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', 30 );
  29 define( 'MSG_WAIT_TIMEOUT', 30 );
  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          *
 123          * @param string $hash the hash of contents, to check validity.
 124          * @param $code Mixed: Optional language code, see documenation of load().
 125          * @return The cache array
 126          */
 127         function getLocalCache( $hash, $code ) {
 128                 global $wgCacheDirectory;
 129
 130                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 131
 132                 # Check file existence
 133                 wfSuppressWarnings();
 134                 $file = fopen( $filename, 'r' );
 135                 wfRestoreWarnings();
 136                 if ( !$file ) {
 137                         return false; // No cache file
 138                 }
 139
 140                 // Check to see if the file has the hash specified
 141                 $localHash = fread( $file, 32 );
 142                 if ( $hash === $localHash ) {
 143                         // All good, get the rest of it
 144                         $serialized = '';
 145                         while ( !feof( $file ) ) {
 146                                 $serialized .= fread( $file, 100000 );
 147                         }
 148                         fclose( $file );
 149                         return unserialize( $serialized );
 150                 } else {
 151                         fclose( $file );
 152                         return false; // Wrong hash
 153                 }
 154         }
 155
 156         /**
 157          * Save the cache to a local file.
 158          */
 159         function saveToLocal( $serialized, $hash, $code ) {
 160                 global $wgCacheDirectory;
 161
 162                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 163                 wfMkdirParents( $wgCacheDirectory, null, __METHOD__ ); // might fail
 164
 165                 wfSuppressWarnings();
 166                 $file = fopen( $filename, 'w' );
 167                 wfRestoreWarnings();
 168
 169                 if ( !$file ) {
 170                         wfDebug( "Unable to open local cache file for writing\n" );
 171                         return;
 172                 }
 173
 174                 fwrite( $file, $hash . $serialized );
 175                 fclose( $file );
 176                 wfSuppressWarnings();
 177                 chmod( $filename, 0666 );
 178                 wfRestoreWarnings();
 179         }
 180
 181         /**
 182          * Loads messages from caches or from database in this order:
 183          * (1) local message cache (if $wgUseLocalMessageCache is enabled)
 184          * (2) memcached
 185          * (3) from the database.
 186          *
 187          * When succesfully loading from (2) or (3), all higher level caches are
 188          * updated for the newest version.
 189          *
 190          * Nothing is loaded if member variable mDisable is true, either manually
 191          * set by calling code or if message loading fails (is this possible?).
 192          *
 193          * Returns true if cache is already populated or it was succesfully populated,
 194          * or false if populating empty cache fails. Also returns true if MessageCache
 195          * is disabled.
 196          *
 197          * @param bool|String $code String: language to which load messages
 198          * @throws MWException
 199          * @return bool
 200          */
 201         function load( $code = false ) {
 202                 global $wgUseLocalMessageCache;
 203
 204                 if( !is_string( $code ) ) {
 205                         # This isn't really nice, so at least make a note about it and try to
 206                         # fall back
 207                         wfDebug( __METHOD__ . " called without providing a language code\n" );
 208                         $code = 'en';
 209                 }
 210
 211                 # Don't do double loading...
 212                 if ( isset( $this->mLoadedLanguages[$code] ) ) {
 213                         return true;
 214                 }
 215
 216                 # 8 lines of code just to say (once) that message cache is disabled
 217                 if ( $this->mDisable ) {
 218                         static $shownDisabled = false;
 219                         if ( !$shownDisabled ) {
 220                                 wfDebug( __METHOD__ . ": disabled\n" );
 221                                 $shownDisabled = true;
 222                         }
 223                         return true;
 224                 }
 225
 226                 # Loading code starts
 227                 wfProfileIn( __METHOD__ );
 228                 $success = false; # Keep track of success
 229                 $staleCache = false; # a cache array with expired data, or false if none has been loaded
 230                 $where = array(); # Debug info, delayed to avoid spamming debug log too much
 231                 $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages
 232
 233                 # Local cache
 234                 # Hash of the contents is stored in memcache, to detect if local cache goes
 235                 # out of date (e.g. due to replace() on some other server)
 236                 if ( $wgUseLocalMessageCache ) {
 237                         wfProfileIn( __METHOD__ . '-fromlocal' );
 238
 239                         $hash = $this->mMemc->get( wfMemcKey( 'messages', $code, 'hash' ) );
 240                         if ( $hash ) {
 241                                 $cache = $this->getLocalCache( $hash, $code );
 242                                 if ( !$cache ) {
 243                                         $where[] = 'local cache is empty or has the wrong hash';
 244                                 } elseif ( $this->isCacheExpired( $cache ) ) {
 245                                         $where[] = 'local cache is expired';
 246                                         $staleCache = $cache;
 247                                 } else {
 248                                         $where[] = 'got from local cache';
 249                                         $success = true;
 250                                         $this->mCache[$code] = $cache;
 251                                 }
 252                         }
 253                         wfProfileOut( __METHOD__ . '-fromlocal' );
 254                 }
 255
 256                 if ( !$success ) {
 257                         # Try the global cache. If it is empty, try to acquire a lock. If
 258                         # the lock can't be acquired, wait for the other thread to finish
 259                         # and then try the global cache a second time.
 260                         for ( $failedAttempts = 0; $failedAttempts < 2; $failedAttempts++ ) {
 261                                 wfProfileIn( __METHOD__ . '-fromcache' );
 262                                 $cache = $this->mMemc->get( $cacheKey );
 263                                 if ( !$cache ) {
 264                                         $where[] = 'global cache is empty';
 265                                 } elseif ( $this->isCacheExpired( $cache ) ) {
 266                                         $where[] = 'global cache is expired';
 267                                         $staleCache = $cache;
 268                                 } else {
 269                                         $where[] = 'got from global cache';
 270                                         $this->mCache[$code] = $cache;
 271                                         $this->saveToCaches( $cache, 'local-only', $code );
 272                                         $success = true;
 273                                 }
 274
 275                                 wfProfileOut( __METHOD__ . '-fromcache' );
 276
 277                                 if ( $success ) {
 278                                         # Done, no need to retry
 279                                         break;
 280                                 }
 281
 282                                 # We need to call loadFromDB. Limit the concurrency to a single
 283                                 # process. This prevents the site from going down when the cache
 284                                 # expires.
 285                                 $statusKey = wfMemcKey( 'messages', $code, 'status' );
 286                                 $acquired = $this->mMemc->add( $statusKey, 'loading', MSG_LOAD_TIMEOUT );
 287                                 if ( $acquired ) {
 288                                         # Unlock the status key if there is an exception
 289                                         $that = $this;
 290                                         $statusUnlocker = new ScopedCallback( function() use ( $that, $statusKey ) {
 291                                                 $that->mMemc->delete( $statusKey );
 292                                         } );
 293
 294                                         # Now let's regenerate
 295                                         $where[] = 'loading from database';
 296
 297                                         # Lock the cache to prevent conflicting writes
 298                                         # If this lock fails, it doesn't really matter, it just means the
 299                                         # write is potentially non-atomic, e.g. the results of a replace()
 300                                         # may be discarded.
 301                                         if ( $this->lock( $cacheKey ) ) {
 302                                                 $mainUnlocker = new ScopedCallback( function() use ( $that, $cacheKey ) {
 303                                                         $that->unlock( $cacheKey );
 304                                                 } );
 305                                         } else {
 306                                                 $mainUnlocker = null;
 307                                                 $where[] = 'could not acquire main lock';
 308                                         }
 309
 310                                         $cache = $this->loadFromDB( $code );
 311                                         $this->mCache[$code] = $cache;
 312                                         $success = true;
 313                                         $saveSuccess = $this->saveToCaches( $cache, 'all', $code );
 314
 315                                         # Unlock
 316                                         ScopedCallback::consume( $mainUnlocker );
 317                                         ScopedCallback::consume( $statusUnlocker );
 318
 319                                         if ( !$saveSuccess ) {
 320                                                 # Cache save has failed.
 321                                                 # There are two main scenarios where this could be a problem:
 322                                                 #
 323                                                 #   - The cache is more than the maximum size (typically
 324                                                 #     1MB compressed).
 325                                                 #
 326                                                 #   - Memcached has no space remaining in the relevant slab
 327                                                 #     class. This is unlikely with recent versions of
 328                                                 #     memcached.
 329                                                 #
 330                                                 # Either way, if there is a local cache, nothing bad will
 331                                                 # happen. If there is no local cache, disabling the message
 332                                                 # cache for all requests avoids incurring a loadFromDB()
 333                                                 # overhead on every request, and thus saves the wiki from
 334                                                 # complete downtime under moderate traffic conditions.
 335                                                 if ( !$wgUseLocalMessageCache ) {
 336                                                         $this->mMemc->set( $statusKey, 'error', 60 * 5 );
 337                                                         $where[] = 'could not save cache, disabled globally for 5 minutes';
 338                                                 } else {
 339                                                         $where[] = "could not save global cache";
 340                                                 }
 341                                         }
 342
 343                                         # Load from DB complete, no need to retry
 344                                         break;
 345                                 } elseif ( $staleCache ) {
 346                                         # Use the stale cache while some other thread constructs the new one
 347                                         $where[] = 'using stale cache';
 348                                         $this->mCache[$code] = $staleCache;
 349                                         $success = true;
 350                                         break;
 351                                 } elseif ( $failedAttempts > 0 ) {
 352                                         # Already retried once, still failed, so don't do another lock/unlock cycle
 353                                         # This case will typically be hit if memcached is down, or if
 354                                         # loadFromDB() takes longer than MSG_WAIT_TIMEOUT
 355                                         $where[] = "could not acquire status key.";
 356                                         break;
 357                                 } else {
 358                                         $status = $this->mMemc->get( $statusKey );
 359                                         if ( $status === 'error' ) {
 360                                                 # Disable cache
 361                                                 break;
 362                                         } else {
 363                                                 # Wait for the other thread to finish, then retry
 364                                                 $where[] = 'waited for other thread to complete';
 365                                                 $this->lock( $cacheKey );
 366                                                 $this->unlock( $cacheKey );
 367                                         }
 368                                 }
 369                         }
 370                 }
 371
 372                 if ( !$success ) {
 373                         $where[] = 'loading FAILED - cache is disabled';
 374                         $this->mDisable = true;
 375                         $this->mCache = false;
 376                         # This used to throw an exception, but that led to nasty side effects like
 377                         # the whole wiki being instantly down if the memcached server died
 378                 } else {
 379                         # All good, just record the success
 380                         $this->mLoadedLanguages[$code] = true;
 381                 }
 382                 $info = implode( ', ', $where );
 383                 wfDebug( __METHOD__ . ": Loading $code... $info\n" );
 384                 wfProfileOut( __METHOD__ );
 385                 return $success;
 386         }
 387
 388         /**
 389          * Loads cacheable messages from the database. Messages bigger than
 390          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 391          * on-demand from the database later.
 392          *
 393          * @param string $code language code.
 394          * @return Array: loaded messages for storing in caches.
 395          */
 396         function loadFromDB( $code ) {
 397                 wfProfileIn( __METHOD__ );
 398                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 399                 $dbr = wfGetDB( DB_SLAVE );
 400                 $cache = array();
 401
 402                 # Common conditions
 403                 $conds = array(
 404                         'page_is_redirect' => 0,
 405                         'page_namespace' => NS_MEDIAWIKI,
 406                 );
 407
 408                 $mostused = array();
 409                 if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
 410                         if ( !isset( $this->mCache[$wgLanguageCode] ) ) {
 411                                 $this->load( $wgLanguageCode );
 412                         }
 413                         $mostused = array_keys( $this->mCache[$wgLanguageCode] );
 414                         foreach ( $mostused as $key => $value ) {
 415                                 $mostused[$key] = "$value/$code";
 416                         }
 417                 }
 418
 419                 if ( count( $mostused ) ) {
 420                         $conds['page_title'] = $mostused;
 421                 } elseif ( $code !== $wgLanguageCode ) {
 422                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
 423                 } else {
 424                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 425                         # other than language code.
 426                         $conds[] = 'page_title NOT' . $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 427                 }
 428
 429                 # Conditions to fetch oversized pages to ignore them
 430                 $bigConds = $conds;
 431                 $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );
 432
 433                 # Load titles for all oversized pages in the MediaWiki namespace
 434                 $res = $dbr->select( 'page', 'page_title', $bigConds, __METHOD__ . "($code)-big" );
 435                 foreach ( $res as $row ) {
 436                         $cache[$row->page_title] = '!TOO BIG';
 437                 }
 438
 439                 # Conditions to load the remaining pages with their contents
 440                 $smallConds = $conds;
 441                 $smallConds[] = 'page_latest=rev_id';
 442                 $smallConds[] = 'rev_text_id=old_id';
 443                 $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );
 444
 445                 $res = $dbr->select(
 446                         array( 'page', 'revision', 'text' ),
 447                         array( 'page_title', 'old_text', 'old_flags' ),
 448                         $smallConds,
 449                         __METHOD__ . "($code)-small"
 450                 );
 451
 452                 foreach ( $res as $row ) {
 453                         $text = Revision::getRevisionText( $row );
 454                         if( $text === false ) {
 455                                 // Failed to fetch data; possible ES errors?
 456                                 // Store a marker to fetch on-demand as a workaround...
 457                                 $entry = '!TOO BIG';
 458                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$row->page_title} ($code)" );
 459                         } else {
 460                                 $entry = ' ' . $text;
 461                         }
 462                         $cache[$row->page_title] = $entry;
 463                 }
 464
 465                 $cache['VERSION'] = MSG_CACHE_VERSION;
 466                 $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );
 467                 wfProfileOut( __METHOD__ );
 468                 return $cache;
 469         }
 470
 471         /**
 472          * Updates cache as necessary when message page is changed
 473          *
 474          * @param string $title name of the page changed.
 475          * @param $text Mixed: new contents of the page.
 476          */
 477         public function replace( $title, $text ) {
 478                 global $wgMaxMsgCacheEntrySize;
 479                 wfProfileIn( __METHOD__ );
 480
 481                 if ( $this->mDisable ) {
 482                         wfProfileOut( __METHOD__ );
 483                         return;
 484                 }
 485
 486                 list( $msg, $code ) = $this->figureMessage( $title );
 487
 488                 $cacheKey = wfMemcKey( 'messages', $code );
 489                 $this->load( $code );
 490                 $this->lock( $cacheKey );
 491
 492                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 493
 494                 if ( $text === false ) {
 495                         # Article was deleted
 496                         $this->mCache[$code][$title] = '!NONEXISTENT';
 497                         $this->mMemc->delete( $titleKey );
 498                 } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 499                         # Check for size
 500                         $this->mCache[$code][$title] = '!TOO BIG';
 501                         $this->mMemc->set( $titleKey, ' ' . $text, $this->mExpiry );
 502                 } else {
 503                         $this->mCache[$code][$title] = ' ' . $text;
 504                         $this->mMemc->delete( $titleKey );
 505                 }
 506
 507                 # Update caches
 508                 $this->saveToCaches( $this->mCache[$code], 'all', $code );
 509                 $this->unlock( $cacheKey );
 510
 511                 // Also delete cached sidebar... just in case it is affected
 512                 $codes = array( $code );
 513                 if ( $code === 'en' ) {
 514                         // Delete all sidebars, like for example on action=purge on the
 515                         // sidebar messages
 516                         $codes = array_keys( Language::fetchLanguageNames() );
 517                 }
 518
 519                 global $wgMemc;
 520                 foreach ( $codes as $code ) {
 521                         $sidebarKey = wfMemcKey( 'sidebar', $code );
 522                         $wgMemc->delete( $sidebarKey );
 523                 }
 524
 525                 // Update the message in the message blob store
 526                 global $wgContLang;
 527                 MessageBlobStore::updateMessage( $wgContLang->lcfirst( $msg ) );
 528
 529                 wfRunHooks( 'MessageCacheReplace', array( $title, $text ) );
 530
 531                 wfProfileOut( __METHOD__ );
 532         }
 533
 534         /**
 535          * Is the given cache array expired due to time passing or a version change?
 536          */
 537         protected function isCacheExpired( $cache ) {
 538                 if ( !isset( $cache['VERSION'] ) || !isset( $cache['EXPIRY'] ) ) {
 539                         return true;
 540                 }
 541                 if ( $cache['VERSION'] != MSG_CACHE_VERSION ) {
 542                         return true;
 543                 }
 544                 if ( wfTimestampNow() >= $cache['EXPIRY'] ) {
 545                         return true;
 546                 }
 547                 return false;
 548         }
 549
 550
 551         /**
 552          * Shortcut to update caches.
 553          *
 554          * @param $cache array: cached messages with a version.
 555          * @param $dest string: Either "local-only" to save to local caches only
 556          *   or "all" to save to all caches.
 557          * @param $code string: Language code.
 558          * @return bool on somekind of error.
 559          */
 560         protected function saveToCaches( $cache, $dest, $code = false ) {
 561                 wfProfileIn( __METHOD__ );
 562                 global $wgUseLocalMessageCache;
 563
 564                 $cacheKey = wfMemcKey( 'messages', $code );
 565
 566                 if ( $dest === 'all' ) {
 567                         $success = $this->mMemc->set( $cacheKey, $cache );
 568                 } else {
 569                         $success = true;
 570                 }
 571
 572                 # Save to local cache
 573                 if ( $wgUseLocalMessageCache ) {
 574                         $serialized = serialize( $cache );
 575                         $hash = md5( $serialized );
 576                         $this->mMemc->set( wfMemcKey( 'messages', $code, 'hash' ), $hash );
 577                         $this->saveToLocal( $serialized, $hash, $code );
 578                 }
 579
 580                 wfProfileOut( __METHOD__ );
 581                 return $success;
 582         }
 583
 584         /**
 585          * Represents a write lock on the messages key
 586          *
 587          * @param $key string
 588          *
 589          * @return Boolean: success
 590          */
 591         function lock( $key ) {
 592                 $lockKey = $key . ':lock';
 593                 $acquired = false;
 594                 $testDone = false;
 595                 for ( $i = 0; $i < MSG_WAIT_TIMEOUT && !$acquired; $i++ ) {
 596                         $acquired = $this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT );
 597                         if ( $acquired ) {
 598                                 break;
 599                         }
 600
 601                         # Fail fast if memcached is totally down
 602                         if ( !$testDone ) {
 603                                 $testDone = true;
 604                                 if ( !$this->mMemc->set( wfMemcKey( 'test' ), 'test', 1 ) ) {
 605                                         break;
 606                                 }
 607                         }
 608                         sleep( 1 );
 609                 }
 610
 611                 return $acquired;
 612         }
 613
 614         function unlock( $key ) {
 615                 $lockKey = $key . ':lock';
 616                 $this->mMemc->delete( $lockKey );
 617         }
 618
 619         /**
 620          * Get a message from either the content language or the user language.
 621          *
 622          * @param $key String: the message cache key
 623          * @param $useDB Boolean: get the message from the DB, false to use only
 624          *               the localisation
 625          * @param bool|string $langcode Code of the language to get the message for, if
 626          *                  it is a valid code create a language for that language,
 627          *                  if it is a string but not a valid code then make a basic
 628          *                  language object, if it is a false boolean then use the
 629          *                  current users language (as a fallback for the old
 630          *                  parameter functionality), or if it is a true boolean
 631          *                  then use the wikis content language (also as a
 632          *                  fallback).
 633          * @param $isFullKey Boolean: specifies whether $key is a two part key
 634          *                   "msg/lang".
 635          *
 636          * @throws MWException
 637          * @return string|bool
 638          */
 639         function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
 640                 global $wgLanguageCode, $wgContLang;
 641
 642                 if ( is_int( $key ) ) {
 643                         // "Non-string key given" exception sometimes happens for numerical strings that become ints somewhere on their way here
 644                         $key = strval( $key );
 645                 }
 646
 647                 if ( !is_string( $key ) ) {
 648                         throw new MWException( 'Non-string key given' );
 649                 }
 650
 651                 if ( strval( $key ) === '' ) {
 652                         # Shortcut: the empty key is always missing
 653                         return false;
 654                 }
 655
 656                 $lang = wfGetLangObj( $langcode );
 657                 if ( !$lang ) {
 658                         throw new MWException( "Bad lang code $langcode given" );
 659                 }
 660
 661                 $langcode = $lang->getCode();
 662
 663                 $message = false;
 664
 665                 # Normalise title-case input (with some inlining)
 666                 $lckey = str_replace( ' ', '_', $key );
 667                 if ( ord( $key ) < 128 ) {
 668                         $lckey[0] = strtolower( $lckey[0] );
 669                         $uckey = ucfirst( $lckey );
 670                 } else {
 671                         $lckey = $wgContLang->lcfirst( $lckey );
 672                         $uckey = $wgContLang->ucfirst( $lckey );
 673                 }
 674
 675                 # Try the MediaWiki namespace
 676                 if( !$this->mDisable && $useDB ) {
 677                         $title = $uckey;
 678                         if( !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 679                                 $title .= '/' . $langcode;
 680                         }
 681                         $message = $this->getMsgFromNamespace( $title, $langcode );
 682                 }
 683
 684                 # Try the array in the language object
 685                 if ( $message === false ) {
 686                         $message = $lang->getMessage( $lckey );
 687                         if ( is_null( $message ) ) {
 688                                 $message = false;
 689                         }
 690                 }
 691
 692                 # Try the array of another language
 693                 if( $message === false ) {
 694                         $parts = explode( '/', $lckey );
 695                         # We may get calls for things that are http-urls from sidebar
 696                         # Let's not load nonexistent languages for those
 697                         # They usually have more than one slash.
 698                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 699                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 700                                 if ( is_null( $message ) ) {
 701                                         $message = false;
 702                                 }
 703                         }
 704                 }
 705
 706                 # Is this a custom message? Try the default language in the db...
 707                 if( ( $message === false || $message === '-' ) &&
 708                         !$this->mDisable && $useDB &&
 709                         !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 710                         $message = $this->getMsgFromNamespace( $uckey, $wgLanguageCode );
 711                 }
 712
 713                 # Final fallback
 714                 if( $message === false ) {
 715                         return false;
 716                 }
 717
 718                 # Fix whitespace
 719                 $message = strtr( $message,
 720                         array(
 721                                 # Fix for trailing whitespace, removed by textarea
 722                                 '&#32;' => ' ',
 723                                 # Fix for NBSP, converted to space by firefox
 724                                 '&nbsp;' => "\xc2\xa0",
 725                                 '&#160;' => "\xc2\xa0",
 726                         ) );
 727
 728                 return $message;
 729         }
 730
 731         /**
 732          * Get a message from the MediaWiki namespace, with caching. The key must
 733          * first be converted to two-part lang/msg form if necessary.
 734          *
 735          * Unlike self::get(), this function doesn't resolve fallback chains, and
 736          * some callers require this behavior. LanguageConverter::parseCachedTable()
 737          * and self::get() are some examples in core.
 738          *
 739          * @param string $title Message cache key with initial uppercase letter.
 740          * @param string $code code denoting the language to try.
 741          *
 742          * @return string|bool False on failure
 743          */
 744         function getMsgFromNamespace( $title, $code ) {
 745                 $this->load( $code );
 746                 if ( isset( $this->mCache[$code][$title] ) ) {
 747                         $entry = $this->mCache[$code][$title];
 748                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 749                                 return substr( $entry, 1 );
 750                         } elseif ( $entry === '!NONEXISTENT' ) {
 751                                 return false;
 752                         } elseif( $entry === '!TOO BIG' ) {
 753                                 // Fall through and try invididual message cache below
 754                         }
 755                 } else {
 756                         // XXX: This is not cached in process cache, should it?
 757                         $message = false;
 758                         wfRunHooks( 'MessagesPreLoad', array( $title, &$message ) );
 759                         if ( $message !== false ) {
 760                                 return $message;
 761                         }
 762
 763                         return false;
 764                 }
 765
 766                 # Try the individual message cache
 767                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 768                 $entry = $this->mMemc->get( $titleKey );
 769                 if ( $entry ) {
 770                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 771                                 $this->mCache[$code][$title] = $entry;
 772                                 return substr( $entry, 1 );
 773                         } elseif ( $entry === '!NONEXISTENT' ) {
 774                                 $this->mCache[$code][$title] = '!NONEXISTENT';
 775                                 return false;
 776                         } else {
 777                                 # Corrupt/obsolete entry, delete it
 778                                 $this->mMemc->delete( $titleKey );
 779                         }
 780                 }
 781
 782                 # Try loading it from the database
 783                 $revision = Revision::newFromTitle(
 784                         Title::makeTitle( NS_MEDIAWIKI, $title ), false, Revision::READ_LATEST
 785                 );
 786                 if ( $revision ) {
 787                         $content = $revision->getContent();
 788                         if ( !$content ) {
 789                                 // A possibly temporary loading failure.
 790                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$title} ($code)" );
 791                                 $message = null; // no negative caching
 792                         } else {
 793                                 // XXX: Is this the right way to turn a Content object into a message?
 794                                 // NOTE: $content is typically either WikitextContent, JavaScriptContent or CssContent.
 795                                 //       MessageContent is *not* used for storing messages, it's only used for wrapping them when needed.
 796                                 $message = $content->getWikitextForTransclusion();
 797
 798                                 if ( $message === false || $message === null ) {
 799                                         wfDebugLog( 'MessageCache', __METHOD__ . ": message content doesn't provide wikitext "
 800                                                                 . "(content model: " . $content->getContentHandler() . ")" );
 801
 802                                         $message = false; // negative caching
 803                                 } else {
 804                                         $this->mCache[$code][$title] = ' ' . $message;
 805                                         $this->mMemc->set( $titleKey, ' ' . $message, $this->mExpiry );
 806                                 }
 807                         }
 808                 } else {
 809                         $message = false; // negative caching
 810                 }
 811
 812                 if ( $message === false ) { // negative caching
 813                         $this->mCache[$code][$title] = '!NONEXISTENT';
 814                         $this->mMemc->set( $titleKey, '!NONEXISTENT', $this->mExpiry );
 815                 }
 816
 817                 return $message;
 818         }
 819
 820         /**
 821          * @param $message string
 822          * @param $interface bool
 823          * @param $language
 824          * @param $title Title
 825          * @return string
 826          */
 827         function transform( $message, $interface = false, $language = null, $title = null ) {
 828                 // Avoid creating parser if nothing to transform
 829                 if( strpos( $message, '{{' ) === false ) {
 830                         return $message;
 831                 }
 832
 833                 if ( $this->mInParser ) {
 834                         return $message;
 835                 }
 836
 837                 $parser = $this->getParser();
 838                 if ( $parser ) {
 839                         $popts = $this->getParserOptions();
 840                         $popts->setInterfaceMessage( $interface );
 841                         $popts->setTargetLanguage( $language );
 842
 843                         $userlang = $popts->setUserLang( $language );
 844                         $this->mInParser = true;
 845                         $message = $parser->transformMsg( $message, $popts, $title );
 846                         $this->mInParser = false;
 847                         $popts->setUserLang( $userlang );
 848                 }
 849                 return $message;
 850         }
 851
 852         /**
 853          * @return Parser
 854          */
 855         function getParser() {
 856                 global $wgParser, $wgParserConf;
 857                 if ( !$this->mParser && isset( $wgParser ) ) {
 858                         # Do some initialisation so that we don't have to do it twice
 859                         $wgParser->firstCallInit();
 860                         # Clone it and store it
 861                         $class = $wgParserConf['class'];
 862                         if ( $class == 'Parser_DiffTest' ) {
 863                                 # Uncloneable
 864                                 $this->mParser = new $class( $wgParserConf );
 865                         } else {
 866                                 $this->mParser = clone $wgParser;
 867                         }
 868                 }
 869                 return $this->mParser;
 870         }
 871
 872         /**
 873          * @param $text string
 874          * @param $title Title
 875          * @param $linestart bool
 876          * @param $interface bool
 877          * @param $language
 878          * @return ParserOutput|string
 879          */
 880         public function parse( $text, $title = null, $linestart = true, $interface = false, $language = null  ) {
 881                 if ( $this->mInParser ) {
 882                         return htmlspecialchars( $text );
 883                 }
 884
 885                 $parser = $this->getParser();
 886                 $popts = $this->getParserOptions();
 887                 $popts->setInterfaceMessage( $interface );
 888                 $popts->setTargetLanguage( $language );
 889
 890                 wfProfileIn( __METHOD__ );
 891                 if ( !$title || !$title instanceof Title ) {
 892                         global $wgTitle;
 893                         $title = $wgTitle;
 894                 }
 895                 // Sometimes $wgTitle isn't set either...
 896                 if ( !$title ) {
 897                         # It's not uncommon having a null $wgTitle in scripts. See r80898
 898                         # Create a ghost title in such case
 899                         $title = Title::newFromText( 'Dwimmerlaik' );
 900                 }
 901
 902                 $this->mInParser = true;
 903                 $res = $parser->parse( $text, $title, $popts, $linestart );
 904                 $this->mInParser = false;
 905
 906                 wfProfileOut( __METHOD__ );
 907                 return $res;
 908         }
 909
 910         function disable() {
 911                 $this->mDisable = true;
 912         }
 913
 914         function enable() {
 915                 $this->mDisable = false;
 916         }
 917
 918         /**
 919          * Clear all stored messages. Mainly used after a mass rebuild.
 920          */
 921         function clear() {
 922                 $langs = Language::fetchLanguageNames( null, 'mw' );
 923                 foreach ( array_keys( $langs ) as $code ) {
 924                         # Global cache
 925                         $this->mMemc->delete( wfMemcKey( 'messages', $code ) );
 926                         # Invalidate all local caches
 927                         $this->mMemc->delete( wfMemcKey( 'messages', $code, 'hash' ) );
 928                 }
 929                 $this->mLoadedLanguages = array();
 930         }
 931
 932         /**
 933          * @param $key
 934          * @return array
 935          */
 936         public function figureMessage( $key ) {
 937                 global $wgLanguageCode;
 938                 $pieces = explode( '/', $key );
 939                 if( count( $pieces ) < 2 ) {
 940                         return array( $key, $wgLanguageCode );
 941                 }
 942
 943                 $lang = array_pop( $pieces );
 944                 if( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
 945                         return array( $key, $wgLanguageCode );
 946                 }
 947
 948                 $message = implode( '/', $pieces );
 949                 return array( $message, $lang );
 950         }
 951
 952         /**
 953          * Get all message keys stored in the message cache for a given language.
 954          * If $code is the content language code, this will return all message keys
 955          * for which MediaWiki:msgkey exists. If $code is another language code, this
 956          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
 957          * @param $code string
 958          * @return array of message keys (strings)
 959          */
 960         public function getAllMessageKeys( $code ) {
 961                 global $wgContLang;
 962                 $this->load( $code );
 963                 if ( !isset( $this->mCache[$code] ) ) {
 964                         // Apparently load() failed
 965                         return null;
 966                 }
 967                 // Remove administrative keys
 968                 $cache = $this->mCache[$code];
 969                 unset( $cache['VERSION'] );
 970                 unset( $cache['EXPIRY'] );
 971                 // Remove any !NONEXISTENT keys
 972                 $cache = array_diff( $cache, array( '!NONEXISTENT' ) );
 973                 // Keys may appear with a capital first letter. lcfirst them.
 974                 return array_map( array( $wgContLang, 'lcfirst' ), array_keys( $cache ) );
 975         }
 976 }