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          * Used for automatic detection of most used messages.
  64          */
  65         protected $mRequestedMessages = array();
  66
  67         /**
  68          * How long the message request counts are stored. Longer period gives
  69          * better sample, but also takes longer to adapt changes. The counts
  70          * are aggregrated per day, regardless of the value of this variable.
  71          */
  72         protected static $mAdaptiveDataAge = 604800; // Is 7*24*3600
  73
  74         /**
  75          * Filter the tail of less used messages that are requested more seldom
  76          * than this factor times the number of request of most requested message.
  77          * These messages are not loaded in the default set, but are still cached
  78          * individually on demand with the normal cache expiry time.
  79          */
  80         protected static $mAdaptiveInclusionThreshold = 0.05;
  81
  82         /**
  83          * Singleton instance
  84          *
  85          * @var MessageCache
  86          */
  87         private static $instance;
  88
  89         /**
  90          * @var bool
  91          */
  92         protected $mInParser = false;
  93
  94         /**
  95          * Get the signleton instance of this class
  96          *
  97          * @since 1.18
  98          * @return MessageCache object
  99          */
 100         public static function singleton() {
 101                 if ( is_null( self::$instance ) ) {
 102                         global $wgUseDatabaseMessages, $wgMsgCacheExpiry;
 103                         self::$instance = new self( wfGetMessageCacheStorage(), $wgUseDatabaseMessages, $wgMsgCacheExpiry );
 104                 }
 105                 return self::$instance;
 106         }
 107
 108         /**
 109          * Destroy the singleton instance
 110          *
 111          * @since 1.18
 112          */
 113         public static function destroyInstance() {
 114                 self::$instance = null;
 115         }
 116
 117         function __construct( $memCached, $useDB, $expiry ) {
 118                 if ( !$memCached ) {
 119                         $memCached = wfGetCache( CACHE_NONE );
 120                 }
 121
 122                 $this->mMemc = $memCached;
 123                 $this->mDisable = !$useDB;
 124                 $this->mExpiry = $expiry;
 125         }
 126
 127         /**
 128          * ParserOptions is lazy initialised.
 129          *
 130          * @return ParserOptions
 131          */
 132         function getParserOptions() {
 133                 if ( !$this->mParserOptions ) {
 134                         $this->mParserOptions = new ParserOptions;
 135                 }
 136                 return $this->mParserOptions;
 137         }
 138
 139         /**
 140          * Try to load the cache from a local file.
 141          * Actual format of the file depends on the $wgLocalMessageCacheSerialized
 142          * setting.
 143          *
 144          * @param $hash String: the hash of contents, to check validity.
 145          * @param $code Mixed: Optional language code, see documenation of load().
 146          * @return bool on failure.
 147          */
 148         function loadFromLocal( $hash, $code ) {
 149                 global $wgCacheDirectory, $wgLocalMessageCacheSerialized;
 150
 151                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 152
 153                 # Check file existence
 154                 wfSuppressWarnings();
 155                 $file = fopen( $filename, 'r' );
 156                 wfRestoreWarnings();
 157                 if ( !$file ) {
 158                         return false; // No cache file
 159                 }
 160
 161                 if ( $wgLocalMessageCacheSerialized ) {
 162                         // Check to see if the file has the hash specified
 163                         $localHash = fread( $file, 32 );
 164                         if ( $hash === $localHash ) {
 165                                 // All good, get the rest of it
 166                                 $serialized = '';
 167                                 while ( !feof( $file ) ) {
 168                                         $serialized .= fread( $file, 100000 );
 169                                 }
 170                                 fclose( $file );
 171                                 return $this->setCache( unserialize( $serialized ), $code );
 172                         } else {
 173                                 fclose( $file );
 174                                 return false; // Wrong hash
 175                         }
 176                 } else {
 177                         $localHash = substr( fread( $file, 40 ), 8 );
 178                         fclose( $file );
 179                         if ( $hash != $localHash ) {
 180                                 return false; // Wrong hash
 181                         }
 182
 183                         # Require overwrites the member variable or just shadows it?
 184                         require( $filename );
 185                         return $this->setCache( $this->mCache, $code );
 186                 }
 187         }
 188
 189         /**
 190          * Save the cache to a local file.
 191          */
 192         function saveToLocal( $serialized, $hash, $code ) {
 193                 global $wgCacheDirectory;
 194
 195                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 196                 wfMkdirParents( $wgCacheDirectory, null, __METHOD__ ); // might fail
 197
 198                 wfSuppressWarnings();
 199                 $file = fopen( $filename, 'w' );
 200                 wfRestoreWarnings();
 201
 202                 if ( !$file ) {
 203                         wfDebug( "Unable to open local cache file for writing\n" );
 204                         return;
 205                 }
 206
 207                 fwrite( $file, $hash . $serialized );
 208                 fclose( $file );
 209                 wfSuppressWarnings();
 210                 chmod( $filename, 0666 );
 211                 wfRestoreWarnings();
 212         }
 213
 214         function saveToScript( $array, $hash, $code ) {
 215                 global $wgCacheDirectory;
 216
 217                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 218                 $tempFilename = $filename . '.tmp';
 219                 wfMkdirParents( $wgCacheDirectory, null, __METHOD__ ); // might fail
 220
 221                 wfSuppressWarnings();
 222                 $file = fopen( $tempFilename, 'w' );
 223                 wfRestoreWarnings();
 224
 225                 if ( !$file ) {
 226                         wfDebug( "Unable to open local cache file for writing\n" );
 227                         return;
 228                 }
 229
 230                 fwrite( $file, "<?php\n//$hash\n\n \$this->mCache = array(" );
 231
 232                 foreach ( $array as $key => $message ) {
 233                         $key = $this->escapeForScript( $key );
 234                         $message = $this->escapeForScript( $message );
 235                         fwrite( $file, "'$key' => '$message',\n" );
 236                 }
 237
 238                 fwrite( $file, ");\n?>" );
 239                 fclose( $file);
 240                 rename( $tempFilename, $filename );
 241         }
 242
 243         function escapeForScript( $string ) {
 244                 $string = str_replace( '\\', '\\\\', $string );
 245                 $string = str_replace( '\'', '\\\'', $string );
 246                 return $string;
 247         }
 248
 249         /**
 250          * Set the cache to $cache, if it is valid. Otherwise set the cache to false.
 251          *
 252          * @return bool
 253          */
 254         function setCache( $cache, $code ) {
 255                 if ( isset( $cache['VERSION'] ) && $cache['VERSION'] == MSG_CACHE_VERSION ) {
 256                         $this->mCache[$code] = $cache;
 257                         return true;
 258                 } else {
 259                         return false;
 260                 }
 261         }
 262
 263         /**
 264          * Loads messages from caches or from database in this order:
 265          * (1) local message cache (if $wgUseLocalMessageCache is enabled)
 266          * (2) memcached
 267          * (3) from the database.
 268          *
 269          * When succesfully loading from (2) or (3), all higher level caches are
 270          * updated for the newest version.
 271          *
 272          * Nothing is loaded if member variable mDisable is true, either manually
 273          * set by calling code or if message loading fails (is this possible?).
 274          *
 275          * Returns true if cache is already populated or it was succesfully populated,
 276          * or false if populating empty cache fails. Also returns true if MessageCache
 277          * is disabled.
 278          *
 279          * @param $code String: language to which load messages
 280          * @return bool
 281          */
 282         function load( $code = false ) {
 283                 global $wgUseLocalMessageCache;
 284
 285                 if( !is_string( $code ) ) {
 286                         # This isn't really nice, so at least make a note about it and try to
 287                         # fall back
 288                         wfDebug( __METHOD__ . " called without providing a language code\n" );
 289                         $code = 'en';
 290                 }
 291
 292                 # Don't do double loading...
 293                 if ( isset( $this->mLoadedLanguages[$code] ) ) {
 294                         return true;
 295                 }
 296
 297                 # 8 lines of code just to say (once) that message cache is disabled
 298                 if ( $this->mDisable ) {
 299                         static $shownDisabled = false;
 300                         if ( !$shownDisabled ) {
 301                                 wfDebug( __METHOD__ . ": disabled\n" );
 302                                 $shownDisabled = true;
 303                         }
 304                         return true;
 305                 }
 306
 307                 # Loading code starts
 308                 wfProfileIn( __METHOD__ );
 309                 $success = false; # Keep track of success
 310                 $where = array(); # Debug info, delayed to avoid spamming debug log too much
 311                 $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages
 312
 313                 # (1) local cache
 314                 # Hash of the contents is stored in memcache, to detect if local cache goes
 315                 # out of date (due to update in other thread?)
 316                 if ( $wgUseLocalMessageCache ) {
 317                         wfProfileIn( __METHOD__ . '-fromlocal' );
 318
 319                         $hash = $this->mMemc->get( wfMemcKey( 'messages', $code, 'hash' ) );
 320                         if ( $hash ) {
 321                                 $success = $this->loadFromLocal( $hash, $code );
 322                                 if ( $success ) $where[] = 'got from local cache';
 323                         }
 324                         wfProfileOut( __METHOD__ . '-fromlocal' );
 325                 }
 326
 327                 # (2) memcache
 328                 # Fails if nothing in cache, or in the wrong version.
 329                 if ( !$success ) {
 330                         wfProfileIn( __METHOD__ . '-fromcache' );
 331                         $cache = $this->mMemc->get( $cacheKey );
 332                         $success = $this->setCache( $cache, $code );
 333                         if ( $success ) {
 334                                 $where[] = 'got from global cache';
 335                                 $this->saveToCaches( $cache, false, $code );
 336                         }
 337                         wfProfileOut( __METHOD__ . '-fromcache' );
 338                 }
 339
 340                 # (3)
 341                 # Nothing in caches... so we need create one and store it in caches
 342                 if ( !$success ) {
 343                         $where[] = 'cache is empty';
 344                         $where[] = 'loading from database';
 345
 346                         $this->lock( $cacheKey );
 347
 348                         # Limit the concurrency of loadFromDB to a single process
 349                         # This prevents the site from going down when the cache expires
 350                         $statusKey = wfMemcKey( 'messages', $code, 'status' );
 351                         $success = $this->mMemc->add( $statusKey, 'loading', MSG_LOAD_TIMEOUT );
 352                         if ( $success ) {
 353                                 $cache = $this->loadFromDB( $code );
 354                                 $success = $this->setCache( $cache, $code );
 355                         }
 356                         if ( $success ) {
 357                                 $success = $this->saveToCaches( $cache, true, $code );
 358                                 if ( $success ) {
 359                                         $this->mMemc->delete( $statusKey );
 360                                 } else {
 361                                         $this->mMemc->set( $statusKey, 'error', 60 * 5 );
 362                                         wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
 363                                 }
 364                         }
 365                         $this->unlock($cacheKey);
 366                 }
 367
 368                 if ( !$success ) {
 369                         # Bad luck... this should not happen
 370                         $where[] = 'loading FAILED - cache is disabled';
 371                         $info = implode( ', ', $where );
 372                         wfDebug( __METHOD__ . ": Loading $code... $info\n" );
 373                         $this->mDisable = true;
 374                         $this->mCache = false;
 375                 } else {
 376                         # All good, just record the success
 377                         $info = implode( ', ', $where );
 378                         wfDebug( __METHOD__ . ": Loading $code... $info\n" );
 379                         $this->mLoadedLanguages[$code] = true;
 380                 }
 381                 wfProfileOut( __METHOD__ );
 382                 return $success;
 383         }
 384
 385         /**
 386          * Loads cacheable messages from the database. Messages bigger than
 387          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 388          * on-demand from the database later.
 389          *
 390          * @param $code String: language code.
 391          * @return Array: loaded messages for storing in caches.
 392          */
 393         function loadFromDB( $code ) {
 394                 wfProfileIn( __METHOD__ );
 395                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 396                 $dbr = wfGetDB( DB_SLAVE );
 397                 $cache = array();
 398
 399                 # Common conditions
 400                 $conds = array(
 401                         'page_is_redirect' => 0,
 402                         'page_namespace' => NS_MEDIAWIKI,
 403                 );
 404
 405                 $mostused = array();
 406                 if ( $wgAdaptiveMessageCache ) {
 407                         $mostused = $this->getMostUsedMessages();
 408                         if ( $code !== $wgLanguageCode ) {
 409                                 foreach ( $mostused as $key => $value ) {
 410                                         $mostused[$key] = "$value/$code";
 411                                 }
 412                         }
 413                 }
 414
 415                 if ( count( $mostused ) ) {
 416                         $conds['page_title'] = $mostused;
 417                 } elseif ( $code !== $wgLanguageCode ) {
 418                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), "/$code" );
 419                 } else {
 420                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 421                         # other than language code.
 422                         $conds[] = 'page_title NOT' . $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 423                 }
 424
 425                 # Conditions to fetch oversized pages to ignore them
 426                 $bigConds = $conds;
 427                 $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );
 428
 429                 # Load titles for all oversized pages in the MediaWiki namespace
 430                 $res = $dbr->select( 'page', 'page_title', $bigConds, __METHOD__ . "($code)-big" );
 431                 foreach ( $res as $row ) {
 432                         $cache[$row->page_title] = '!TOO BIG';
 433                 }
 434
 435                 # Conditions to load the remaining pages with their contents
 436                 $smallConds = $conds;
 437                 $smallConds[] = 'page_latest=rev_id';
 438                 $smallConds[] = 'rev_text_id=old_id';
 439                 $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );
 440
 441                 $res = $dbr->select(
 442                         array( 'page', 'revision', 'text' ),
 443                         array( 'page_title', 'old_text', 'old_flags' ),
 444                         $smallConds,
 445                         __METHOD__ . "($code)-small"
 446                 );
 447
 448                 foreach ( $res as $row ) {
 449                         $text = Revision::getRevisionText( $row );
 450                         if( $text === false ) {
 451                                 // Failed to fetch data; possible ES errors?
 452                                 // Store a marker to fetch on-demand as a workaround...
 453                                 $entry = '!TOO BIG';
 454                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$row->page_title} ($code)" );
 455                         } else {
 456                                 $entry = ' ' . $text;
 457                         }
 458                         $cache[$row->page_title] = $entry;
 459                 }
 460
 461                 foreach ( $mostused as $key ) {
 462                         if ( !isset( $cache[$key] ) ) {
 463                                 $cache[$key] = '!NONEXISTENT';
 464                         }
 465                 }
 466
 467                 $cache['VERSION'] = MSG_CACHE_VERSION;
 468                 wfProfileOut( __METHOD__ );
 469                 return $cache;
 470         }
 471
 472         /**
 473          * Updates cache as necessary when message page is changed
 474          *
 475          * @param $title String: name of the page changed.
 476          * @param $text Mixed: new contents of the page.
 477          */
 478         public function replace( $title, $text ) {
 479                 global $wgMaxMsgCacheEntrySize;
 480                 wfProfileIn( __METHOD__ );
 481
 482                 if ( $this->mDisable ) {
 483                         wfProfileOut( __METHOD__ );
 484                         return;
 485                 }
 486
 487                 list( $msg, $code ) = $this->figureMessage( $title );
 488
 489                 $cacheKey = wfMemcKey( 'messages', $code );
 490                 $this->load( $code );
 491                 $this->lock( $cacheKey );
 492
 493                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 494
 495                 if ( $text === false ) {
 496                         # Article was deleted
 497                         $this->mCache[$code][$title] = '!NONEXISTENT';
 498                         $this->mMemc->delete( $titleKey );
 499                 } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 500                         # Check for size
 501                         $this->mCache[$code][$title] = '!TOO BIG';
 502                         $this->mMemc->set( $titleKey, ' ' . $text, $this->mExpiry );
 503                 } else {
 504                         $this->mCache[$code][$title] = ' ' . $text;
 505                         $this->mMemc->delete( $titleKey );
 506                 }
 507
 508                 # Update caches
 509                 $this->saveToCaches( $this->mCache[$code], true, $code );
 510                 $this->unlock( $cacheKey );
 511
 512                 // Also delete cached sidebar... just in case it is affected
 513                 $codes = array( $code );
 514                 if ( $code === 'en'  ) {
 515                         // Delete all sidebars, like for example on action=purge on the
 516                         // sidebar messages
 517                         $codes = array_keys( Language::fetchLanguageNames() );
 518                 }
 519
 520                 global $wgMemc;
 521                 foreach ( $codes as $code ) {
 522                         $sidebarKey = wfMemcKey( 'sidebar', $code );
 523                         $wgMemc->delete( $sidebarKey );
 524                 }
 525
 526                 // Update the message in the message blob store
 527                 global $wgContLang;
 528                 MessageBlobStore::updateMessage( $wgContLang->lcfirst( $msg ) );
 529
 530                 wfRunHooks( 'MessageCacheReplace', array( $title, $text ) );
 531
 532                 wfProfileOut( __METHOD__ );
 533         }
 534
 535         /**
 536          * Shortcut to update caches.
 537          *
 538          * @param $cache Array: cached messages with a version.
 539          * @param $memc Bool: Wether to update or not memcache.
 540          * @param $code String: Language code.
 541          * @return bool on somekind of error.
 542          */
 543         protected function saveToCaches( $cache, $memc = true, $code = false ) {
 544                 wfProfileIn( __METHOD__ );
 545                 global $wgUseLocalMessageCache, $wgLocalMessageCacheSerialized;
 546
 547                 $cacheKey = wfMemcKey( 'messages', $code );
 548
 549                 if ( $memc ) {
 550                         $success = $this->mMemc->set( $cacheKey, $cache, $this->mExpiry );
 551                 } else {
 552                         $success = true;
 553                 }
 554
 555                 # Save to local cache
 556                 if ( $wgUseLocalMessageCache ) {
 557                         $serialized = serialize( $cache );
 558                         $hash = md5( $serialized );
 559                         $this->mMemc->set( wfMemcKey( 'messages', $code, 'hash' ), $hash, $this->mExpiry );
 560                         if ($wgLocalMessageCacheSerialized) {
 561                                 $this->saveToLocal( $serialized, $hash, $code );
 562                         } else {
 563                                 $this->saveToScript( $cache, $hash, $code );
 564                         }
 565                 }
 566
 567                 wfProfileOut( __METHOD__ );
 568                 return $success;
 569         }
 570
 571         /**
 572          * Represents a write lock on the messages key
 573          *
 574          * @param $key string
 575          *
 576          * @return Boolean: success
 577          */
 578         function lock( $key ) {
 579                 $lockKey = $key . ':lock';
 580                 for ( $i = 0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
 581                         sleep( 1 );
 582                 }
 583
 584                 return $i >= MSG_WAIT_TIMEOUT;
 585         }
 586
 587         function unlock( $key ) {
 588                 $lockKey = $key . ':lock';
 589                 $this->mMemc->delete( $lockKey );
 590         }
 591
 592         /**
 593          * Get a message from either the content language or the user language.
 594          *
 595          * @param $key String: the message cache key
 596          * @param $useDB Boolean: get the message from the DB, false to use only
 597          *               the localisation
 598          * @param $langcode String: code of the language to get the message for, if
 599          *                  it is a valid code create a language for that language,
 600          *                  if it is a string but not a valid code then make a basic
 601          *                  language object, if it is a false boolean then use the
 602          *                  current users language (as a fallback for the old
 603          *                  parameter functionality), or if it is a true boolean
 604          *                  then use the wikis content language (also as a
 605          *                  fallback).
 606          * @param $isFullKey Boolean: specifies whether $key is a two part key
 607          *                   "msg/lang".
 608          *
 609          * @return string|bool
 610          */
 611         function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
 612                 global $wgLanguageCode, $wgContLang;
 613
 614                 if ( is_int( $key ) ) {
 615                         // "Non-string key given" exception sometimes happens for numerical strings that become ints somewhere on their way here
 616                         $key = strval( $key );
 617                 }
 618
 619                 if ( !is_string( $key ) ) {
 620                         throw new MWException( 'Non-string key given' );
 621                 }
 622
 623                 if ( strval( $key ) === '' ) {
 624                         # Shortcut: the empty key is always missing
 625                         return false;
 626                 }
 627
 628                 $lang = wfGetLangObj( $langcode );
 629                 if ( !$lang ) {
 630                         throw new MWException( "Bad lang code $langcode given" );
 631                 }
 632
 633                 $langcode = $lang->getCode();
 634
 635                 $message = false;
 636
 637                 # Normalise title-case input (with some inlining)
 638                 $lckey = str_replace( ' ', '_', $key );
 639                 if ( ord( $key ) < 128 ) {
 640                         $lckey[0] = strtolower( $lckey[0] );
 641                         $uckey = ucfirst( $lckey );
 642                 } else {
 643                         $lckey = $wgContLang->lcfirst( $lckey );
 644                         $uckey = $wgContLang->ucfirst( $lckey );
 645                 }
 646
 647                 /**
 648                  * Record each message request, but only once per request.
 649                  * This information is not used unless $wgAdaptiveMessageCache
 650                  * is enabled.
 651                  */
 652                 $this->mRequestedMessages[$uckey] = true;
 653
 654                 # Try the MediaWiki namespace
 655                 if( !$this->mDisable && $useDB ) {
 656                         $title = $uckey;
 657                         if( !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 658                                 $title .= '/' . $langcode;
 659                         }
 660                         $message = $this->getMsgFromNamespace( $title, $langcode );
 661                 }
 662
 663                 # Try the array in the language object
 664                 if ( $message === false ) {
 665                         $message = $lang->getMessage( $lckey );
 666                         if ( is_null( $message ) ) {
 667                                 $message = false;
 668                         }
 669                 }
 670
 671                 # Try the array of another language
 672                 if( $message === false ) {
 673                         $parts = explode( '/', $lckey );
 674                         # We may get calls for things that are http-urls from sidebar
 675                         # Let's not load nonexistent languages for those
 676                         # They usually have more than one slash.
 677                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 678                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 679                                 if ( is_null( $message ) ) {
 680                                         $message = false;
 681                                 }
 682                         }
 683                 }
 684
 685                 # Is this a custom message? Try the default language in the db...
 686                 if( ( $message === false || $message === '-' ) &&
 687                         !$this->mDisable && $useDB &&
 688                         !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 689                         $message = $this->getMsgFromNamespace( $uckey, $wgLanguageCode );
 690                 }
 691
 692                 # Final fallback
 693                 if( $message === false ) {
 694                         return false;
 695                 }
 696
 697                 # Fix whitespace
 698                 $message = strtr( $message,
 699                         array(
 700                                 # Fix for trailing whitespace, removed by textarea
 701                                 '&#32;' => ' ',
 702                                 # Fix for NBSP, converted to space by firefox
 703                                 '&nbsp;' => "\xc2\xa0",
 704                                 '&#160;' => "\xc2\xa0",
 705                         ) );
 706
 707                 return $message;
 708         }
 709
 710         /**
 711          * Get a message from the MediaWiki namespace, with caching. The key must
 712          * first be converted to two-part lang/msg form if necessary.
 713          *
 714          * @param $title String: Message cache key with initial uppercase letter.
 715          * @param $code String: code denoting the language to try.
 716          *
 717          * @return string|bool False on failure
 718          */
 719         function getMsgFromNamespace( $title, $code ) {
 720                 global $wgAdaptiveMessageCache;
 721
 722                 $this->load( $code );
 723                 if ( isset( $this->mCache[$code][$title] ) ) {
 724                         $entry = $this->mCache[$code][$title];
 725                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 726                                 return substr( $entry, 1 );
 727                         } elseif ( $entry === '!NONEXISTENT' ) {
 728                                 return false;
 729                         } elseif( $entry === '!TOO BIG' ) {
 730                                 // Fall through and try invididual message cache below
 731                         }
 732                 } else {
 733                         // XXX: This is not cached in process cache, should it?
 734                         $message = false;
 735                         wfRunHooks( 'MessagesPreLoad', array( $title, &$message ) );
 736                         if ( $message !== false ) {
 737                                 return $message;
 738                         }
 739
 740                         /**
 741                          * If message cache is in normal mode, it is guaranteed
 742                          * (except bugs) that there is always entry (or placeholder)
 743                          * in the cache if message exists. Thus we can do minor
 744                          * performance improvement and return false early.
 745                          */
 746                         if ( !$wgAdaptiveMessageCache ) {
 747                                 return false;
 748                         }
 749                 }
 750
 751                 # Try the individual message cache
 752                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 753                 $entry = $this->mMemc->get( $titleKey );
 754                 if ( $entry ) {
 755                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 756                                 $this->mCache[$code][$title] = $entry;
 757                                 return substr( $entry, 1 );
 758                         } elseif ( $entry === '!NONEXISTENT' ) {
 759                                 $this->mCache[$code][$title] = '!NONEXISTENT';
 760                                 return false;
 761                         } else {
 762                                 # Corrupt/obsolete entry, delete it
 763                                 $this->mMemc->delete( $titleKey );
 764                         }
 765                 }
 766
 767                 # Try loading it from the database
 768                 $revision = Revision::newFromTitle( Title::makeTitle( NS_MEDIAWIKI, $title ) );
 769                 if ( $revision ) {
 770                         $message = $revision->getText();
 771                         if ($message === false) {
 772                                 // A possibly temporary loading failure.
 773                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$title} ($code)" );
 774                         } else {
 775                                 $this->mCache[$code][$title] = ' ' . $message;
 776                                 $this->mMemc->set( $titleKey, ' ' . $message, $this->mExpiry );
 777                         }
 778                 } else {
 779                         $message = false;
 780                         $this->mCache[$code][$title] = '!NONEXISTENT';
 781                         $this->mMemc->set( $titleKey, '!NONEXISTENT', $this->mExpiry );
 782                 }
 783
 784                 return $message;
 785         }
 786
 787         /**
 788          * @param $message string
 789          * @param $interface bool
 790          * @param $language
 791          * @param $title Title
 792          * @return string
 793          */
 794         function transform( $message, $interface = false, $language = null, $title = null ) {
 795                 // Avoid creating parser if nothing to transform
 796                 if( strpos( $message, '{{' ) === false ) {
 797                         return $message;
 798                 }
 799
 800                 if ( $this->mInParser ) {
 801                         return $message;
 802                 }
 803
 804                 $parser = $this->getParser();
 805                 if ( $parser ) {
 806                         $popts = $this->getParserOptions();
 807                         $popts->setInterfaceMessage( $interface );
 808                         $popts->setTargetLanguage( $language );
 809
 810                         $userlang = $popts->setUserLang( $language );
 811                         $this->mInParser = true;
 812                         $message = $parser->transformMsg( $message, $popts, $title );
 813                         $this->mInParser = false;
 814                         $popts->setUserLang( $userlang );
 815                 }
 816                 return $message;
 817         }
 818
 819         /**
 820          * @return Parser
 821          */
 822         function getParser() {
 823                 global $wgParser, $wgParserConf;
 824                 if ( !$this->mParser && isset( $wgParser ) ) {
 825                         # Do some initialisation so that we don't have to do it twice
 826                         $wgParser->firstCallInit();
 827                         # Clone it and store it
 828                         $class = $wgParserConf['class'];
 829                         if ( $class == 'Parser_DiffTest' ) {
 830                                 # Uncloneable
 831                                 $this->mParser = new $class( $wgParserConf );
 832                         } else {
 833                                 $this->mParser = clone $wgParser;
 834                         }
 835                 }
 836                 return $this->mParser;
 837         }
 838
 839         /**
 840          * @param $text string
 841          * @param $title Title
 842          * @param $linestart bool
 843          * @param $interface bool
 844          * @param $language
 845          * @return ParserOutput
 846          */
 847         public function parse( $text, $title = null, $linestart = true, $interface = false, $language = null  ) {
 848                 if ( $this->mInParser ) {
 849                         return htmlspecialchars( $text );
 850                 }
 851
 852                 $parser = $this->getParser();
 853                 $popts = $this->getParserOptions();
 854                 $popts->setInterfaceMessage( $interface );
 855                 $popts->setTargetLanguage( $language );
 856
 857                 wfProfileIn( __METHOD__ );
 858                 if ( !$title || !$title instanceof Title ) {
 859                         global $wgTitle;
 860                         $title = $wgTitle;
 861                 }
 862                 // Sometimes $wgTitle isn't set either...
 863                 if ( !$title ) {
 864                         # It's not uncommon having a null $wgTitle in scripts. See r80898
 865                         # Create a ghost title in such case
 866                         $title = Title::newFromText( 'Dwimmerlaik' );
 867                 }
 868
 869                 $this->mInParser = true;
 870                 $res = $parser->parse( $text, $title, $popts, $linestart );
 871                 $this->mInParser = false;
 872
 873                 wfProfileOut( __METHOD__ );
 874                 return $res;
 875         }
 876
 877         function disable() {
 878                 $this->mDisable = true;
 879         }
 880
 881         function enable() {
 882                 $this->mDisable = false;
 883         }
 884
 885         /**
 886          * Clear all stored messages. Mainly used after a mass rebuild.
 887          */
 888         function clear() {
 889                 $langs = Language::fetchLanguageNames( null, 'mw' );
 890                 foreach ( array_keys($langs) as $code ) {
 891                         # Global cache
 892                         $this->mMemc->delete( wfMemcKey( 'messages', $code ) );
 893                         # Invalidate all local caches
 894                         $this->mMemc->delete( wfMemcKey( 'messages', $code, 'hash' ) );
 895                 }
 896                 $this->mLoadedLanguages = array();
 897         }
 898
 899         /**
 900          * @param $key
 901          * @return array
 902          */
 903         public function figureMessage( $key ) {
 904                 global $wgLanguageCode;
 905                 $pieces = explode( '/', $key );
 906                 if( count( $pieces ) < 2 ) {
 907                         return array( $key, $wgLanguageCode );
 908                 }
 909
 910                 $lang = array_pop( $pieces );
 911                 if( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
 912                         return array( $key, $wgLanguageCode );
 913                 }
 914
 915                 $message = implode( '/', $pieces );
 916                 return array( $message, $lang );
 917         }
 918
 919         public static function logMessages() {
 920                 wfProfileIn( __METHOD__ );
 921                 global $wgAdaptiveMessageCache;
 922                 if ( !$wgAdaptiveMessageCache || !self::$instance instanceof MessageCache ) {
 923                         wfProfileOut( __METHOD__ );
 924                         return;
 925                 }
 926
 927                 $cachekey = wfMemckey( 'message-profiling' );
 928                 $cache = wfGetCache( CACHE_DB );
 929                 $data = $cache->get( $cachekey );
 930
 931                 if ( !$data ) {
 932                         $data = array();
 933                 }
 934
 935                 $age = self::$mAdaptiveDataAge;
 936                 $filterDate = substr( wfTimestamp( TS_MW, time() - $age ), 0, 8 );
 937                 foreach ( array_keys( $data ) as $key ) {
 938                         if ( $key < $filterDate ) {
 939                                 unset( $data[$key] );
 940                         }
 941                 }
 942
 943                 $index = substr( wfTimestampNow(), 0, 8 );
 944                 if ( !isset( $data[$index] ) ) {
 945                         $data[$index] = array();
 946                 }
 947
 948                 foreach ( self::$instance->mRequestedMessages as $message => $_ ) {
 949                         if ( !isset( $data[$index][$message] ) ) {
 950                                 $data[$index][$message] = 0;
 951                         }
 952                         $data[$index][$message]++;
 953                 }
 954
 955                 $cache->set( $cachekey, $data );
 956                 wfProfileOut( __METHOD__ );
 957         }
 958
 959         /**
 960          * @return array
 961          */
 962         public function getMostUsedMessages() {
 963                 wfProfileIn( __METHOD__ );
 964                 $cachekey = wfMemcKey( 'message-profiling' );
 965                 $cache = wfGetCache( CACHE_DB );
 966                 $data = $cache->get( $cachekey );
 967                 if ( !$data ) {
 968                         wfProfileOut( __METHOD__ );
 969                         return array();
 970                 }
 971
 972                 $list = array();
 973
 974                 foreach( $data as $messages ) {
 975                         foreach( $messages as $message => $count ) {
 976                                 $key = $message;
 977                                 if ( !isset( $list[$key] ) ) {
 978                                         $list[$key] = 0;
 979                                 }
 980                                 $list[$key] += $count;
 981                         }
 982                 }
 983
 984                 $max = max( $list );
 985                 foreach ( $list as $message => $count ) {
 986                         if ( $count < intval( $max * self::$mAdaptiveInclusionThreshold ) ) {
 987                                 unset( $list[$message] );
 988                         }
 989                 }
 990
 991                 wfProfileOut( __METHOD__ );
 992                 return array_keys( $list );
 993         }
 994
 995         /**
 996          * Get all message keys stored in the message cache for a given language.
 997          * If $code is the content language code, this will return all message keys
 998          * for which MediaWiki:msgkey exists. If $code is another language code, this
 999          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
1000          * @param $code string
1001          * @return array of message keys (strings)
1002          */
1003         public function getAllMessageKeys( $code ) {
1004                 global $wgContLang;
1005                 $this->load( $code );
1006                 if ( !isset( $this->mCache[$code] ) ) {
1007                         // Apparently load() failed
1008                         return null;
1009                 }
1010                 $cache = $this->mCache[$code]; // Copy the cache
1011                 unset( $cache['VERSION'] ); // Remove the VERSION key
1012                 $cache = array_diff( $cache, array( '!NONEXISTENT' ) ); // Remove any !NONEXISTENT keys
1013                 // Keys may appear with a capital first letter. lcfirst them.
1014                 return array_map( array( $wgContLang, 'lcfirst' ), array_keys( $cache ) );
1015         }
1016 }