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 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                         $this->lock( $cacheKey );
 331                         # Limit the concurrency of loadFromDB to a single process
 332                         # This prevents the site from going down when the cache expires
 333                         $statusKey = wfMemcKey( 'messages', $code, 'status' );
 334                         $success = $this->mMemc->add( $statusKey, 'loading', MSG_LOAD_TIMEOUT );
 335                         if ( $success ) { // acquired lock
 336                                 $cache = $this->loadFromDB( $code );
 337                                 $success = $this->setCache( $cache, $code );
 338                                 if ( $success ) { // messages loaded
 339                                         $success = $this->saveToCaches( $cache, true, $code );
 340                                         if ( $success ) {
 341                                                 $this->mMemc->delete( $statusKey );
 342                                         } else {
 343                                                 $this->mMemc->set( $statusKey, 'error', 60 * 5 );
 344                                                 wfDebug( __METHOD__ . ": set() error: restart memcached server!\n" );
 345                                                 $exception = new MWException( "Could not save cache for '$code'." );
 346                                         }
 347                                 } else {
 348                                         $this->mMemc->delete( $statusKey );
 349                                         $exception = new MWException( "Could not load cache from DB for '$code'." );
 350                                 }
 351                         } else {
 352                                 $exception = new MWException( "Could not acquire '$statusKey' lock." );
 353                         }
 354                         $this->unlock( $cacheKey );
 355                 }
 356
 357                 if ( !$success ) {
 358                         $this->mDisable = true;
 359                         $this->mCache = false;
 360                         // This used to go on, but that led to lots of nasty side
 361                         // effects like gadgets and sidebar getting cached with their
 362                         // default content
 363                         if ( $exception instanceof Exception ) {
 364                                 throw $exception;
 365                         } else {
 366                                 throw new MWException( "MessageCache failed to load messages" );
 367                         }
 368                 } else {
 369                         # All good, just record the success
 370                         $info = implode( ', ', $where );
 371                         wfDebug( __METHOD__ . ": Loading $code... $info\n" );
 372                         $this->mLoadedLanguages[$code] = true;
 373                 }
 374                 wfProfileOut( __METHOD__ );
 375                 return $success;
 376         }
 377
 378         /**
 379          * Loads cacheable messages from the database. Messages bigger than
 380          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 381          * on-demand from the database later.
 382          *
 383          * @param $code String: language code.
 384          * @return Array: loaded messages for storing in caches.
 385          */
 386         function loadFromDB( $code ) {
 387                 wfProfileIn( __METHOD__ );
 388                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 389                 $dbr = wfGetDB( DB_SLAVE );
 390                 $cache = array();
 391
 392                 # Common conditions
 393                 $conds = array(
 394                         'page_is_redirect' => 0,
 395                         'page_namespace' => NS_MEDIAWIKI,
 396                 );
 397
 398                 $mostused = array();
 399                 if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
 400                         if ( !isset( $this->mCache[$wgLanguageCode] ) ) {
 401                                 $this->load( $wgLanguageCode );
 402                         }
 403                         $mostused = array_keys( $this->mCache[$wgLanguageCode] );
 404                         foreach ( $mostused as $key => $value ) {
 405                                 $mostused[$key] = "$value/$code";
 406                         }
 407                 }
 408
 409                 if ( count( $mostused ) ) {
 410                         $conds['page_title'] = $mostused;
 411                 } elseif ( $code !== $wgLanguageCode ) {
 412                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
 413                 } else {
 414                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 415                         # other than language code.
 416                         $conds[] = 'page_title NOT' . $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 417                 }
 418
 419                 # Conditions to fetch oversized pages to ignore them
 420                 $bigConds = $conds;
 421                 $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );
 422
 423                 # Load titles for all oversized pages in the MediaWiki namespace
 424                 $res = $dbr->select( 'page', 'page_title', $bigConds, __METHOD__ . "($code)-big" );
 425                 foreach ( $res as $row ) {
 426                         $cache[$row->page_title] = '!TOO BIG';
 427                 }
 428
 429                 # Conditions to load the remaining pages with their contents
 430                 $smallConds = $conds;
 431                 $smallConds[] = 'page_latest=rev_id';
 432                 $smallConds[] = 'rev_text_id=old_id';
 433                 $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );
 434
 435                 $res = $dbr->select(
 436                         array( 'page', 'revision', 'text' ),
 437                         array( 'page_title', 'old_text', 'old_flags' ),
 438                         $smallConds,
 439                         __METHOD__ . "($code)-small"
 440                 );
 441
 442                 foreach ( $res as $row ) {
 443                         $text = Revision::getRevisionText( $row );
 444                         if( $text === false ) {
 445                                 // Failed to fetch data; possible ES errors?
 446                                 // Store a marker to fetch on-demand as a workaround...
 447                                 $entry = '!TOO BIG';
 448                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$row->page_title} ($code)" );
 449                         } else {
 450                                 $entry = ' ' . $text;
 451                         }
 452                         $cache[$row->page_title] = $entry;
 453                 }
 454
 455                 $cache['VERSION'] = MSG_CACHE_VERSION;
 456                 wfProfileOut( __METHOD__ );
 457                 return $cache;
 458         }
 459
 460         /**
 461          * Updates cache as necessary when message page is changed
 462          *
 463          * @param $title String: name of the page changed.
 464          * @param $text Mixed: new contents of the page.
 465          */
 466         public function replace( $title, $text ) {
 467                 global $wgMaxMsgCacheEntrySize;
 468                 wfProfileIn( __METHOD__ );
 469
 470                 if ( $this->mDisable ) {
 471                         wfProfileOut( __METHOD__ );
 472                         return;
 473                 }
 474
 475                 list( $msg, $code ) = $this->figureMessage( $title );
 476
 477                 $cacheKey = wfMemcKey( 'messages', $code );
 478                 $this->load( $code );
 479                 $this->lock( $cacheKey );
 480
 481                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 482
 483                 if ( $text === false ) {
 484                         # Article was deleted
 485                         $this->mCache[$code][$title] = '!NONEXISTENT';
 486                         $this->mMemc->delete( $titleKey );
 487                 } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 488                         # Check for size
 489                         $this->mCache[$code][$title] = '!TOO BIG';
 490                         $this->mMemc->set( $titleKey, ' ' . $text, $this->mExpiry );
 491                 } else {
 492                         $this->mCache[$code][$title] = ' ' . $text;
 493                         $this->mMemc->delete( $titleKey );
 494                 }
 495
 496                 # Update caches
 497                 $this->saveToCaches( $this->mCache[$code], true, $code );
 498                 $this->unlock( $cacheKey );
 499
 500                 // Also delete cached sidebar... just in case it is affected
 501                 $codes = array( $code );
 502                 if ( $code === 'en' ) {
 503                         // Delete all sidebars, like for example on action=purge on the
 504                         // sidebar messages
 505                         $codes = array_keys( Language::fetchLanguageNames() );
 506                 }
 507
 508                 global $wgMemc;
 509                 foreach ( $codes as $code ) {
 510                         $sidebarKey = wfMemcKey( 'sidebar', $code );
 511                         $wgMemc->delete( $sidebarKey );
 512                 }
 513
 514                 // Update the message in the message blob store
 515                 global $wgContLang;
 516                 MessageBlobStore::updateMessage( $wgContLang->lcfirst( $msg ) );
 517
 518                 wfRunHooks( 'MessageCacheReplace', array( $title, $text ) );
 519
 520                 wfProfileOut( __METHOD__ );
 521         }
 522
 523         /**
 524          * Shortcut to update caches.
 525          *
 526          * @param $cache Array: cached messages with a version.
 527          * @param $memc Bool: Wether to update or not memcache.
 528          * @param $code String: Language code.
 529          * @return bool on somekind of error.
 530          */
 531         protected function saveToCaches( $cache, $memc = true, $code = false ) {
 532                 wfProfileIn( __METHOD__ );
 533                 global $wgUseLocalMessageCache, $wgLocalMessageCacheSerialized;
 534
 535                 $cacheKey = wfMemcKey( 'messages', $code );
 536
 537                 if ( $memc ) {
 538                         $success = $this->mMemc->set( $cacheKey, $cache, $this->mExpiry );
 539                 } else {
 540                         $success = true;
 541                 }
 542
 543                 # Save to local cache
 544                 if ( $wgUseLocalMessageCache ) {
 545                         $serialized = serialize( $cache );
 546                         $hash = md5( $serialized );
 547                         $this->mMemc->set( wfMemcKey( 'messages', $code, 'hash' ), $hash, $this->mExpiry );
 548                         if ( $wgLocalMessageCacheSerialized ) {
 549                                 $this->saveToLocal( $serialized, $hash, $code );
 550                         } else {
 551                                 $this->saveToScript( $cache, $hash, $code );
 552                         }
 553                 }
 554
 555                 wfProfileOut( __METHOD__ );
 556                 return $success;
 557         }
 558
 559         /**
 560          * Represents a write lock on the messages key
 561          *
 562          * @param $key string
 563          *
 564          * @return Boolean: success
 565          */
 566         function lock( $key ) {
 567                 $lockKey = $key . ':lock';
 568                 for ( $i = 0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
 569                         sleep( 1 );
 570                 }
 571
 572                 return $i >= MSG_WAIT_TIMEOUT;
 573         }
 574
 575         function unlock( $key ) {
 576                 $lockKey = $key . ':lock';
 577                 $this->mMemc->delete( $lockKey );
 578         }
 579
 580         /**
 581          * Get a message from either the content language or the user language.
 582          *
 583          * @param $key String: the message cache key
 584          * @param $useDB Boolean: get the message from the DB, false to use only
 585          *               the localisation
 586          * @param bool|string $langcode Code of the language to get the message for, if
 587          *                  it is a valid code create a language for that language,
 588          *                  if it is a string but not a valid code then make a basic
 589          *                  language object, if it is a false boolean then use the
 590          *                  current users language (as a fallback for the old
 591          *                  parameter functionality), or if it is a true boolean
 592          *                  then use the wikis content language (also as a
 593          *                  fallback).
 594          * @param $isFullKey Boolean: specifies whether $key is a two part key
 595          *                   "msg/lang".
 596          *
 597          * @throws MWException
 598          * @return string|bool
 599          */
 600         function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
 601                 global $wgLanguageCode, $wgContLang;
 602
 603                 if ( is_int( $key ) ) {
 604                         // "Non-string key given" exception sometimes happens for numerical strings that become ints somewhere on their way here
 605                         $key = strval( $key );
 606                 }
 607
 608                 if ( !is_string( $key ) ) {
 609                         throw new MWException( 'Non-string key given' );
 610                 }
 611
 612                 if ( strval( $key ) === '' ) {
 613                         # Shortcut: the empty key is always missing
 614                         return false;
 615                 }
 616
 617                 $lang = wfGetLangObj( $langcode );
 618                 if ( !$lang ) {
 619                         throw new MWException( "Bad lang code $langcode given" );
 620                 }
 621
 622                 $langcode = $lang->getCode();
 623
 624                 $message = false;
 625
 626                 # Normalise title-case input (with some inlining)
 627                 $lckey = str_replace( ' ', '_', $key );
 628                 if ( ord( $key ) < 128 ) {
 629                         $lckey[0] = strtolower( $lckey[0] );
 630                         $uckey = ucfirst( $lckey );
 631                 } else {
 632                         $lckey = $wgContLang->lcfirst( $lckey );
 633                         $uckey = $wgContLang->ucfirst( $lckey );
 634                 }
 635
 636                 # Try the MediaWiki namespace
 637                 if( !$this->mDisable && $useDB ) {
 638                         $title = $uckey;
 639                         if( !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 640                                 $title .= '/' . $langcode;
 641                         }
 642                         $message = $this->getMsgFromNamespace( $title, $langcode );
 643                 }
 644
 645                 # Try the array in the language object
 646                 if ( $message === false ) {
 647                         $message = $lang->getMessage( $lckey );
 648                         if ( is_null( $message ) ) {
 649                                 $message = false;
 650                         }
 651                 }
 652
 653                 # Try the array of another language
 654                 if( $message === false ) {
 655                         $parts = explode( '/', $lckey );
 656                         # We may get calls for things that are http-urls from sidebar
 657                         # Let's not load nonexistent languages for those
 658                         # They usually have more than one slash.
 659                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 660                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 661                                 if ( is_null( $message ) ) {
 662                                         $message = false;
 663                                 }
 664                         }
 665                 }
 666
 667                 # Is this a custom message? Try the default language in the db...
 668                 if( ( $message === false || $message === '-' ) &&
 669                         !$this->mDisable && $useDB &&
 670                         !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 671                         $message = $this->getMsgFromNamespace( $uckey, $wgLanguageCode );
 672                 }
 673
 674                 # Final fallback
 675                 if( $message === false ) {
 676                         return false;
 677                 }
 678
 679                 # Fix whitespace
 680                 $message = strtr( $message,
 681                         array(
 682                                 # Fix for trailing whitespace, removed by textarea
 683                                 '&#32;' => ' ',
 684                                 # Fix for NBSP, converted to space by firefox
 685                                 '&nbsp;' => "\xc2\xa0",
 686                                 '&#160;' => "\xc2\xa0",
 687                         ) );
 688
 689                 return $message;
 690         }
 691
 692         /**
 693          * Get a message from the MediaWiki namespace, with caching. The key must
 694          * first be converted to two-part lang/msg form if necessary.
 695          *
 696          * @param $title String: Message cache key with initial uppercase letter.
 697          * @param $code String: code denoting the language to try.
 698          *
 699          * @return string|bool False on failure
 700          */
 701         function getMsgFromNamespace( $title, $code ) {
 702                 $this->load( $code );
 703                 if ( isset( $this->mCache[$code][$title] ) ) {
 704                         $entry = $this->mCache[$code][$title];
 705                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 706                                 return substr( $entry, 1 );
 707                         } elseif ( $entry === '!NONEXISTENT' ) {
 708                                 return false;
 709                         } elseif( $entry === '!TOO BIG' ) {
 710                                 // Fall through and try invididual message cache below
 711                         }
 712                 } else {
 713                         // XXX: This is not cached in process cache, should it?
 714                         $message = false;
 715                         wfRunHooks( 'MessagesPreLoad', array( $title, &$message ) );
 716                         if ( $message !== false ) {
 717                                 return $message;
 718                         }
 719
 720                         return false;
 721                 }
 722
 723                 # Try the individual message cache
 724                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 725                 $entry = $this->mMemc->get( $titleKey );
 726                 if ( $entry ) {
 727                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 728                                 $this->mCache[$code][$title] = $entry;
 729                                 return substr( $entry, 1 );
 730                         } elseif ( $entry === '!NONEXISTENT' ) {
 731                                 $this->mCache[$code][$title] = '!NONEXISTENT';
 732                                 return false;
 733                         } else {
 734                                 # Corrupt/obsolete entry, delete it
 735                                 $this->mMemc->delete( $titleKey );
 736                         }
 737                 }
 738
 739                 # Try loading it from the database
 740                 $revision = Revision::newFromTitle(
 741                         Title::makeTitle( NS_MEDIAWIKI, $title ), false, Revision::READ_LATEST
 742                 );
 743                 if ( $revision ) {
 744                         $content = $revision->getContent();
 745                         if ( !$content ) {
 746                                 // A possibly temporary loading failure.
 747                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$title} ($code)" );
 748                                 $message = null; // no negative caching
 749                         } else {
 750                                 // XXX: Is this the right way to turn a Content object into a message?
 751                                 // NOTE: $content is typically either WikitextContent, JavaScriptContent or CssContent.
 752                                 //       MessageContent is *not* used for storing messages, it's only used for wrapping them when needed.
 753                                 $message = $content->getWikitextForTransclusion();
 754
 755                                 if ( $message === false || $message === null ) {
 756                                         wfDebugLog( 'MessageCache', __METHOD__ . ": message content doesn't provide wikitext "
 757                                                                 . "(content model: " . $content->getContentHandler() . ")" );
 758
 759                                         $message = false; // negative caching
 760                                 } else {
 761                                         $this->mCache[$code][$title] = ' ' . $message;
 762                                         $this->mMemc->set( $titleKey, ' ' . $message, $this->mExpiry );
 763                                 }
 764                         }
 765                 } else {
 766                         $message = false; // negative caching
 767                 }
 768
 769                 if ( $message === false ) { // negative caching
 770                         $this->mCache[$code][$title] = '!NONEXISTENT';
 771                         $this->mMemc->set( $titleKey, '!NONEXISTENT', $this->mExpiry );
 772                 }
 773
 774                 return $message;
 775         }
 776
 777         /**
 778          * @param $message string
 779          * @param $interface bool
 780          * @param $language
 781          * @param $title Title
 782          * @return string
 783          */
 784         function transform( $message, $interface = false, $language = null, $title = null ) {
 785                 // Avoid creating parser if nothing to transform
 786                 if( strpos( $message, '{{' ) === false ) {
 787                         return $message;
 788                 }
 789
 790                 if ( $this->mInParser ) {
 791                         return $message;
 792                 }
 793
 794                 $parser = $this->getParser();
 795                 if ( $parser ) {
 796                         $popts = $this->getParserOptions();
 797                         $popts->setInterfaceMessage( $interface );
 798                         $popts->setTargetLanguage( $language );
 799
 800                         $userlang = $popts->setUserLang( $language );
 801                         $this->mInParser = true;
 802                         $message = $parser->transformMsg( $message, $popts, $title );
 803                         $this->mInParser = false;
 804                         $popts->setUserLang( $userlang );
 805                 }
 806                 return $message;
 807         }
 808
 809         /**
 810          * @return Parser
 811          */
 812         function getParser() {
 813                 global $wgParser, $wgParserConf;
 814                 if ( !$this->mParser && isset( $wgParser ) ) {
 815                         # Do some initialisation so that we don't have to do it twice
 816                         $wgParser->firstCallInit();
 817                         # Clone it and store it
 818                         $class = $wgParserConf['class'];
 819                         if ( $class == 'Parser_DiffTest' ) {
 820                                 # Uncloneable
 821                                 $this->mParser = new $class( $wgParserConf );
 822                         } else {
 823                                 $this->mParser = clone $wgParser;
 824                         }
 825                 }
 826                 return $this->mParser;
 827         }
 828
 829         /**
 830          * @param $text string
 831          * @param $title Title
 832          * @param $linestart bool
 833          * @param $interface bool
 834          * @param $language
 835          * @return ParserOutput|string
 836          */
 837         public function parse( $text, $title = null, $linestart = true, $interface = false, $language = null  ) {
 838                 if ( $this->mInParser ) {
 839                         return htmlspecialchars( $text );
 840                 }
 841
 842                 $parser = $this->getParser();
 843                 $popts = $this->getParserOptions();
 844                 $popts->setInterfaceMessage( $interface );
 845                 $popts->setTargetLanguage( $language );
 846
 847                 wfProfileIn( __METHOD__ );
 848                 if ( !$title || !$title instanceof Title ) {
 849                         global $wgTitle;
 850                         $title = $wgTitle;
 851                 }
 852                 // Sometimes $wgTitle isn't set either...
 853                 if ( !$title ) {
 854                         # It's not uncommon having a null $wgTitle in scripts. See r80898
 855                         # Create a ghost title in such case
 856                         $title = Title::newFromText( 'Dwimmerlaik' );
 857                 }
 858
 859                 $this->mInParser = true;
 860                 $res = $parser->parse( $text, $title, $popts, $linestart );
 861                 $this->mInParser = false;
 862
 863                 wfProfileOut( __METHOD__ );
 864                 return $res;
 865         }
 866
 867         function disable() {
 868                 $this->mDisable = true;
 869         }
 870
 871         function enable() {
 872                 $this->mDisable = false;
 873         }
 874
 875         /**
 876          * Clear all stored messages. Mainly used after a mass rebuild.
 877          */
 878         function clear() {
 879                 $langs = Language::fetchLanguageNames( null, 'mw' );
 880                 foreach ( array_keys( $langs ) as $code ) {
 881                         # Global cache
 882                         $this->mMemc->delete( wfMemcKey( 'messages', $code ) );
 883                         # Invalidate all local caches
 884                         $this->mMemc->delete( wfMemcKey( 'messages', $code, 'hash' ) );
 885                 }
 886                 $this->mLoadedLanguages = array();
 887         }
 888
 889         /**
 890          * @param $key
 891          * @return array
 892          */
 893         public function figureMessage( $key ) {
 894                 global $wgLanguageCode;
 895                 $pieces = explode( '/', $key );
 896                 if( count( $pieces ) < 2 ) {
 897                         return array( $key, $wgLanguageCode );
 898                 }
 899
 900                 $lang = array_pop( $pieces );
 901                 if( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
 902                         return array( $key, $wgLanguageCode );
 903                 }
 904
 905                 $message = implode( '/', $pieces );
 906                 return array( $message, $lang );
 907         }
 908
 909         /**
 910          * Get all message keys stored in the message cache for a given language.
 911          * If $code is the content language code, this will return all message keys
 912          * for which MediaWiki:msgkey exists. If $code is another language code, this
 913          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
 914          * @param $code string
 915          * @return array of message keys (strings)
 916          */
 917         public function getAllMessageKeys( $code ) {
 918                 global $wgContLang;
 919                 $this->load( $code );
 920                 if ( !isset( $this->mCache[$code] ) ) {
 921                         // Apparently load() failed
 922                         return null;
 923                 }
 924                 $cache = $this->mCache[$code]; // Copy the cache
 925                 unset( $cache['VERSION'] ); // Remove the VERSION key
 926                 $cache = array_diff( $cache, array( '!NONEXISTENT' ) ); // Remove any !NONEXISTENT keys
 927                 // Keys may appear with a capital first letter. lcfirst them.
 928                 return array_map( array( $wgContLang, 'lcfirst' ), array_keys( $cache ) );
 929         }
 930 }