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 $hash String: 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 $code String: language to which load messages
 261          * @return bool
 262          */
 263         function load( $code = false ) {
 264                 global $wgUseLocalMessageCache;
 265
 266                 if( !is_string( $code ) ) {
 267                         # This isn't really nice, so at least make a note about it and try to
 268                         # fall back
 269                         wfDebug( __METHOD__ . " called without providing a language code\n" );
 270                         $code = 'en';
 271                 }
 272
 273                 # Don't do double loading...
 274                 if ( isset( $this->mLoadedLanguages[$code] ) ) {
 275                         return true;
 276                 }
 277
 278                 # 8 lines of code just to say (once) that message cache is disabled
 279                 if ( $this->mDisable ) {
 280                         static $shownDisabled = false;
 281                         if ( !$shownDisabled ) {
 282                                 wfDebug( __METHOD__ . ": disabled\n" );
 283                                 $shownDisabled = true;
 284                         }
 285                         return true;
 286                 }
 287
 288                 # Loading code starts
 289                 wfProfileIn( __METHOD__ );
 290                 $success = false; # Keep track of success
 291                 $where = array(); # Debug info, delayed to avoid spamming debug log too much
 292                 $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages
 293
 294                 # (1) local cache
 295                 # Hash of the contents is stored in memcache, to detect if local cache goes
 296                 # out of date (due to update in other thread?)
 297                 if ( $wgUseLocalMessageCache ) {
 298                         wfProfileIn( __METHOD__ . '-fromlocal' );
 299
 300                         $hash = $this->mMemc->get( wfMemcKey( 'messages', $code, 'hash' ) );
 301                         if ( $hash ) {
 302                                 $success = $this->loadFromLocal( $hash, $code );
 303                                 if ( $success ) $where[] = 'got from local cache';
 304                         }
 305                         wfProfileOut( __METHOD__ . '-fromlocal' );
 306                 }
 307
 308                 # (2) memcache
 309                 # Fails if nothing in cache, or in the wrong version.
 310                 if ( !$success ) {
 311                         wfProfileIn( __METHOD__ . '-fromcache' );
 312                         $cache = $this->mMemc->get( $cacheKey );
 313                         $success = $this->setCache( $cache, $code );
 314                         if ( $success ) {
 315                                 $where[] = 'got from global cache';
 316                                 $this->saveToCaches( $cache, false, $code );
 317                         }
 318                         wfProfileOut( __METHOD__ . '-fromcache' );
 319                 }
 320
 321                 # (3)
 322                 # Nothing in caches... so we need create one and store it in caches
 323                 if ( !$success ) {
 324                         $where[] = 'cache is empty';
 325                         $where[] = 'loading from database';
 326
 327                         $this->lock( $cacheKey );
 328
 329                         # Limit the concurrency of loadFromDB to a single process
 330                         # This prevents the site from going down when the cache expires
 331                         $statusKey = wfMemcKey( 'messages', $code, 'status' );
 332                         $success = $this->mMemc->add( $statusKey, 'loading', MSG_LOAD_TIMEOUT );
 333                         if ( $success ) {
 334                                 $cache = $this->loadFromDB( $code );
 335                                 $success = $this->setCache( $cache, $code );
 336                         }
 337                         if ( $success ) {
 338                                 $success = $this->saveToCaches( $cache, true, $code );
 339                                 if ( $success ) {
 340                                         $this->mMemc->delete( $statusKey );
 341                                 } else {
 342                                         $this->mMemc->set( $statusKey, 'error', 60 * 5 );
 343                                         wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
 344                                 }
 345                         }
 346                         $this->unlock($cacheKey);
 347                 }
 348
 349                 if ( !$success ) {
 350                         # Bad luck... this should not happen
 351                         $where[] = 'loading FAILED - cache is disabled';
 352                         $info = implode( ', ', $where );
 353                         wfDebug( __METHOD__ . ": Loading $code... $info\n" );
 354                         $this->mDisable = true;
 355                         $this->mCache = false;
 356                 } else {
 357                         # All good, just record the success
 358                         $info = implode( ', ', $where );
 359                         wfDebug( __METHOD__ . ": Loading $code... $info\n" );
 360                         $this->mLoadedLanguages[$code] = true;
 361                 }
 362                 wfProfileOut( __METHOD__ );
 363                 return $success;
 364         }
 365
 366         /**
 367          * Loads cacheable messages from the database. Messages bigger than
 368          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 369          * on-demand from the database later.
 370          *
 371          * @param $code String: language code.
 372          * @return Array: loaded messages for storing in caches.
 373          */
 374         function loadFromDB( $code ) {
 375                 wfProfileIn( __METHOD__ );
 376                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 377                 $dbr = wfGetDB( DB_SLAVE );
 378                 $cache = array();
 379
 380                 # Common conditions
 381                 $conds = array(
 382                         'page_is_redirect' => 0,
 383                         'page_namespace' => NS_MEDIAWIKI,
 384                 );
 385
 386                 $mostused = array();
 387                 if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
 388                         if ( !isset( $this->mCache[$wgLanguageCode] ) ) {
 389                                 $this->load( $wgLanguageCode );
 390                         }
 391                         $mostused = array_keys( $this->mCache[$wgLanguageCode] );
 392                         foreach ( $mostused as $key => $value ) {
 393                                 $mostused[$key] = "$value/$code";
 394                         }
 395                 }
 396
 397                 if ( count( $mostused ) ) {
 398                         $conds['page_title'] = $mostused;
 399                 } elseif ( $code !== $wgLanguageCode ) {
 400                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
 401                 } else {
 402                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 403                         # other than language code.
 404                         $conds[] = 'page_title NOT' . $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 405                 }
 406
 407                 # Conditions to fetch oversized pages to ignore them
 408                 $bigConds = $conds;
 409                 $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );
 410
 411                 # Load titles for all oversized pages in the MediaWiki namespace
 412                 $res = $dbr->select( 'page', 'page_title', $bigConds, __METHOD__ . "($code)-big" );
 413                 foreach ( $res as $row ) {
 414                         $cache[$row->page_title] = '!TOO BIG';
 415                 }
 416
 417                 # Conditions to load the remaining pages with their contents
 418                 $smallConds = $conds;
 419                 $smallConds[] = 'page_latest=rev_id';
 420                 $smallConds[] = 'rev_text_id=old_id';
 421                 $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );
 422
 423                 $res = $dbr->select(
 424                         array( 'page', 'revision', 'text' ),
 425                         array( 'page_title', 'old_text', 'old_flags' ),
 426                         $smallConds,
 427                         __METHOD__ . "($code)-small"
 428                 );
 429
 430                 foreach ( $res as $row ) {
 431                         $text = Revision::getRevisionText( $row );
 432                         if( $text === false ) {
 433                                 // Failed to fetch data; possible ES errors?
 434                                 // Store a marker to fetch on-demand as a workaround...
 435                                 $entry = '!TOO BIG';
 436                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$row->page_title} ($code)" );
 437                         } else {
 438                                 $entry = ' ' . $text;
 439                         }
 440                         $cache[$row->page_title] = $entry;
 441                 }
 442
 443                 $cache['VERSION'] = MSG_CACHE_VERSION;
 444                 wfProfileOut( __METHOD__ );
 445                 return $cache;
 446         }
 447
 448         /**
 449          * Updates cache as necessary when message page is changed
 450          *
 451          * @param $title String: name of the page changed.
 452          * @param $text Mixed: new contents of the page.
 453          */
 454         public function replace( $title, $text ) {
 455                 global $wgMaxMsgCacheEntrySize;
 456                 wfProfileIn( __METHOD__ );
 457
 458                 if ( $this->mDisable ) {
 459                         wfProfileOut( __METHOD__ );
 460                         return;
 461                 }
 462
 463                 list( $msg, $code ) = $this->figureMessage( $title );
 464
 465                 $cacheKey = wfMemcKey( 'messages', $code );
 466                 $this->load( $code );
 467                 $this->lock( $cacheKey );
 468
 469                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 470
 471                 if ( $text === false ) {
 472                         # Article was deleted
 473                         $this->mCache[$code][$title] = '!NONEXISTENT';
 474                         $this->mMemc->delete( $titleKey );
 475                 } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 476                         # Check for size
 477                         $this->mCache[$code][$title] = '!TOO BIG';
 478                         $this->mMemc->set( $titleKey, ' ' . $text, $this->mExpiry );
 479                 } else {
 480                         $this->mCache[$code][$title] = ' ' . $text;
 481                         $this->mMemc->delete( $titleKey );
 482                 }
 483
 484                 # Update caches
 485                 $this->saveToCaches( $this->mCache[$code], true, $code );
 486                 $this->unlock( $cacheKey );
 487
 488                 // Also delete cached sidebar... just in case it is affected
 489                 $codes = array( $code );
 490                 if ( $code === 'en'  ) {
 491                         // Delete all sidebars, like for example on action=purge on the
 492                         // sidebar messages
 493                         $codes = array_keys( Language::fetchLanguageNames() );
 494                 }
 495
 496                 global $wgMemc;
 497                 foreach ( $codes as $code ) {
 498                         $sidebarKey = wfMemcKey( 'sidebar', $code );
 499                         $wgMemc->delete( $sidebarKey );
 500                 }
 501
 502                 // Update the message in the message blob store
 503                 global $wgContLang;
 504                 MessageBlobStore::updateMessage( $wgContLang->lcfirst( $msg ) );
 505
 506                 wfRunHooks( 'MessageCacheReplace', array( $title, $text ) );
 507
 508                 wfProfileOut( __METHOD__ );
 509         }
 510
 511         /**
 512          * Shortcut to update caches.
 513          *
 514          * @param $cache Array: cached messages with a version.
 515          * @param $memc Bool: Wether to update or not memcache.
 516          * @param $code String: Language code.
 517          * @return bool on somekind of error.
 518          */
 519         protected function saveToCaches( $cache, $memc = true, $code = false ) {
 520                 wfProfileIn( __METHOD__ );
 521                 global $wgUseLocalMessageCache, $wgLocalMessageCacheSerialized;
 522
 523                 $cacheKey = wfMemcKey( 'messages', $code );
 524
 525                 if ( $memc ) {
 526                         $success = $this->mMemc->set( $cacheKey, $cache, $this->mExpiry );
 527                 } else {
 528                         $success = true;
 529                 }
 530
 531                 # Save to local cache
 532                 if ( $wgUseLocalMessageCache ) {
 533                         $serialized = serialize( $cache );
 534                         $hash = md5( $serialized );
 535                         $this->mMemc->set( wfMemcKey( 'messages', $code, 'hash' ), $hash, $this->mExpiry );
 536                         if ($wgLocalMessageCacheSerialized) {
 537                                 $this->saveToLocal( $serialized, $hash, $code );
 538                         } else {
 539                                 $this->saveToScript( $cache, $hash, $code );
 540                         }
 541                 }
 542
 543                 wfProfileOut( __METHOD__ );
 544                 return $success;
 545         }
 546
 547         /**
 548          * Represents a write lock on the messages key
 549          *
 550          * @param $key string
 551          *
 552          * @return Boolean: success
 553          */
 554         function lock( $key ) {
 555                 $lockKey = $key . ':lock';
 556                 for ( $i = 0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
 557                         sleep( 1 );
 558                 }
 559
 560                 return $i >= MSG_WAIT_TIMEOUT;
 561         }
 562
 563         function unlock( $key ) {
 564                 $lockKey = $key . ':lock';
 565                 $this->mMemc->delete( $lockKey );
 566         }
 567
 568         /**
 569          * Get a message from either the content language or the user language.
 570          *
 571          * @param $key String: the message cache key
 572          * @param $useDB Boolean: get the message from the DB, false to use only
 573          *               the localisation
 574          * @param bool|string $langcode Code of the language to get the message for, if
 575          *                  it is a valid code create a language for that language,
 576          *                  if it is a string but not a valid code then make a basic
 577          *                  language object, if it is a false boolean then use the
 578          *                  current users language (as a fallback for the old
 579          *                  parameter functionality), or if it is a true boolean
 580          *                  then use the wikis content language (also as a
 581          *                  fallback).
 582          * @param $isFullKey Boolean: specifies whether $key is a two part key
 583          *                   "msg/lang".
 584          *
 585          * @throws MWException
 586          * @return string|bool
 587          */
 588         function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
 589                 global $wgLanguageCode, $wgContLang;
 590
 591                 if ( is_int( $key ) ) {
 592                         // "Non-string key given" exception sometimes happens for numerical strings that become ints somewhere on their way here
 593                         $key = strval( $key );
 594                 }
 595
 596                 if ( !is_string( $key ) ) {
 597                         throw new MWException( 'Non-string key given' );
 598                 }
 599
 600                 if ( strval( $key ) === '' ) {
 601                         # Shortcut: the empty key is always missing
 602                         return false;
 603                 }
 604
 605                 $lang = wfGetLangObj( $langcode );
 606                 if ( !$lang ) {
 607                         throw new MWException( "Bad lang code $langcode given" );
 608                 }
 609
 610                 $langcode = $lang->getCode();
 611
 612                 $message = false;
 613
 614                 # Normalise title-case input (with some inlining)
 615                 $lckey = str_replace( ' ', '_', $key );
 616                 if ( ord( $key ) < 128 ) {
 617                         $lckey[0] = strtolower( $lckey[0] );
 618                         $uckey = ucfirst( $lckey );
 619                 } else {
 620                         $lckey = $wgContLang->lcfirst( $lckey );
 621                         $uckey = $wgContLang->ucfirst( $lckey );
 622                 }
 623
 624                 # Try the MediaWiki namespace
 625                 if( !$this->mDisable && $useDB ) {
 626                         $title = $uckey;
 627                         if( !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 628                                 $title .= '/' . $langcode;
 629                         }
 630                         $message = $this->getMsgFromNamespace( $title, $langcode );
 631                 }
 632
 633                 # Try the array in the language object
 634                 if ( $message === false ) {
 635                         $message = $lang->getMessage( $lckey );
 636                         if ( is_null( $message ) ) {
 637                                 $message = false;
 638                         }
 639                 }
 640
 641                 # Try the array of another language
 642                 if( $message === false ) {
 643                         $parts = explode( '/', $lckey );
 644                         # We may get calls for things that are http-urls from sidebar
 645                         # Let's not load nonexistent languages for those
 646                         # They usually have more than one slash.
 647                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 648                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 649                                 if ( is_null( $message ) ) {
 650                                         $message = false;
 651                                 }
 652                         }
 653                 }
 654
 655                 # Is this a custom message? Try the default language in the db...
 656                 if( ( $message === false || $message === '-' ) &&
 657                         !$this->mDisable && $useDB &&
 658                         !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 659                         $message = $this->getMsgFromNamespace( $uckey, $wgLanguageCode );
 660                 }
 661
 662                 # Final fallback
 663                 if( $message === false ) {
 664                         return false;
 665                 }
 666
 667                 # Fix whitespace
 668                 $message = strtr( $message,
 669                         array(
 670                                 # Fix for trailing whitespace, removed by textarea
 671                                 '&#32;' => ' ',
 672                                 # Fix for NBSP, converted to space by firefox
 673                                 '&nbsp;' => "\xc2\xa0",
 674                                 '&#160;' => "\xc2\xa0",
 675                         ) );
 676
 677                 return $message;
 678         }
 679
 680         /**
 681          * Get a message from the MediaWiki namespace, with caching. The key must
 682          * first be converted to two-part lang/msg form if necessary.
 683          *
 684          * @param $title String: Message cache key with initial uppercase letter.
 685          * @param $code String: code denoting the language to try.
 686          *
 687          * @return string|bool False on failure
 688          */
 689         function getMsgFromNamespace( $title, $code ) {
 690                 $this->load( $code );
 691                 if ( isset( $this->mCache[$code][$title] ) ) {
 692                         $entry = $this->mCache[$code][$title];
 693                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 694                                 return substr( $entry, 1 );
 695                         } elseif ( $entry === '!NONEXISTENT' ) {
 696                                 return false;
 697                         } elseif( $entry === '!TOO BIG' ) {
 698                                 // Fall through and try invididual message cache below
 699                         }
 700                 } else {
 701                         // XXX: This is not cached in process cache, should it?
 702                         $message = false;
 703                         wfRunHooks( 'MessagesPreLoad', array( $title, &$message ) );
 704                         if ( $message !== false ) {
 705                                 return $message;
 706                         }
 707
 708                         return false;
 709                 }
 710
 711                 # Try the individual message cache
 712                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 713                 $entry = $this->mMemc->get( $titleKey );
 714                 if ( $entry ) {
 715                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 716                                 $this->mCache[$code][$title] = $entry;
 717                                 return substr( $entry, 1 );
 718                         } elseif ( $entry === '!NONEXISTENT' ) {
 719                                 $this->mCache[$code][$title] = '!NONEXISTENT';
 720                                 return false;
 721                         } else {
 722                                 # Corrupt/obsolete entry, delete it
 723                                 $this->mMemc->delete( $titleKey );
 724                         }
 725                 }
 726
 727                 # Try loading it from the database
 728                 $revision = Revision::newFromTitle(
 729                         Title::makeTitle( NS_MEDIAWIKI, $title ), false, Revision::READ_LATEST
 730                 );
 731                 if ( $revision ) {
 732                         $content = $revision->getContent();
 733                         if ( !$content ) {
 734                                 // A possibly temporary loading failure.
 735                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$title} ($code)" );
 736                                 $message = null; // no negative caching
 737                         } else {
 738                                 // XXX: Is this the right way to turn a Content object into a message?
 739                                 // NOTE: $content is typically either WikitextContent, JavaScriptContent or CssContent.
 740                                 //       MessageContent is *not* used for storing messages, it's only used for wrapping them when needed.
 741                                 $message = $content->getWikitextForTransclusion();
 742
 743                                 if ( $message === false || $message === null ) {
 744                                         wfDebugLog( 'MessageCache', __METHOD__ . ": message content doesn't provide wikitext "
 745                                                                 . "(content model: " . $content->getContentHandler() . ")" );
 746
 747                                         $message = false; // negative caching
 748                                 } else {
 749                                         $this->mCache[$code][$title] = ' ' . $message;
 750                                         $this->mMemc->set( $titleKey, ' ' . $message, $this->mExpiry );
 751                                 }
 752                         }
 753                 } else {
 754                         $message = false; // negative caching
 755                 }
 756
 757                 if ( $message === false ) { // negative caching
 758                         $this->mCache[$code][$title] = '!NONEXISTENT';
 759                         $this->mMemc->set( $titleKey, '!NONEXISTENT', $this->mExpiry );
 760                 }
 761
 762                 return $message;
 763         }
 764
 765         /**
 766          * @param $message string
 767          * @param $interface bool
 768          * @param $language
 769          * @param $title Title
 770          * @return string
 771          */
 772         function transform( $message, $interface = false, $language = null, $title = null ) {
 773                 // Avoid creating parser if nothing to transform
 774                 if( strpos( $message, '{{' ) === false ) {
 775                         return $message;
 776                 }
 777
 778                 if ( $this->mInParser ) {
 779                         return $message;
 780                 }
 781
 782                 $parser = $this->getParser();
 783                 if ( $parser ) {
 784                         $popts = $this->getParserOptions();
 785                         $popts->setInterfaceMessage( $interface );
 786                         $popts->setTargetLanguage( $language );
 787
 788                         $userlang = $popts->setUserLang( $language );
 789                         $this->mInParser = true;
 790                         $message = $parser->transformMsg( $message, $popts, $title );
 791                         $this->mInParser = false;
 792                         $popts->setUserLang( $userlang );
 793                 }
 794                 return $message;
 795         }
 796
 797         /**
 798          * @return Parser
 799          */
 800         function getParser() {
 801                 global $wgParser, $wgParserConf;
 802                 if ( !$this->mParser && isset( $wgParser ) ) {
 803                         # Do some initialisation so that we don't have to do it twice
 804                         $wgParser->firstCallInit();
 805                         # Clone it and store it
 806                         $class = $wgParserConf['class'];
 807                         if ( $class == 'Parser_DiffTest' ) {
 808                                 # Uncloneable
 809                                 $this->mParser = new $class( $wgParserConf );
 810                         } else {
 811                                 $this->mParser = clone $wgParser;
 812                         }
 813                 }
 814                 return $this->mParser;
 815         }
 816
 817         /**
 818          * @param $text string
 819          * @param $title Title
 820          * @param $linestart bool
 821          * @param $interface bool
 822          * @param $language
 823          * @return ParserOutput|string
 824          */
 825         public function parse( $text, $title = null, $linestart = true, $interface = false, $language = null  ) {
 826                 if ( $this->mInParser ) {
 827                         return htmlspecialchars( $text );
 828                 }
 829
 830                 $parser = $this->getParser();
 831                 $popts = $this->getParserOptions();
 832                 $popts->setInterfaceMessage( $interface );
 833                 $popts->setTargetLanguage( $language );
 834
 835                 wfProfileIn( __METHOD__ );
 836                 if ( !$title || !$title instanceof Title ) {
 837                         global $wgTitle;
 838                         $title = $wgTitle;
 839                 }
 840                 // Sometimes $wgTitle isn't set either...
 841                 if ( !$title ) {
 842                         # It's not uncommon having a null $wgTitle in scripts. See r80898
 843                         # Create a ghost title in such case
 844                         $title = Title::newFromText( 'Dwimmerlaik' );
 845                 }
 846
 847                 $this->mInParser = true;
 848                 $res = $parser->parse( $text, $title, $popts, $linestart );
 849                 $this->mInParser = false;
 850
 851                 wfProfileOut( __METHOD__ );
 852                 return $res;
 853         }
 854
 855         function disable() {
 856                 $this->mDisable = true;
 857         }
 858
 859         function enable() {
 860                 $this->mDisable = false;
 861         }
 862
 863         /**
 864          * Clear all stored messages. Mainly used after a mass rebuild.
 865          */
 866         function clear() {
 867                 $langs = Language::fetchLanguageNames( null, 'mw' );
 868                 foreach ( array_keys( $langs ) as $code ) {
 869                         # Global cache
 870                         $this->mMemc->delete( wfMemcKey( 'messages', $code ) );
 871                         # Invalidate all local caches
 872                         $this->mMemc->delete( wfMemcKey( 'messages', $code, 'hash' ) );
 873                 }
 874                 $this->mLoadedLanguages = array();
 875         }
 876
 877         /**
 878          * @param $key
 879          * @return array
 880          */
 881         public function figureMessage( $key ) {
 882                 global $wgLanguageCode;
 883                 $pieces = explode( '/', $key );
 884                 if( count( $pieces ) < 2 ) {
 885                         return array( $key, $wgLanguageCode );
 886                 }
 887
 888                 $lang = array_pop( $pieces );
 889                 if( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
 890                         return array( $key, $wgLanguageCode );
 891                 }
 892
 893                 $message = implode( '/', $pieces );
 894                 return array( $message, $lang );
 895         }
 896
 897         /**
 898          * Get all message keys stored in the message cache for a given language.
 899          * If $code is the content language code, this will return all message keys
 900          * for which MediaWiki:msgkey exists. If $code is another language code, this
 901          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
 902          * @param $code string
 903          * @return array of message keys (strings)
 904          */
 905         public function getAllMessageKeys( $code ) {
 906                 global $wgContLang;
 907                 $this->load( $code );
 908                 if ( !isset( $this->mCache[$code] ) ) {
 909                         // Apparently load() failed
 910                         return null;
 911                 }
 912                 $cache = $this->mCache[$code]; // Copy the cache
 913                 unset( $cache['VERSION'] ); // Remove the VERSION key
 914                 $cache = array_diff( $cache, array( '!NONEXISTENT' ) ); // Remove any !NONEXISTENT keys
 915                 // Keys may appear with a capital first letter. lcfirst them.
 916                 return array_map( array( $wgContLang, 'lcfirst' ), array_keys( $cache ) );
 917         }
 918 }