includes/MessageCache.php

   1 <?php
   2 /**
   3  *
   4  * @package MediaWiki
   5  * @subpackage Cache
   6  */
   7
   8 /**
   9  *
  10  */
  11 define( 'MSG_LOAD_TIMEOUT', 60);
  12 define( 'MSG_LOCK_TIMEOUT', 10);
  13 define( 'MSG_WAIT_TIMEOUT', 10);
  14 define( 'MSG_CACHE_VERSION', 1 );
  15
  16 /**
  17  * Message cache
  18  * Performs various MediaWiki namespace-related functions
  19  *
  20  * @package MediaWiki
  21  */
  22 class MessageCache {
  23         var $mCache, $mUseCache, $mDisable, $mExpiry;
  24         var $mMemcKey, $mKeys, $mParserOptions, $mParser;
  25         var $mExtensionMessages = array();
  26         var $mInitialised = false;
  27         var $mDeferred = true;
  28
  29         function __construct( &$memCached, $useDB, $expiry, $memcPrefix) {
  30                 wfProfileIn( __METHOD__ );
  31
  32                 $this->mUseCache = !is_null( $memCached );
  33                 $this->mMemc = &$memCached;
  34                 $this->mDisable = !$useDB;
  35                 $this->mExpiry = $expiry;
  36                 $this->mDisableTransform = false;
  37                 $this->mMemcKey = $memcPrefix.':messages';
  38                 $this->mKeys = false; # initialised on demand
  39                 $this->mInitialised = true;
  40                 $this->mParser = null;
  41
  42                 # When we first get asked for a message,
  43                 # then we'll fill up the cache. If we
  44                 # can return a cache hit, this saves
  45                 # some extra milliseconds
  46                 $this->mDeferred = true;
  47
  48                 wfProfileOut( __METHOD__ );
  49         }
  50
  51         function getParserOptions() {
  52                 if ( !$this->mParserOptions ) {
  53                         $this->mParserOptions = new ParserOptions;
  54                 }
  55                 return $this->mParserOptions;
  56         }
  57
  58         /**
  59          * Try to load the cache from a local file
  60          */
  61         function loadFromLocal( $hash ) {
  62                 global $wgLocalMessageCache;
  63
  64                 $this->mCache = false;
  65                 if ( $wgLocalMessageCache === false ) {
  66                         return;
  67                 }
  68
  69                 $filename = "$wgLocalMessageCache/messages-" . wfWikiID();
  70
  71                 wfSuppressWarnings();
  72                 $file = fopen( $filename, 'r' );
  73                 wfRestoreWarnings();
  74                 if ( !$file ) {
  75                         return;
  76                 }
  77
  78                 // Check to see if the file has the hash specified
  79                 $localHash = fread( $file, 32 );
  80                 if ( $hash == $localHash ) {
  81                         // All good, get the rest of it
  82                         $serialized = fread( $file, 10000000 );
  83                         $this->setCache( unserialize( $serialized ) );
  84                 }
  85                 fclose( $file );
  86         }
  87
  88         /**
  89          * Save the cache to a local file
  90          */
  91         function saveToLocal( $serialized, $hash ) {
  92                 global $wgLocalMessageCache;
  93
  94                 if ( $wgLocalMessageCache === false ) {
  95                         return;
  96                 }
  97
  98                 $filename = "$wgLocalMessageCache/messages-" . wfWikiID();
  99                 $oldUmask = umask( 0 );
 100                 wfMkdirParents( $wgLocalMessageCache, 0777 );
 101                 umask( $oldUmask );
 102
 103                 $file = fopen( $filename, 'w' );
 104                 if ( !$file ) {
 105                         wfDebug( "Unable to open local cache file for writing\n" );
 106                         return;
 107                 }
 108
 109                 fwrite( $file, $hash . $serialized );
 110                 fclose( $file );
 111                 @chmod( $filename, 0666 );
 112         }
 113
 114         function loadFromScript( $hash ) {
 115                 global $wgLocalMessageCache;
 116                 if ( $wgLocalMessageCache === false ) {
 117                         return;
 118                 }
 119
 120                 $filename = "$wgLocalMessageCache/messages-" . wfWikiID();
 121
 122                 wfSuppressWarnings();
 123                 $file = fopen( $filename, 'r' );
 124                 wfRestoreWarnings();
 125                 if ( !$file ) {
 126                         return;
 127                 }
 128                 $localHash=substr(fread($file,40),8);
 129                 fclose($file);
 130                 if ($hash!=$localHash) {
 131                         return;
 132                 }
 133                 require("$wgLocalMessageCache/messages-" . wfWikiID());
 134                 $this->setCache( $this->mCache);
 135         }
 136
 137         function saveToScript($array, $hash) {
 138                 global $wgLocalMessageCache;
 139                 if ( $wgLocalMessageCache === false ) {
 140                         return;
 141                 }
 142
 143                 $filename = "$wgLocalMessageCache/messages-" . wfWikiID();
 144                 $oldUmask = umask( 0 );
 145                 wfMkdirParents( $wgLocalMessageCache, 0777 );
 146                 umask( $oldUmask );
 147                 $file = fopen( $filename.'.tmp', 'w');
 148                 fwrite($file,"<?php\n//$hash\n\n \$this->mCache = array(");
 149
 150                 foreach ($array as $key => $message) {
 151                         fwrite($file, "'". $this->escapeForScript($key).
 152                                 "' => '" . $this->escapeForScript($message).
 153                                 "',\n");
 154                 }
 155                 fwrite($file,");\n?>");
 156                 fclose($file);
 157                 rename($filename.'.tmp',$filename);
 158         }
 159
 160         function escapeForScript($string) {
 161                 $string = str_replace( '\\', '\\\\', $string );
 162                 $string = str_replace( '\'', '\\\'', $string );
 163                 return $string;
 164         }
 165
 166         /**
 167          * Set the cache to $cache, if it is valid. Otherwise set the cache to false.
 168          */
 169         function setCache( $cache ) {
 170                 if ( isset( $cache['VERSION'] ) && $cache['VERSION'] == MSG_CACHE_VERSION ) {
 171                         $this->mCache = $cache;
 172                 } else {
 173                         $this->mCache = false;
 174                 }
 175         }
 176
 177         /**
 178          * Loads messages either from memcached or the database, if not disabled
 179          * On error, quietly switches to a fallback mode
 180          * Returns false for a reportable error, true otherwise
 181          */
 182         function load() {
 183                 global $wgLocalMessageCache, $wgLocalMessageCacheSerialized;
 184
 185                 if ( $this->mDisable ) {
 186                         static $shownDisabled = false;
 187                         if ( !$shownDisabled ) {
 188                                 wfDebug( "MessageCache::load(): disabled\n" );
 189                                 $shownDisabled = true;
 190                         }
 191                         return true;
 192                 }
 193                 if ( !$this->mUseCache ) {
 194                         $this->mDeferred = false;
 195                         return true;
 196                 }
 197
 198                 $fname = 'MessageCache::load';
 199                 wfProfileIn( $fname );
 200                 $success = true;
 201
 202                 $this->mCache = false;
 203
 204                 # Try local cache
 205                 wfProfileIn( $fname.'-fromlocal' );
 206                 $hash = $this->mMemc->get( "{$this->mMemcKey}-hash" );
 207                 if ( $hash ) {
 208                         if ($wgLocalMessageCacheSerialized) {
 209                                 $this->loadFromLocal( $hash );
 210                         } else {
 211                                 $this->loadFromScript( $hash );
 212                         }
 213                         if ( $this->mCache ) {
 214                                 wfDebug( "MessageCache::load(): got from local cache\n" );
 215                         }
 216                 }
 217                 wfProfileOut( $fname.'-fromlocal' );
 218
 219                 # Try memcached
 220                 if ( !$this->mCache ) {
 221                         wfProfileIn( $fname.'-fromcache' );
 222                         $this->setCache( $this->mMemc->get( $this->mMemcKey ) );
 223                         if ( $this->mCache ) {
 224                                 wfDebug( "MessageCache::load(): got from global cache\n" );
 225                                 # Save to local cache
 226                                 if ( $wgLocalMessageCache !== false ) {
 227                                         $serialized = serialize( $this->mCache );
 228                                         if ( !$hash ) {
 229                                                 $hash = md5( $serialized );
 230                                                 $this->mMemc->set( "{$this->mMemcKey}-hash", $hash, $this->mExpiry );
 231                                         }
 232                                         if ($wgLocalMessageCacheSerialized) {
 233                                                 $this->saveToLocal( $serialized,$hash );
 234                                         } else {
 235                                                 $this->saveToScript( $this->mCache, $hash );
 236                                         }
 237                                 }
 238                         }
 239                         wfProfileOut( $fname.'-fromcache' );
 240                 }
 241
 242
 243                 # If there's nothing in memcached, load all the messages from the database
 244                 if ( !$this->mCache ) {
 245                         wfDebug( "MessageCache::load(): cache is empty\n" );
 246                         $this->lock();
 247                         # Other threads don't need to load the messages if another thread is doing it.
 248                         $success = $this->mMemc->add( $this->mMemcKey.'-status', "loading", MSG_LOAD_TIMEOUT );
 249                         if ( $success ) {
 250                                 wfProfileIn( $fname.'-load' );
 251                                 wfDebug( "MessageCache::load(): loading all messages from DB\n" );
 252                                 $this->loadFromDB();
 253                                 wfProfileOut( $fname.'-load' );
 254
 255                                 # Save in memcached
 256                                 # Keep trying if it fails, this is kind of important
 257                                 wfProfileIn( $fname.'-save' );
 258                                 for ($i=0; $i<20 &&
 259                                                    !$this->mMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry );
 260                                          $i++ ) {
 261                                         usleep(mt_rand(500000,1500000));
 262                                 }
 263
 264                                 # Save to local cache
 265                                 if ( $wgLocalMessageCache !== false ) {
 266                                         $serialized = serialize( $this->mCache );
 267                                         $hash = md5( $serialized );
 268                                         $this->mMemc->set( "{$this->mMemcKey}-hash", $hash, $this->mExpiry );
 269                                         if ($wgLocalMessageCacheSerialized) {
 270                                                 $this->saveToLocal( $serialized,$hash );
 271                                         } else {
 272                                                 $this->saveToScript( $this->mCache, $hash );
 273                                         }
 274                                 }
 275
 276                                 wfProfileOut( $fname.'-save' );
 277                                 if ( $i == 20 ) {
 278                                         $this->mMemc->set( $this->mMemcKey.'-status', 'error', 60*5 );
 279                                         wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
 280                                 } else {
 281                                         $this->mMemc->delete( $this->mMemcKey.'-status' );
 282                                 }
 283                         }
 284                         $this->unlock();
 285                 }
 286
 287                 if ( !is_array( $this->mCache ) ) {
 288                         wfDebug( "MessageCache::load(): unable to load cache, disabled\n" );
 289                         $this->mDisable = true;
 290                         $this->mCache = false;
 291                 }
 292                 wfProfileOut( $fname );
 293                 $this->mDeferred = false;
 294                 return $success;
 295         }
 296
 297         /**
 298          * Loads all or main part of cacheable messages from the database
 299          */
 300         function loadFromDB() {
 301                 global $wgLang, $wgMaxMsgCacheEntrySize;
 302
 303                 wfProfileIn( __METHOD__ );
 304                 $dbr =& wfGetDB( DB_SLAVE );
 305                 $this->mCache = array();
 306
 307                 # Load titles for all oversized pages in the MediaWiki namespace
 308                 $res = $dbr->select( 'page', 'page_title',
 309                         array(
 310                                 'page_len > ' . intval( $wgMaxMsgCacheEntrySize ),
 311                                 'page_is_redirect' => 0,
 312                                 'page_namespace' => NS_MEDIAWIKI,
 313                         ),
 314                         __METHOD__ );
 315                 while ( $row = $dbr->fetchObject( $res ) ) {
 316                         $this->mCache[$row->page_title] = '!TOO BIG';
 317                 }
 318                 $dbr->freeResult( $res );
 319
 320                 # Load text for the remaining pages
 321                 $res = $dbr->select( array( 'page', 'revision', 'text' ),
 322                         array( 'page_title', 'old_text', 'old_flags' ),
 323                         array(
 324                                 'page_is_redirect' => 0,
 325                                 'page_namespace' => NS_MEDIAWIKI,
 326                                 'page_latest=rev_id',
 327                                 'rev_text_id=old_id',
 328                                 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize ) ),
 329                         __METHOD__ );
 330
 331                 for ( $row = $dbr->fetchObject( $res ); $row; $row = $dbr->fetchObject( $res ) ) {
 332                         $this->mCache[$row->page_title] = ' ' . Revision::getRevisionText( $row );
 333                 }
 334                 $this->mCache['VERSION'] = MSG_CACHE_VERSION;
 335                 $dbr->freeResult( $res );
 336                 wfProfileOut( __METHOD__ );
 337         }
 338
 339         /**
 340          * Not really needed anymore
 341          */
 342         function getKeys() {
 343                 global $wgContLang;
 344                 if ( !$this->mKeys ) {
 345                         $this->mKeys = array();
 346                         $allMessages = Language::getMessagesFor( 'en' );
 347                         foreach ( $allMessages as $key => $unused ) {
 348                                 $title = $wgContLang->ucfirst( $key );
 349                                 array_push( $this->mKeys, $title );
 350                         }
 351                 }
 352                 return $this->mKeys;
 353         }
 354
 355         function replace( $title, $text ) {
 356                 global $wgLocalMessageCache, $wgLocalMessageCacheSerialized, $parserMemc;
 357                 global $wgMaxMsgCacheEntrySize;
 358
 359                 wfProfileIn( __METHOD__ );
 360                 $this->lock();
 361                 $this->load();
 362                 $parserMemc->delete(wfMemcKey('sidebar'));
 363                 if ( is_array( $this->mCache ) ) {
 364                         if ( $text === false ) {
 365                                 # Article was deleted
 366                                 unset( $this->mCache[$title] );
 367                                 $this->mMemc->delete( "$this->mMemcKey:{$title}" );
 368                         } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 369                                 $this->mCache[$title] = '!TOO BIG';
 370                                 $this->mMemc->set( "$this->mMemcKey:{$title}", ' '.$text, $this->mExpiry );
 371                         } else {
 372                                 $this->mCache[$title] = ' ' . $text;
 373                                 $this->mMemc->delete( "$this->mMemcKey:{$title}" );
 374                         }
 375                         $this->mMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry );
 376
 377                         # Save to local cache
 378                         if ( $wgLocalMessageCache !== false ) {
 379                                 $serialized = serialize( $this->mCache );
 380                                 $hash = md5( $serialized );
 381                                 $this->mMemc->set( "{$this->mMemcKey}-hash", $hash, $this->mExpiry );
 382                                 if ($wgLocalMessageCacheSerialized) {
 383                                         $this->saveToLocal( $serialized,$hash );
 384                                 } else {
 385                                         $this->saveToScript( $this->mCache, $hash );
 386                                 }
 387                         }
 388                 }
 389                 $this->unlock();
 390                 wfProfileOut( __METHOD__ );
 391         }
 392
 393         /**
 394          * Returns success
 395          * Represents a write lock on the messages key
 396          */
 397         function lock() {
 398                 if ( !$this->mUseCache ) {
 399                         return true;
 400                 }
 401
 402                 $lockKey = $this->mMemcKey . 'lock';
 403                 for ($i=0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
 404                         sleep(1);
 405                 }
 406
 407                 return $i >= MSG_WAIT_TIMEOUT;
 408         }
 409
 410         function unlock() {
 411                 if ( !$this->mUseCache ) {
 412                         return;
 413                 }
 414
 415                 $lockKey = $this->mMemcKey . 'lock';
 416                 $this->mMemc->delete( $lockKey );
 417         }
 418
 419         /**
 420          * Get a message from either the content language or the user language.
 421          *
 422          * @param string $key The message cache key
 423          * @param bool $useDB Get the message from the DB, false to use only the localisation
 424          * @param bool $forContent Get the message from the content language rather than the
 425          *                         user language
 426          * @param bool $isFullKey Specifies whether $key is a two part key "lang/msg".
 427          */
 428         function get( $key, $useDB = true, $forContent = true, $isFullKey = false ) {
 429                 global $wgContLanguageCode, $wgContLang, $wgLang;
 430                 if( $forContent ) {
 431                         $lang =& $wgContLang;
 432                 } else {
 433                         $lang =& $wgLang;
 434                 }
 435                 $langcode = $lang->getCode();
 436                 # If uninitialised, someone is trying to call this halfway through Setup.php
 437                 if( !$this->mInitialised ) {
 438                         return '&lt;' . htmlspecialchars($key) . '&gt;';
 439                 }
 440                 # If cache initialization was deferred, start it now.
 441                 if( $this->mDeferred && !$this->mDisable && $useDB ) {
 442                         $this->load();
 443                 }
 444
 445                 $message = false;
 446
 447                 # Try the MediaWiki namespace
 448                 if( !$this->mDisable && $useDB ) {
 449                         $title = $wgContLang->ucfirst( $key );
 450                         if(!$isFullKey && ($langcode != $wgContLanguageCode) ) {
 451                                 $title .= '/' . $langcode;
 452                         }
 453                         $message = $this->getMsgFromNamespace( $title );
 454                 }
 455                 # Try the extension array
 456                 if( $message === false && isset( $this->mExtensionMessages[$langcode][$key] ) ) {
 457                         $message = $this->mExtensionMessages[$langcode][$key];
 458                 }
 459                 if ( $message === false && isset( $this->mExtensionMessages['en'][$key] ) ) {
 460                         $message = $this->mExtensionMessages['en'][$key];
 461                 }
 462
 463                 # Try the array in the language object
 464                 if( $message === false ) {
 465                         #wfDebug( "Trying language object for message $key\n" );
 466                         wfSuppressWarnings();
 467                         $message = $lang->getMessage( $key );
 468                         wfRestoreWarnings();
 469                         if ( is_null( $message ) ) {
 470                                 $message = false;
 471                         }
 472                 }
 473
 474                 # Try the array of another language
 475                 if( $message === false && strpos( $key, '/' ) ) {
 476                         $message = explode( '/', $key );
 477                         if ( $message[1] ) {
 478                                 wfSuppressWarnings();
 479                                 $message = Language::getMessageFor( $message[0], $message[1] );
 480                                 wfRestoreWarnings();
 481                                 if ( is_null( $message ) ) {
 482                                         $message = false;
 483                                 }
 484                         } else {
 485                                 $message = false;
 486                         }
 487                 }
 488
 489                 # Is this a custom message? Try the default language in the db...
 490                 if( ($message === false || $message === '-' ) &&
 491                         !$this->mDisable && $useDB &&
 492                         !$isFullKey && ($langcode != $wgContLanguageCode) ) {
 493                         $message = $this->getMsgFromNamespace( $wgContLang->ucfirst( $key ) );
 494                 }
 495
 496                 # Final fallback
 497                 if( $message === false ) {
 498                         return '&lt;' . htmlspecialchars($key) . '&gt;';
 499                 }
 500
 501                 # Replace brace tags
 502                 $message = $this->transform( $message );
 503                 return $message;
 504         }
 505
 506         /**
 507          * Get a message from the MediaWiki namespace, with caching. The key must
 508          * first be converted to two-part lang/msg form if necessary.
 509          *
 510          * @param string $title Message cache key with initial uppercase letter
 511          */
 512         function getMsgFromNamespace( $title ) {
 513                 $message = false;
 514                 $type = false;
 515
 516                 # Try the cache
 517                 if( $this->mUseCache && isset( $this->mCache[$title] ) ) {
 518                         $entry = $this->mCache[$title];
 519                         $type = substr( $entry, 0, 1 );
 520                         if ( $type == ' ' ) {
 521                                 return substr( $entry, 1 );
 522                         }
 523                 }
 524
 525                 # Call message hooks, in case they are defined
 526                 wfRunHooks('MessagesPreLoad', array( $title, &$message ) );
 527                 if ( $message !== false ) {
 528                         return $message;
 529                 }
 530
 531                 # If there is no cache entry and no placeholder, it doesn't exist
 532                 if ( $type != '!' && $message === false ) {
 533                         return false;
 534                 }
 535
 536                 $memcKey = $this->mMemcKey . ':' . $title;
 537
 538                 # Try the individual message cache
 539                 if ( $this->mUseCache ) {
 540                         $entry = $this->mMemc->get( $memcKey );
 541                         if ( $entry ) {
 542                                 $type = substr( $entry, 0, 1 );
 543
 544                                 if ( $type == ' ' ) {
 545                                         $message = substr( $entry, 1 );
 546                                         $this->mCache[$title] = $message;
 547                                         return $message;
 548                                 } elseif ( $entry == '!NONEXISTENT' ) {
 549                                         return false;
 550                                 } else {
 551                                         # Corrupt/obsolete entry, delete it
 552                                         $this->mMemc->delete( $memcKey );
 553                                 }
 554
 555                         }
 556                 }
 557
 558                 # Try loading it from the DB
 559                 $revision = Revision::newFromTitle( Title::makeTitle( NS_MEDIAWIKI, $title ) );
 560                 if( $revision ) {
 561                         $message = $revision->getText();
 562                         if ($this->mUseCache) {
 563                                 $this->mCache[$title] = ' ' . $message;
 564                                 $this->mMemc->set( $memcKey, $message, $this->mExpiry );
 565                         }
 566                 } else {
 567                         # Negative caching
 568                         # Use some special text instead of false, because false gets converted to '' somewhere
 569                         $this->mMemc->set( $memcKey, '!NONEXISTENT', $this->mExpiry );
 570                         $this->mCache[$title] = false;
 571                 }
 572
 573                 return $message;
 574         }
 575
 576         function transform( $message ) {
 577                 global $wgParser;
 578                 if ( !$this->mParser && isset( $wgParser ) ) {
 579                         # Do some initialisation so that we don't have to do it twice
 580                         $wgParser->firstCallInit();
 581                         # Clone it and store it
 582                         $this->mParser = clone $wgParser;
 583                 }
 584                 if ( !$this->mDisableTransform && $this->mParser ) {
 585                         if( strpos( $message, '{{' ) !== false ) {
 586                                 $message = $this->mParser->transformMsg( $message, $this->getParserOptions() );
 587                         }
 588                 }
 589                 return $message;
 590         }
 591
 592         function disable() { $this->mDisable = true; }
 593         function enable() { $this->mDisable = false; }
 594         function disableTransform() { $this->mDisableTransform = true; }
 595         function enableTransform() { $this->mDisableTransform = false; }
 596         function setTransform( $x ) { $this->mDisableTransform = $x; }
 597         function getTransform() { return $this->mDisableTransform; }
 598
 599         /**
 600          * Add a message to the cache
 601          *
 602          * @param mixed $key
 603          * @param mixed $value
 604          * @param string $lang The messages language, English by default
 605          */
 606         function addMessage( $key, $value, $lang = 'en' ) {
 607                 $this->mExtensionMessages[$lang][$key] = $value;
 608         }
 609
 610         /**
 611          * Add an associative array of message to the cache
 612          *
 613          * @param array $messages An associative array of key => values to be added
 614          * @param string $lang The messages language, English by default
 615          */
 616         function addMessages( $messages, $lang = 'en' ) {
 617                 wfProfileIn( __METHOD__ );
 618                 if ( isset( $this->mExtensionMessages[$lang] ) ) {
 619                         $this->mExtensionMessages[$lang] = $messages + $this->mExtensionMessages[$lang];
 620                 } else {
 621                         $this->mExtensionMessages[$lang] = $messages;
 622                 }
 623                 wfProfileOut( __METHOD__ );
 624         }
 625
 626         /**
 627          * Add a 2-D array of messages by lang. Useful for extensions.
 628          * Introduced in 1.9. Please do not use it for now, for backwards compatibility.
 629          *
 630          * @param array $messages The array to be added
 631          */
 632         function addMessagesByLang( $messages ) {
 633                 wfProfileIn( __METHOD__ );
 634                 foreach ( $messages as $key => $value ) {
 635                         $this->addMessages( $value, $key );
 636                 }
 637                 wfProfileOut( __METHOD__ );
 638         }
 639
 640         /**
 641          * Get the extension messages for a specific language
 642          *
 643          * @param string $lang The messages language, English by default
 644          */
 645         function getExtensionMessagesFor( $lang = 'en' ) {
 646                 wfProfileIn( __METHOD__ );
 647                 $messages = array();
 648                 if ( isset( $this->mExtensionMessages[$lang] ) ) {
 649                         $messages = $this->mExtensionMessages[$lang];
 650                 }
 651                 if ( $lang != 'en' ) {
 652                         $messages = $messages + $this->mExtensionMessages['en'];
 653                 }
 654                 wfProfileOut( __METHOD__ );
 655                 return $messages;
 656         }
 657
 658         /**
 659          * Clear all stored messages. Mainly used after a mass rebuild.
 660          */
 661         function clear() {
 662                 global $wgLocalMessageCache;
 663                 if( $this->mUseCache ) {
 664                         # Global cache
 665                         $this->mMemc->delete( $this->mMemcKey );
 666                         # Invalidate all local caches
 667                         $this->mMemc->delete( "{$this->mMemcKey}-hash" );
 668                 }
 669         }
 670
 671         static function loadAllMessages() {
 672                 # Some extensions will load their messages when you load their class file
 673                 wfLoadAllExtensions();
 674                 # Others will respond to this hook
 675                 wfRunHooks( 'LoadAllMessages' );
 676                 # Still others will respond to neither, they are EVIL. We sometimes need to know!
 677         }
 678 }
 679 ?>