includes/cache/MessageCache.php

   1 <?php
   2 /**
   3  * Localisation messages cache.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Cache
  22  */
  23 use MediaWiki\MediaWikiServices;
  24 use Wikimedia\ScopedCallback;
  25 use MediaWiki\Logger\LoggerFactory;
  26 use Wikimedia\Rdbms\Database;
  27
  28 /**
  29  * MediaWiki message cache structure version.
  30  * Bump this whenever the message cache format has changed.
  31  */
  32 define( 'MSG_CACHE_VERSION', 2 );
  33
  34 /**
  35  * Cache of messages that are defined by MediaWiki namespace pages or by hooks
  36  *
  37  * Performs various MediaWiki namespace-related functions
  38  * @ingroup Cache
  39  */
  40 class MessageCache {
  41         const FOR_UPDATE = 1; // force message reload
  42
  43         /** How long to wait for memcached locks */
  44         const WAIT_SEC = 15;
  45         /** How long memcached locks last */
  46         const LOCK_TTL = 30;
  47
  48         /**
  49          * Process cache of loaded messages that are defined in MediaWiki namespace
  50          *
  51          * @var MapCacheLRU Map of (language code => key => " <MESSAGE>" or "!TOO BIG" or "!ERROR")
  52          */
  53         protected $cache;
  54
  55         /**
  56          * Map of (lowercase message key => index) for all software defined messages
  57          *
  58          * @var array
  59          */
  60         protected $overridable;
  61
  62         /**
  63          * @var bool[] Map of (language code => boolean)
  64          */
  65         protected $cacheVolatile = [];
  66
  67         /**
  68          * Should mean that database cannot be used, but check
  69          * @var bool $mDisable
  70          */
  71         protected $mDisable;
  72
  73         /**
  74          * Lifetime for cache, used by object caching.
  75          * Set on construction, see __construct().
  76          */
  77         protected $mExpiry;
  78
  79         /**
  80          * Message cache has its own parser which it uses to transform messages
  81          * @var ParserOptions
  82          */
  83         protected $mParserOptions;
  84         /** @var Parser */
  85         protected $mParser;
  86
  87         /**
  88          * @var bool $mInParser
  89          */
  90         protected $mInParser = false;
  91
  92         /** @var WANObjectCache */
  93         protected $wanCache;
  94         /** @var BagOStuff */
  95         protected $clusterCache;
  96         /** @var BagOStuff */
  97         protected $srvCache;
  98         /** @var Language */
  99         protected $contLang;
 100
 101         /**
 102          * Track which languages have been loaded by load().
 103          * @var array
 104          */
 105         private $loadedLanguages = [];
 106
 107         /**
 108          * 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 int $expiry Lifetime for cache. @see $mExpiry.
 141          * @param Language|null $contLang Content language of site
 142          */
 143         public function __construct(
 144                 WANObjectCache $wanCache,
 145                 BagOStuff $clusterCache,
 146                 BagOStuff $serverCache,
 147                 $useDB,
 148                 $expiry,
 149                 Language $contLang = null
 150         ) {
 151                 $this->wanCache = $wanCache;
 152                 $this->clusterCache = $clusterCache;
 153                 $this->srvCache = $serverCache;
 154
 155                 $this->cache = new MapCacheLRU( 5 ); // limit size for sanity
 156
 157                 $this->mDisable = !$useDB;
 158                 $this->mExpiry = $expiry;
 159                 $this->contLang = $contLang ?? MediaWikiServices::getInstance()->getContentLanguage();
 160         }
 161
 162         /**
 163          * ParserOptions is lazy initialised.
 164          *
 165          * @return ParserOptions
 166          */
 167         function getParserOptions() {
 168                 global $wgUser;
 169
 170                 if ( !$this->mParserOptions ) {
 171                         if ( !$wgUser->isSafeToLoad() ) {
 172                                 // $wgUser isn't unstubbable yet, so don't try to get a
 173                                 // ParserOptions for it. And don't cache this ParserOptions
 174                                 // either.
 175                                 $po = ParserOptions::newFromAnon();
 176                                 $po->setAllowUnsafeRawHtml( false );
 177                                 $po->setTidy( true );
 178                                 return $po;
 179                         }
 180
 181                         $this->mParserOptions = new ParserOptions;
 182                         // Messages may take parameters that could come
 183                         // from malicious sources. As a precaution, disable
 184                         // the <html> parser tag when parsing messages.
 185                         $this->mParserOptions->setAllowUnsafeRawHtml( false );
 186                         // For the same reason, tidy the output!
 187                         $this->mParserOptions->setTidy( true );
 188                 }
 189
 190                 return $this->mParserOptions;
 191         }
 192
 193         /**
 194          * Try to load the cache from APC.
 195          *
 196          * @param string $code Optional language code, see documentation of load().
 197          * @return array|bool The cache array, or false if not in cache.
 198          */
 199         protected function getLocalCache( $code ) {
 200                 $cacheKey = $this->srvCache->makeKey( __CLASS__, $code );
 201
 202                 return $this->srvCache->get( $cacheKey );
 203         }
 204
 205         /**
 206          * Save the cache to APC.
 207          *
 208          * @param string $code
 209          * @param array $cache The cache array
 210          */
 211         protected function saveToLocalCache( $code, $cache ) {
 212                 $cacheKey = $this->srvCache->makeKey( __CLASS__, $code );
 213                 $this->srvCache->set( $cacheKey, $cache );
 214         }
 215
 216         /**
 217          * Loads messages from caches or from database in this order:
 218          * (1) local message cache (if $wgUseLocalMessageCache is enabled)
 219          * (2) memcached
 220          * (3) from the database.
 221          *
 222          * When successfully loading from (2) or (3), all higher level caches are
 223          * updated for the newest version.
 224          *
 225          * Nothing is loaded if member variable mDisable is true, either manually
 226          * set by calling code or if message loading fails (is this possible?).
 227          *
 228          * Returns true if cache is already populated or it was successfully populated,
 229          * or false if populating empty cache fails. Also returns true if MessageCache
 230          * is disabled.
 231          *
 232          * @param string $code Language to which load messages
 233          * @param int|null $mode Use MessageCache::FOR_UPDATE to skip process cache [optional]
 234          * @throws InvalidArgumentException
 235          * @return bool
 236          */
 237         protected function load( $code, $mode = null ) {
 238                 if ( !is_string( $code ) ) {
 239                         throw new InvalidArgumentException( "Missing language code" );
 240                 }
 241
 242                 # Don't do double loading...
 243                 if ( isset( $this->loadedLanguages[$code] ) && $mode != self::FOR_UPDATE ) {
 244                         return true;
 245                 }
 246
 247                 $this->overridable = array_flip( Language::getMessageKeysFor( $code ) );
 248
 249                 # 8 lines of code just to say (once) that message cache is disabled
 250                 if ( $this->mDisable ) {
 251                         static $shownDisabled = false;
 252                         if ( !$shownDisabled ) {
 253                                 wfDebug( __METHOD__ . ": disabled\n" );
 254                                 $shownDisabled = true;
 255                         }
 256
 257                         return true;
 258                 }
 259
 260                 # Loading code starts
 261                 $success = false; # Keep track of success
 262                 $staleCache = false; # a cache array with expired data, or false if none has been loaded
 263                 $where = []; # Debug info, delayed to avoid spamming debug log too much
 264
 265                 # Hash of the contents is stored in memcache, to detect if data-center cache
 266                 # or local cache goes out of date (e.g. due to replace() on some other server)
 267                 list( $hash, $hashVolatile ) = $this->getValidationHash( $code );
 268                 $this->cacheVolatile[$code] = $hashVolatile;
 269
 270                 # Try the local cache and check against the cluster hash key...
 271                 $cache = $this->getLocalCache( $code );
 272                 if ( !$cache ) {
 273                         $where[] = 'local cache is empty';
 274                 } elseif ( !isset( $cache['HASH'] ) || $cache['HASH'] !== $hash ) {
 275                         $where[] = 'local cache has the wrong hash';
 276                         $staleCache = $cache;
 277                 } elseif ( $this->isCacheExpired( $cache ) ) {
 278                         $where[] = 'local cache is expired';
 279                         $staleCache = $cache;
 280                 } elseif ( $hashVolatile ) {
 281                         $where[] = 'local cache validation key is expired/volatile';
 282                         $staleCache = $cache;
 283                 } else {
 284                         $where[] = 'got from local cache';
 285                         $this->cache->set( $code, $cache );
 286                         $success = true;
 287                 }
 288
 289                 if ( !$success ) {
 290                         $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
 291                         # Try the global cache. If it is empty, try to acquire a lock. If
 292                         # the lock can't be acquired, wait for the other thread to finish
 293                         # and then try the global cache a second time.
 294                         for ( $failedAttempts = 0; $failedAttempts <= 1; $failedAttempts++ ) {
 295                                 if ( $hashVolatile && $staleCache ) {
 296                                         # Do not bother fetching the whole cache blob to avoid I/O.
 297                                         # Instead, just try to get the non-blocking $statusKey lock
 298                                         # below, and use the local stale value if it was not acquired.
 299                                         $where[] = 'global cache is presumed expired';
 300                                 } else {
 301                                         $cache = $this->clusterCache->get( $cacheKey );
 302                                         if ( !$cache ) {
 303                                                 $where[] = 'global cache is empty';
 304                                         } elseif ( $this->isCacheExpired( $cache ) ) {
 305                                                 $where[] = 'global cache is expired';
 306                                                 $staleCache = $cache;
 307                                         } elseif ( $hashVolatile ) {
 308                                                 # DB results are replica DB lag prone until the holdoff TTL passes.
 309                                                 # By then, updates should be reflected in loadFromDBWithLock().
 310                                                 # One thread regenerates the cache while others use old values.
 311                                                 $where[] = 'global cache is expired/volatile';
 312                                                 $staleCache = $cache;
 313                                         } else {
 314                                                 $where[] = 'got from global cache';
 315                                                 $this->cache->set( $code, $cache );
 316                                                 $this->saveToCaches( $cache, 'local-only', $code );
 317                                                 $success = true;
 318                                         }
 319                                 }
 320
 321                                 if ( $success ) {
 322                                         # Done, no need to retry
 323                                         break;
 324                                 }
 325
 326                                 # We need to call loadFromDB. Limit the concurrency to one process.
 327                                 # This prevents the site from going down when the cache expires.
 328                                 # Note that the DB slam protection lock here is non-blocking.
 329                                 $loadStatus = $this->loadFromDBWithLock( $code, $where, $mode );
 330                                 if ( $loadStatus === true ) {
 331                                         $success = true;
 332                                         break;
 333                                 } elseif ( $staleCache ) {
 334                                         # Use the stale cache while some other thread constructs the new one
 335                                         $where[] = 'using stale cache';
 336                                         $this->cache->set( $code, $staleCache );
 337                                         $success = true;
 338                                         break;
 339                                 } elseif ( $failedAttempts > 0 ) {
 340                                         # Already blocked once, so avoid another lock/unlock cycle.
 341                                         # This case will typically be hit if memcached is down, or if
 342                                         # loadFromDB() takes longer than LOCK_WAIT.
 343                                         $where[] = "could not acquire status key.";
 344                                         break;
 345                                 } elseif ( $loadStatus === 'cantacquire' ) {
 346                                         # Wait for the other thread to finish, then retry. Normally,
 347                                         # the memcached get() will then yield the other thread's result.
 348                                         $where[] = 'waited for other thread to complete';
 349                                         $this->getReentrantScopedLock( $cacheKey );
 350                                 } else {
 351                                         # Disable cache; $loadStatus is 'disabled'
 352                                         break;
 353                                 }
 354                         }
 355                 }
 356
 357                 if ( !$success ) {
 358                         $where[] = 'loading FAILED - cache is disabled';
 359                         $this->mDisable = true;
 360                         $this->cache->set( $code, [] );
 361                         wfDebugLog( 'MessageCacheError', __METHOD__ . ": Failed to load $code\n" );
 362                         # This used to throw an exception, but that led to nasty side effects like
 363                         # the whole wiki being instantly down if the memcached server died
 364                 } else {
 365                         # All good, just record the success
 366                         $this->loadedLanguages[$code] = true;
 367                 }
 368
 369                 if ( !$this->cache->has( $code ) ) { // sanity
 370                         throw new LogicException( "Process cache for '$code' should be set by now." );
 371                 }
 372
 373                 $info = implode( ', ', $where );
 374                 wfDebugLog( 'MessageCache', __METHOD__ . ": Loading $code... $info\n" );
 375
 376                 return $success;
 377         }
 378
 379         /**
 380          * @param string $code
 381          * @param array &$where List of wfDebug() comments
 382          * @param int|null $mode Use MessageCache::FOR_UPDATE to use DB_MASTER
 383          * @return bool|string True on success or one of ("cantacquire", "disabled")
 384          */
 385         protected function loadFromDBWithLock( $code, array &$where, $mode = null ) {
 386                 # If cache updates on all levels fail, give up on message overrides.
 387                 # This is to avoid easy site outages; see $saveSuccess comments below.
 388                 $statusKey = $this->clusterCache->makeKey( 'messages', $code, 'status' );
 389                 $status = $this->clusterCache->get( $statusKey );
 390                 if ( $status === 'error' ) {
 391                         $where[] = "could not load; method is still globally disabled";
 392                         return 'disabled';
 393                 }
 394
 395                 # Now let's regenerate
 396                 $where[] = 'loading from database';
 397
 398                 # Lock the cache to prevent conflicting writes.
 399                 # This lock is non-blocking so stale cache can quickly be used.
 400                 # Note that load() will call a blocking getReentrantScopedLock()
 401                 # after this if it really need to wait for any current thread.
 402                 $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
 403                 $scopedLock = $this->getReentrantScopedLock( $cacheKey, 0 );
 404                 if ( !$scopedLock ) {
 405                         $where[] = 'could not acquire main lock';
 406                         return 'cantacquire';
 407                 }
 408
 409                 $cache = $this->loadFromDB( $code, $mode );
 410                 $this->cache->set( $code, $cache );
 411                 $saveSuccess = $this->saveToCaches( $cache, 'all', $code );
 412
 413                 if ( !$saveSuccess ) {
 414                         /**
 415                          * Cache save has failed.
 416                          *
 417                          * There are two main scenarios where this could be a problem:
 418                          * - The cache is more than the maximum size (typically 1MB compressed).
 419                          * - Memcached has no space remaining in the relevant slab class. This is
 420                          *   unlikely with recent versions of memcached.
 421                          *
 422                          * Either way, if there is a local cache, nothing bad will happen. If there
 423                          * is no local cache, disabling the message cache for all requests avoids
 424                          * incurring a loadFromDB() overhead on every request, and thus saves the
 425                          * wiki from complete downtime under moderate traffic conditions.
 426                          */
 427                         if ( $this->srvCache instanceof EmptyBagOStuff ) {
 428                                 $this->clusterCache->set( $statusKey, 'error', 60 * 5 );
 429                                 $where[] = 'could not save cache, disabled globally for 5 minutes';
 430                         } else {
 431                                 $where[] = "could not save global cache";
 432                         }
 433                 }
 434
 435                 return true;
 436         }
 437
 438         /**
 439          * Loads cacheable messages from the database. Messages bigger than
 440          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 441          * on-demand from the database later.
 442          *
 443          * @param string $code Language code
 444          * @param int|null $mode Use MessageCache::FOR_UPDATE to skip process cache
 445          * @return array Loaded messages for storing in caches
 446          */
 447         protected function loadFromDB( $code, $mode = null ) {
 448                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 449
 450                 // (T164666) The query here performs really poorly on WMF's
 451                 // contributions replicas. We don't have a way to say "any group except
 452                 // contributions", so for the moment let's specify 'api'.
 453                 // @todo: Get rid of this hack.
 454                 $dbr = wfGetDB( ( $mode == self::FOR_UPDATE ) ? DB_MASTER : DB_REPLICA, 'api' );
 455
 456                 $cache = [];
 457
 458                 $mostused = []; // list of "<cased message key>/<code>"
 459                 if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
 460                         if ( !$this->cache->has( $wgLanguageCode ) ) {
 461                                 $this->load( $wgLanguageCode );
 462                         }
 463                         $mostused = array_keys( $this->cache->get( $wgLanguageCode ) );
 464                         foreach ( $mostused as $key => $value ) {
 465                                 $mostused[$key] = "$value/$code";
 466                         }
 467                 }
 468
 469                 // Get the list of software-defined messages in core/extensions
 470                 $overridable = array_flip( Language::getMessageKeysFor( $wgLanguageCode ) );
 471
 472                 // Common conditions
 473                 $conds = [
 474                         'page_is_redirect' => 0,
 475                         'page_namespace' => NS_MEDIAWIKI,
 476                 ];
 477                 if ( count( $mostused ) ) {
 478                         $conds['page_title'] = $mostused;
 479                 } elseif ( $code !== $wgLanguageCode ) {
 480                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
 481                 } else {
 482                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 483                         # other than language code.
 484                         $conds[] = 'page_title NOT' .
 485                                 $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 486                 }
 487
 488                 // Set the stubs for oversized software-defined messages in the main cache map
 489                 $res = $dbr->select(
 490                         'page',
 491                         [ 'page_title', 'page_latest' ],
 492                         array_merge( $conds, [ 'page_len > ' . intval( $wgMaxMsgCacheEntrySize ) ] ),
 493                         __METHOD__ . "($code)-big"
 494                 );
 495                 foreach ( $res as $row ) {
 496                         // Include entries/stubs for all keys in $mostused in adaptive mode
 497                         if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $row->page_title, $overridable ) ) {
 498                                 $cache[$row->page_title] = '!TOO BIG';
 499                         }
 500                         // At least include revision ID so page changes are reflected in the hash
 501                         $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
 502                 }
 503
 504                 // Set the text for small software-defined messages in the main cache map
 505                 $revisionStore = MediaWikiServices::getInstance()->getRevisionStore();
 506                 $revQuery = $revisionStore->getQueryInfo( [ 'page', 'user' ] );
 507
 508                 // T231196: MySQL/MariaDB (10.1.37) can sometimes irrationally decide that querying `actor` then
 509                 // `revision` then `page` is somehow better than starting with `page`. Tell it not to reorder the
 510                 // query (and also reorder it ourselves because as generated by RevisionStore it'll have
 511                 // `revision` first rather than `page`).
 512                 $revQuery['joins']['revision'] = $revQuery['joins']['page'];
 513                 unset( $revQuery['joins']['page'] );
 514                 // It isn't actually necesssary to reorder $revQuery['tables'] as Database does the right thing
 515                 // when join conditions are given for all joins, but Gergő is wary of relying on that so pull
 516                 // `page` to the start.
 517                 $revQuery['tables'] = array_merge(
 518                         [ 'page' ],
 519                         array_diff( $revQuery['tables'], [ 'page' ] )
 520                 );
 521
 522                 $res = $dbr->select(
 523                         $revQuery['tables'],
 524                         $revQuery['fields'],
 525                         array_merge( $conds, [
 526                                 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize ),
 527                                 'page_latest = rev_id' // get the latest revision only
 528                         ] ),
 529                         __METHOD__ . "($code)-small",
 530                         [ 'STRAIGHT_JOIN' ],
 531                         $revQuery['joins']
 532                 );
 533                 foreach ( $res as $row ) {
 534                         // Include entries/stubs for all keys in $mostused in adaptive mode
 535                         if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $row->page_title, $overridable ) ) {
 536                                 try {
 537                                         $rev = $revisionStore->newRevisionFromRow( $row );
 538                                         $content = $rev->getContent( MediaWiki\Revision\SlotRecord::MAIN );
 539                                         $text = $this->getMessageTextFromContent( $content );
 540                                 } catch ( Exception $ex ) {
 541                                         $text = false;
 542                                 }
 543
 544                                 if ( !is_string( $text ) ) {
 545                                         $entry = '!ERROR';
 546                                         wfDebugLog(
 547                                                 'MessageCache',
 548                                                 __METHOD__
 549                                                 . ": failed to load message page text for {$row->page_title} ($code)"
 550                                         );
 551                                 } else {
 552                                         $entry = ' ' . $text;
 553                                 }
 554                                 $cache[$row->page_title] = $entry;
 555                         } else {
 556                                 // T193271: cache object gets too big and slow to generate.
 557                                 // At least include revision ID so page changes are reflected in the hash.
 558                                 $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
 559                         }
 560                 }
 561
 562                 $cache['VERSION'] = MSG_CACHE_VERSION;
 563                 ksort( $cache );
 564
 565                 # Hash for validating local cache (APC). No need to take into account
 566                 # messages larger than $wgMaxMsgCacheEntrySize, since those are only
 567                 # stored and fetched from memcache.
 568                 $cache['HASH'] = md5( serialize( $cache ) );
 569                 $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );
 570                 unset( $cache['EXCESSIVE'] ); // only needed for hash
 571
 572                 return $cache;
 573         }
 574
 575         /**
 576          * @param string $name Message name (possibly with /code suffix)
 577          * @param array $overridable Map of (key => unused) for software-defined messages
 578          * @return bool
 579          */
 580         private function isMainCacheable( $name, array $overridable ) {
 581                 // Convert first letter to lowercase, and strip /code suffix
 582                 $name = $this->contLang->lcfirst( $name );
 583                 $msg = preg_replace( '/\/[a-z0-9-]{2,}$/', '', $name );
 584                 // Include common conversion table pages. This also avoids problems with
 585                 // Installer::parse() bailing out due to disallowed DB queries (T207979).
 586                 return ( isset( $overridable[$msg] ) || strpos( $name, 'conversiontable/' ) === 0 );
 587         }
 588
 589         /**
 590          * Updates cache as necessary when message page is changed
 591          *
 592          * @param string $title Message cache key with initial uppercase letter
 593          * @param string|bool $text New contents of the page (false if deleted)
 594          */
 595         public function replace( $title, $text ) {
 596                 global $wgLanguageCode;
 597
 598                 if ( $this->mDisable ) {
 599                         return;
 600                 }
 601
 602                 list( $msg, $code ) = $this->figureMessage( $title );
 603                 if ( strpos( $title, '/' ) !== false && $code === $wgLanguageCode ) {
 604                         // Content language overrides do not use the /<code> suffix
 605                         return;
 606                 }
 607
 608                 // (a) Update the process cache with the new message text
 609                 if ( $text === false ) {
 610                         // Page deleted
 611                         $this->cache->setField( $code, $title, '!NONEXISTENT' );
 612                 } else {
 613                         // Ignore $wgMaxMsgCacheEntrySize so the process cache is up to date
 614                         $this->cache->setField( $code, $title, ' ' . $text );
 615                 }
 616
 617                 // (b) Update the shared caches in a deferred update with a fresh DB snapshot
 618                 DeferredUpdates::addUpdate(
 619                         new MessageCacheUpdate( $code, $title, $msg ),
 620                         DeferredUpdates::PRESEND
 621                 );
 622         }
 623
 624         /**
 625          * @param string $code
 626          * @param array[] $replacements List of (title, message key) pairs
 627          * @throws MWException
 628          */
 629         public function refreshAndReplaceInternal( $code, array $replacements ) {
 630                 global $wgMaxMsgCacheEntrySize;
 631
 632                 // Allow one caller at a time to avoid race conditions
 633                 $scopedLock = $this->getReentrantScopedLock(
 634                         $this->clusterCache->makeKey( 'messages', $code )
 635                 );
 636                 if ( !$scopedLock ) {
 637                         foreach ( $replacements as list( $title ) ) {
 638                                 LoggerFactory::getInstance( 'MessageCache' )->error(
 639                                         __METHOD__ . ': could not acquire lock to update {title} ({code})',
 640                                         [ 'title' => $title, 'code' => $code ] );
 641                         }
 642
 643                         return;
 644                 }
 645
 646                 // Load the existing cache to update it in the local DC cache.
 647                 // The other DCs will see a hash mismatch.
 648                 if ( $this->load( $code, self::FOR_UPDATE ) ) {
 649                         $cache = $this->cache->get( $code );
 650                 } else {
 651                         // Err? Fall back to loading from the database.
 652                         $cache = $this->loadFromDB( $code, self::FOR_UPDATE );
 653                 }
 654                 // Check if individual cache keys should exist and update cache accordingly
 655                 $newTextByTitle = []; // map of (title => content)
 656                 $newBigTitles = []; // map of (title => latest revision ID), like EXCESSIVE in loadFromDB()
 657                 foreach ( $replacements as list( $title ) ) {
 658                         $page = WikiPage::factory( Title::makeTitle( NS_MEDIAWIKI, $title ) );
 659                         $page->loadPageData( $page::READ_LATEST );
 660                         $text = $this->getMessageTextFromContent( $page->getContent() );
 661                         // Remember the text for the blob store update later on
 662                         $newTextByTitle[$title] = $text;
 663                         // Note that if $text is false, then $cache should have a !NONEXISTANT entry
 664                         if ( !is_string( $text ) ) {
 665                                 $cache[$title] = '!NONEXISTENT';
 666                         } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 667                                 $cache[$title] = '!TOO BIG';
 668                                 $newBigTitles[$title] = $page->getLatest();
 669                         } else {
 670                                 $cache[$title] = ' ' . $text;
 671                         }
 672                 }
 673                 // Update HASH for the new key. Incorporates various administrative keys,
 674                 // including the old HASH (and thereby the EXCESSIVE value from loadFromDB()
 675                 // and previous replace() calls), but that doesn't really matter since we
 676                 // only ever compare it for equality with a copy saved by saveToCaches().
 677                 $cache['HASH'] = md5( serialize( $cache + [ 'EXCESSIVE' => $newBigTitles ] ) );
 678                 // Update the too-big WAN cache entries now that we have the new HASH
 679                 foreach ( $newBigTitles as $title => $id ) {
 680                         // Match logic of loadCachedMessagePageEntry()
 681                         $this->wanCache->set(
 682                                 $this->bigMessageCacheKey( $cache['HASH'], $title ),
 683                                 ' ' . $newTextByTitle[$title],
 684                                 $this->mExpiry
 685                         );
 686                 }
 687                 // Mark this cache as definitely being "latest" (non-volatile) so
 688                 // load() calls do not try to refresh the cache with replica DB data
 689                 $cache['LATEST'] = time();
 690                 // Update the process cache
 691                 $this->cache->set( $code, $cache );
 692                 // Pre-emptively update the local datacenter cache so things like edit filter and
 693                 // blacklist changes are reflected immediately; these often use MediaWiki: pages.
 694                 // The datacenter handling replace() calls should be the same one handling edits
 695                 // as they require HTTP POST.
 696                 $this->saveToCaches( $cache, 'all', $code );
 697                 // Release the lock now that the cache is saved
 698                 ScopedCallback::consume( $scopedLock );
 699
 700                 // Relay the purge. Touching this check key expires cache contents
 701                 // and local cache (APC) validation hash across all datacenters.
 702                 $this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
 703
 704                 // Purge the messages in the message blob store and fire any hook handlers
 705                 $blobStore = MediaWikiServices::getInstance()->getResourceLoader()->getMessageBlobStore();
 706                 foreach ( $replacements as list( $title, $msg ) ) {
 707                         $blobStore->updateMessage( $this->contLang->lcfirst( $msg ) );
 708                         Hooks::run( 'MessageCacheReplace', [ $title, $newTextByTitle[$title] ] );
 709                 }
 710         }
 711
 712         /**
 713          * Is the given cache array expired due to time passing or a version change?
 714          *
 715          * @param array $cache
 716          * @return bool
 717          */
 718         protected function isCacheExpired( $cache ) {
 719                 if ( !isset( $cache['VERSION'] ) || !isset( $cache['EXPIRY'] ) ) {
 720                         return true;
 721                 }
 722                 if ( $cache['VERSION'] != MSG_CACHE_VERSION ) {
 723                         return true;
 724                 }
 725                 if ( wfTimestampNow() >= $cache['EXPIRY'] ) {
 726                         return true;
 727                 }
 728
 729                 return false;
 730         }
 731
 732         /**
 733          * Shortcut to update caches.
 734          *
 735          * @param array $cache Cached messages with a version.
 736          * @param string $dest Either "local-only" to save to local caches only
 737          *   or "all" to save to all caches.
 738          * @param string|bool $code Language code (default: false)
 739          * @return bool
 740          */
 741         protected function saveToCaches( array $cache, $dest, $code = false ) {
 742                 if ( $dest === 'all' ) {
 743                         $cacheKey = $this->clusterCache->makeKey( 'messages', $code );
 744                         $success = $this->clusterCache->set( $cacheKey, $cache );
 745                         $this->setValidationHash( $code, $cache );
 746                 } else {
 747                         $success = true;
 748                 }
 749
 750                 $this->saveToLocalCache( $code, $cache );
 751
 752                 return $success;
 753         }
 754
 755         /**
 756          * Get the md5 used to validate the local APC cache
 757          *
 758          * @param string $code
 759          * @return array (hash or false, bool expiry/volatility status)
 760          */
 761         protected function getValidationHash( $code ) {
 762                 $curTTL = null;
 763                 $value = $this->wanCache->get(
 764                         $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
 765                         $curTTL,
 766                         [ $this->getCheckKey( $code ) ]
 767                 );
 768
 769                 if ( $value ) {
 770                         $hash = $value['hash'];
 771                         if ( ( time() - $value['latest'] ) < WANObjectCache::TTL_MINUTE ) {
 772                                 // Cache was recently updated via replace() and should be up-to-date.
 773                                 // That method is only called in the primary datacenter and uses FOR_UPDATE.
 774                                 // Also, it is unlikely that the current datacenter is *now* secondary one.
 775                                 $expired = false;
 776                         } else {
 777                                 // See if the "check" key was bumped after the hash was generated
 778                                 $expired = ( $curTTL < 0 );
 779                         }
 780                 } else {
 781                         // No hash found at all; cache must regenerate to be safe
 782                         $hash = false;
 783                         $expired = true;
 784                 }
 785
 786                 return [ $hash, $expired ];
 787         }
 788
 789         /**
 790          * Set the md5 used to validate the local disk cache
 791          *
 792          * If $cache has a 'LATEST' UNIX timestamp key, then the hash will not
 793          * be treated as "volatile" by getValidationHash() for the next few seconds.
 794          * This is triggered when $cache is generated using FOR_UPDATE mode.
 795          *
 796          * @param string $code
 797          * @param array $cache Cached messages with a version
 798          */
 799         protected function setValidationHash( $code, array $cache ) {
 800                 $this->wanCache->set(
 801                         $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
 802                         [
 803                                 'hash' => $cache['HASH'],
 804                                 'latest' => $cache['LATEST'] ?? 0
 805                         ],
 806                         WANObjectCache::TTL_INDEFINITE
 807                 );
 808         }
 809
 810         /**
 811          * @param string $key A language message cache key that stores blobs
 812          * @param int $timeout Wait timeout in seconds
 813          * @return null|ScopedCallback
 814          */
 815         protected function getReentrantScopedLock( $key, $timeout = self::WAIT_SEC ) {
 816                 return $this->clusterCache->getScopedLock( $key, $timeout, self::LOCK_TTL, __METHOD__ );
 817         }
 818
 819         /**
 820          * Get a message from either the content language or the user language.
 821          *
 822          * First, assemble a list of languages to attempt getting the message from. This
 823          * chain begins with the requested language and its fallbacks and then continues with
 824          * the content language and its fallbacks. For each language in the chain, the following
 825          * process will occur (in this order):
 826          *  1. If a language-specific override, i.e., [[MW:msg/lang]], is available, use that.
 827          *     Note: for the content language, there is no /lang subpage.
 828          *  2. Fetch from the static CDB cache.
 829          *  3. If available, check the database for fallback language overrides.
 830          *
 831          * This process provides a number of guarantees. When changing this code, make sure all
 832          * of these guarantees are preserved.
 833          *  * If the requested language is *not* the content language, then the CDB cache for that
 834          *    specific language will take precedence over the root database page ([[MW:msg]]).
 835          *  * Fallbacks will be just that: fallbacks. A fallback language will never be reached if
 836          *    the message is available *anywhere* in the language for which it is a fallback.
 837          *
 838          * @param string $key The message key
 839          * @param bool $useDB If true, look for the message in the DB, false
 840          *   to use only the compiled l10n cache.
 841          * @param bool|string|object $langcode Code of the language to get the message for.
 842          *   - If string and a valid code, will create a standard language object
 843          *   - If string but not a valid code, will create a basic language object
 844          *   - If boolean and false, create object from the current users language
 845          *   - If boolean and true, create object from the wikis content language
 846          *   - If language object, use it as given
 847          *
 848          * @throws MWException When given an invalid key
 849          * @return string|bool False if the message doesn't exist, otherwise the
 850          *   message (which can be empty)
 851          */
 852         function get( $key, $useDB = true, $langcode = true ) {
 853                 if ( is_int( $key ) ) {
 854                         // Fix numerical strings that somehow become ints
 855                         // on their way here
 856                         $key = (string)$key;
 857                 } elseif ( !is_string( $key ) ) {
 858                         throw new MWException( 'Non-string key given' );
 859                 } elseif ( $key === '' ) {
 860                         // Shortcut: the empty key is always missing
 861                         return false;
 862                 }
 863
 864                 // Normalise title-case input (with some inlining)
 865                 $lckey = self::normalizeKey( $key );
 866
 867                 Hooks::run( 'MessageCache::get', [ &$lckey ] );
 868
 869                 // Loop through each language in the fallback list until we find something useful
 870                 $message = $this->getMessageFromFallbackChain(
 871                         wfGetLangObj( $langcode ),
 872                         $lckey,
 873                         !$this->mDisable && $useDB
 874                 );
 875
 876                 // If we still have no message, maybe the key was in fact a full key so try that
 877                 if ( $message === false ) {
 878                         $parts = explode( '/', $lckey );
 879                         // We may get calls for things that are http-urls from sidebar
 880                         // Let's not load nonexistent languages for those
 881                         // They usually have more than one slash.
 882                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 883                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 884                                 if ( $message === null ) {
 885                                         $message = false;
 886                                 }
 887                         }
 888                 }
 889
 890                 // Post-processing if the message exists
 891                 if ( $message !== false ) {
 892                         // Fix whitespace
 893                         $message = str_replace(
 894                                 [
 895                                         # Fix for trailing whitespace, removed by textarea
 896                                         '&#32;',
 897                                         # Fix for NBSP, converted to space by firefox
 898                                         '&nbsp;',
 899                                         '&#160;',
 900                                         '&shy;'
 901                                 ],
 902                                 [
 903                                         ' ',
 904                                         "\u{00A0}",
 905                                         "\u{00A0}",
 906                                         "\u{00AD}"
 907                                 ],
 908                                 $message
 909                         );
 910                 }
 911
 912                 return $message;
 913         }
 914
 915         /**
 916          * Given a language, try and fetch messages from that language.
 917          *
 918          * Will also consider fallbacks of that language, the site language, and fallbacks for
 919          * the site language.
 920          *
 921          * @see MessageCache::get
 922          * @param Language|StubObject $lang Preferred language
 923          * @param string $lckey Lowercase key for the message (as for localisation cache)
 924          * @param bool $useDB Whether to include messages from the wiki database
 925          * @return string|bool The message, or false if not found
 926          */
 927         protected function getMessageFromFallbackChain( $lang, $lckey, $useDB ) {
 928                 $alreadyTried = [];
 929
 930                 // First try the requested language.
 931                 $message = $this->getMessageForLang( $lang, $lckey, $useDB, $alreadyTried );
 932                 if ( $message !== false ) {
 933                         return $message;
 934                 }
 935
 936                 // Now try checking the site language.
 937                 $message = $this->getMessageForLang( $this->contLang, $lckey, $useDB, $alreadyTried );
 938                 return $message;
 939         }
 940
 941         /**
 942          * Given a language, try and fetch messages from that language and its fallbacks.
 943          *
 944          * @see MessageCache::get
 945          * @param Language|StubObject $lang Preferred language
 946          * @param string $lckey Lowercase key for the message (as for localisation cache)
 947          * @param bool $useDB Whether to include messages from the wiki database
 948          * @param bool[] $alreadyTried Contains true for each language that has been tried already
 949          * @return string|bool The message, or false if not found
 950          */
 951         private function getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried ) {
 952                 $langcode = $lang->getCode();
 953
 954                 // Try checking the database for the requested language
 955                 if ( $useDB ) {
 956                         $uckey = $this->contLang->ucfirst( $lckey );
 957
 958                         if ( !isset( $alreadyTried[$langcode] ) ) {
 959                                 $message = $this->getMsgFromNamespace(
 960                                         $this->getMessagePageName( $langcode, $uckey ),
 961                                         $langcode
 962                                 );
 963                                 if ( $message !== false ) {
 964                                         return $message;
 965                                 }
 966                                 $alreadyTried[$langcode] = true;
 967                         }
 968                 } else {
 969                         $uckey = null;
 970                 }
 971
 972                 // Check the CDB cache
 973                 $message = $lang->getMessage( $lckey );
 974                 if ( $message !== null ) {
 975                         return $message;
 976                 }
 977
 978                 // Try checking the database for all of the fallback languages
 979                 if ( $useDB ) {
 980                         $fallbackChain = Language::getFallbacksFor( $langcode );
 981
 982                         foreach ( $fallbackChain as $code ) {
 983                                 if ( isset( $alreadyTried[$code] ) ) {
 984                                         continue;
 985                                 }
 986
 987                                 $message = $this->getMsgFromNamespace(
 988                                         $this->getMessagePageName( $code, $uckey ), $code );
 989
 990                                 if ( $message !== false ) {
 991                                         return $message;
 992                                 }
 993                                 $alreadyTried[$code] = true;
 994                         }
 995                 }
 996
 997                 return false;
 998         }
 999
1000         /**
1001          * Get the message page name for a given language
1002          *
1003          * @param string $langcode
1004          * @param string $uckey Uppercase key for the message
1005          * @return string The page name
1006          */
1007         private function getMessagePageName( $langcode, $uckey ) {
1008                 global $wgLanguageCode;
1009
1010                 if ( $langcode === $wgLanguageCode ) {
1011                         // Messages created in the content language will not have the /lang extension
1012                         return $uckey;
1013                 } else {
1014                         return "$uckey/$langcode";
1015                 }
1016         }
1017
1018         /**
1019          * Get a message from the MediaWiki namespace, with caching. The key must
1020          * first be converted to two-part lang/msg form if necessary.
1021          *
1022          * Unlike self::get(), this function doesn't resolve fallback chains, and
1023          * some callers require this behavior. LanguageConverter::parseCachedTable()
1024          * and self::get() are some examples in core.
1025          *
1026          * @param string $title Message cache key with initial uppercase letter
1027          * @param string $code Code denoting the language to try
1028          * @return string|bool The message, or false if it does not exist or on error
1029          */
1030         public function getMsgFromNamespace( $title, $code ) {
1031                 // Load all MediaWiki page definitions into cache. Note that individual keys
1032                 // already loaded into cache during this request remain in the cache, which
1033                 // includes the value of hook-defined messages.
1034                 $this->load( $code );
1035
1036                 $entry = $this->cache->getField( $code, $title );
1037
1038                 if ( $entry !== null ) {
1039                         // Message page exists as an override of a software messages
1040                         if ( substr( $entry, 0, 1 ) === ' ' ) {
1041                                 // The message exists and is not '!TOO BIG' or '!ERROR'
1042                                 return (string)substr( $entry, 1 );
1043                         } elseif ( $entry === '!NONEXISTENT' ) {
1044                                 // The text might be '-' or missing due to some data loss
1045                                 return false;
1046                         }
1047                         // Load the message page, utilizing the individual message cache.
1048                         // If the page does not exist, there will be no hook handler fallbacks.
1049                         $entry = $this->loadCachedMessagePageEntry(
1050                                 $title,
1051                                 $code,
1052                                 $this->cache->getField( $code, 'HASH' )
1053                         );
1054                 } else {
1055                         // Message page either does not exist or does not override a software message
1056                         if ( !$this->isMainCacheable( $title, $this->overridable ) ) {
1057                                 // Message page does not override any software-defined message. A custom
1058                                 // message might be defined to have content or settings specific to the wiki.
1059                                 // Load the message page, utilizing the individual message cache as needed.
1060                                 $entry = $this->loadCachedMessagePageEntry(
1061                                         $title,
1062                                         $code,
1063                                         $this->cache->getField( $code, 'HASH' )
1064                                 );
1065                         }
1066                         if ( $entry === null || substr( $entry, 0, 1 ) !== ' ' ) {
1067                                 // Message does not have a MediaWiki page definition; try hook handlers
1068                                 $message = false;
1069                                 Hooks::run( 'MessagesPreLoad', [ $title, &$message, $code ] );
1070                                 if ( $message !== false ) {
1071                                         $this->cache->setField( $code, $title, ' ' . $message );
1072                                 } else {
1073                                         $this->cache->setField( $code, $title, '!NONEXISTENT' );
1074                                 }
1075
1076                                 return $message;
1077                         }
1078                 }
1079
1080                 if ( $entry !== false && substr( $entry, 0, 1 ) === ' ' ) {
1081                         if ( $this->cacheVolatile[$code] ) {
1082                                 // Make sure that individual keys respect the WAN cache holdoff period too
1083                                 LoggerFactory::getInstance( 'MessageCache' )->debug(
1084                                         __METHOD__ . ': loading volatile key \'{titleKey}\'',
1085                                         [ 'titleKey' => $title, 'code' => $code ] );
1086                         } else {
1087                                 $this->cache->setField( $code, $title, $entry );
1088                         }
1089                         // The message exists, so make sure a string is returned
1090                         return (string)substr( $entry, 1 );
1091                 }
1092
1093                 $this->cache->setField( $code, $title, '!NONEXISTENT' );
1094
1095                 return false;
1096         }
1097
1098         /**
1099          * @param string $dbKey
1100          * @param string $code
1101          * @param string $hash
1102          * @return string Either " <MESSAGE>" or "!NONEXISTANT"
1103          */
1104         private function loadCachedMessagePageEntry( $dbKey, $code, $hash ) {
1105                 $fname = __METHOD__;
1106                 return $this->srvCache->getWithSetCallback(
1107                         $this->srvCache->makeKey( 'messages-big', $hash, $dbKey ),
1108                         IExpiringStore::TTL_MINUTE,
1109                         function () use ( $code, $dbKey, $hash, $fname ) {
1110                                 return $this->wanCache->getWithSetCallback(
1111                                         $this->bigMessageCacheKey( $hash, $dbKey ),
1112                                         $this->mExpiry,
1113                                         function ( $oldValue, &$ttl, &$setOpts ) use ( $dbKey, $code, $fname ) {
1114                                                 // Try loading the message from the database
1115                                                 $dbr = wfGetDB( DB_REPLICA );
1116                                                 $setOpts += Database::getCacheSetOptions( $dbr );
1117                                                 // Use newKnownCurrent() to avoid querying revision/user tables
1118                                                 $title = Title::makeTitle( NS_MEDIAWIKI, $dbKey );
1119                                                 $revision = Revision::newKnownCurrent( $dbr, $title );
1120                                                 if ( !$revision ) {
1121                                                         // The wiki doesn't have a local override page. Cache absence with normal TTL.
1122                                                         // When overrides are created, self::replace() takes care of the cache.
1123                                                         return '!NONEXISTENT';
1124                                                 }
1125                                                 $content = $revision->getContent();
1126                                                 if ( $content ) {
1127                                                         $message = $this->getMessageTextFromContent( $content );
1128                                                 } else {
1129                                                         LoggerFactory::getInstance( 'MessageCache' )->warning(
1130                                                                 $fname . ': failed to load page text for \'{titleKey}\'',
1131                                                                 [ 'titleKey' => $dbKey, 'code' => $code ]
1132                                                         );
1133                                                         $message = null;
1134                                                 }
1135
1136                                                 if ( !is_string( $message ) ) {
1137                                                         // Revision failed to load Content, or Content is incompatible with wikitext.
1138                                                         // Possibly a temporary loading failure.
1139                                                         $ttl = 5;
1140
1141                                                         return '!NONEXISTENT';
1142                                                 }
1143
1144                                                 return ' ' . $message;
1145                                         }
1146                                 );
1147                         }
1148                 );
1149         }
1150
1151         /**
1152          * @param string $message
1153          * @param bool $interface
1154          * @param Language|null $language
1155          * @param Title|null $title
1156          * @return string
1157          */
1158         public function transform( $message, $interface = false, $language = null, $title = null ) {
1159                 // Avoid creating parser if nothing to transform
1160                 if ( strpos( $message, '{{' ) === false ) {
1161                         return $message;
1162                 }
1163
1164                 if ( $this->mInParser ) {
1165                         return $message;
1166                 }
1167
1168                 $parser = $this->getParser();
1169                 if ( $parser ) {
1170                         $popts = $this->getParserOptions();
1171                         $popts->setInterfaceMessage( $interface );
1172                         $popts->setTargetLanguage( $language );
1173
1174                         $userlang = $popts->setUserLang( $language );
1175                         $this->mInParser = true;
1176                         $message = $parser->transformMsg( $message, $popts, $title );
1177                         $this->mInParser = false;
1178                         $popts->setUserLang( $userlang );
1179                 }
1180
1181                 return $message;
1182         }
1183
1184         /**
1185          * @return Parser
1186          */
1187         public function getParser() {
1188                 global $wgParserConf;
1189                 if ( !$this->mParser ) {
1190                         $parser = MediaWikiServices::getInstance()->getParser();
1191                         # Do some initialisation so that we don't have to do it twice
1192                         $parser->firstCallInit();
1193                         # Clone it and store it
1194                         $class = $wgParserConf['class'];
1195                         if ( $class == ParserDiffTest::class ) {
1196                                 # Uncloneable
1197                                 $this->mParser = new $class( $wgParserConf );
1198                         } else {
1199                                 $this->mParser = clone $parser;
1200                         }
1201                 }
1202
1203                 return $this->mParser;
1204         }
1205
1206         /**
1207          * @param string $text
1208          * @param Title|null $title
1209          * @param bool $linestart Whether or not this is at the start of a line
1210          * @param bool $interface Whether this is an interface message
1211          * @param Language|string|null $language Language code
1212          * @return ParserOutput|string
1213          */
1214         public function parse( $text, $title = null, $linestart = true,
1215                 $interface = false, $language = null
1216         ) {
1217                 global $wgTitle;
1218
1219                 if ( $this->mInParser ) {
1220                         return htmlspecialchars( $text );
1221                 }
1222
1223                 $parser = $this->getParser();
1224                 $popts = $this->getParserOptions();
1225                 $popts->setInterfaceMessage( $interface );
1226
1227                 if ( is_string( $language ) ) {
1228                         $language = Language::factory( $language );
1229                 }
1230                 $popts->setTargetLanguage( $language );
1231
1232                 if ( !$title || !$title instanceof Title ) {
1233                         wfDebugLog( 'GlobalTitleFail', __METHOD__ . ' called by ' .
1234                                 wfGetAllCallers( 6 ) . ' with no title set.' );
1235                         $title = $wgTitle;
1236                 }
1237                 // Sometimes $wgTitle isn't set either...
1238                 if ( !$title ) {
1239                         # It's not uncommon having a null $wgTitle in scripts. See r80898
1240                         # Create a ghost title in such case
1241                         $title = Title::makeTitle( NS_SPECIAL, 'Badtitle/title not set in ' . __METHOD__ );
1242                 }
1243
1244                 $this->mInParser = true;
1245                 $res = $parser->parse( $text, $title, $popts, $linestart );
1246                 $this->mInParser = false;
1247
1248                 return $res;
1249         }
1250
1251         public function disable() {
1252                 $this->mDisable = true;
1253         }
1254
1255         public function enable() {
1256                 $this->mDisable = false;
1257         }
1258
1259         /**
1260          * Whether DB/cache usage is disabled for determining messages
1261          *
1262          * If so, this typically indicates either:
1263          *   - a) load() failed to find a cached copy nor query the DB
1264          *   - b) we are in a special context or error mode that cannot use the DB
1265          * If the DB is ignored, any derived HTML output or cached objects may be wrong.
1266          * To avoid long-term cache pollution, TTLs can be adjusted accordingly.
1267          *
1268          * @return bool
1269          * @since 1.27
1270          */
1271         public function isDisabled() {
1272                 return $this->mDisable;
1273         }
1274
1275         /**
1276          * Clear all stored messages in global and local cache
1277          *
1278          * Mainly used after a mass rebuild
1279          */
1280         public function clear() {
1281                 $langs = Language::fetchLanguageNames( null, 'mw' );
1282                 foreach ( array_keys( $langs ) as $code ) {
1283                         $this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
1284                 }
1285                 $this->cache->clear();
1286                 $this->loadedLanguages = [];
1287         }
1288
1289         /**
1290          * @param string $key
1291          * @return array
1292          */
1293         public function figureMessage( $key ) {
1294                 global $wgLanguageCode;
1295
1296                 $pieces = explode( '/', $key );
1297                 if ( count( $pieces ) < 2 ) {
1298                         return [ $key, $wgLanguageCode ];
1299                 }
1300
1301                 $lang = array_pop( $pieces );
1302                 if ( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
1303                         return [ $key, $wgLanguageCode ];
1304                 }
1305
1306                 $message = implode( '/', $pieces );
1307
1308                 return [ $message, $lang ];
1309         }
1310
1311         /**
1312          * Get all message keys stored in the message cache for a given language.
1313          * If $code is the content language code, this will return all message keys
1314          * for which MediaWiki:msgkey exists. If $code is another language code, this
1315          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
1316          * @param string $code Language code
1317          * @return array Array of message keys (strings)
1318          */
1319         public function getAllMessageKeys( $code ) {
1320                 $this->load( $code );
1321                 if ( !$this->cache->has( $code ) ) {
1322                         // Apparently load() failed
1323                         return null;
1324                 }
1325                 // Remove administrative keys
1326                 $cache = $this->cache->get( $code );
1327                 unset( $cache['VERSION'] );
1328                 unset( $cache['EXPIRY'] );
1329                 unset( $cache['EXCESSIVE'] );
1330                 // Remove any !NONEXISTENT keys
1331                 $cache = array_diff( $cache, [ '!NONEXISTENT' ] );
1332
1333                 // Keys may appear with a capital first letter. lcfirst them.
1334                 return array_map( [ $this->contLang, 'lcfirst' ], array_keys( $cache ) );
1335         }
1336
1337         /**
1338          * Purge message caches when a MediaWiki: page is created, updated, or deleted
1339          *
1340          * @param Title $title Message page title
1341          * @param Content|null $content New content for edit/create, null on deletion
1342          * @since 1.29
1343          */
1344         public function updateMessageOverride( Title $title, Content $content = null ) {
1345                 $msgText = $this->getMessageTextFromContent( $content );
1346                 if ( $msgText === null ) {
1347                         $msgText = false; // treat as not existing
1348                 }
1349
1350                 $this->replace( $title->getDBkey(), $msgText );
1351
1352                 if ( $this->contLang->hasVariants() ) {
1353                         $this->contLang->updateConversionTable( $title );
1354                 }
1355         }
1356
1357         /**
1358          * @param string $code Language code
1359          * @return string WAN cache key usable as a "check key" against language page edits
1360          */
1361         public function getCheckKey( $code ) {
1362                 return $this->wanCache->makeKey( 'messages', $code );
1363         }
1364
1365         /**
1366          * @param Content|null $content Content or null if the message page does not exist
1367          * @return string|bool|null Returns false if $content is null and null on error
1368          */
1369         private function getMessageTextFromContent( Content $content = null ) {
1370                 // @TODO: could skip pseudo-messages like js/css here, based on content model
1371                 if ( $content ) {
1372                         // Message page exists...
1373                         // XXX: Is this the right way to turn a Content object into a message?
1374                         // NOTE: $content is typically either WikitextContent, JavaScriptContent or
1375                         //       CssContent. MessageContent is *not* used for storing messages, it's
1376                         //       only used for wrapping them when needed.
1377                         $msgText = $content->getWikitextForTransclusion();
1378                         if ( $msgText === false || $msgText === null ) {
1379                                 // This might be due to some kind of misconfiguration...
1380                                 $msgText = null;
1381                                 LoggerFactory::getInstance( 'MessageCache' )->warning(
1382                                         __METHOD__ . ": message content doesn't provide wikitext "
1383                                         . "(content model: " . $content->getModel() . ")" );
1384                         }
1385                 } else {
1386                         // Message page does not exist...
1387                         $msgText = false;
1388                 }
1389
1390                 return $msgText;
1391         }
1392
1393         /**
1394          * @param string $hash Hash for this version of the entire key/value overrides map
1395          * @param string $title Message cache key with initial uppercase letter
1396          * @return string
1397          */
1398         private function bigMessageCacheKey( $hash, $title ) {
1399                 return $this->wanCache->makeKey( 'messages-big', $hash, $title );
1400         }
1401 }