includes/MessageCache.php

   1 <?php
   2 /**
   3  *
   4  * @addtogroup Cache
   5  */
   6
   7 /**
   8  *
   9  */
  10 define( 'MSG_LOAD_TIMEOUT', 60);
  11 define( 'MSG_LOCK_TIMEOUT', 10);
  12 define( 'MSG_WAIT_TIMEOUT', 10);
  13 define( 'MSG_CACHE_VERSION', 1 );
  14
  15 /**
  16  * Message cache
  17  * Performs various MediaWiki namespace-related functions
  18  *
  19  */
  20 class MessageCache {
  21         var $mCache, $mUseCache, $mDisable, $mExpiry;
  22         var $mMemcKey, $mKeys, $mParserOptions, $mParser;
  23         var $mExtensionMessages = array();
  24         var $mInitialised = false;
  25         var $mDeferred = true;
  26         var $mAllMessagesLoaded;
  27
  28         function __construct( &$memCached, $useDB, $expiry, $memcPrefix) {
  29                 wfProfileIn( __METHOD__ );
  30
  31                 $this->mUseCache = !is_null( $memCached );
  32                 $this->mMemc = &$memCached;
  33                 $this->mDisable = !$useDB;
  34                 $this->mExpiry = $expiry;
  35                 $this->mDisableTransform = false;
  36                 $this->mMemcKey = $memcPrefix.':messages';
  37                 $this->mKeys = false; # initialised on demand
  38                 $this->mInitialised = true;
  39                 $this->mParser = null;
  40
  41                 # When we first get asked for a message,
  42                 # then we'll fill up the cache. If we
  43                 # can return a cache hit, this saves
  44                 # some extra milliseconds
  45                 $this->mDeferred = true;
  46
  47                 wfProfileOut( __METHOD__ );
  48         }
  49
  50         function getParserOptions() {
  51                 if ( !$this->mParserOptions ) {
  52                         $this->mParserOptions = new ParserOptions;
  53                 }
  54                 return $this->mParserOptions;
  55         }
  56
  57         /**
  58          * Try to load the cache from a local file
  59          */
  60         function loadFromLocal( $hash ) {
  61                 global $wgLocalMessageCache, $wgLocalMessageCacheSerialized;
  62
  63                 if ( $wgLocalMessageCache === false ) {
  64                         return;
  65                 }
  66
  67                 $filename = "$wgLocalMessageCache/messages-" . wfWikiID();
  68
  69                 wfSuppressWarnings();
  70                 $file = fopen( $filename, 'r' );
  71                 wfRestoreWarnings();
  72                 if ( !$file ) {
  73                         return;
  74                 }
  75
  76                 if ( $wgLocalMessageCacheSerialized ) {
  77                         // Check to see if the file has the hash specified
  78                         $localHash = fread( $file, 32 );
  79                         if ( $hash === $localHash ) {
  80                                 // All good, get the rest of it
  81                                 $serialized = '';
  82                                 while ( !feof( $file ) ) {
  83                                         $serialized .= fread( $file, 100000 );
  84                                 }
  85                                 $this->setCache( unserialize( $serialized ) );
  86                         }
  87                         fclose( $file );
  88                 } else {
  89                         $localHash=substr(fread($file,40),8);
  90                         fclose($file);
  91                         if ($hash!=$localHash) {
  92                                 return;
  93                         }
  94
  95                         require("$wgLocalMessageCache/messages-" . wfWikiID());
  96                         $this->setCache( $this->mCache);
  97                 }
  98         }
  99
 100         /**
 101          * Save the cache to a local file
 102          */
 103         function saveToLocal( $serialized, $hash ) {
 104                 global $wgLocalMessageCache, $wgLocalMessageCacheSerialized;
 105
 106                 if ( $wgLocalMessageCache === false ) {
 107                         return;
 108                 }
 109
 110                 $filename = "$wgLocalMessageCache/messages-" . wfWikiID();
 111                 $oldUmask = umask( 0 );
 112                 wfMkdirParents( $wgLocalMessageCache, 0777 );
 113                 umask( $oldUmask );
 114
 115                 $file = fopen( $filename, 'w' );
 116                 if ( !$file ) {
 117                         wfDebug( "Unable to open local cache file for writing\n" );
 118                         return;
 119                 }
 120
 121                 fwrite( $file, $hash . $serialized );
 122                 fclose( $file );
 123                 @chmod( $filename, 0666 );
 124         }
 125
 126         function loadFromScript( $hash ) {
 127                 wfDeprecated( __METHOD__ );
 128                 $this->loadFromLocal( $hash );
 129         }
 130
 131         function saveToScript($array, $hash) {
 132                 global $wgLocalMessageCache;
 133                 if ( $wgLocalMessageCache === false ) {
 134                         return;
 135                 }
 136
 137                 $filename = "$wgLocalMessageCache/messages-" . wfWikiID();
 138                 $oldUmask = umask( 0 );
 139                 wfMkdirParents( $wgLocalMessageCache, 0777 );
 140                 umask( $oldUmask );
 141                 $file = fopen( $filename.'.tmp', 'w');
 142                 fwrite($file,"<?php\n//$hash\n\n \$this->mCache = array(");
 143
 144                 foreach ($array as $key => $message) {
 145                         fwrite($file, "'". $this->escapeForScript($key).
 146                                 "' => '" . $this->escapeForScript($message).
 147                                 "',\n");
 148                 }
 149                 fwrite($file,");\n?>");
 150                 fclose($file);
 151                 rename($filename.'.tmp',$filename);
 152         }
 153
 154         function escapeForScript($string) {
 155                 $string = str_replace( '\\', '\\\\', $string );
 156                 $string = str_replace( '\'', '\\\'', $string );
 157                 return $string;
 158         }
 159
 160         /**
 161          * Set the cache to $cache, if it is valid. Otherwise set the cache to false.
 162          */
 163         function setCache( $cache ) {
 164                 if ( isset( $cache['VERSION'] ) && $cache['VERSION'] == MSG_CACHE_VERSION ) {
 165                         $this->mCache = $cache;
 166                 } else {
 167                         $this->mCache = false;
 168                 }
 169         }
 170
 171         /**
 172          * Loads messages either from memcached or the database, if not disabled
 173          * On error, quietly switches to a fallback mode
 174          * Returns false for a reportable error, true otherwise
 175          */
 176         function load() {
 177                 global $wgLocalMessageCache, $wgLocalMessageCacheSerialized;
 178
 179                 if ( $this->mDisable ) {
 180                         static $shownDisabled = false;
 181                         if ( !$shownDisabled ) {
 182                                 wfDebug( "MessageCache::load(): disabled\n" );
 183                                 $shownDisabled = true;
 184                         }
 185                         return true;
 186                 }
 187                 if ( !$this->mUseCache ) {
 188                         $this->mDeferred = false;
 189                         return true;
 190                 }
 191
 192                 $fname = 'MessageCache::load';
 193                 wfProfileIn( $fname );
 194                 $success = true;
 195
 196                 $this->mCache = false;
 197
 198                 # Try local cache
 199                 if ( $wgLocalMessageCache !== false ) {
 200                         wfProfileIn( $fname.'-fromlocal' );
 201                         $hash = $this->mMemc->get( "{$this->mMemcKey}-hash" );
 202                         if ( $hash ) {
 203                                 $this->loadFromLocal( $hash );
 204                                 if ( $this->mCache ) {
 205                                         wfDebug( "MessageCache::load(): got from local cache\n" );
 206                                 }
 207                         }
 208                         wfProfileOut( $fname.'-fromlocal' );
 209                 }
 210
 211                 # Try memcached
 212                 if ( !$this->mCache ) {
 213                         wfProfileIn( $fname.'-fromcache' );
 214                         $this->setCache( $this->mMemc->get( $this->mMemcKey ) );
 215                         if ( $this->mCache ) {
 216                                 wfDebug( "MessageCache::load(): got from global cache\n" );
 217                                 # Save to local cache
 218                                 if ( $wgLocalMessageCache !== false ) {
 219                                         $serialized = serialize( $this->mCache );
 220                                         if ( !$hash ) {
 221                                                 $hash = md5( $serialized );
 222                                                 $this->mMemc->set( "{$this->mMemcKey}-hash", $hash, $this->mExpiry );
 223                                         }
 224                                         if ($wgLocalMessageCacheSerialized) {
 225                                                 $this->saveToLocal( $serialized,$hash );
 226                                         } else {
 227                                                 $this->saveToScript( $this->mCache, $hash );
 228                                         }
 229                                 }
 230                         }
 231                         wfProfileOut( $fname.'-fromcache' );
 232                 }
 233
 234
 235                 # If there's nothing in memcached, load all the messages from the database
 236                 if ( !$this->mCache ) {
 237                         wfDebug( "MessageCache::load(): cache is empty\n" );
 238                         $this->lock();
 239                         # Other threads don't need to load the messages if another thread is doing it.
 240                         $success = $this->mMemc->add( $this->mMemcKey.'-status', "loading", MSG_LOAD_TIMEOUT );
 241                         if ( $success ) {
 242                                 wfProfileIn( $fname.'-load' );
 243                                 wfDebug( "MessageCache::load(): loading all messages from DB\n" );
 244                                 $this->loadFromDB();
 245                                 wfProfileOut( $fname.'-load' );
 246
 247                                 # Save in memcached
 248                                 # Keep trying if it fails, this is kind of important
 249                                 wfProfileIn( $fname.'-save' );
 250                                 for ($i=0; $i<20 &&
 251                                                    !$this->mMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry );
 252                                          $i++ ) {
 253                                         usleep(mt_rand(500000,1500000));
 254                                 }
 255
 256                                 # Save to local cache
 257                                 if ( $wgLocalMessageCache !== false ) {
 258                                         $serialized = serialize( $this->mCache );
 259                                         $hash = md5( $serialized );
 260                                         $this->mMemc->set( "{$this->mMemcKey}-hash", $hash, $this->mExpiry );
 261                                         if ($wgLocalMessageCacheSerialized) {
 262                                                 $this->saveToLocal( $serialized,$hash );
 263                                         } else {
 264                                                 $this->saveToScript( $this->mCache, $hash );
 265                                         }
 266                                 }
 267
 268                                 wfProfileOut( $fname.'-save' );
 269                                 if ( $i == 20 ) {
 270                                         $this->mMemc->set( $this->mMemcKey.'-status', 'error', 60*5 );
 271                                         wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
 272                                 } else {
 273                                         $this->mMemc->delete( $this->mMemcKey.'-status' );
 274                                 }
 275                         }
 276                         $this->unlock();
 277                 }
 278
 279                 if ( !is_array( $this->mCache ) ) {
 280                         wfDebug( "MessageCache::load(): unable to load cache, disabled\n" );
 281                         $this->mDisable = true;
 282                         $this->mCache = false;
 283                 }
 284                 wfProfileOut( $fname );
 285                 $this->mDeferred = false;
 286                 return $success;
 287         }
 288
 289         /**
 290          * Loads all or main part of cacheable messages from the database
 291          */
 292         function loadFromDB() {
 293                 global $wgMaxMsgCacheEntrySize;
 294
 295                 wfProfileIn( __METHOD__ );
 296                 $dbr = wfGetDB( DB_SLAVE );
 297                 $this->mCache = array();
 298
 299                 # Load titles for all oversized pages in the MediaWiki namespace
 300                 $res = $dbr->select( 'page', 'page_title',
 301                         array(
 302                                 'page_len > ' . intval( $wgMaxMsgCacheEntrySize ),
 303                                 'page_is_redirect' => 0,
 304                                 'page_namespace' => NS_MEDIAWIKI,
 305                         ),
 306                         __METHOD__ );
 307                 while ( $row = $dbr->fetchObject( $res ) ) {
 308                         $this->mCache[$row->page_title] = '!TOO BIG';
 309                 }
 310                 $dbr->freeResult( $res );
 311
 312                 # Load text for the remaining pages
 313                 $res = $dbr->select( array( 'page', 'revision', 'text' ),
 314                         array( 'page_title', 'old_text', 'old_flags' ),
 315                         array(
 316                                 'page_is_redirect' => 0,
 317                                 'page_namespace' => NS_MEDIAWIKI,
 318                                 'page_latest=rev_id',
 319                                 'rev_text_id=old_id',
 320                                 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize ) ),
 321                         __METHOD__ );
 322
 323                 for ( $row = $dbr->fetchObject( $res ); $row; $row = $dbr->fetchObject( $res ) ) {
 324                         $this->mCache[$row->page_title] = ' ' . Revision::getRevisionText( $row );
 325                 }
 326                 $this->mCache['VERSION'] = MSG_CACHE_VERSION;
 327                 $dbr->freeResult( $res );
 328                 wfProfileOut( __METHOD__ );
 329         }
 330
 331         /**
 332          * Not really needed anymore
 333          */
 334         function getKeys() {
 335                 global $wgContLang;
 336                 if ( !$this->mKeys ) {
 337                         $this->mKeys = array();
 338                         $allMessages = Language::getMessagesFor( 'en' );
 339                         foreach ( $allMessages as $key => $unused ) {
 340                                 $title = $wgContLang->ucfirst( $key );
 341                                 array_push( $this->mKeys, $title );
 342                         }
 343                 }
 344                 return $this->mKeys;
 345         }
 346
 347         function replace( $title, $text ) {
 348                 global $wgLocalMessageCache, $wgLocalMessageCacheSerialized, $parserMemc;
 349                 global $wgMaxMsgCacheEntrySize;
 350
 351                 wfProfileIn( __METHOD__ );
 352                 $this->lock();
 353                 $this->load();
 354                 if ( is_array( $this->mCache ) ) {
 355                         if ( $text === false ) {
 356                                 # Article was deleted
 357                                 unset( $this->mCache[$title] );
 358                                 $this->mMemc->delete( "$this->mMemcKey:{$title}" );
 359                         } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 360                                 $this->mCache[$title] = '!TOO BIG';
 361                                 $this->mMemc->set( "$this->mMemcKey:{$title}", ' '.$text, $this->mExpiry );
 362                         } else {
 363                                 $this->mCache[$title] = ' ' . $text;
 364                                 $this->mMemc->delete( "$this->mMemcKey:{$title}" );
 365                         }
 366                         $this->mMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry );
 367
 368                         # Save to local cache
 369                         if ( $wgLocalMessageCache !== false ) {
 370                                 $serialized = serialize( $this->mCache );
 371                                 $hash = md5( $serialized );
 372                                 $this->mMemc->set( "{$this->mMemcKey}-hash", $hash, $this->mExpiry );
 373                                 if ($wgLocalMessageCacheSerialized) {
 374                                         $this->saveToLocal( $serialized,$hash );
 375                                 } else {
 376                                         $this->saveToScript( $this->mCache, $hash );
 377                                 }
 378                         }
 379                 }
 380                 $this->unlock();
 381                 $parserMemc->delete(wfMemcKey('sidebar'));
 382                 wfProfileOut( __METHOD__ );
 383         }
 384
 385         /**
 386          * Returns success
 387          * Represents a write lock on the messages key
 388          */
 389         function lock() {
 390                 if ( !$this->mUseCache ) {
 391                         return true;
 392                 }
 393
 394                 $lockKey = $this->mMemcKey . 'lock';
 395                 for ($i=0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
 396                         sleep(1);
 397                 }
 398
 399                 return $i >= MSG_WAIT_TIMEOUT;
 400         }
 401
 402         function unlock() {
 403                 if ( !$this->mUseCache ) {
 404                         return;
 405                 }
 406
 407                 $lockKey = $this->mMemcKey . 'lock';
 408                 $this->mMemc->delete( $lockKey );
 409         }
 410
 411         /**
 412          * Get a message from either the content language or the user language.
 413          *
 414          * @param string $key The message cache key
 415          * @param bool $useDB Get the message from the DB, false to use only the localisation
 416          * @param bool $forContent Get the message from the content language rather than the
 417          *                         user language
 418          * @param bool $isFullKey Specifies whether $key is a two part key "lang/msg".
 419          */
 420         function get( $key, $useDB = true, $forContent = true, $isFullKey = false ) {
 421                 global $wgContLanguageCode, $wgContLang, $wgLang;
 422                 if( $forContent ) {
 423                         $lang =& $wgContLang;
 424                 } else {
 425                         $lang =& $wgLang;
 426                 }
 427                 $langcode = $lang->getCode();
 428                 # If uninitialised, someone is trying to call this halfway through Setup.php
 429                 if( !$this->mInitialised ) {
 430                         return '&lt;' . htmlspecialchars($key) . '&gt;';
 431                 }
 432                 # If cache initialization was deferred, start it now.
 433                 if( $this->mDeferred && !$this->mDisable && $useDB ) {
 434                         $this->load();
 435                 }
 436
 437                 $message = false;
 438
 439                 # Normalise title-case input
 440                 $lckey = $wgContLang->lcfirst( $key );
 441                 $lckey = str_replace( ' ', '_', $lckey );
 442
 443                 # Try the MediaWiki namespace
 444                 if( !$this->mDisable && $useDB ) {
 445                         $title = $wgContLang->ucfirst( $lckey );
 446                         if(!$isFullKey && ($langcode != $wgContLanguageCode) ) {
 447                                 $title .= '/' . $langcode;
 448                         }
 449                         $message = $this->getMsgFromNamespace( $title );
 450                 }
 451                 # Try the extension array
 452                 if( $message === false && isset( $this->mExtensionMessages[$langcode][$lckey] ) ) {
 453                         $message = $this->mExtensionMessages[$langcode][$lckey];
 454                 }
 455                 if ( $message === false && isset( $this->mExtensionMessages['en'][$lckey] ) ) {
 456                         $message = $this->mExtensionMessages['en'][$lckey];
 457                 }
 458
 459                 # Try the array in the language object
 460                 if( $message === false ) {
 461                         #wfDebug( "Trying language object for message $key\n" );
 462                         wfSuppressWarnings();
 463                         $message = $lang->getMessage( $lckey );
 464                         wfRestoreWarnings();
 465                         if ( is_null( $message ) ) {
 466                                 $message = false;
 467                         }
 468                 }
 469
 470                 # Try the array of another language
 471                 $pos = strrpos( $lckey, '/' );
 472                 if( $message === false && $pos !== false) {
 473                         $mkey = substr( $lckey, 0, $pos );
 474                         $code = substr( $lckey, $pos+1 );
 475                         if ( $code ) {
 476                                 $validCodes = array_keys( Language::getLanguageNames() );
 477                                 if ( in_array( $code, $validCodes ) ) {
 478                                         $message = Language::getMessageFor( $mkey, $code );
 479                                         if ( is_null( $message ) ) {
 480                                                 $message = false;
 481                                         }
 482                                 } else {
 483                                         wfDebug( __METHOD__ . ": Invalid code $code for $mkey/$code, not trying messages array\n" );
 484                                 }
 485                         }
 486                 }
 487
 488                 # Is this a custom message? Try the default language in the db...
 489                 if( ($message === false || $message === '-' ) &&
 490                         !$this->mDisable && $useDB &&
 491                         !$isFullKey && ($langcode != $wgContLanguageCode) ) {
 492                         $message = $this->getMsgFromNamespace( $wgContLang->ucfirst( $lckey ) );
 493                 }
 494
 495                 # Final fallback
 496                 if( $message === false ) {
 497                         return '&lt;' . htmlspecialchars($key) . '&gt;';
 498                 }
 499                 return $message;
 500         }
 501
 502         /**
 503          * Get a message from the MediaWiki namespace, with caching. The key must
 504          * first be converted to two-part lang/msg form if necessary.
 505          *
 506          * @param string $title Message cache key with initial uppercase letter
 507          */
 508         function getMsgFromNamespace( $title ) {
 509                 $message = false;
 510                 $type = false;
 511
 512                 # Try the cache
 513                 if( $this->mUseCache && isset( $this->mCache[$title] ) ) {
 514                         $entry = $this->mCache[$title];
 515                         $type = substr( $entry, 0, 1 );
 516                         if ( $type == ' ' ) {
 517                                 return substr( $entry, 1 );
 518                         }
 519                 }
 520
 521                 # Call message hooks, in case they are defined
 522                 wfRunHooks('MessagesPreLoad', array( $title, &$message ) );
 523                 if ( $message !== false ) {
 524                         return $message;
 525                 }
 526
 527                 # If there is no cache entry and no placeholder, it doesn't exist
 528                 if ( $type != '!' && $message === false ) {
 529                         return false;
 530                 }
 531
 532                 $memcKey = $this->mMemcKey . ':' . $title;
 533
 534                 # Try the individual message cache
 535                 if ( $this->mUseCache ) {
 536                         $entry = $this->mMemc->get( $memcKey );
 537                         if ( $entry ) {
 538                                 $type = substr( $entry, 0, 1 );
 539
 540                                 if ( $type == ' ' ) {
 541                                         $message = substr( $entry, 1 );
 542                                         $this->mCache[$title] = $entry;
 543                                         return $message;
 544                                 } elseif ( $entry == '!NONEXISTENT' ) {
 545                                         return false;
 546                                 } else {
 547                                         # Corrupt/obsolete entry, delete it
 548                                         $this->mMemc->delete( $memcKey );
 549                                 }
 550
 551                         }
 552                 }
 553
 554                 # Try loading it from the DB
 555                 $revision = Revision::newFromTitle( Title::makeTitle( NS_MEDIAWIKI, $title ) );
 556                 if( $revision ) {
 557                         $message = $revision->getText();
 558                         if ($this->mUseCache) {
 559                                 $this->mCache[$title] = ' ' . $message;
 560                                 $this->mMemc->set( $memcKey, $message, $this->mExpiry );
 561                         }
 562                 } else {
 563                         # Negative caching
 564                         # Use some special text instead of false, because false gets converted to '' somewhere
 565                         $this->mMemc->set( $memcKey, '!NONEXISTENT', $this->mExpiry );
 566                         $this->mCache[$title] = false;
 567                 }
 568
 569                 return $message;
 570         }
 571
 572         function transform( $message, $interface = false ) {
 573                 global $wgParser;
 574                 if ( !$this->mParser && isset( $wgParser ) ) {
 575                         # Do some initialisation so that we don't have to do it twice
 576                         $wgParser->firstCallInit();
 577                         # Clone it and store it
 578                         $this->mParser = clone $wgParser;
 579                 }
 580                 if ( $this->mParser ) {
 581                         if( strpos( $message, '{{' ) !== false ) {
 582                                 $popts = $this->getParserOptions();
 583                                 $popts->setInterfaceMessage( $interface );
 584                                 $message = $this->mParser->transformMsg( $message, $popts );
 585                         }
 586                 }
 587                 return $message;
 588         }
 589
 590         function disable() { $this->mDisable = true; }
 591         function enable() { $this->mDisable = false; }
 592
 593         /** @deprecated */
 594         function disableTransform(){
 595                 wfDeprecated( __METHOD__ );
 596         }
 597         function enableTransform() {
 598                 wfDeprecated( __METHOD__ );
 599         }
 600         function setTransform( $x ) {
 601                 wfDeprecated( __METHOD__ );
 602         }
 603         function getTransform() {
 604                 wfDeprecated( __METHOD__ );
 605                 return false;
 606         }
 607
 608         /**
 609          * Add a message to the cache
 610          *
 611          * @param mixed $key
 612          * @param mixed $value
 613          * @param string $lang The messages language, English by default
 614          */
 615         function addMessage( $key, $value, $lang = 'en' ) {
 616                 $this->mExtensionMessages[$lang][$key] = $value;
 617         }
 618
 619         /**
 620          * Add an associative array of message to the cache
 621          *
 622          * @param array $messages An associative array of key => values to be added
 623          * @param string $lang The messages language, English by default
 624          */
 625         function addMessages( $messages, $lang = 'en' ) {
 626                 wfProfileIn( __METHOD__ );
 627                 if ( !is_array( $messages ) ) {
 628                         throw new MWException( __METHOD__.': Invalid message array' );
 629                 }
 630                 if ( isset( $this->mExtensionMessages[$lang] ) ) {
 631                         $this->mExtensionMessages[$lang] = $messages + $this->mExtensionMessages[$lang];
 632                 } else {
 633                         $this->mExtensionMessages[$lang] = $messages;
 634                 }
 635                 wfProfileOut( __METHOD__ );
 636         }
 637
 638         /**
 639          * Add a 2-D array of messages by lang. Useful for extensions.
 640          *
 641          * @param array $messages The array to be added
 642          */
 643         function addMessagesByLang( $messages ) {
 644                 wfProfileIn( __METHOD__ );
 645                 foreach ( $messages as $key => $value ) {
 646                         $this->addMessages( $value, $key );
 647                 }
 648                 wfProfileOut( __METHOD__ );
 649         }
 650
 651         /**
 652          * Get the extension messages for a specific language. Only English, interface
 653          * and content language are guaranteed to be loaded.
 654          *
 655          * @param string $lang The messages language, English by default
 656          */
 657         function getExtensionMessagesFor( $lang = 'en' ) {
 658                 wfProfileIn( __METHOD__ );
 659                 $messages = array();
 660                 if ( isset( $this->mExtensionMessages[$lang] ) ) {
 661                         $messages = $this->mExtensionMessages[$lang];
 662                 }
 663                 if ( $lang != 'en' ) {
 664                         $messages = $messages + $this->mExtensionMessages['en'];
 665                 }
 666                 wfProfileOut( __METHOD__ );
 667                 return $messages;
 668         }
 669
 670         /**
 671          * Clear all stored messages. Mainly used after a mass rebuild.
 672          */
 673         function clear() {
 674                 global $wgLocalMessageCache;
 675                 if( $this->mUseCache ) {
 676                         # Global cache
 677                         $this->mMemc->delete( $this->mMemcKey );
 678                         # Invalidate all local caches
 679                         $this->mMemc->delete( "{$this->mMemcKey}-hash" );
 680                 }
 681         }
 682
 683         function loadAllMessages() {
 684                 global $wgExtensionMessagesFiles;
 685                 if ( $this->mAllMessagesLoaded ) {
 686                         return;
 687                 }
 688                 $this->mAllMessagesLoaded = true;
 689
 690                 # Some extensions will load their messages when you load their class file
 691                 wfLoadAllExtensions();
 692                 # Others will respond to this hook
 693                 wfRunHooks( 'LoadAllMessages' );
 694                 # Some register their messages in $wgExtensionMessagesFiles
 695                 foreach ( $wgExtensionMessagesFiles as $name => $file ) {
 696                         if ( $file ) {
 697                                 $this->loadMessagesFile( $file );
 698                                 $wgExtensionMessagesFiles[$name] = false;
 699                         }
 700                 }
 701                 # Still others will respond to neither, they are EVIL. We sometimes need to know!
 702         }
 703
 704         /**
 705          * Load messages from a given file
 706          */
 707         function loadMessagesFile( $filename ) {
 708                 global $wgLang, $wgContLang;
 709                 $messages = $magicWords = false;
 710                 require( $filename );
 711
 712                 /*
 713                  * Load only languages that are usually used, and merge all fallbacks,
 714                  * except English.
 715                  */
 716                 $langs = array_unique( array( 'en', $wgContLang->getCode(), $wgLang->getCode() ) );
 717                 foreach( $langs as $code ) {
 718                         $fbcode = $code;
 719                         $mergedMessages = array();
 720                         do {
 721                                 if ( isset($messages[$fbcode]) ) {
 722                                         $mergedMessages += $messages[$fbcode];
 723                                 }
 724                                 $fbcode = Language::getFallbackfor( $fbcode );
 725                         } while( $fbcode && $fbcode !== 'en' );
 726
 727                         if ( !empty($mergedMessages) )
 728                                 $this->addMessages( $mergedMessages, $code );
 729                 }
 730
 731                 if ( $magicWords !== false ) {
 732                         global $wgContLang;
 733                         $wgContLang->addMagicWordsByLang( $magicWords );
 734                 }
 735         }
 736 }