache->set( $code, $cache );
 313                                                 $this->saveToCaches( $cache, 'local-only', $code );
 314                                                 $success = true;
 315                                         }
 316                                 }
 317
 318                                 if ( $success ) {
 319                                         # Done, no need to retry
 320                                         break;
 321                                 }
 322
 323                                 # We need to call loadFromDB. Limit the concurrency to one process.
 324                                 # This prevents the site from going down when the cache expires.
 325                                 # Note that the DB slam protection lock here is non-blocking.
 326                                 $loadStatus = $this->loadFromDBWithLock( $code, $where, $mode );
 327                                 if ( $loadStatus === true ) {
 328                                         $success = true;
 329                                         break;
 330                                 } elseif ( $staleCache ) {
 331                                         # Use the stale cache while some other thread constructs the new one
 332                                         $where[] = 'using stale cache';
 333                                         $this->cache->set( $code, $staleCache );
 334                                         $success = true;
 335                                         break;
 336                                 } elseif ( $failedAttempts > 0 ) {
 337                                         # Already blocked once, so avoid another lock/unlock cycle.
 338                                         # This case will typically be hit if memcached is down, or if
 339                                         # loadFromDB() takes longer than LOCK_WAIT.
 340                                         $where[] = "could not acquire status key.";
 341                                         break;
 342                                 } elseif ( $loadStatus === 'cantacquire' ) {
 343                                         # Wait for the other thread to finish, then retry. Normally,
 344                                         # the memcached get() will then yield the other thread's result.
 345                                         $where[] = 'waited for other thread to complete';
 346                                         $this->getReentrantScopedLock( $cacheKey );
 347                                 } else {
 348                                         # Disable cache; $loadStatus is 'disabled'
 349                                         break;
 350                                 }
 351                         }
 352                 }
 353
 354                 if ( !$success ) {
 355                         $where[] = 'loading FAILED - cache is disabled';
 356                         $this->mDisable = true;
 357                         $this->cache->set( $code, [] );
 358                         wfDebugLog( 'MessageCacheError', __METHOD__ . ": Failed to load $code\n" );
 359                         # This used to throw an exception, but that led to nasty side effects like
 360                         # the whole wiki being instantly down if the memcached server died
 361                 } else {
 362                         # All good, just record the success
 363                         $this->loadedLanguages[$code] = true;
 364                 }
 365
 366                 if ( !$this->cache->has( $code ) ) { // sanity
 367                         throw new LogicException( "Process cache for '$code' should be set by now." );
 368                 }
 369
 370                 $info = implode( ', ', $where );
 371                 wfDebugLog( 'MessageCache', __METHOD__ . ": Loading $code... $info\n" );
 372
 373                 return $success;
 374         }
 375
 376         /**
 377          * @param string $code
 378          * @param array &$where List of wfDebug() comments
 379          * @param int|null $mode Use MessageCache::FOR_UPDATE to use DB_MASTER
 380          * @return bool|string True on success or one of ("cantacquire", "disabled")
 381          */
 382         protected function loadFromDBWithLock( $code, array &$where, $mode = null ) {
 383                 # If cache updates on all levels fail, give up on message overrides.
 384                 # This is to avoid easy site outages; see $saveSuccess comments below.
 385                 $statusKey = $this->clusterCache->makeKey( 'messages', $code, 'status' );
 386                 $status = $this->clusterCache->get( $statusKey );
 387                 if ( $status === 'error' ) {
 388                         $where[] = "could not load; method is still globally disabled";
 389                         return 'disabled';
 390                 }
 391
 392                 # Now let's regenerate
 393                 $where[] = 'loading from database';
 394
 395                 # Lock the cache to prevent conflicting writes.
 396                 # This lock is non-blocking so stale cache can quickly be used.
 397                 # Note that load() will call a blocking getReentrantScopedLock()
 398                 # after this if it really need to wait for any current thread.
 399                 $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
 400                 $scopedLock = $this->getReentrantScopedLock( $cacheKey, 0 );
 401                 if ( !$scopedLock ) {
 402                         $where[] = 'could not acquire main lock';
 403                         return 'cantacquire';
 404                 }
 405
 406                 $cache = $this->loadFromDB( $code, $mode );
 407                 $this->cache->set( $code, $cache );
 408                 $saveSuccess = $this->saveToCaches( $cache, 'all', $code );
 409
 410                 if ( !$saveSuccess ) {
 411                         /**
 412                          * Cache save has failed.
 413                          *
 414                          * There are two main scenarios where this could be a problem:
 415                          * - The cache is more than the maximum size (typically 1MB compressed).
 416                          * - Memcached has no space remaining in the relevant slab class. This is
 417                          *   unlikely with recent versions of memcached.
 418                          *
 419                          * Either way, if there is a local cache, nothing bad will happen. If there
 420                          * is no local cache, disabling the message cache for all requests avoids
 421                          * incurring a loadFromDB() overhead on every request, and thus saves the
 422                          * wiki from complete downtime under moderate traffic conditions.
 423                          */
 424                         if ( $this->srvCache instanceof EmptyBagOStuff ) {
 425                                 $this->clusterCache->set( $statusKey, 'error', 60 * 5 );
 426                                 $where[] = 'could not save cache, disabled globally for 5 minutes';
 427                         } else {
 428                                 $where[] = "could not save global cache";
 429                         }
 430                 }
 431
 432                 return true;
 433         }
 434
 435         /**
 436          * Loads cacheable messages from the database. Messages bigger than
 437          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 438          * on-demand from the database later.
 439          *
 440          * @param string $code Language code
 441          * @param int|null $mode Use MessageCache::FOR_UPDATE to skip process cache
 442          * @return array Loaded messages for storing in caches
 443          */
 444         protected function loadFromDB( $code, $mode = null ) {
 445                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 446
 447                 // (T164666) The query here performs really poorly on WMF's
 448                 // contributions replicas. We don't have a way to say "any group except
 449                 // contributions", so for the moment let's specify 'api'.
 450                 // @todo: Get rid of this hack.
 451                 $dbr = wfGetDB( ( $mode == self::FOR_UPDATE ) ? DB_MASTER : DB_REPLICA, 'api' );
 452
 453                 $cache = [];
 454
 455                 $mostused = []; // list of "<cased message key>/<code>"
 456                 if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
 457                         if ( !$this->cache->has( $wgLanguageCode ) ) {
 458                                 $this->load( $wgLanguageCode );
 459                         }
 460                         $mostused = array_keys( $this->cache->get( $wgLanguageCode ) );
 461                         foreach ( $mostused as $key => $value ) {
 462                                 $mostused[$key] = "$value/$code";
 463                         }
 464                 }
 465
 466                 // Get the list of software-defined messages in core/extensions
 467                 $overridable = array_flip( Language::getMessageKeysFor( $wgLanguageCode ) );
 468
 469                 // Common conditions
 470                 $conds = [
 471                         'page_is_redirect' => 0,
 472                         'page_namespace' => NS_MEDIAWIKI,
 473                 ];
 474                 if ( count( $mostused ) ) {
 475                         $conds['page_title'] = $mostused;
 476                 } elseif ( $code !== $wgLanguageCode ) {
 477                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
 478                 } else {
 479                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 480                         # other than language code.
 481                         $conds[] = 'page_title NOT' .
 482                                 $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 483                 }
 484
 485                 // Set the stubs for oversized software-defined messages in the main cache map
 486                 $res = $dbr->select(
 487                         'page',
 488                         [ 'page_title', 'page_latest' ],
 489                         array_merge( $conds, [ 'page_len > ' . intval( $wgMaxMsgCacheEntrySize ) ] ),
 490                         __METHOD__ . "($code)-big"
 491                 );
 492                 foreach ( $res as $row ) {
 493                         // Include entries/stubs for all keys in $mostused in adaptive mode
 494                         if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $row->page_title, $overridable ) ) {
 495                                 $cache[$row->page_title] = '!TOO BIG';
 496                         }
 497                         // At least include revision ID so page changes are reflected in the hash
 498                         $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
 499                 }
 500
 501                 // Set the text for small software-defined messages in the main cache map
 502                 $revisionStore = MediaWikiServices::getInstance()->getRevisionStore();
 503                 $revQuery = $revisionStore->getQueryInfo( [ 'page', 'user' ] );
 504
 505                 // T231196: MySQL/MariaDB (10.1.37) can sometimes irrationally decide that querying `actor` then
 506                 // `revision` then `page` is somehow better than starting with `page`. Tell it not to reorder the
 507                 // query (and also reorder it ourselves because as generated by RevisionStore it'll have
 508                 // `revision` first rather than `page`).
 509                 $revQuery['joins']['revision'] = $revQuery['joins']['page'];
 510                 unset( $revQuery['joins']['page'] );
 511                 // It isn't actually necesssary to reorder $revQuery['tables'] as Database does the right thing
 512                 // when join conditions are given for all joins, but Gergő is wary of relying on that so pull
 513                 // `page` to the start.
 514                 $revQuery['tables'] = array_merge(
 515                         [ 'page' ],
 516                         array_diff( $revQuery['tables'], [ 'page' ] )
 517                 );
 518
 519                 $res = $dbr->select(
 520                         $revQuery['tables'],
 521                         $revQuery['fields'],
 522                         array_merge( $conds, [
 523                                 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize ),
 524                                 'page_latest = rev_id' // get the latest revision only
 525                         ] ),
 526                         __METHOD__ . "($code)-small",
 527                         [ 'STRAIGHT_JOIN' ],
 528                         $revQuery['joins']
 529                 );
 530                 foreach ( $res as $row ) {
 531                         // Include entries/stubs for all keys in $mostused in adaptive mode
 532                         if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $row->page_title, $overridable ) ) {
 533                                 try {
 534                                         $rev = $revisionStore->newRevisionFromRow( $row );
 535                                         $content = $rev->getContent( MediaWiki\Revision\SlotRecord::MAIN );
 536                                         $text = $this->getMessageTextFromContent( $content );
 537                                 } catch ( Exception $ex ) {
 538                                         $text = false;
 539                                 }
 540
 541                                 if ( !is_string( $text ) ) {
 542                                         $entry = '!ERROR';
 543                                         wfDebugLog(
 544                                                 'MessageCache',
 545                                                 __METHOD__
 546                                                 . ": failed to load message page text for {$row->page_title} ($code)"
 547                                         );
 548                                 } else {
 549                                         $entry = ' ' . $text;
 550                                 }
 551                                 $cache[$row->page_title] = $entry;
 552                         } else {
 553                                 // T193271: cache object gets too big and slow to generate.
 554                                 // At least include revision ID so page changes are reflected in the hash.
 555                                 $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
 556                         }
 557                 }
 558
 559                 $cache['VERSION'] = MSG_CACHE_VERSION;
 560                 ksort( $cache );
 561
 562                 # Hash for validating local cache (APC). No need to take into account
 563                 # messages larger than $wgMaxMsgCacheEntrySize, since those are only
 564                 # stored and fetched from memcache.
 565                 $cache['HASH'] = md5( serialize( $cache ) );
 566                 $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + self::WAN_TTL );
 567                 unset( $cache['EXCESSIVE'] ); // only needed for hash
 568
 569                 return $cache;
 570         }
 571
 572         /**
 573          * @param string $name Message name (possibly with /code suffix)
 574          * @param array $overridable Map of (key => unused) for software-defined messages
 575          * @return bool
 576          */
 577         private function isMainCacheable( $name, array $overridable ) {
 578                 // Convert first letter to lowercase, and strip /code suffix
 579                 $name = $this->contLang->lcfirst( $name );
 580                 $msg = preg_replace( '/\/[a-z0-9-]{2,}$/', '', $name );
 581                 // Include common conversion table pages. This also avoids problems with
 582                 // Installer::parse() bailing out due to disallowed DB queries (T207979).
 583                 return ( isset( $overridable[$msg] ) || strpos( $name, 'conversiontable/' ) === 0 );
 584         }
 585
 586         /**
 587          * Updates cache as necessary when message page is changed
 588          *
 589          * @param string $title Message cache key with initial uppercase letter
 590          * @param string|bool $text New contents of the page (false if deleted)
 591          */
 592         public function replace( $title, $text ) {
 593                 global $wgLanguageCode;
 594
 595                 if ( $this->mDisable ) {
 596                         return;
 597                 }
 598
 599                 list( $msg, $code ) = $this->figureMessage( $title );
 600                 if ( strpos( $title, '/' ) !== false && $code === $wgLanguageCode ) {
 601                         // Content language overrides do not use the /<code> suffix
 602                         return;
 603                 }
 604
 605                 // (a) Update the process cache with the new message text
 606                 if ( $text === false ) {
 607                         // Page deleted
 608                         $this->cache->setField( $code, $title, '!NONEXISTENT' );
 609                 } else {
 610                         // Ignore $wgMaxMsgCacheEntrySize so the process cache is up to date
 611                         $this->cache->setField( $code, $title, ' ' . $text );
 612                 }
 613
 614                 // (b) Update the shared caches in a deferred update with a fresh DB snapshot
 615                 DeferredUpdates::addUpdate(
 616                         new MessageCacheUpdate( $code, $title, $msg ),
 617                         DeferredUpdates::PRESEND
 618                 );
 619         }
 620
 621         /**
 622          * @param string $code
 623          * @param array[] $replacements List of (title, message key) pairs
 624          * @throws MWException
 625          */
 626         public function refreshAndReplaceInternal( $code, array $replacements ) {
 627                 global $wgMaxMsgCacheEntrySize;
 628
 629                 // Allow one caller at a time to avoid race conditions
 630                 $scopedLock = $this->getReentrantScopedLock(
 631                         $this->clusterCache->makeKey( 'messages', $code )
 632                 );
 633                 if ( !$scopedLock ) {
 634                         foreach ( $replacements as list( $title ) ) {
 635                                 LoggerFactory::getInstance( 'MessageCache' )->error(
 636                                         __METHOD__ . ': could not acquire lock to update {title} ({code})',
 637                                         [ 'title' => $title, 'code' => $code ] );
 638                         }
 639
 640                         return;
 641                 }
 642
 643                 // Load the existing cache to update it in the local DC cache.
 644                 // The other DCs will see a hash mismatch.
 645                 if ( $this->load( $code, self::FOR_UPDATE ) ) {
 646                         $cache = $this->cache->get( $code );
 647                 } else {
 648                         // Err? Fall back to loading from the database.
 649                         $cache = $this->loadFromDB( $code, self::FOR_UPDATE );
 650                 }
 651                 // Check if individual cache keys should exist and update cache accordingly
 652                 $newTextByTitle = []; // map of (title => content)
 653                 $newBigTitles = []; // map of (title => latest revision ID), like EXCESSIVE in loadFromDB()
 654                 foreach ( $replacements as list( $title ) ) {
 655                         $page = WikiPage::factory( Title::makeTitle( NS_MEDIAWIKI, $title ) );
 656                         $page->loadPageData( $page::READ_LATEST );
 657                         $text = $this->getMessageTextFromContent( $page->getContent() );
 658                         // Remember the text for the blob store update later on
 659                         $newTextByTitle[$title] = $text;
 660                         // Note that if $text is false, then $cache should have a !NONEXISTANT entry
 661                         if ( !is_string( $text ) ) {
 662                                 $cache[$title] = '!NONEXISTENT';
 663                         } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 664                                 $cache[$title] = '!TOO BIG';
 665                                 $newBigTitles[$title] = $page->getLatest();
 666                         } else {
 667                                 $cache[$title] = ' ' . $text;
 668                         }
 669                 }
 670                 // Update HASH for the new key. Incorporates various administrative keys,
 671                 // including the old HASH (and thereby the EXCESSIVE value from loadFromDB()
 672                 // and previous replace() calls), but that doesn't really matter since we
 673                 // only ever compare it for equality with a copy saved by saveToCaches().
 674                 $cache['HASH'] = md5( serialize( $cache + [ 'EXCESSIVE' => $newBigTitles ] ) );
 675                 // Update the too-big WAN cache entries now that we have the new HASH
 676                 foreach ( $newBigTitles as $title => $id ) {
 677                         // Match logic of loadCachedMessagePageEntry()
 678                         $this->wanCache->set(
 679                                 $this->bigMessageCacheKey( $cache['HASH'], $title ),
 680                                 ' ' . $newTextByTitle[$title],
 681                                 self::WAN_TTL
 682                         );
 683                 }
 684                 // Mark this cache as definitely being "latest" (non-volatile) so
 685                 // load() calls do not try to refresh the cache with replica DB data
 686                 $cache['LATEST'] = time();
 687                 // Update the process cache
 688                 $this->cache->set( $code, $cache );
 689                 // Pre-emptively update the local datacenter cache so things like edit filter and
 690                 // blacklist changes are reflected immediately; these often use MediaWiki: pages.
 691                 // The datacenter handling replace() calls should be the same one handling edits
 692                 // as they require HTTP POST.
 693                 $this->saveToCaches( $cache, 'all', $code );
 694                 // Release the lock now that the cache is saved
 695                 ScopedCallback::consume( $scopedLock );
 696
 697                 // Relay the purge. Touching this check key expires cache contents
 698                 // and local cache (APC) validation hash across all datacenters.
 699                 $this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
 700
 701                 // Purge the messages in the message blob store and fire any hook handlers
 702                 $blobStore = MediaWikiServices::getInstance()->getResourceLoader()->getMessageBlobStore();
 703                 foreach ( $replacements as list( $title, $msg ) ) {
 704                         $blobStore->updateMessage( $this->contLang->lcfirst( $msg ) );
 705                         Hooks::run( 'MessageCacheReplace', [ $title, $newTextByTitle[$title] ] );
 706                 }
 707         }
 708
 709         /**
 710          * Is the given cache array expired due to time passing or a version change?
 711          *
 712          * @param array $cache
 713          * @return bool
 714          */
 715         protected function isCacheExpired( $cache ) {
 716                 if ( !isset( $cache['VERSION'] ) || !isset( $cache['EXPIRY'] ) ) {
 717                         return true;
 718                 }
 719                 if ( $cache['VERSION'] != MSG_CACHE_VERSION ) {
 720                         return true;
 721                 }
 722                 if ( wfTimestampNow() >= $cache['EXPIRY'] ) {
 723                         return true;
 724                 }
 725
 726                 return false;
 727         }
 728
 729         /**
 730          * Shortcut to update caches.
 731          *
 732          * @param array $cache Cached messages with a version.
 733          * @param string $dest Either "local-only" to save to local caches only
 734          *   or "all" to save to all caches.
 735          * @param string|bool $code Language code (default: false)
 736          * @return bool
 737          */
 738         protected function saveToCaches( array $cache, $dest, $code = false ) {
 739                 if ( $dest === 'all' ) {
 740                         $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
 741                         $success = $this->clusterCache->set( $cacheKey, $cache );
 742                         $this->setValidationHash( $code, $cache );
 743                 } else {
 744                         $success = true;
 745                 }
 746
 747                 $this->saveToLocalCache( $code, $cache );
 748
 749                 return $success;
 750         }
 751
 752         /**
 753          * Get the md5 used to validate the local APC cache
 754          *
 755          * @param string $code
 756          * @return array (hash or false, bool expiry/volatility status)
 757          */
 758         protected function getValidationHash( $code ) {
 759                 $curTTL = null;
 760                 $value = $this->wanCache->get(
 761                         $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
 762                         $curTTL,
 763                         [ $this->getCheckKey( $code ) ]
 764                 );
 765
 766                 if ( $value ) {
 767                         $hash = $value['hash'];
 768                         if ( ( time() - $value['latest'] ) < WANObjectCache::TTL_MINUTE ) {
 769                                 // Cache was recently updated via replace() and should be up-to-date.
 770                                 // That method is only called in the primary datacenter and uses FOR_UPDATE.
 771                                 // Also, it is unlikely that the current datacenter is *now* secondary one.
 772                                 $expired = false;
 773                         } else {
 774                                 // See if the "check" key was bumped after the hash was generated
 775                                 $expired = ( $curTTL < 0 );
 776                         }
 777                 } else {
 778                         // No hash found at all; cache must regenerate to be safe
 779                         $hash = false;
 780                         $expired = true;
 781                 }
 782
 783                 return [ $hash, $expired ];
 784         }
 785
 786         /**
 787          * Set the md5 used to validate the local disk cache
 788          *
 789          * If $cache has a 'LATEST' UNIX timestamp key, then the hash will not
 790          * be treated as "volatile" by getValidationHash() for the next few seconds.
 791          * This is triggered when $cache is generated using FOR_UPDATE mode.
 792          *
 793          * @param string $code
 794          * @param array $cache Cached messages with a version
 795          */
 796         protected function setValidationHash( $code, array $cache ) {
 797                 $this->wanCache->set(
 798                         $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
 799                         [
 800                                 'hash' => $cache['HASH'],
 801                                 'latest' => $cache['LATEST'] ?? 0
 802                         ],
 803                         WANObjectCache::TTL_INDEFINITE
 804                 );
 805         }
 806
 807         /**
 808          * @param string $key A language message cache key that stores blobs
 809          * @param int $timeout Wait timeout in seconds
 810          * @return null|ScopedCallback
 811          */
 812         protected function getReentrantScopedLock( $key, $timeout = self::WAIT_SEC ) {
 813                 return $this->clusterCache->getScopedLock( $key, $timeout, self::LOCK_TTL, __METHOD__ );
 814         }
 815
 816         /**
 817          * Get a message from either the content language or the user language.
 818          *
 819          * First, assemble a list of languages to attempt getting the message from. This
 820          * chain begins with the requested language and its fallbacks and then continues with
 821          * the content language and its fallbacks. For each language in the chain, the following
 822          * process will occur (in this order):
 823          *  1. If a language-specific override, i.e., [[MW:msg/lang]], is available, use that.
 824          *     Note: for the content language, there is no /lang subpage.
 825          *  2. Fetch from the static CDB cache.
 826          *  3. If available, check the database for fallback language overrides.
 827          *
 828          * This process provides a number of guarantees. When changing this code, make sure all
 829          * of these guarantees are preserved.
 830          *  * If the requested language is *not* the content language, then the CDB cache for that
 831          *    specific language will take precedence over the root database page ([[MW:msg]]).
 832          *  * Fallbacks will be just that: fallbacks. A fallback language will never be reached if
 833          *    the message is available *anywhere* in the language for which it is a fallback.
 834          *
 835          * @param string $key The message key
 836          * @param bool $useDB If true, look for the message in the DB, false
 837          *   to use only the compiled l10n cache.
 838          * @param bool|string|object $langcode Code of the language to get the message for.
 839          *   - If string and a valid code, will create a standard language object
 840          *   - If string but not a valid code, will create a basic language object
 841          *   - If boolean and false, create object from the current users language
 842          *   - If boolean and true, create object from the wikis content language
 843          *   - If language object, use it as given
 844          *
 845          * @throws MWException When given an invalid key
 846          * @return string|bool False if the message doesn't exist, otherwise the
 847          *   message (which can be empty)
 848          */
 849         function get( $key, $useDB = true, $langcode = true ) {
 850                 if ( is_int( $key ) ) {
 851                         // Fix numerical strings that somehow become ints
 852                         // on their way here
 853                         $key = (string)$key;
 854                 } elseif ( !is_string( $key ) ) {
 855                         throw new MWException( 'Non-string key given' );
 856                 } elseif ( $key === '' ) {
 857                         // Shortcut: the empty key is always missing
 858                         return false;
 859                 }
 860
 861                 // Normalise title-case input (with some inlining)
 862                 $lckey = self::normalizeKey( $key );
 863
 864                 Hooks::run( 'MessageCache::get', [ &$lckey ] );
 865
 866                 // Loop through each language in the fallback list until we find something useful
 867                 $message = $this->getMessageFromFallbackChain(
 868                         wfGetLangObj( $langcode ),
 869                         $lckey,
 870                         !$this->mDisable && $useDB
 871                 );
 872
 873                 // If we still have no message, maybe the key was in fact a full key so try that
 874                 if ( $message === false ) {
 875                         $parts = explode( '/', $lckey );
 876                         // We may get calls for things that are http-urls from sidebar
 877                         // Let's not load nonexistent languages for those
 878                         // They usually have more than one slash.
 879                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 880                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 881                                 if ( $message === null ) {
 882                                         $message = false;
 883                                 }
 884                         }
 885                 }
 886
 887                 // Post-processing if the message exists
 888                 if ( $message !== false ) {
 889                         // Fix whitespace
 890                         $message = str_replace(
 891                                 [
 892                                         # Fix for trailing whitespace, removed by textarea
 893                                         '&#32;',
 894                                         # Fix for NBSP, converted to space by firefox
 895                                         '&nbsp;',
 896                                         '&#160;',
 897                                         '&shy;'
 898                                 ],
 899                                 [
 900                                         ' ',
 901                                         "\u{00A0}",
 902                                         "\u{00A0}",
 903                                         "\u{00AD}"
 904                                 ],
 905                                 $message
 906                         );
 907                 }
 908
 909                 return $message;
 910         }
 911
 912         /**
 913          * Given a language, try and fetch messages from that language.
 914          *
 915          * Will also consider fallbacks of that language, the site language, and fallbacks for
 916          * the site language.
 917          *
 918          * @see MessageCache::get
 919          * @param Language|StubObject $lang Preferred language
 920          * @param string $lckey Lowercase key for the message (as for localisation cache)
 921          * @param bool $useDB Whether to include messages from the wiki database
 922          * @return string|bool The message, or false if not found
 923          */
 924         protected function getMessageFromFallbackChain( $lang, $lckey, $useDB ) {
 925                 $alreadyTried = [];
 926
 927                 // First try the requested language.
 928                 $message = $this->getMessageForLang( $lang, $lckey, $useDB, $alreadyTried );
 929                 if ( $message !== false ) {
 930                         return $message;
 931                 }
 932
 933                 // Now try checking the site language.
 934                 $message = $this->getMessageForLang( $this->contLang, $lckey, $useDB, $alreadyTried );
 935                 return $message;
 936         }
 937
 938         /**
 939          * Given a language, try and fetch messages from that language and its fallbacks.
 940          *
 941          * @see MessageCache::get
 942          * @param Language|StubObject $lang Preferred language
 943          * @param string $lckey Lowercase key for the message (as for localisation cache)
 944          * @param bool $useDB Whether to include messages from the wiki database
 945          * @param bool[] $alreadyTried Contains true for each language that has been tried already
 946          * @return string|bool The message, or false if not found
 947          */
 948         private function getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried ) {
 949                 $langcode = $lang->getCode();
 950
 951                 // Try checking the database for the requested language
 952                 if ( $useDB ) {
 953                         $uckey = $this->contLang->ucfirst( $lckey );
 954
 955                         if ( !isset( $alreadyTried[$langcode] ) ) {
 956                                 $message = $this->getMsgFromNamespace(
 957                                         $this->getMessagePageName( $langcode, $uckey ),
 958                                         $langcode
 959                                 );
 960                                 if ( $message !== false ) {
 961                                         return $message;
 962                                 }
 963                                 $alreadyTried[$langcode] = true;
 964                         }
 965                 } else {
 966                         $uckey = null;
 967                 }
 968
 969                 // Check the CDB cache
 970                 $message = $lang->getMessage( $lckey );
 971                 if ( $message !== null ) {
 972                         return $message;
 973                 }
 974
 975                 // Try checking the database for all of the fallback languages
 976                 if ( $useDB ) {
 977                         $fallbackChain = Language::getFallbacksFor( $langcode );
 978
 979                         foreach ( $fallbackChain as $code ) {
 980                                 if ( isset( $alreadyTried[$code] ) ) {
 981                                         continue;
 982                                 }
 983
 984                                 $message = $this->getMsgFromNamespace(
 985                                         $this->getMessagePageName( $code, $uckey ), $code );
 986
 987                                 if ( $message !== false ) {
 988                                         return $message;
 989                                 }
 990                                 $alreadyTried[$code] = true;
 991                         }
 992                 }
 993
 994                 return false;
 995         }
 996
 997         /**
 998          * Get the message page name for a given language
 999          *
1000          * @param string $langcode
1001          * @param string $uckey Uppercase key for the message
1002          * @return string The page name
1003          */
1004         private function getMessagePageName( $langcode, $uckey ) {
1005                 global $wgLanguageCode;
1006
1007                 if ( $langcode === $wgLanguageCode ) {
1008                         // Messages created in the content language will not have the /lang extension
1009                         return $uckey;
1010                 } else {
1011                         return "$uckey/$langcode";
1012                 }
1013         }
1014
1015         /**
1016          * Get a message from the MediaWiki namespace, with caching. The key must
1017          * first be converted to two-part lang/msg form if necessary.
1018          *
1019          * Unlike self::get(), this function doesn't resolve fallback chains, and
1020          * some callers require this behavior. LanguageConverter::parseCachedTable()
1021          * and self::get() are some examples in core.
1022          *
1023          * @param string $title Message cache key with initial uppercase letter
1024          * @param string $code Code denoting the language to try
1025          * @return string|bool The message, or false if it does not exist or on error
1026          */
1027         public function getMsgFromNamespace( $title, $code ) {
1028                 // Load all MediaWiki page definitions into cache. Note that individual keys
1029                 // already loaded into cache during this request remain in the cache, which
1030                 // includes the value of hook-defined messages.
1031                 $this->load( $code );
1032
1033                 $entry = $this->cache->getField( $code, $title );
1034
1035                 if ( $entry !== null ) {
1036                         // Message page exists as an override of a software messages
1037                         if ( substr( $entry, 0, 1 ) === ' ' ) {
1038                                 // The message exists and is not '!TOO BIG' or '!ERROR'
1039                                 return (string)substr( $entry, 1 );
1040                         } elseif ( $entry === '!NONEXISTENT' ) {
1041                                 // The text might be '-' or missing due to some data loss
1042                                 return false;
1043                         }
1044                         // Load the message page, utilizing the individual message cache.
1045                         // If the page does not exist, there will be no hook handler fallbacks.
1046                         $entry = $this->loadCachedMessagePageEntry(
1047                                 $title,
1048                                 $code,
1049                                 $this->cache->getField( $code, 'HASH' )
1050                         );
1051                 } else {
1052                         // Message page either does not exist or does not override a software message
1053                         if ( !$this->isMainCacheable( $title, $this->overridable ) ) {
1054                                 // Message page does not override any software-defined message. A custom
1055                                 // message might be defined to have content or settings specific to the wiki.
1056                                 // Load the message page, utilizing the individual message cache as needed.
1057                                 $entry = $this->loadCachedMessagePageEntry(
1058                                         $title,
1059                                         $code,
1060                                         $this->cache->getField( $code, 'HASH' )
1061                                 );
1062                         }
1063                         if ( $entry === null || substr( $entry, 0, 1 ) !== ' ' ) {
1064                                 // Message does not have a MediaWiki page definition; try hook handlers
1065                                 $message = false;
1066                                 Hooks::run( 'MessagesPreLoad', [ $title, &$message, $code ] );
1067                                 if ( $message !== false ) {
1068                                         $this->cache->setField( $code, $title, ' ' . $message );
1069                                 } else {
1070                                         $this->cache->setField( $code, $title, '!NONEXISTENT' );
1071                                 }
1072
1073                                 return $message;
1074                         }
1075                 }
1076
1077                 if ( $entry !== false && substr( $entry, 0, 1 ) === ' ' ) {
1078                         if ( $this->cacheVolatile[$code] ) {
1079                                 // Make sure that individual keys respect the WAN cache holdoff period too
1080                                 LoggerFactory::getInstance( 'MessageCache' )->debug(
1081                                         __METHOD__ . ': loading volatile key \'{titleKey}\'',
1082                                         [ 'titleKey' => $title, 'code' => $code ] );
1083                         } else {
1084                                 $this->cache->setField( $code, $title, $entry );
1085                         }
1086                         // The message exists, so make sure a string is returned
1087                         return (string)substr( $entry, 1 );
1088                 }
1089
1090                 $this->cache->setField( $code, $title, '!NONEXISTENT' );
1091
1092                 return false;
1093         }
1094
1095         /**
1096          * @param string $dbKey
1097          * @param string $code
1098          * @param string $hash
1099          * @return string Either " <MESSAGE>" or "!NONEXISTANT"
1100          */
1101         private function loadCachedMessagePageEntry( $dbKey, $code, $hash ) {
1102                 $fname = __METHOD__;
1103                 return $this->srvCache->getWithSetCallback(
1104                         $this->srvCache->makeKey( 'messages-big', $hash, $dbKey ),
1105                         BagOStuff::TTL_HOUR,
1106                         function () use ( $code, $dbKey, $hash, $fname ) {
1107                                 return $this->wanCache->getWithSetCallback(
1108                                         $this->bigMessageCacheKey( $hash, $dbKey ),
1109                                         self::WAN_TTL,
1110                                         function ( $oldValue, &$ttl, &$setOpts ) use ( $dbKey, $code, $fname ) {
1111                                                 // Try loading the message from the database
1112                                                 $dbr = wfGetDB( DB_REPLICA );
1113                                                 $setOpts += Database::getCacheSetOptions( $dbr );
1114                                                 // Use newKnownCurrent() to avoid querying revision/user tables
1115                                                 $title = Title::makeTitle( NS_MEDIAWIKI, $dbKey );
1116                                                 $revision = Revision::newKnownCurrent( $dbr, $title );
1117                                                 if ( !$revision ) {
1118                                                         // The wiki doesn't have a local override page. Cache absence with normal TTL.
1119                                                         // When overrides are created, self::replace() takes care of the cache.
1120                                                         return '!NONEXISTENT';
1121                                                 }
1122                                                 $content = $revision->getContent();
1123                                                 if ( $content ) {
1124                                                         $message = $this->getMessageTextFromContent( $content );
1125                                                 } else {
1126                                                         LoggerFactory::getInstance( 'MessageCache' )->warning(
1127                                                                 $fname . ': failed to load page text for \'{titleKey}\'',
1128                                                                 [ 'titleKey' => $dbKey, 'code' => $code ]
1129                                                         );
1130                                                         $message = null;
1131                                                 }
1132
1133                                                 if ( !is_string( $message ) ) {
1134                                                         // Revision failed to load Content, or Content is incompatible with wikitext.
1135                                                         // Possibly a temporary loading failure.
1136                                                         $ttl = 5;
1137
1138                                                         return '!NONEXISTENT';
1139                                                 }
1140
1141                                                 return ' ' . $message;
1142                                         }
1143                                 );
1144                         }
1145                 );
1146         }
1147
1148         /**
1149          * @param string $message
1150          * @param bool $interface
1151          * @param Language|null $language
1152          * @param Title|null $title
1153          * @return string
1154          */
1155         public function transform( $message, $interface = false, $language = null, $title = null ) {
1156                 // Avoid creating parser if nothing to transform
1157                 if ( strpos( $message, '{{' ) === false ) {
1158                         return $message;
1159                 }
1160
1161                 if ( $this->mInParser ) {
1162                         return $message;
1163                 }
1164
1165                 $parser = $this->getParser();
1166                 if ( $parser ) {
1167                         $popts = $this->getParserOptions();
1168                         $popts->setInterfaceMessage( $interface );
1169                         $popts->setTargetLanguage( $language );
1170
1171                         $userlang = $popts->setUserLang( $language );
1172                         $this->mInParser = true;
1173                         $message = $parser->transformMsg( $message, $popts, $title );
1174                         $this->mInParser = false;
1175                         $popts->setUserLang( $userlang );
1176                 }
1177
1178                 return $message;
1179         }
1180
1181         /**
1182          * @return Parser
1183          */
1184         public function getParser() {
1185                 global $wgParserConf;
1186                 if ( !$this->mParser ) {
1187                         $parser = MediaWikiServices::getInstance()->getParser();
1188                         # Do some initialisation so that we don't have to do it twice
1189                         $parser->firstCallInit();
1190                         # Clone it and store it
1191                         $class = $wgParserConf['class'];
1192                         if ( $class == ParserDiffTest::class ) {
1193                                 # Uncloneable
1194                                 // @phan-suppress-next-line PhanTypeMismatchProperty
1195                                 $this->mParser = new $class( $wgParserConf );
1196                         } else {
1197                                 $this->mParser = clone $parser;
1198                         }
1199                 }
1200
1201                 return $this->mParser;
1202         }
1203
1204         /**
1205          * @param string $text
1206          * @param Title|null $title
1207          * @param bool $linestart Whether or not this is at the start of a line
1208          * @param bool $interface Whether this is an interface message
1209          * @param Language|string|null $language Language code
1210          * @return ParserOutput|string
1211          */
1212         public function parse( $text, $title = null, $linestart = true,
1213                 $interface = false, $language = null
1214         ) {
1215                 global $wgTitle;
1216
1217                 if ( $this->mInParser ) {
1218                         return htmlspecialchars( $text );
1219                 }
1220
1221                 $parser = $this->getParser();
1222                 $popts = $this->getParserOptions();
1223                 $popts->setInterfaceMessage( $interface );
1224
1225                 if ( is_string( $language ) ) {
1226                         $language = Language::factory( $language );
1227                 }
1228                 $popts->setTargetLanguage( $language );
1229
1230                 if ( !$title || !$title instanceof Title ) {
1231                         wfDebugLog( 'GlobalTitleFail', __METHOD__ . ' called by ' .
1232                                 wfGetAllCallers( 6 ) . ' with no title set.' );
1233                         $title = $wgTitle;
1234                 }
1235                 // Sometimes $wgTitle isn't set either...
1236                 if ( !$title ) {
1237                         # It's not uncommon having a null $wgTitle in scripts. See r80898
1238                         # Create a ghost title in such case
1239                         $title = Title::makeTitle( NS_SPECIAL, 'Badtitle/title not set in ' . __METHOD__ );
1240                 }
1241
1242                 $this->mInParser = true;
1243                 $res = $parser->parse( $text, $title, $popts, $linestart );
1244                 $this->mInParser = false;
1245
1246                 return $res;
1247         }
1248
1249         public function disable() {
1250                 $this->mDisable = true;
1251         }
1252
1253         public function enable() {
1254                 $this->mDisable = false;
1255         }
1256
1257         /**
1258          * Whether DB/cache usage is disabled for determining messages
1259          *
1260          * If so, this typically indicates either:
1261          *   - a) load() failed to find a cached copy nor query the DB
1262          *   - b) we are in a special context or error mode that cannot use the DB
1263          * If the DB is ignored, any derived HTML output or cached objects may be wrong.
1264          * To avoid long-term cache pollution, TTLs can be adjusted accordingly.
1265          *
1266          * @return bool
1267          * @since 1.27
1268          */
1269         public function isDisabled() {
1270                 return $this->mDisable;
1271         }
1272
1273         /**
1274          * Clear all stored messages in global and local cache
1275          *
1276          * Mainly used after a mass rebuild
1277          */
1278         public function clear() {
1279                 $langs = Language::fetchLanguageNames( null, 'mw' );
1280                 foreach ( array_keys( $langs ) as $code ) {
1281                         $this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
1282                 }
1283                 $this->cache->clear();
1284                 $this->loadedLanguages = [];
1285         }
1286
1287         /**
1288          * @param string $key
1289          * @return array
1290          */
1291         public function figureMessage( $key ) {
1292                 global $wgLanguageCode;
1293
1294                 $pieces = explode( '/', $key );
1295                 if ( count( $pieces ) < 2 ) {
1296                         return [ $key, $wgLanguageCode ];
1297                 }
1298
1299                 $lang = array_pop( $pieces );
1300                 if ( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
1301                         return [ $key, $wgLanguageCode ];
1302                 }
1303
1304                 $message = implode( '/', $pieces );
1305
1306                 return [ $message, $lang ];
1307         }
1308
1309         /**
1310          * Get all message keys stored in the message cache for a given language.
1311          * If $code is the content language code, this will return all message keys
1312          * for which MediaWiki:msgkey exists. If $code is another language code, this
1313          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
1314          * @param string $code Language code
1315          * @return array Array of message keys (strings)
1316          */
1317         public function getAllMessageKeys( $code ) {
1318                 $this->load( $code );
1319                 if ( !$this->cache->has( $code ) ) {
1320                         // Apparently load() failed
1321                         return null;
1322                 }
1323                 // Remove administrative keys
1324                 $cache = $this->cache->get( $code );
1325                 unset( $cache['VERSION'] );
1326                 unset( $cache['EXPIRY'] );
1327                 unset( $cache['EXCESSIVE'] );
1328                 // Remove any !NONEXISTENT keys
1329                 $cache = array_diff( $cache, [ '!NONEXISTENT' ] );
1330
1331                 // Keys may appear with a capital first letter. lcfirst them.
1332                 return array_map( [ $this->contLang, 'lcfirst' ], array_keys( $cache ) );
1333         }
1334
1335         /**
1336          * Purge message caches when a MediaWiki: page is created, updated, or deleted
1337          *
1338          * @param Title $title Message page title
1339          * @param Content|null $content New content for edit/create, null on deletion
1340          * @since 1.29
1341          */
1342         public function updateMessageOverride( Title $title, Content $content = null ) {
1343                 $msgText = $this->getMessageTextFromContent( $content );
1344                 if ( $msgText === null ) {
1345                         $msgText = false; // treat as not existing
1346                 }
1347
1348                 $this->replace( $title->getDBkey(), $msgText );
1349
1350                 if ( $this->contLang->hasVariants() ) {
1351                         $this->contLang->updateConversionTable( $title );
1352                 }
1353         }
1354
1355         /**
1356          * @param string $code Language code
1357          * @return string WAN cache key usable as a "check key" against language page edits
1358          */
1359         public function getCheckKey( $code ) {
1360                 return $this->wanCache->makeKey( 'messages', $code );
1361         }
1362
1363         /**
1364          * @param Content|null $content Content or null if the message page does not exist
1365          * @return string|bool|null Returns false if $content is null and null on error
1366          */
1367         private function getMessageTextFromContent( Content $content = null ) {
1368                 // @TODO: could skip pseudo-messages like js/css here, based on content model
1369                 if ( $content ) {
1370                         // Message page exists...
1371                         // XXX: Is this the right way to turn a Content object into a message?
1372                         // NOTE: $content is typically either WikitextContent, JavaScriptContent or
1373                         //       CssContent. MessageContent is *not* used for storing messages, it's
1374                         //       only used for wrapping them when needed.
1375                         $msgText = $content->getWikitextForTransclusion();
1376                         if ( $msgText === false || $msgText === null ) {
1377                                 // This might be due to some kind of misconfiguration...
1378                                 $msgText = null;
1379                                 LoggerFactory::getInstance( 'MessageCache' )->warning(
1380                                         __METHOD__ . ": message content doesn't provide wikitext "
1381                                         . "(content model: " . $content->getModel() . ")" );
1382                         }
1383                 } else {
1384                         // Message page does not exist...
1385                         $msgText = false;
1386                 }
1387
1388                 return $msgText;
1389         }
1390
1391         /**
1392          * @param string $hash Hash for this version of the entire key/value overrides map
1393          * @param string $title Message cache key with initial uppercase letter
1394          * @return string
1395          */
1396         private function bigMessageCacheKey( $hash, $title ) {
1397                 return $this->wanCache->makeKey( 'messages-big', $hash, $title );
1398         }
1399 }