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