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
  24 /**
  25  *
  26  */
  27 define( 'MSG_LOAD_TIMEOUT', 60 );
  28 define( 'MSG_LOCK_TIMEOUT', 10 );
  29 define( 'MSG_WAIT_TIMEOUT', 10 );
  30 define( 'MSG_CACHE_VERSION', 1 );
  31
  32 /**
  33  * Message cache
  34  * Performs various MediaWiki namespace-related functions
  35  * @ingroup Cache
  36  */
  37 class MessageCache {
  38         /**
  39          * Process local cache of loaded messages that are defined in
  40          * MediaWiki namespace. First array level is a language code,
  41          * second level is message key and the values are either message
  42          * content prefixed with space, or !NONEXISTENT for negative
  43          * caching.
  44          */
  45         protected $mCache;
  46
  47         // Should  mean that database cannot be used, but check
  48         protected $mDisable;
  49
  50         /// Lifetime for cache, used by object caching
  51         protected $mExpiry;
  52
  53         /**
  54          * Message cache has it's own parser which it uses to transform
  55          * messages.
  56          */
  57         protected $mParserOptions, $mParser;
  58
  59         /// Variable for tracking which variables are already loaded
  60         protected $mLoadedLanguages = array();
  61
  62         /**
  63          * Singleton instance
  64          *
  65          * @var MessageCache
  66          */
  67         private static $instance;
  68
  69         /**
  70          * @var bool
  71          */
  72         protected $mInParser = false;
  73
  74         /**
  75          * Get the signleton instance of this class
  76          *
  77          * @since 1.18
  78          * @return MessageCache object
  79          */
  80         public static function singleton() {
  81                 if ( is_null( self::$instance ) ) {
  82                         global $wgUseDatabaseMessages, $wgMsgCacheExpiry;
  83                         self::$instance = new self( wfGetMessageCacheStorage(), $wgUseDatabaseMessages, $wgMsgCacheExpiry );
  84                 }
  85                 return self::$instance;
  86         }
  87
  88         /**
  89          * Destroy the singleton instance
  90          *
  91          * @since 1.18
  92          */
  93         public static function destroyInstance() {
  94                 self::$instance = null;
  95         }
  96
  97         function __construct( $memCached, $useDB, $expiry ) {
  98                 if ( !$memCached ) {
  99                         $memCached = wfGetCache( CACHE_NONE );
 100                 }
 101
 102                 $this->mMemc = $memCached;
 103                 $this->mDisable = !$useDB;
 104                 $this->mExpiry = $expiry;
 105         }
 106
 107         /**
 108          * ParserOptions is lazy initialised.
 109          *
 110          * @return ParserOptions
 111          */
 112         function getParserOptions() {
 113                 if ( !$this->mParserOptions ) {
 114                         $this->mParserOptions = new ParserOptions;
 115                         $this->mParserOptions->setEditSection( false );
 116                 }
 117                 return $this->mParserOptions;
 118         }
 119
 120         /**
 121          * Try to load the cache from a local file.
 122          * Actual format of the file depends on the $wgLocalMessageCacheSerialized
 123          * setting.
 124          *
 125          * @param string $hash the hash of contents, to check validity.
 126          * @param $code Mixed: Optional language code, see documenation of load().
 127          * @return bool on failure.
 128          */
 129         function loadFromLocal( $hash, $code ) {
 130                 global $wgCacheDirectory, $wgLocalMessageCacheSerialized;
 131
 132                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 133
 134                 # Check file existence
 135                 wfSuppressWarnings();
 136                 $file = fopen( $filename, 'r' );
 137                 wfRestoreWarnings();
 138                 if ( !$file ) {
 139                         return false; // No cache file
 140                 }
 141
 142                 if ( $wgLocalMessageCacheSerialized ) {
 143                         // Check to see if the file has the hash specified
 144                         $localHash = fread( $file, 32 );
 145                         if ( $hash === $localHash ) {
 146                                 // All good, get the rest of it
 147                                 $serialized = '';
 148                                 while ( !feof( $file ) ) {
 149                                         $serialized .= fread( $file, 100000 );
 150                                 }
 151                                 fclose( $file );
 152                                 return $this->setCache( unserialize( $serialized ), $code );
 153                         } else {
 154                                 fclose( $file );
 155                                 return false; // Wrong hash
 156                         }
 157                 } else {
 158                         $localHash = substr( fread( $file, 40 ), 8 );
 159                         fclose( $file );
 160                         if ( $hash != $localHash ) {
 161                                 return false; // Wrong hash
 162                         }
 163
 164                         # Require overwrites the member variable or just shadows it?
 165                         require( $filename );
 166                         return $this->setCache( $this->mCache, $code );
 167                 }
 168         }
 169
 170         /**
 171          * Save the cache to a local file.
 172          */
 173         function saveToLocal( $serialized, $hash, $code ) {
 174                 global $wgCacheDirectory;
 175
 176                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 177                 wfMkdirParents( $wgCacheDirectory, null, __METHOD__ ); // might fail
 178
 179                 wfSuppressWarnings();
 180                 $file = fopen( $filename, 'w' );
 181                 wfRestoreWarnings();
 182
 183                 if ( !$file ) {
 184                         wfDebug( "Unable to open local cache file for writing\n" );
 185                         return;
 186                 }
 187
 188                 fwrite( $file, $hash . $serialized );
 189                 fclose( $file );
 190                 wfSuppressWarnings();
 191                 chmod( $filename, 0666 );
 192                 wfRestoreWarnings();
 193         }
 194
 195         function saveToScript( $array, $hash, $code ) {
 196                 global $wgCacheDirectory;
 197
 198                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 199                 $tempFilename = $filename . '.tmp';
 200                 wfMkdirParents( $wgCacheDirectory, null, __METHOD__ ); // might fail
 201
 202                 wfSuppressWarnings();
 203                 $file = fopen( $tempFilename, 'w' );
 204                 wfRestoreWarnings();
 205
 206                 if ( !$file ) {
 207                         wfDebug( "Unable to open local cache file for writing\n" );
 208                         return;
 209                 }
 210
 211                 fwrite( $file, "<?php\n//$hash\n\n \$this->mCache = array(" );
 212
 213                 foreach ( $array as $key => $message ) {
 214                         $key = $this->escapeForScript( $key );
 215                         $message = $this->escapeForScript( $message );
 216                         fwrite( $file, "'$key' => '$message',\n" );
 217                 }
 218
 219                 fwrite( $file, ");\n?>" );
 220                 fclose( $file);
 221                 rename( $tempFilename, $filename );
 222         }
 223
 224         function escapeForScript( $string ) {
 225                 $string = str_replace( '\\', '\\\\', $string );
 226                 $string = str_replace( '\'', '\\\'', $string );
 227                 return $string;
 228         }
 229
 230         /**
 231          * Set the cache to $cache, if it is valid. Otherwise set the cache to false.
 232          *
 233          * @return bool
 234          */
 235         function setCache( $cache, $code ) {
 236                 if ( isset( $cache['VERSION'] ) && $cache['VERSION'] == MSG_CACHE_VERSION ) {
 237                         $this->mCache[$code] = $cache;
 238                         return true;
 239                 } else {
 240                         return false;
 241                 }
 242         }
 243
 244         /**
 245          * Loads messages from caches or from database in this order:
 246          * (1) local message cache (if $wgUseLocalMessageCache is enabled)
 247          * (2) memcached
 248          * (3) from the database.
 249          *
 250          * When succesfully loading from (2) or (3), all higher level caches are
 251          * updated for the newest version.
 252          *
 253          * Nothing is loaded if member variable mDisable is true, either manually
 254          * set by calling code or if message loading fails (is this possible?).
 255          *
 256          * Returns true if cache is already populated or it was succesfully populated,
 257          * or false if populating empty cache fails. Also returns true if MessageCache
 258          * is disabled.
 259          *
 260          * @param bool|String $code String: language to which load messages
 261          * @throws MWException
 262          * @return bool
 263          */
 264         function load( $code = false ) {
 265                 global $wgUseLocalMessageCache;
 266
 267                 $exception = null; // deferred error
 268
 269                 if( !is_string( $code ) ) {
 270                         # This isn't really nice, so at least make a note about it and try to
 271                         # fall back
 272                         wfDebug( __METHOD__ . " called without providing a language code\n" );
 273                         $code = 'en';
 274                 }
 275
 276                 # Don't do double loading...
 277                 if ( isset( $this->mLoadedLanguages[$code] ) ) {
 278                         return true;
 279                 }
 280
 281                 # 8 lines of code just to say (once) that message cache is disabled
 282                 if ( $this->mDisable ) {
 283                         static $shownDisabled = false;
 284                         if ( !$shownDisabled ) {
 285                                 wfDebug( __METHOD__ . ": disabled\n" );
 286                                 $shownDisabled = true;
 287                         }
 288                         return true;
 289                 }
 290
 291                 # Loading code starts
 292                 wfProfileIn( __METHOD__ );
 293                 $success = false; # Keep track of success
 294                 $where = array(); # Debug info, delayed to avoid spamming debug log too much
 295                 $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages
 296
 297                 # (1) local cache
 298                 # Hash of the contents is stored in memcache, to detect if local cache goes
 299                 # out of date (due to update in other thread?)
 300                 if ( $wgUseLocalMessageCache ) {
 301                         wfProfileIn( __METHOD__ . '-fromlocal' );
 302
 303                         $hash = $this->mMemc->get( wfMemcKey( 'messages', $code, 'hash' ) );
 304                         if ( $hash ) {
 305                                 $success = $this->loadFromLocal( $hash, $code );
 306                                 if ( $success ) $where[] = 'got from local cache';
 307                         }
 308                         wfProfileOut( __METHOD__ . '-fromlocal' );
 309                 }
 310
 311                 # (2) memcache
 312                 # Fails if nothing in cache, or in the wrong version.
 313                 if ( !$success ) {
 314                         wfProfileIn( __METHOD__ . '-fromcache' );
 315                         $cache = $this->mMemc->get( $cacheKey );
 316                         $success = $this->setCache( $cache, $code );
 317                         if ( $success ) {
 318                                 $where[] = 'got from global cache';
 319                                 $this->saveToCaches( $cache, false, $code );
 320                         }
 321                         wfProfileOut( __METHOD__ . '-fromcache' );
 322                 }
 323
 324                 # (3)
 325                 # Nothing in caches... so we need create one and store it in caches
 326                 if ( !$success ) {
 327                         $where[] = 'cache is empty';
 328                         $where[] = 'loading from database';
 329
 330                         if ( $this->lock( $cacheKey ) ) {
 331                                 $that = $this;
 332                                 $osc = new ScopedCallback( function() use ( $that, $cacheKey ) {
 333                                         $that->unlock( $cacheKey );
 334                                 } );
 335                         }
 336                         # Limit the concurrency of loadFromDB to a single process
 337                         # This prevents the site from going down when the cache expires
 338                         $statusKey = wfMemcKey( 'messages', $code, 'status' );
 339                         $success = $this->mMemc->add( $statusKey, 'loading', MSG_LOAD_TIMEOUT );
 340                         if ( $success ) { // acquired lock
 341                                 $cache = $this->mMemc;
 342                                 $isc = new ScopedCallback( function() use ( $cache, $statusKey ) {
 343                                         $cache->delete( $statusKey );
 344                                 } );
 345                                 $cache = $this->loadFromDB( $code );
 346                                 $success = $this->setCache( $cache, $code );
 347                                 if ( $success ) { // messages loaded
 348                                         $success = $this->saveToCaches( $cache, true, $code );
 349                                         $isc = null; // unlock
 350                                         if ( !$success ) {
 351                                                 $this->mMemc->set( $statusKey, 'error', 60 * 5 );
 352                                                 wfDebug( __METHOD__ . ": set() error: restart memcached server!\n" );
 353                                                 $exception = new MWException( "Could not save cache for '$code'." );
 354                                         }
 355                                 } else {
 356                                         $isc = null; // unlock
 357                                         $exception = new MWException( "Could not load cache from DB for '$code'." );
 358                                 }
 359                         } else {
 360                                 $exception = new MWException( "Could not acquire '$statusKey' lock." );
 361                         }
 362                         $osc = null; // unlock
 363                 }
 364
 365                 if ( !$success ) {
 366                         $this->mDisable = true;
 367                         $this->mCache = false;
 368                         // This used to go on, but that led to lots of nasty side
 369                         // effects like gadgets and sidebar getting cached with their
 370                         // default content
 371                         if ( $exception instanceof Exception ) {
 372                                 throw $exception;
 373                         } else {
 374                                 throw new MWException( "MessageCache failed to load messages" );
 375                         }
 376                 } else {
 377                         # All good, just record the success
 378                         $info = implode( ', ', $where );
 379                         wfDebug( __METHOD__ . ": Loading $code... $info\n" );
 380                         $this->mLoadedLanguages[$code] = true;
 381                 }
 382                 wfProfileOut( __METHOD__ );
 383                 return $success;
 384         }
 385
 386         /**
 387          * Loads cacheable messages from the database. Messages bigger than
 388          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 389          * on-demand from the database later.
 390          *
 391          * @param string $code language code.
 392          * @return Array: loaded messages for storing in caches.
 393          */
 394         function loadFromDB( $code ) {
 395                 wfProfileIn( __METHOD__ );
 396                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 397                 $dbr = wfGetDB( DB_SLAVE );
 398                 $cache = array();
 399
 400                 # Common conditions
 401                 $conds = array(
 402                         'page_is_redirect' => 0,
 403                         'page_namespace' => NS_MEDIAWIKI,
 404                 );
 405
 406                 $mostused = array();
 407                 if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
 408                         if ( !isset( $this->mCache[$wgLanguageCode] ) ) {
 409                                 $this->load( $wgLanguageCode );
 410                         }
 411                         $mostused = array_keys( $this->mCache[$wgLanguageCode] );
 412                         foreach ( $mostused as $key => $value ) {
 413                                 $mostused[$key] = "$value/$code";
 414                         }
 415                 }
 416
 417                 if ( count( $mostused ) ) {
 418                         $conds['page_title'] = $mostused;
 419                 } elseif ( $code !== $wgLanguageCode ) {
 420                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
 421                 } else {
 422                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 423                         # other than language code.
 424                         $conds[] = 'page_title NOT' . $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 425                 }
 426
 427                 # Conditions to fetch oversized pages to ignore them
 428                 $bigConds = $conds;
 429                 $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );
 430
 431                 # Load titles for all oversized pages in the MediaWiki namespace
 432                 $res = $dbr->select( 'page', 'page_title', $bigConds, __METHOD__ . "($code)-big" );
 433                 foreach ( $res as $row ) {
 434                         $cache[$row->page_title] = '!TOO BIG';
 435                 }
 436
 437                 # Conditions to load the remaining pages with their contents
 438                 $smallConds = $conds;
 439                 $smallConds[] = 'page_latest=rev_id';
 440                 $smallConds[] = 'rev_text_id=old_id';
 441                 $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );
 442
 443                 $res = $dbr->select(
 444                         array( 'page', 'revision', 'text' ),
 445                         array( 'page_title', 'old_text', 'old_flags' ),
 446                         $smallConds,
 447                         __METHOD__ . "($code)-small"
 448                 );
 449
 450                 foreach ( $res as $row ) {
 451                         $text = Revision::getRevisionText( $row );
 452                         if( $text === false ) {
 453                                 // Failed to fetch data; possible ES errors?
 454                                 // Store a marker to fetch on-demand as a workaround...
 455                                 $entry = '!TOO BIG';
 456                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$row->page_title} ($code)" );
 457                         } else {
 458                                 $entry = ' ' . $text;
 459                         }
 460                         $cache[$row->page_title] = $entry;
 461                 }
 462
 463                 $cache['VERSION'] = MSG_CACHE_VERSION;
 464                 wfProfileOut( __METHOD__ );
 465                 return $cache;
 466         }
 467
 468         /**
 469          * Updates cache as necessary when message page is changed
 470          *
 471          * @param string $title name of the page changed.
 472          * @param $text Mixed: new contents of the page.
 473          */
 474         public function replace( $title, $text ) {
 475                 global $wgMaxMsgCacheEntrySize;
 476                 wfProfileIn( __METHOD__ );
 477
 478                 if ( $this->mDisable ) {
 479                         wfProfileOut( __METHOD__ );
 480                         return;
 481                 }
 482
 483                 list( $msg, $code ) = $this->figureMessage( $title );
 484
 485                 $cacheKey = wfMemcKey( 'messages', $code );
 486                 $this->load( $code );
 487                 $this->lock( $cacheKey );
 488
 489                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 490
 491                 if ( $text === false ) {
 492                         # Article was deleted
 493                         $this->mCache[$code][$title] = '!NONEXISTENT';
 494                         $this->mMemc->delete( $titleKey );
 495                 } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 496                         # Check for size
 497                         $this->mCache[$code][$title] = '!TOO BIG';
 498                         $this->mMemc->set( $titleKey, ' ' . $text, $this->mExpiry );
 499                 } else {
 500                         $this->mCache[$code][$title] = ' ' . $text;
 501                         $this->mMemc->delete( $titleKey );
 502                 }
 503
 504                 # Update caches
 505                 $this->saveToCaches( $this->mCache[$code], true, $code );
 506                 $this->unlock( $cacheKey );
 507
 508                 // Also delete cached sidebar... just in case it is affected
 509                 $codes = array( $code );
 510                 if ( $code === 'en' ) {
 511                         // Delete all sidebars, like for example on action=purge on the
 512                         // sidebar messages
 513                         $codes = array_keys( Language::fetchLanguageNames() );
 514                 }
 515
 516                 global $wgMemc;
 517                 foreach ( $codes as $code ) {
 518                         $sidebarKey = wfMemcKey( 'sidebar', $code );
 519                         $wgMemc->delete( $sidebarKey );
 520                 }
 521
 522                 // Update the message in the message blob store
 523                 global $wgContLang;
 524                 MessageBlobStore::updateMessage( $wgContLang->lcfirst( $msg ) );
 525
 526                 wfRunHooks( 'MessageCacheReplace', array( $title, $text ) );
 527
 528                 wfProfileOut( __METHOD__ );
 529         }
 530
 531         /**
 532          * Shortcut to update caches.
 533          *
 534          * @param array $cache cached messages with a version.
 535          * @param bool $memc Wether to update or not memcache.
 536          * @param string $code Language code.
 537          * @return bool on somekind of error.
 538          */
 539         protected function saveToCaches( $cache, $memc = true, $code = false ) {
 540                 wfProfileIn( __METHOD__ );
 541                 global $wgUseLocalMessageCache, $wgLocalMessageCacheSerialized;
 542
 543                 $cacheKey = wfMemcKey( 'messages', $code );
 544
 545                 if ( $memc ) {
 546                         $success = $this->mMemc->set( $cacheKey, $cache, $this->mExpiry );
 547                 } else {
 548                         $success = true;
 549                 }
 550
 551                 # Save to local cache
 552                 if ( $wgUseLocalMessageCache ) {
 553                         $serialized = serialize( $cache );
 554                         $hash = md5( $serialized );
 555                         $this->mMemc->set( wfMemcKey( 'messages', $code, 'hash' ), $hash, $this->mExpiry );
 556                         if ( $wgLocalMessageCacheSerialized ) {
 557                                 $this->saveToLocal( $serialized, $hash, $code );
 558                         } else {
 559                                 $this->saveToScript( $cache, $hash, $code );
 560                         }
 561                 }
 562
 563                 wfProfileOut( __METHOD__ );
 564                 return $success;
 565         }
 566
 567         /**
 568          * Represents a write lock on the messages key
 569          *
 570          * @param $key string
 571          *
 572          * @return Boolean: success
 573          */
 574         function lock( $key ) {
 575                 $lockKey = $key . ':lock';
 576                 for ( $i = 0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
 577                         sleep( 1 );
 578                 }
 579
 580                 return $i >= MSG_WAIT_TIMEOUT;
 581         }
 582
 583         function unlock( $key ) {
 584                 $lockKey = $key . ':lock';
 585                 $this->mMemc->delete( $lockKey );
 586         }
 587
 588         /**
 589          * Get a message from either the content language or the user language.
 590          *
 591          * @param $key String: the message cache key
 592          * @param $useDB Boolean: get the message from the DB, false to use only
 593          *               the localisation
 594          * @param bool|string $langcode Code of the language to get the message for, if
 595          *                  it is a valid code create a language for that language,
 596          *                  if it is a string but not a valid code then make a basic
 597          *                  language object, if it is a false boolean then use the
 598          *                  current users language (as a fallback for the old
 599          *                  parameter functionality), or if it is a true boolean
 600          *                  then use the wikis content language (also as a
 601          *                  fallback).
 602          * @param $isFullKey Boolean: specifies whether $key is a two part key
 603          *                   "msg/lang".
 604          *
 605          * @throws MWException
 606          * @return string|bool
 607          */
 608         function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
 609                 global $wgLanguageCode, $wgContLang;
 610
 611                 if ( is_int( $key ) ) {
 612                         // "Non-string key given" exception sometimes happens for numerical strings that become ints somewhere on their way here
 613                         $key = strval( $key );
 614                 }
 615
 616                 if ( !is_string( $key ) ) {
 617                         throw new MWException( 'Non-string key given' );
 618                 }
 619
 620                 if ( strval( $key ) === '' ) {
 621                         # Shortcut: the empty key is always missing
 622                         return false;
 623                 }
 624
 625                 $lang = wfGetLangObj( $langcode );
 626                 if ( !$lang ) {
 627                         throw new MWException( "Bad lang code $langcode given" );
 628                 }
 629
 630                 $langcode = $lang->getCode();
 631
 632                 $message = false;
 633
 634                 # Normalise title-case input (with some inlining)
 635                 $lckey = str_replace( ' ', '_', $key );
 636                 if ( ord( $key ) < 128 ) {
 637                         $lckey[0] = strtolower( $lckey[0] );
 638                         $uckey = ucfirst( $lckey );
 639                 } else {
 640                         $lckey = $wgContLang->lcfirst( $lckey );
 641                         $uckey = $wgContLang->ucfirst( $lckey );
 642                 }
 643
 644                 # Try the MediaWiki namespace
 645                 if( !$this->mDisable && $useDB ) {
 646                         $title = $uckey;
 647                         if( !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 648                                 $title .= '/' . $langcode;
 649                         }
 650                         $message = $this->getMsgFromNamespace( $title, $langcode );
 651                 }
 652
 653                 # Try the array in the language object
 654                 if ( $message === false ) {
 655                         $message = $lang->getMessage( $lckey );
 656                         if ( is_null( $message ) ) {
 657                                 $message = false;
 658                         }
 659                 }
 660
 661                 # Try the array of another language
 662                 if( $message === false ) {
 663                         $parts = explode( '/', $lckey );
 664                         # We may get calls for things that are http-urls from sidebar
 665                         # Let's not load nonexistent languages for those
 666                         # They usually have more than one slash.
 667                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 668                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 669                                 if ( is_null( $message ) ) {
 670                                         $message = false;
 671                                 }
 672                         }
 673                 }
 674
 675                 # Is this a custom message? Try the default language in the db...
 676                 if( ( $message === false || $message === '-' ) &&
 677                         !$this->mDisable && $useDB &&
 678                         !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 679                         $message = $this->getMsgFromNamespace( $uckey, $wgLanguageCode );
 680                 }
 681
 682                 # Final fallback
 683                 if( $message === false ) {
 684                         return false;
 685                 }
 686
 687                 # Fix whitespace
 688                 $message = strtr( $message,
 689                         array(
 690                                 # Fix for trailing whitespace, removed by textarea
 691                                 '&#32;' => ' ',
 692                                 # Fix for NBSP, converted to space by firefox
 693                                 '&nbsp;' => "\xc2\xa0",
 694                                 '&#160;' => "\xc2\xa0",
 695                         ) );
 696
 697                 return $message;
 698         }
 699
 700         /**
 701          * Get a message from the MediaWiki namespace, with caching. The key must
 702          * first be converted to two-part lang/msg form if necessary.
 703          *
 704          * @param string $title Message cache key with initial uppercase letter.
 705          * @param string $code code denoting the language to try.
 706          *
 707          * @return string|bool False on failure
 708          */
 709         function getMsgFromNamespace( $title, $code ) {
 710                 $this->load( $code );
 711                 if ( isset( $this->mCache[$code][$title] ) ) {
 712                         $entry = $this->mCache[$code][$title];
 713                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 714                                 return substr( $entry, 1 );
 715                         } elseif ( $entry === '!NONEXISTENT' ) {
 716                                 return false;
 717                         } elseif( $entry === '!TOO BIG' ) {
 718                                 // Fall through and try invididual message cache below
 719                         }
 720                 } else {
 721                         // XXX: This is not cached in process cache, should it?
 722                         $message = false;
 723                         wfRunHooks( 'MessagesPreLoad', array( $title, &$message ) );
 724                         if ( $message !== false ) {
 725                                 return $message;
 726                         }
 727
 728                         return false;
 729                 }
 730
 731                 # Try the individual message cache
 732                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 733                 $entry = $this->mMemc->get( $titleKey );
 734                 if ( $entry ) {
 735                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 736                                 $this->mCache[$code][$title] = $entry;
 737                                 return substr( $entry, 1 );
 738                         } elseif ( $entry === '!NONEXISTENT' ) {
 739                                 $this->mCache[$code][$title] = '!NONEXISTENT';
 740                                 return false;
 741                         } else {
 742                                 # Corrupt/obsolete entry, delete it
 743                                 $this->mMemc->delete( $titleKey );
 744                         }
 745                 }
 746
 747                 # Try loading it from the database
 748                 $revision = Revision::newFromTitle(
 749                         Title::makeTitle( NS_MEDIAWIKI, $title ), false, Revision::READ_LATEST
 750                 );
 751                 if ( $revision ) {
 752                         $content = $revision->getContent();
 753                         if ( !$content ) {
 754                                 // A possibly temporary loading failure.
 755                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$title} ($code)" );
 756                                 $message = null; // no negative caching
 757                         } else {
 758                                 // XXX: Is this the right way to turn a Content object into a message?
 759                                 // NOTE: $content is typically either WikitextContent, JavaScriptContent or CssContent.
 760                                 //       MessageContent is *not* used for storing messages, it's only used for wrapping them when needed.
 761                                 $message = $content->getWikitextForTransclusion();
 762
 763                                 if ( $message === false || $message === null ) {
 764                                         wfDebugLog( 'MessageCache', __METHOD__ . ": message content doesn't provide wikitext "
 765                                                                 . "(content model: " . $content->getContentHandler() . ")" );
 766
 767                                         $message = false; // negative caching
 768                                 } else {
 769                                         $this->mCache[$code][$title] = ' ' . $message;
 770                                         $this->mMemc->set( $titleKey, ' ' . $message, $this->mExpiry );
 771                                 }
 772                         }
 773                 } else {
 774                         $message = false; // negative caching
 775                 }
 776
 777                 if ( $message === false ) { // negative caching
 778                         $this->mCache[$code][$title] = '!NONEXISTENT';
 779                         $this->mMemc->set( $titleKey, '!NONEXISTENT', $this->mExpiry );
 780                 }
 781
 782                 return $message;
 783         }
 784
 785         /**
 786          * @param $message string
 787          * @param $interface bool
 788          * @param $language
 789          * @param $title Title
 790          * @return string
 791          */
 792         function transform( $message, $interface = false, $language = null, $title = null ) {
 793                 // Avoid creating parser if nothing to transform
 794                 if( strpos( $message, '{{' ) === false ) {
 795                         return $message;
 796                 }
 797
 798                 if ( $this->mInParser ) {
 799                         return $message;
 800                 }
 801
 802                 $parser = $this->getParser();
 803                 if ( $parser ) {
 804                         $popts = $this->getParserOptions();
 805                         $popts->setInterfaceMessage( $interface );
 806                         $popts->setTargetLanguage( $language );
 807
 808                         $userlang = $popts->setUserLang( $language );
 809                         $this->mInParser = true;
 810                         $message = $parser->transformMsg( $message, $popts, $title );
 811                         $this->mInParser = false;
 812                         $popts->setUserLang( $userlang );
 813                 }
 814                 return $message;
 815         }
 816
 817         /**
 818          * @return Parser
 819          */
 820         function getParser() {
 821                 global $wgParser, $wgParserConf;
 822                 if ( !$this->mParser && isset( $wgParser ) ) {
 823                         # Do some initialisation so that we don't have to do it twice
 824                         $wgParser->firstCallInit();
 825                         # Clone it and store it
 826                         $class = $wgParserConf['class'];
 827                         if ( $class == 'Parser_DiffTest' ) {
 828                                 # Uncloneable
 829                                 $this->mParser = new $class( $wgParserConf );
 830                         } else {
 831                                 $this->mParser = clone $wgParser;
 832                         }
 833                 }
 834                 return $this->mParser;
 835         }
 836
 837         /**
 838          * @param $text string
 839          * @param $title Title
 840          * @param $linestart bool
 841          * @param $interface bool
 842          * @param $language
 843          * @return ParserOutput|string
 844          */
 845         public function parse( $text, $title = null, $linestart = true, $interface = false, $language = null  ) {
 846                 if ( $this->mInParser ) {
 847                         return htmlspecialchars( $text );
 848                 }
 849
 850                 $parser = $this->getParser();
 851                 $popts = $this->getParserOptions();
 852                 $popts->setInterfaceMessage( $interface );
 853                 $popts->setTargetLanguage( $language );
 854
 855                 wfProfileIn( __METHOD__ );
 856                 if ( !$title || !$title instanceof Title ) {
 857                         global $wgTitle;
 858                         $title = $wgTitle;
 859                 }
 860                 // Sometimes $wgTitle isn't set either...
 861                 if ( !$title ) {
 862                         # It's not uncommon having a null $wgTitle in scripts. See r80898
 863                         # Create a ghost title in such case
 864                         $title = Title::newFromText( 'Dwimmerlaik' );
 865                 }
 866
 867                 $this->mInParser = true;
 868                 $res = $parser->parse( $text, $title, $popts, $linestart );
 869                 $this->mInParser = false;
 870
 871                 wfProfileOut( __METHOD__ );
 872                 return $res;
 873         }
 874
 875         function disable() {
 876                 $this->mDisable = true;
 877         }
 878
 879         function enable() {
 880                 $this->mDisable = false;
 881         }
 882
 883         /**
 884          * Clear all stored messages. Mainly used after a mass rebuild.
 885          */
 886         function clear() {
 887                 $langs = Language::fetchLanguageNames( null, 'mw' );
 888                 foreach ( array_keys( $langs ) as $code ) {
 889                         # Global cache
 890                         $this->mMemc->delete( wfMemcKey( 'messages', $code ) );
 891                         # Invalidate all local caches
 892                         $this->mMemc->delete( wfMemcKey( 'messages', $code, 'hash' ) );
 893                 }
 894                 $this->mLoadedLanguages = array();
 895         }
 896
 897         /**
 898          * @param $key
 899          * @return array
 900          */
 901         public function figureMessage( $key ) {
 902                 global $wgLanguageCode;
 903                 $pieces = explode( '/', $key );
 904                 if( count( $pieces ) < 2 ) {
 905                         return array( $key, $wgLanguageCode );
 906                 }
 907
 908                 $lang = array_pop( $pieces );
 909                 if( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
 910                         return array( $key, $wgLanguageCode );
 911                 }
 912
 913                 $message = implode( '/', $pieces );
 914                 return array( $message, $lang );
 915         }
 916
 917         /**
 918          * Get all message keys stored in the message cache for a given language.
 919          * If $code is the content language code, this will return all message keys
 920          * for which MediaWiki:msgkey exists. If $code is another language code, this
 921          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
 922          * @param $code string
 923          * @return array of message keys (strings)
 924          */
 925         public function getAllMessageKeys( $code ) {
 926                 global $wgContLang;
 927                 $this->load( $code );
 928                 if ( !isset( $this->mCache[$code] ) ) {
 929                         // Apparently load() failed
 930                         return null;
 931                 }
 932                 $cache = $this->mCache[$code]; // Copy the cache
 933                 unset( $cache['VERSION'] ); // Remove the VERSION key
 934                 $cache = array_diff( $cache, array( '!NONEXISTENT' ) ); // Remove any !NONEXISTENT keys
 935                 // Keys may appear with a capital first letter. lcfirst them.
 936                 return array_map( array( $wgContLang, 'lcfirst' ), array_keys( $cache ) );
 937         }
 938 }