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
  27 /**
  28  * MediaWiki message cache structure version.
  29  * Bump this whenever the message cache format has changed.
  30  */
  31 define( 'MSG_CACHE_VERSION', 2 );
  32
  33 /**
  34  * Message cache
  35  * Performs various MediaWiki namespace-related functions
  36  * @ingroup Cache
  37  */
  38 class MessageCache {
  39         const FOR_UPDATE = 1; // force message reload
  40
  41         /** How long to wait for memcached locks */
  42         const WAIT_SEC = 15;
  43         /** How long memcached locks last */
  44         const LOCK_TTL = 30;
  45
  46         /**
  47          * Process local cache of loaded messages that are defined in
  48          * MediaWiki namespace. First array level is a language code,
  49          * second level is message key and the values are either message
  50          * content prefixed with space, or !NONEXISTENT for negative
  51          * caching.
  52          * @var array $mCache
  53          */
  54         protected $mCache;
  55
  56         /**
  57          * @var bool[] Map of (language code => boolean)
  58          */
  59         protected $mCacheVolatile = [];
  60
  61         /**
  62          * Should mean that database cannot be used, but check
  63          * @var bool $mDisable
  64          */
  65         protected $mDisable;
  66
  67         /**
  68          * Lifetime for cache, used by object caching.
  69          * Set on construction, see __construct().
  70          */
  71         protected $mExpiry;
  72
  73         /**
  74          * Message cache has its own parser which it uses to transform messages
  75          * @var ParserOptions
  76          */
  77         protected $mParserOptions;
  78         /** @var Parser */
  79         protected $mParser;
  80
  81         /**
  82          * Variable for tracking which variables are already loaded
  83          * @var array $mLoadedLanguages
  84          */
  85         protected $mLoadedLanguages = [];
  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
  99         /**
 100          * Singleton instance
 101          *
 102          * @var MessageCache $instance
 103          */
 104         private static $instance;
 105
 106         /**
 107          * Get the signleton instance of this class
 108          *
 109          * @since 1.18
 110          * @return MessageCache
 111          */
 112         public static function singleton() {
 113                 if ( self::$instance === null ) {
 114                         global $wgUseDatabaseMessages, $wgMsgCacheExpiry, $wgUseLocalMessageCache;
 115                         self::$instance = new self(
 116                                 MediaWikiServices::getInstance()->getMainWANObjectCache(),
 117                                 wfGetMessageCacheStorage(),
 118                                 $wgUseLocalMessageCache
 119                                         ? MediaWikiServices::getInstance()->getLocalServerObjectCache()
 120                                         : new EmptyBagOStuff(),
 121                                 $wgUseDatabaseMessages,
 122                                 $wgMsgCacheExpiry
 123                         );
 124                 }
 125
 126                 return self::$instance;
 127         }
 128
 129         /**
 130          * Destroy the singleton instance
 131          *
 132          * @since 1.18
 133          */
 134         public static function destroyInstance() {
 135                 self::$instance = null;
 136         }
 137
 138         /**
 139          * Normalize message key input
 140          *
 141          * @param string $key Input message key to be normalized
 142          * @return string Normalized message key
 143          */
 144         public static function normalizeKey( $key ) {
 145                 global $wgContLang;
 146
 147                 $lckey = strtr( $key, ' ', '_' );
 148                 if ( ord( $lckey ) < 128 ) {
 149                         $lckey[0] = strtolower( $lckey[0] );
 150                 } else {
 151                         $lckey = $wgContLang->lcfirst( $lckey );
 152                 }
 153
 154                 return $lckey;
 155         }
 156
 157         /**
 158          * @param WANObjectCache $wanCache WAN cache instance
 159          * @param BagOStuff $clusterCache Cluster cache instance
 160          * @param BagOStuff $srvCache Server cache instance
 161          * @param bool $useDB Whether to look for message overrides (e.g. MediaWiki: pages)
 162          * @param int $expiry Lifetime for cache. @see $mExpiry.
 163          */
 164         public function __construct(
 165                 WANObjectCache $wanCache,
 166                 BagOStuff $clusterCache,
 167                 BagOStuff $srvCache,
 168                 $useDB,
 169                 $expiry
 170         ) {
 171                 $this->wanCache = $wanCache;
 172                 $this->clusterCache = $clusterCache;
 173                 $this->srvCache = $srvCache;
 174
 175                 $this->mDisable = !$useDB;
 176                 $this->mExpiry = $expiry;
 177         }
 178
 179         /**
 180          * ParserOptions is lazy initialised.
 181          *
 182          * @return ParserOptions
 183          */
 184         function getParserOptions() {
 185                 global $wgUser;
 186
 187                 if ( !$this->mParserOptions ) {
 188                         if ( !$wgUser->isSafeToLoad() ) {
 189                                 // $wgUser isn't unstubbable yet, so don't try to get a
 190                                 // ParserOptions for it. And don't cache this ParserOptions
 191                                 // either.
 192                                 $po = ParserOptions::newFromAnon();
 193                                 $po->setEditSection( false );
 194                                 return $po;
 195                         }
 196
 197                         $this->mParserOptions = new ParserOptions;
 198                         $this->mParserOptions->setEditSection( false );
 199                 }
 200
 201                 return $this->mParserOptions;
 202         }
 203
 204         /**
 205          * Try to load the cache from APC.
 206          *
 207          * @param string $code Optional language code, see documenation of load().
 208          * @return array|bool The cache array, or false if not in cache.
 209          */
 210         protected function getLocalCache( $code ) {
 211                 $cacheKey = wfMemcKey( __CLASS__, $code );
 212
 213                 return $this->srvCache->get( $cacheKey );
 214         }
 215
 216         /**
 217          * Save the cache to APC.
 218          *
 219          * @param string $code
 220          * @param array $cache The cache array
 221          */
 222         protected function saveToLocalCache( $code, $cache ) {
 223                 $cacheKey = wfMemcKey( __CLASS__, $code );
 224                 $this->srvCache->set( $cacheKey, $cache );
 225         }
 226
 227         /**
 228          * Loads messages from caches or from database in this order:
 229          * (1) local message cache (if $wgUseLocalMessageCache is enabled)
 230          * (2) memcached
 231          * (3) from the database.
 232          *
 233          * When succesfully loading from (2) or (3), all higher level caches are
 234          * updated for the newest version.
 235          *
 236          * Nothing is loaded if member variable mDisable is true, either manually
 237          * set by calling code or if message loading fails (is this possible?).
 238          *
 239          * Returns true if cache is already populated or it was succesfully populated,
 240          * or false if populating empty cache fails. Also returns true if MessageCache
 241          * is disabled.
 242          *
 243          * @param string $code Language to which load messages
 244          * @param integer $mode Use MessageCache::FOR_UPDATE to skip process cache [optional]
 245          * @throws MWException
 246          * @return bool
 247          */
 248         protected function load( $code, $mode = null ) {
 249                 if ( !is_string( $code ) ) {
 250                         throw new InvalidArgumentException( "Missing language code" );
 251                 }
 252
 253                 # Don't do double loading...
 254                 if ( isset( $this->mLoadedLanguages[$code] ) && $mode != self::FOR_UPDATE ) {
 255                         return true;
 256                 }
 257
 258                 # 8 lines of code just to say (once) that message cache is disabled
 259                 if ( $this->mDisable ) {
 260                         static $shownDisabled = false;
 261                         if ( !$shownDisabled ) {
 262                                 wfDebug( __METHOD__ . ": disabled\n" );
 263                                 $shownDisabled = true;
 264                         }
 265
 266                         return true;
 267                 }
 268
 269                 # Loading code starts
 270                 $success = false; # Keep track of success
 271                 $staleCache = false; # a cache array with expired data, or false if none has been loaded
 272                 $where = []; # Debug info, delayed to avoid spamming debug log too much
 273
 274                 # Hash of the contents is stored in memcache, to detect if data-center cache
 275                 # or local cache goes out of date (e.g. due to replace() on some other server)
 276                 list( $hash, $hashVolatile ) = $this->getValidationHash( $code );
 277                 $this->mCacheVolatile[$code] = $hashVolatile;
 278
 279                 # Try the local cache and check against the cluster hash key...
 280                 $cache = $this->getLocalCache( $code );
 281                 if ( !$cache ) {
 282                         $where[] = 'local cache is empty';
 283                 } elseif ( !isset( $cache['HASH'] ) || $cache['HASH'] !== $hash ) {
 284                         $where[] = 'local cache has the wrong hash';
 285                         $staleCache = $cache;
 286                 } elseif ( $this->isCacheExpired( $cache ) ) {
 287                         $where[] = 'local cache is expired';
 288                         $staleCache = $cache;
 289                 } elseif ( $hashVolatile ) {
 290                         $where[] = 'local cache validation key is expired/volatile';
 291                         $staleCache = $cache;
 292                 } else {
 293                         $where[] = 'got from local cache';
 294                         $success = true;
 295                         $this->mCache[$code] = $cache;
 296                 }
 297
 298                 if ( !$success ) {
 299                         $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages
 300                         # Try the global cache. If it is empty, try to acquire a lock. If
 301                         # the lock can't be acquired, wait for the other thread to finish
 302                         # and then try the global cache a second time.
 303                         for ( $failedAttempts = 0; $failedAttempts <= 1; $failedAttempts++ ) {
 304                                 if ( $hashVolatile && $staleCache ) {
 305                                         # Do not bother fetching the whole cache blob to avoid I/O.
 306                                         # Instead, just try to get the non-blocking $statusKey lock
 307                                         # below, and use the local stale value if it was not acquired.
 308                                         $where[] = 'global cache is presumed expired';
 309                                 } else {
 310                                         $cache = $this->clusterCache->get( $cacheKey );
 311                                         if ( !$cache ) {
 312                                                 $where[] = 'global cache is empty';
 313                                         } elseif ( $this->isCacheExpired( $cache ) ) {
 314                                                 $where[] = 'global cache is expired';
 315                                                 $staleCache = $cache;
 316                                         } elseif ( $hashVolatile ) {
 317                                                 # DB results are replica DB lag prone until the holdoff TTL passes.
 318                                                 # By then, updates should be reflected in loadFromDBWithLock().
 319                                                 # One thread renerates the cache while others use old values.
 320                                                 $where[] = 'global cache is expired/volatile';
 321                                                 $staleCache = $cache;
 322                                         } else {
 323                                                 $where[] = 'got from global cache';
 324                                                 $this->mCache[$code] = $cache;
 325                                                 $this->saveToCaches( $cache, 'local-only', $code );
 326                                                 $success = true;
 327                                         }
 328                                 }
 329
 330                                 if ( $success ) {
 331                                         # Done, no need to retry
 332                                         break;
 333                                 }
 334
 335                                 # We need to call loadFromDB. Limit the concurrency to one process.
 336                                 # This prevents the site from going down when the cache expires.
 337                                 # Note that the DB slam protection lock here is non-blocking.
 338                                 $loadStatus = $this->loadFromDBWithLock( $code, $where, $mode );
 339                                 if ( $loadStatus === true ) {
 340                                         $success = true;
 341                                         break;
 342                                 } elseif ( $staleCache ) {
 343                                         # Use the stale cache while some other thread constructs the new one
 344                                         $where[] = 'using stale cache';
 345                                         $this->mCache[$code] = $staleCache;
 346                                         $success = true;
 347                                         break;
 348                                 } elseif ( $failedAttempts > 0 ) {
 349                                         # Already blocked once, so avoid another lock/unlock cycle.
 350                                         # This case will typically be hit if memcached is down, or if
 351                                         # loadFromDB() takes longer than LOCK_WAIT.
 352                                         $where[] = "could not acquire status key.";
 353                                         break;
 354                                 } elseif ( $loadStatus === 'cantacquire' ) {
 355                                         # Wait for the other thread to finish, then retry. Normally,
 356                                         # the memcached get() will then yeild the other thread's result.
 357                                         $where[] = 'waited for other thread to complete';
 358                                         $this->getReentrantScopedLock( $cacheKey );
 359                                 } else {
 360                                         # Disable cache; $loadStatus is 'disabled'
 361                                         break;
 362                                 }
 363                         }
 364                 }
 365
 366                 if ( !$success ) {
 367                         $where[] = 'loading FAILED - cache is disabled';
 368                         $this->mDisable = true;
 369                         $this->mCache = false;
 370                         wfDebugLog( 'MessageCacheError', __METHOD__ . ": Failed to load $code\n" );
 371                         # This used to throw an exception, but that led to nasty side effects like
 372                         # the whole wiki being instantly down if the memcached server died
 373                 } else {
 374                         # All good, just record the success
 375                         $this->mLoadedLanguages[$code] = true;
 376                 }
 377
 378                 $info = implode( ', ', $where );
 379                 wfDebugLog( 'MessageCache', __METHOD__ . ": Loading $code... $info\n" );
 380
 381                 return $success;
 382         }
 383
 384         /**
 385          * @param string $code
 386          * @param array $where List of wfDebug() comments
 387          * @param integer $mode Use MessageCache::FOR_UPDATE to use DB_MASTER
 388          * @return bool|string True on success or one of ("cantacquire", "disabled")
 389          */
 390         protected function loadFromDBWithLock( $code, array &$where, $mode = null ) {
 391                 # If cache updates on all levels fail, give up on message overrides.
 392                 # This is to avoid easy site outages; see $saveSuccess comments below.
 393                 $statusKey = wfMemcKey( 'messages', $code, 'status' );
 394                 $status = $this->clusterCache->get( $statusKey );
 395                 if ( $status === 'error' ) {
 396                         $where[] = "could not load; method is still globally disabled";
 397                         return 'disabled';
 398                 }
 399
 400                 # Now let's regenerate
 401                 $where[] = 'loading from database';
 402
 403                 # Lock the cache to prevent conflicting writes.
 404                 # This lock is non-blocking so stale cache can quickly be used.
 405                 # Note that load() will call a blocking getReentrantScopedLock()
 406                 # after this if it really need to wait for any current thread.
 407                 $cacheKey = wfMemcKey( 'messages', $code );
 408                 $scopedLock = $this->getReentrantScopedLock( $cacheKey, 0 );
 409                 if ( !$scopedLock ) {
 410                         $where[] = 'could not acquire main lock';
 411                         return 'cantacquire';
 412                 }
 413
 414                 $cache = $this->loadFromDB( $code, $mode );
 415                 $this->mCache[$code] = $cache;
 416                 $saveSuccess = $this->saveToCaches( $cache, 'all', $code );
 417
 418                 if ( !$saveSuccess ) {
 419                         /**
 420                          * Cache save has failed.
 421                          *
 422                          * There are two main scenarios where this could be a problem:
 423                          * - The cache is more than the maximum size (typically 1MB compressed).
 424                          * - Memcached has no space remaining in the relevant slab class. This is
 425                          *   unlikely with recent versions of memcached.
 426                          *
 427                          * Either way, if there is a local cache, nothing bad will happen. If there
 428                          * is no local cache, disabling the message cache for all requests avoids
 429                          * incurring a loadFromDB() overhead on every request, and thus saves the
 430                          * wiki from complete downtime under moderate traffic conditions.
 431                          */
 432                         if ( $this->srvCache instanceof EmptyBagOStuff ) {
 433                                 $this->clusterCache->set( $statusKey, 'error', 60 * 5 );
 434                                 $where[] = 'could not save cache, disabled globally for 5 minutes';
 435                         } else {
 436                                 $where[] = "could not save global cache";
 437                         }
 438                 }
 439
 440                 return true;
 441         }
 442
 443         /**
 444          * Loads cacheable messages from the database. Messages bigger than
 445          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 446          * on-demand from the database later.
 447          *
 448          * @param string $code Language code
 449          * @param integer $mode Use MessageCache::FOR_UPDATE to skip process cache
 450          * @return array Loaded messages for storing in caches
 451          */
 452         function loadFromDB( $code, $mode = null ) {
 453                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 454
 455                 $dbr = wfGetDB( ( $mode == self::FOR_UPDATE ) ? DB_MASTER : DB_REPLICA );
 456
 457                 $cache = [];
 458
 459                 # Common conditions
 460                 $conds = [
 461                         'page_is_redirect' => 0,
 462                         'page_namespace' => NS_MEDIAWIKI,
 463                 ];
 464
 465                 $mostused = [];
 466                 if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
 467                         if ( !isset( $this->mCache[$wgLanguageCode] ) ) {
 468                                 $this->load( $wgLanguageCode );
 469                         }
 470                         $mostused = array_keys( $this->mCache[$wgLanguageCode] );
 471                         foreach ( $mostused as $key => $value ) {
 472                                 $mostused[$key] = "$value/$code";
 473                         }
 474                 }
 475
 476                 if ( count( $mostused ) ) {
 477                         $conds['page_title'] = $mostused;
 478                 } elseif ( $code !== $wgLanguageCode ) {
 479                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
 480                 } else {
 481                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 482                         # other than language code.
 483                         $conds[] = 'page_title NOT' . $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 484                 }
 485
 486                 # Conditions to fetch oversized pages to ignore them
 487                 $bigConds = $conds;
 488                 $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );
 489
 490                 # Load titles for all oversized pages in the MediaWiki namespace
 491                 $res = $dbr->select(
 492                         'page',
 493                         [ 'page_title', 'page_latest' ],
 494                         $bigConds,
 495                         __METHOD__ . "($code)-big"
 496                 );
 497                 foreach ( $res as $row ) {
 498                         $cache[$row->page_title] = '!TOO BIG';
 499                         // At least include revision ID so page changes are reflected in the hash
 500                         $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
 501                 }
 502
 503                 # Conditions to load the remaining pages with their contents
 504                 $smallConds = $conds;
 505                 $smallConds[] = 'page_latest=rev_id';
 506                 $smallConds[] = 'rev_text_id=old_id';
 507                 $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );
 508
 509                 $res = $dbr->select(
 510                         [ 'page', 'revision', 'text' ],
 511                         [ 'page_title', 'old_text', 'old_flags' ],
 512                         $smallConds,
 513                         __METHOD__ . "($code)-small"
 514                 );
 515
 516                 foreach ( $res as $row ) {
 517                         $text = Revision::getRevisionText( $row );
 518                         if ( $text === false ) {
 519                                 // Failed to fetch data; possible ES errors?
 520                                 // Store a marker to fetch on-demand as a workaround...
 521                                 // TODO Use a differnt marker
 522                                 $entry = '!TOO BIG';
 523                                 wfDebugLog(
 524                                         'MessageCache',
 525                                         __METHOD__
 526                                                 . ": failed to load message page text for {$row->page_title} ($code)"
 527                                 );
 528                         } else {
 529                                 $entry = ' ' . $text;
 530                         }
 531                         $cache[$row->page_title] = $entry;
 532                 }
 533
 534                 $cache['VERSION'] = MSG_CACHE_VERSION;
 535                 ksort( $cache );
 536
 537                 # Hash for validating local cache (APC). No need to take into account
 538                 # messages larger than $wgMaxMsgCacheEntrySize, since those are only
 539                 # stored and fetched from memcache.
 540                 $cache['HASH'] = md5( serialize( $cache ) );
 541                 $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );
 542
 543                 return $cache;
 544         }
 545
 546         /**
 547          * Updates cache as necessary when message page is changed
 548          *
 549          * @param string|bool $title Name of the page changed (false if deleted)
 550          * @param string|bool $text New contents of the page (false if deleted)
 551          */
 552         public function replace( $title, $text ) {
 553                 global $wgMaxMsgCacheEntrySize, $wgContLang, $wgLanguageCode;
 554
 555                 if ( $this->mDisable ) {
 556                         return;
 557                 }
 558
 559                 list( $msg, $code ) = $this->figureMessage( $title );
 560                 if ( strpos( $title, '/' ) !== false && $code === $wgLanguageCode ) {
 561                         // Content language overrides do not use the /<code> suffix
 562                         return;
 563                 }
 564
 565                 // Note that if the cache is volatile, load() may trigger a DB fetch.
 566                 // In that case we reenter/reuse the existing cache key lock to avoid
 567                 // a self-deadlock. This is safe as no reads happen *directly* in this
 568                 // method between getReentrantScopedLock() and load() below. There is
 569                 // no risk of data "changing under our feet" for replace().
 570                 $scopedLock = $this->getReentrantScopedLock( wfMemcKey( 'messages', $code ) );
 571                 // Load the messages from the master DB to avoid race conditions
 572                 $this->load( $code, self::FOR_UPDATE );
 573
 574                 // Load the new value into the process cache...
 575                 if ( $text === false ) {
 576                         $this->mCache[$code][$title] = '!NONEXISTENT';
 577                 } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 578                         $this->mCache[$code][$title] = '!TOO BIG';
 579                         // Pre-fill the individual key cache with the known latest message text
 580                         $key = $this->wanCache->makeKey( 'messages-big', $this->mCache[$code]['HASH'], $title );
 581                         $this->wanCache->set( $key, " $text", $this->mExpiry );
 582                 } else {
 583                         $this->mCache[$code][$title] = ' ' . $text;
 584                 }
 585                 // Mark this cache as definitely being "latest" (non-volatile) so
 586                 // load() calls do not try to refresh the cache with replica DB data
 587                 $this->mCache[$code]['LATEST'] = time();
 588
 589                 // Update caches if the lock was acquired
 590                 if ( $scopedLock ) {
 591                         $this->saveToCaches( $this->mCache[$code], 'all', $code );
 592                 } else {
 593                         LoggerFactory::getInstance( 'MessageCache' )->error(
 594                                 __METHOD__ . ': could not acquire lock to update {title} ({code})',
 595                                 [ 'title' => $title, 'code' => $code ] );
 596                 }
 597
 598                 ScopedCallback::consume( $scopedLock );
 599                 // Relay the purge. Touching this check key expires cache contents
 600                 // and local cache (APC) validation hash across all datacenters.
 601                 $this->wanCache->touchCheckKey( wfMemcKey( 'messages', $code ) );
 602
 603                 // Also delete cached sidebar... just in case it is affected
 604                 $codes = [ $code ];
 605                 if ( $code === 'en' ) {
 606                         // Delete all sidebars, like for example on action=purge on the
 607                         // sidebar messages
 608                         $codes = array_keys( Language::fetchLanguageNames() );
 609                 }
 610
 611                 foreach ( $codes as $code ) {
 612                         $sidebarKey = wfMemcKey( 'sidebar', $code );
 613                         $this->wanCache->delete( $sidebarKey );
 614                 }
 615
 616                 // Update the message in the message blob store
 617                 $resourceloader = RequestContext::getMain()->getOutput()->getResourceLoader();
 618                 $blobStore = $resourceloader->getMessageBlobStore();
 619                 $blobStore->updateMessage( $wgContLang->lcfirst( $msg ) );
 620
 621                 Hooks::run( 'MessageCacheReplace', [ $title, $text ] );
 622         }
 623
 624         /**
 625          * Is the given cache array expired due to time passing or a version change?
 626          *
 627          * @param array $cache
 628          * @return bool
 629          */
 630         protected function isCacheExpired( $cache ) {
 631                 if ( !isset( $cache['VERSION'] ) || !isset( $cache['EXPIRY'] ) ) {
 632                         return true;
 633                 }
 634                 if ( $cache['VERSION'] != MSG_CACHE_VERSION ) {
 635                         return true;
 636                 }
 637                 if ( wfTimestampNow() >= $cache['EXPIRY'] ) {
 638                         return true;
 639                 }
 640
 641                 return false;
 642         }
 643
 644         /**
 645          * Shortcut to update caches.
 646          *
 647          * @param array $cache Cached messages with a version.
 648          * @param string $dest Either "local-only" to save to local caches only
 649          *   or "all" to save to all caches.
 650          * @param string|bool $code Language code (default: false)
 651          * @return bool
 652          */
 653         protected function saveToCaches( array $cache, $dest, $code = false ) {
 654                 if ( $dest === 'all' ) {
 655                         $cacheKey = wfMemcKey( 'messages', $code );
 656                         $success = $this->clusterCache->set( $cacheKey, $cache );
 657                         $this->setValidationHash( $code, $cache );
 658                 } else {
 659                         $success = true;
 660                 }
 661
 662                 $this->saveToLocalCache( $code, $cache );
 663
 664                 return $success;
 665         }
 666
 667         /**
 668          * Get the md5 used to validate the local APC cache
 669          *
 670          * @param string $code
 671          * @return array (hash or false, bool expiry/volatility status)
 672          */
 673         protected function getValidationHash( $code ) {
 674                 $curTTL = null;
 675                 $value = $this->wanCache->get(
 676                         $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
 677                         $curTTL,
 678                         [ wfMemcKey( 'messages', $code ) ]
 679                 );
 680
 681                 if ( $value ) {
 682                         $hash = $value['hash'];
 683                         if ( ( time() - $value['latest'] ) < WANObjectCache::TTL_MINUTE ) {
 684                                 // Cache was recently updated via replace() and should be up-to-date.
 685                                 // That method is only called in the primary datacenter and uses FOR_UPDATE.
 686                                 // Also, it is unlikely that the current datacenter is *now* secondary one.
 687                                 $expired = false;
 688                         } else {
 689                                 // See if the "check" key was bumped after the hash was generated
 690                                 $expired = ( $curTTL < 0 );
 691                         }
 692                 } else {
 693                         // No hash found at all; cache must regenerate to be safe
 694                         $hash = false;
 695                         $expired = true;
 696                 }
 697
 698                 return [ $hash, $expired ];
 699         }
 700
 701         /**
 702          * Set the md5 used to validate the local disk cache
 703          *
 704          * If $cache has a 'LATEST' UNIX timestamp key, then the hash will not
 705          * be treated as "volatile" by getValidationHash() for the next few seconds.
 706          * This is triggered when $cache is generated using FOR_UPDATE mode.
 707          *
 708          * @param string $code
 709          * @param array $cache Cached messages with a version
 710          */
 711         protected function setValidationHash( $code, array $cache ) {
 712                 $this->wanCache->set(
 713                         $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
 714                         [
 715                                 'hash' => $cache['HASH'],
 716                                 'latest' => isset( $cache['LATEST'] ) ? $cache['LATEST'] : 0
 717                         ],
 718                         WANObjectCache::TTL_INDEFINITE
 719                 );
 720         }
 721
 722         /**
 723          * @param string $key A language message cache key that stores blobs
 724          * @param integer $timeout Wait timeout in seconds
 725          * @return null|ScopedCallback
 726          */
 727         protected function getReentrantScopedLock( $key, $timeout = self::WAIT_SEC ) {
 728                 return $this->clusterCache->getScopedLock( $key, $timeout, self::LOCK_TTL, __METHOD__ );
 729         }
 730
 731         /**
 732          * Get a message from either the content language or the user language.
 733          *
 734          * First, assemble a list of languages to attempt getting the message from. This
 735          * chain begins with the requested language and its fallbacks and then continues with
 736          * the content language and its fallbacks. For each language in the chain, the following
 737          * process will occur (in this order):
 738          *  1. If a language-specific override, i.e., [[MW:msg/lang]], is available, use that.
 739          *     Note: for the content language, there is no /lang subpage.
 740          *  2. Fetch from the static CDB cache.
 741          *  3. If available, check the database for fallback language overrides.
 742          *
 743          * This process provides a number of guarantees. When changing this code, make sure all
 744          * of these guarantees are preserved.
 745          *  * If the requested language is *not* the content language, then the CDB cache for that
 746          *    specific language will take precedence over the root database page ([[MW:msg]]).
 747          *  * Fallbacks will be just that: fallbacks. A fallback language will never be reached if
 748          *    the message is available *anywhere* in the language for which it is a fallback.
 749          *
 750          * @param string $key The message key
 751          * @param bool $useDB If true, look for the message in the DB, false
 752          *   to use only the compiled l10n cache.
 753          * @param bool|string|object $langcode Code of the language to get the message for.
 754          *   - If string and a valid code, will create a standard language object
 755          *   - If string but not a valid code, will create a basic language object
 756          *   - If boolean and false, create object from the current users language
 757          *   - If boolean and true, create object from the wikis content language
 758          *   - If language object, use it as given
 759          * @param bool $isFullKey Specifies whether $key is a two part key "msg/lang".
 760          *
 761          * @throws MWException When given an invalid key
 762          * @return string|bool False if the message doesn't exist, otherwise the
 763          *   message (which can be empty)
 764          */
 765         function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
 766                 if ( is_int( $key ) ) {
 767                         // Fix numerical strings that somehow become ints
 768                         // on their way here
 769                         $key = (string)$key;
 770                 } elseif ( !is_string( $key ) ) {
 771                         throw new MWException( 'Non-string key given' );
 772                 } elseif ( $key === '' ) {
 773                         // Shortcut: the empty key is always missing
 774                         return false;
 775                 }
 776
 777                 // For full keys, get the language code from the key
 778                 $pos = strrpos( $key, '/' );
 779                 if ( $isFullKey && $pos !== false ) {
 780                         $langcode = substr( $key, $pos + 1 );
 781                         $key = substr( $key, 0, $pos );
 782                 }
 783
 784                 // Normalise title-case input (with some inlining)
 785                 $lckey = MessageCache::normalizeKey( $key );
 786
 787                 Hooks::run( 'MessageCache::get', [ &$lckey ] );
 788
 789                 // Loop through each language in the fallback list until we find something useful
 790                 $lang = wfGetLangObj( $langcode );
 791                 $message = $this->getMessageFromFallbackChain(
 792                         $lang,
 793                         $lckey,
 794                         !$this->mDisable && $useDB
 795                 );
 796
 797                 // If we still have no message, maybe the key was in fact a full key so try that
 798                 if ( $message === false ) {
 799                         $parts = explode( '/', $lckey );
 800                         // We may get calls for things that are http-urls from sidebar
 801                         // Let's not load nonexistent languages for those
 802                         // They usually have more than one slash.
 803                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 804                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 805                                 if ( $message === null ) {
 806                                         $message = false;
 807                                 }
 808                         }
 809                 }
 810
 811                 // Post-processing if the message exists
 812                 if ( $message !== false ) {
 813                         // Fix whitespace
 814                         $message = str_replace(
 815                                 [
 816                                         # Fix for trailing whitespace, removed by textarea
 817                                         '&#32;',
 818                                         # Fix for NBSP, converted to space by firefox
 819                                         '&nbsp;',
 820                                         '&#160;',
 821                                         '&shy;'
 822                                 ],
 823                                 [
 824                                         ' ',
 825                                         "\xc2\xa0",
 826                                         "\xc2\xa0",
 827                                         "\xc2\xad"
 828                                 ],
 829                                 $message
 830                         );
 831                 }
 832
 833                 return $message;
 834         }
 835
 836         /**
 837          * Given a language, try and fetch messages from that language.
 838          *
 839          * Will also consider fallbacks of that language, the site language, and fallbacks for
 840          * the site language.
 841          *
 842          * @see MessageCache::get
 843          * @param Language|StubObject $lang Preferred language
 844          * @param string $lckey Lowercase key for the message (as for localisation cache)
 845          * @param bool $useDB Whether to include messages from the wiki database
 846          * @return string|bool The message, or false if not found
 847          */
 848         protected function getMessageFromFallbackChain( $lang, $lckey, $useDB ) {
 849                 global $wgContLang;
 850
 851                 $alreadyTried = [];
 852
 853                  // First try the requested language.
 854                 $message = $this->getMessageForLang( $lang, $lckey, $useDB, $alreadyTried );
 855                 if ( $message !== false ) {
 856                         return $message;
 857                 }
 858
 859                 // Now try checking the site language.
 860                 $message = $this->getMessageForLang( $wgContLang, $lckey, $useDB, $alreadyTried );
 861                 return $message;
 862         }
 863
 864         /**
 865          * Given a language, try and fetch messages from that language and its fallbacks.
 866          *
 867          * @see MessageCache::get
 868          * @param Language|StubObject $lang Preferred language
 869          * @param string $lckey Lowercase key for the message (as for localisation cache)
 870          * @param bool $useDB Whether to include messages from the wiki database
 871          * @param bool[] $alreadyTried Contains true for each language that has been tried already
 872          * @return string|bool The message, or false if not found
 873          */
 874         private function getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried ) {
 875                 global $wgContLang;
 876
 877                 $langcode = $lang->getCode();
 878
 879                 // Try checking the database for the requested language
 880                 if ( $useDB ) {
 881                         $uckey = $wgContLang->ucfirst( $lckey );
 882
 883                         if ( !isset( $alreadyTried[ $langcode ] ) ) {
 884                                 $message = $this->getMsgFromNamespace(
 885                                         $this->getMessagePageName( $langcode, $uckey ),
 886                                         $langcode
 887                                 );
 888
 889                                 if ( $message !== false ) {
 890                                         return $message;
 891                                 }
 892                                 $alreadyTried[ $langcode ] = true;
 893                         }
 894                 } else {
 895                         $uckey = null;
 896                 }
 897
 898                 // Check the CDB cache
 899                 $message = $lang->getMessage( $lckey );
 900                 if ( $message !== null ) {
 901                         return $message;
 902                 }
 903
 904                 // Try checking the database for all of the fallback languages
 905                 if ( $useDB ) {
 906                         $fallbackChain = Language::getFallbacksFor( $langcode );
 907
 908                         foreach ( $fallbackChain as $code ) {
 909                                 if ( isset( $alreadyTried[ $code ] ) ) {
 910                                         continue;
 911                                 }
 912
 913                                 $message = $this->getMsgFromNamespace(
 914                                         $this->getMessagePageName( $code, $uckey ), $code );
 915
 916                                 if ( $message !== false ) {
 917                                         return $message;
 918                                 }
 919                                 $alreadyTried[ $code ] = true;
 920                         }
 921                 }
 922
 923                 return false;
 924         }
 925
 926         /**
 927          * Get the message page name for a given language
 928          *
 929          * @param string $langcode
 930          * @param string $uckey Uppercase key for the message
 931          * @return string The page name
 932          */
 933         private function getMessagePageName( $langcode, $uckey ) {
 934                 global $wgLanguageCode;
 935
 936                 if ( $langcode === $wgLanguageCode ) {
 937                         // Messages created in the content language will not have the /lang extension
 938                         return $uckey;
 939                 } else {
 940                         return "$uckey/$langcode";
 941                 }
 942         }
 943
 944         /**
 945          * Get a message from the MediaWiki namespace, with caching. The key must
 946          * first be converted to two-part lang/msg form if necessary.
 947          *
 948          * Unlike self::get(), this function doesn't resolve fallback chains, and
 949          * some callers require this behavior. LanguageConverter::parseCachedTable()
 950          * and self::get() are some examples in core.
 951          *
 952          * @param string $title Message cache key with initial uppercase letter.
 953          * @param string $code Code denoting the language to try.
 954          * @return string|bool The message, or false if it does not exist or on error
 955          */
 956         public function getMsgFromNamespace( $title, $code ) {
 957                 $this->load( $code );
 958                 if ( isset( $this->mCache[$code][$title] ) ) {
 959                         $entry = $this->mCache[$code][$title];
 960                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 961                                 // The message exists, so make sure a string is returned.
 962                                 return (string)substr( $entry, 1 );
 963                         } elseif ( $entry === '!NONEXISTENT' ) {
 964                                 return false;
 965                         } elseif ( $entry === '!TOO BIG' ) {
 966                                 // Fall through and try invididual message cache below
 967                         }
 968                 } else {
 969                         // XXX: This is not cached in process cache, should it?
 970                         $message = false;
 971                         Hooks::run( 'MessagesPreLoad', [ $title, &$message, $code ] );
 972                         if ( $message !== false ) {
 973                                 return $message;
 974                         }
 975
 976                         return false;
 977                 }
 978
 979                 // Try the individual message cache
 980                 $titleKey = $this->wanCache->makeKey( 'messages-big', $this->mCache[$code]['HASH'], $title );
 981
 982                 if ( $this->mCacheVolatile[$code] ) {
 983                         $entry = false;
 984                         // Make sure that individual keys respect the WAN cache holdoff period too
 985                         LoggerFactory::getInstance( 'MessageCache' )->debug(
 986                                 __METHOD__ . ': loading volatile key \'{titleKey}\'',
 987                                 [ 'titleKey' => $titleKey, 'code' => $code ] );
 988                 } else {
 989                         $entry = $this->wanCache->get( $titleKey );
 990                 }
 991
 992                 if ( $entry !== false ) {
 993                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 994                                 $this->mCache[$code][$title] = $entry;
 995                                 // The message exists, so make sure a string is returned
 996                                 return (string)substr( $entry, 1 );
 997                         } elseif ( $entry === '!NONEXISTENT' ) {
 998                                 $this->mCache[$code][$title] = '!NONEXISTENT';
 999
1000                                 return false;
1001                         } else {
1002                                 // Corrupt/obsolete entry, delete it
1003                                 $this->wanCache->delete( $titleKey );
1004                         }
1005                 }
1006
1007                 // Try loading the message from the database
1008                 $dbr = wfGetDB( DB_REPLICA );
1009                 $cacheOpts = Database::getCacheSetOptions( $dbr );
1010                 // Use newKnownCurrent() to avoid querying revision/user tables
1011                 $titleObj = Title::makeTitle( NS_MEDIAWIKI, $title );
1012                 if ( $titleObj->getLatestRevID() ) {
1013                         $revision = Revision::newKnownCurrent(
1014                                 $dbr,
1015                                 $titleObj->getArticleID(),
1016                                 $titleObj->getLatestRevID()
1017                         );
1018                 } else {
1019                         $revision = false;
1020                 }
1021
1022                 if ( $revision ) {
1023                         $content = $revision->getContent();
1024                         if ( $content ) {
1025                                 $message = $this->getMessageTextFromContent( $content );
1026                                 if ( is_string( $message ) ) {
1027                                         $this->mCache[$code][$title] = ' ' . $message;
1028                                         $this->wanCache->set( $titleKey, ' ' . $message, $this->mExpiry, $cacheOpts );
1029                                 }
1030                         } else {
1031                                 // A possibly temporary loading failure
1032                                 LoggerFactory::getInstance( 'MessageCache' )->warning(
1033                                         __METHOD__ . ': failed to load message page text for \'{titleKey}\'',
1034                                         [ 'titleKey' => $titleKey, 'code' => $code ] );
1035                                 $message = null; // no negative caching
1036                         }
1037                 } else {
1038                         $message = false; // negative caching
1039                 }
1040
1041                 if ( $message === false ) { // negative caching
1042                         $this->mCache[$code][$title] = '!NONEXISTENT';
1043                         $this->wanCache->set( $titleKey, '!NONEXISTENT', $this->mExpiry, $cacheOpts );
1044                 }
1045
1046                 return $message;
1047         }
1048
1049         /**
1050          * @param string $message
1051          * @param bool $interface
1052          * @param string $language Language code
1053          * @param Title $title
1054          * @return string
1055          */
1056         function transform( $message, $interface = false, $language = null, $title = null ) {
1057                 // Avoid creating parser if nothing to transform
1058                 if ( strpos( $message, '{{' ) === false ) {
1059                         return $message;
1060                 }
1061
1062                 if ( $this->mInParser ) {
1063                         return $message;
1064                 }
1065
1066                 $parser = $this->getParser();
1067                 if ( $parser ) {
1068                         $popts = $this->getParserOptions();
1069                         $popts->setInterfaceMessage( $interface );
1070                         $popts->setTargetLanguage( $language );
1071
1072                         $userlang = $popts->setUserLang( $language );
1073                         $this->mInParser = true;
1074                         $message = $parser->transformMsg( $message, $popts, $title );
1075                         $this->mInParser = false;
1076                         $popts->setUserLang( $userlang );
1077                 }
1078
1079                 return $message;
1080         }
1081
1082         /**
1083          * @return Parser
1084          */
1085         function getParser() {
1086                 global $wgParser, $wgParserConf;
1087
1088                 if ( !$this->mParser && isset( $wgParser ) ) {
1089                         # Do some initialisation so that we don't have to do it twice
1090                         $wgParser->firstCallInit();
1091                         # Clone it and store it
1092                         $class = $wgParserConf['class'];
1093                         if ( $class == 'ParserDiffTest' ) {
1094                                 # Uncloneable
1095                                 $this->mParser = new $class( $wgParserConf );
1096                         } else {
1097                                 $this->mParser = clone $wgParser;
1098                         }
1099                 }
1100
1101                 return $this->mParser;
1102         }
1103
1104         /**
1105          * @param string $text
1106          * @param Title $title
1107          * @param bool $linestart Whether or not this is at the start of a line
1108          * @param bool $interface Whether this is an interface message
1109          * @param Language|string $language Language code
1110          * @return ParserOutput|string
1111          */
1112         public function parse( $text, $title = null, $linestart = true,
1113                 $interface = false, $language = null
1114         ) {
1115                 global $wgTitle;
1116
1117                 if ( $this->mInParser ) {
1118                         return htmlspecialchars( $text );
1119                 }
1120
1121                 $parser = $this->getParser();
1122                 $popts = $this->getParserOptions();
1123                 $popts->setInterfaceMessage( $interface );
1124
1125                 if ( is_string( $language ) ) {
1126                         $language = Language::factory( $language );
1127                 }
1128                 $popts->setTargetLanguage( $language );
1129
1130                 if ( !$title || !$title instanceof Title ) {
1131                         wfDebugLog( 'GlobalTitleFail', __METHOD__ . ' called by ' .
1132                                 wfGetAllCallers( 6 ) . ' with no title set.' );
1133                         $title = $wgTitle;
1134                 }
1135                 // Sometimes $wgTitle isn't set either...
1136                 if ( !$title ) {
1137                         # It's not uncommon having a null $wgTitle in scripts. See r80898
1138                         # Create a ghost title in such case
1139                         $title = Title::makeTitle( NS_SPECIAL, 'Badtitle/title not set in ' . __METHOD__ );
1140                 }
1141
1142                 $this->mInParser = true;
1143                 $res = $parser->parse( $text, $title, $popts, $linestart );
1144                 $this->mInParser = false;
1145
1146                 return $res;
1147         }
1148
1149         function disable() {
1150                 $this->mDisable = true;
1151         }
1152
1153         function enable() {
1154                 $this->mDisable = false;
1155         }
1156
1157         /**
1158          * Whether DB/cache usage is disabled for determining messages
1159          *
1160          * If so, this typically indicates either:
1161          *   - a) load() failed to find a cached copy nor query the DB
1162          *   - b) we are in a special context or error mode that cannot use the DB
1163          * If the DB is ignored, any derived HTML output or cached objects may be wrong.
1164          * To avoid long-term cache pollution, TTLs can be adjusted accordingly.
1165          *
1166          * @return bool
1167          * @since 1.27
1168          */
1169         public function isDisabled() {
1170                 return $this->mDisable;
1171         }
1172
1173         /**
1174          * Clear all stored messages. Mainly used after a mass rebuild.
1175          */
1176         function clear() {
1177                 $langs = Language::fetchLanguageNames( null, 'mw' );
1178                 foreach ( array_keys( $langs ) as $code ) {
1179                         # Global and local caches
1180                         $this->wanCache->touchCheckKey( wfMemcKey( 'messages', $code ) );
1181                 }
1182
1183                 $this->mLoadedLanguages = [];
1184         }
1185
1186         /**
1187          * @param string $key
1188          * @return array
1189          */
1190         public function figureMessage( $key ) {
1191                 global $wgLanguageCode;
1192
1193                 $pieces = explode( '/', $key );
1194                 if ( count( $pieces ) < 2 ) {
1195                         return [ $key, $wgLanguageCode ];
1196                 }
1197
1198                 $lang = array_pop( $pieces );
1199                 if ( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
1200                         return [ $key, $wgLanguageCode ];
1201                 }
1202
1203                 $message = implode( '/', $pieces );
1204
1205                 return [ $message, $lang ];
1206         }
1207
1208         /**
1209          * Get all message keys stored in the message cache for a given language.
1210          * If $code is the content language code, this will return all message keys
1211          * for which MediaWiki:msgkey exists. If $code is another language code, this
1212          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
1213          * @param string $code Language code
1214          * @return array Array of message keys (strings)
1215          */
1216         public function getAllMessageKeys( $code ) {
1217                 global $wgContLang;
1218
1219                 $this->load( $code );
1220                 if ( !isset( $this->mCache[$code] ) ) {
1221                         // Apparently load() failed
1222                         return null;
1223                 }
1224                 // Remove administrative keys
1225                 $cache = $this->mCache[$code];
1226                 unset( $cache['VERSION'] );
1227                 unset( $cache['EXPIRY'] );
1228                 unset( $cache['EXCESSIVE'] );
1229                 // Remove any !NONEXISTENT keys
1230                 $cache = array_diff( $cache, [ '!NONEXISTENT' ] );
1231
1232                 // Keys may appear with a capital first letter. lcfirst them.
1233                 return array_map( [ $wgContLang, 'lcfirst' ], array_keys( $cache ) );
1234         }
1235
1236         /**
1237          * Purge message caches when a MediaWiki: page is created, updated, or deleted
1238          *
1239          * @param Title $title Message page title
1240          * @param Content|null $content New content for edit/create, null on deletion
1241          * @since 1.29
1242          */
1243         public function updateMessageOverride( Title $title, Content $content = null ) {
1244                 global $wgContLang;
1245
1246                 $msgText = $this->getMessageTextFromContent( $content );
1247                 if ( $msgText === null ) {
1248                         $msgText = false; // treat as not existing
1249                 }
1250
1251                 $this->replace( $title->getDBkey(), $msgText );
1252
1253                 if ( $wgContLang->hasVariants() ) {
1254                         $wgContLang->updateConversionTable( $title );
1255                 }
1256         }
1257
1258         /**
1259          * @param Content|null $content Content or null if the message page does not exist
1260          * @return string|bool|null Returns false if $content is null and null on error
1261          */
1262         private function getMessageTextFromContent( Content $content = null ) {
1263                 // @TODO: could skip pseudo-messages like js/css here, based on content model
1264                 if ( $content ) {
1265                         // Message page exists...
1266                         // XXX: Is this the right way to turn a Content object into a message?
1267                         // NOTE: $content is typically either WikitextContent, JavaScriptContent or
1268                         //       CssContent. MessageContent is *not* used for storing messages, it's
1269                         //       only used for wrapping them when needed.
1270                         $msgText = $content->getWikitextForTransclusion();
1271                         if ( $msgText === false || $msgText === null ) {
1272                                 // This might be due to some kind of misconfiguration...
1273                                 $msgText = null;
1274                                 LoggerFactory::getInstance( 'MessageCache' )->warning(
1275                                         __METHOD__ . ": message content doesn't provide wikitext "
1276                                         . "(content model: " . $content->getModel() . ")" );
1277                         }
1278                 } else {
1279                         // Message page does not exist...
1280                         $msgText = false;
1281                 }
1282
1283                 return $msgText;
1284         }
1285 }