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  * MediaWiki message cache structure version.
  26  * Bump this whenever the message cache format has changed.
  27  */
  28 define( 'MSG_CACHE_VERSION', 2 );
  29
  30 /**
  31  * Message cache
  32  * Performs various MediaWiki namespace-related functions
  33  * @ingroup Cache
  34  */
  35 class MessageCache {
  36         const FOR_UPDATE = 1; // force message reload
  37
  38         /** How long to wait for memcached locks */
  39         const WAIT_SEC = 15;
  40         /** How long memcached locks last */
  41         const LOCK_TTL = 30;
  42
  43         /**
  44          * Process local cache of loaded messages that are defined in
  45          * MediaWiki namespace. First array level is a language code,
  46          * second level is message key and the values are either message
  47          * content prefixed with space, or !NONEXISTENT for negative
  48          * caching.
  49          * @var array $mCache
  50          */
  51         protected $mCache;
  52
  53         /**
  54          * Should mean that database cannot be used, but check
  55          * @var bool $mDisable
  56          */
  57         protected $mDisable;
  58
  59         /**
  60          * Lifetime for cache, used by object caching.
  61          * Set on construction, see __construct().
  62          */
  63         protected $mExpiry;
  64
  65         /**
  66          * Message cache has its own parser which it uses to transform
  67          * messages.
  68          */
  69         protected $mParserOptions, $mParser;
  70
  71         /**
  72          * Variable for tracking which variables are already loaded
  73          * @var array $mLoadedLanguages
  74          */
  75         protected $mLoadedLanguages = [];
  76
  77         /**
  78          * @var bool $mInParser
  79          */
  80         protected $mInParser = false;
  81
  82         /** @var BagOStuff */
  83         protected $mMemc;
  84         /** @var WANObjectCache */
  85         protected $wanCache;
  86
  87         /**
  88          * Singleton instance
  89          *
  90          * @var MessageCache $instance
  91          */
  92         private static $instance;
  93
  94         /**
  95          * Get the signleton instance of this class
  96          *
  97          * @since 1.18
  98          * @return MessageCache
  99          */
 100         public static function singleton() {
 101                 if ( self::$instance === null ) {
 102                         global $wgUseDatabaseMessages, $wgMsgCacheExpiry;
 103                         self::$instance = new self(
 104                                 wfGetMessageCacheStorage(),
 105                                 $wgUseDatabaseMessages,
 106                                 $wgMsgCacheExpiry
 107                         );
 108                 }
 109
 110                 return self::$instance;
 111         }
 112
 113         /**
 114          * Destroy the singleton instance
 115          *
 116          * @since 1.18
 117          */
 118         public static function destroyInstance() {
 119                 self::$instance = null;
 120         }
 121
 122         /**
 123          * Normalize message key input
 124          *
 125          * @param string $key Input message key to be normalized
 126          * @return string Normalized message key
 127          */
 128         public static function normalizeKey( $key ) {
 129                 global $wgContLang;
 130                 $lckey = strtr( $key, ' ', '_' );
 131                 if ( ord( $lckey ) < 128 ) {
 132                         $lckey[0] = strtolower( $lckey[0] );
 133                 } else {
 134                         $lckey = $wgContLang->lcfirst( $lckey );
 135                 }
 136
 137                 return $lckey;
 138         }
 139
 140         /**
 141          * @param BagOStuff $memCached A cache instance. If none, fall back to CACHE_NONE.
 142          * @param bool $useDB
 143          * @param int $expiry Lifetime for cache. @see $mExpiry.
 144          */
 145         function __construct( $memCached, $useDB, $expiry ) {
 146                 global $wgUseLocalMessageCache;
 147
 148                 if ( !$memCached ) {
 149                         $memCached = wfGetCache( CACHE_NONE );
 150                 }
 151
 152                 $this->mMemc = $memCached;
 153                 $this->mDisable = !$useDB;
 154                 $this->mExpiry = $expiry;
 155
 156                 if ( $wgUseLocalMessageCache ) {
 157                         $this->localCache = ObjectCache::getLocalServerInstance( CACHE_NONE );
 158                 } else {
 159                         $this->localCache = wfGetCache( CACHE_NONE );
 160                 }
 161
 162                 $this->wanCache = ObjectCache::getMainWANInstance();
 163         }
 164
 165         /**
 166          * ParserOptions is lazy initialised.
 167          *
 168          * @return ParserOptions
 169          */
 170         function getParserOptions() {
 171                 global $wgUser;
 172
 173                 if ( !$this->mParserOptions ) {
 174                         if ( !$wgUser->isSafeToLoad() ) {
 175                                 // $wgUser isn't unstubbable yet, so don't try to get a
 176                                 // ParserOptions for it. And don't cache this ParserOptions
 177                                 // either.
 178                                 $po = ParserOptions::newFromAnon();
 179                                 $po->setEditSection( false );
 180                                 return $po;
 181                         }
 182
 183                         $this->mParserOptions = new ParserOptions;
 184                         $this->mParserOptions->setEditSection( false );
 185                 }
 186
 187                 return $this->mParserOptions;
 188         }
 189
 190         /**
 191          * Try to load the cache from APC.
 192          *
 193          * @param string $code Optional language code, see documenation of load().
 194          * @return array|bool The cache array, or false if not in cache.
 195          */
 196         protected function getLocalCache( $code ) {
 197                 $cacheKey = wfMemcKey( __CLASS__, $code );
 198
 199                 return $this->localCache->get( $cacheKey );
 200         }
 201
 202         /**
 203          * Save the cache to APC.
 204          *
 205          * @param string $code
 206          * @param array $cache The cache array
 207          */
 208         protected function saveToLocalCache( $code, $cache ) {
 209                 $cacheKey = wfMemcKey( __CLASS__, $code );
 210                 $this->localCache->set( $cacheKey, $cache );
 211         }
 212
 213         /**
 214          * Loads messages from caches or from database in this order:
 215          * (1) local message cache (if $wgUseLocalMessageCache is enabled)
 216          * (2) memcached
 217          * (3) from the database.
 218          *
 219          * When succesfully loading from (2) or (3), all higher level caches are
 220          * updated for the newest version.
 221          *
 222          * Nothing is loaded if member variable mDisable is true, either manually
 223          * set by calling code or if message loading fails (is this possible?).
 224          *
 225          * Returns true if cache is already populated or it was succesfully populated,
 226          * or false if populating empty cache fails. Also returns true if MessageCache
 227          * is disabled.
 228          *
 229          * @param bool|string $code Language to which load messages
 230          * @param integer $mode Use MessageCache::FOR_UPDATE to skip process cache
 231          * @throws MWException
 232          * @return bool
 233          */
 234         function load( $code = false, $mode = null ) {
 235                 if ( !is_string( $code ) ) {
 236                         # This isn't really nice, so at least make a note about it and try to
 237                         # fall back
 238                         wfDebug( __METHOD__ . " called without providing a language code\n" );
 239                         $code = 'en';
 240                 }
 241
 242                 # Don't do double loading...
 243                 if ( isset( $this->mLoadedLanguages[$code] ) && $mode != self::FOR_UPDATE ) {
 244                         return true;
 245                 }
 246
 247                 # 8 lines of code just to say (once) that message cache is disabled
 248                 if ( $this->mDisable ) {
 249                         static $shownDisabled = false;
 250                         if ( !$shownDisabled ) {
 251                                 wfDebug( __METHOD__ . ": disabled\n" );
 252                                 $shownDisabled = true;
 253                         }
 254
 255                         return true;
 256                 }
 257
 258                 # Loading code starts
 259                 $success = false; # Keep track of success
 260                 $staleCache = false; # a cache array with expired data, or false if none has been loaded
 261                 $where = []; # Debug info, delayed to avoid spamming debug log too much
 262
 263                 # Hash of the contents is stored in memcache, to detect if data-center cache
 264                 # or local cache goes out of date (e.g. due to replace() on some other server)
 265                 list( $hash, $hashVolatile ) = $this->getValidationHash( $code );
 266
 267                 # Try the local cache and check against the cluster hash key...
 268                 $cache = $this->getLocalCache( $code );
 269                 if ( !$cache ) {
 270                         $where[] = 'local cache is empty';
 271                 } elseif ( !isset( $cache['HASH'] ) || $cache['HASH'] !== $hash ) {
 272                         $where[] = 'local cache has the wrong hash';
 273                         $staleCache = $cache;
 274                 } elseif ( $this->isCacheExpired( $cache ) ) {
 275                         $where[] = 'local cache is expired';
 276                         $staleCache = $cache;
 277                 } elseif ( $hashVolatile ) {
 278                         $where[] = 'local cache validation key is expired/volatile';
 279                         $staleCache = $cache;
 280                 } else {
 281                         $where[] = 'got from local cache';
 282                         $success = true;
 283                         $this->mCache[$code] = $cache;
 284                 }
 285
 286                 if ( !$success ) {
 287                         $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages
 288                         # Try the global cache. If it is empty, try to acquire a lock. If
 289                         # the lock can't be acquired, wait for the other thread to finish
 290                         # and then try the global cache a second time.
 291                         for ( $failedAttempts = 0; $failedAttempts <= 1; $failedAttempts++ ) {
 292                                 if ( $hashVolatile && $staleCache ) {
 293                                         # Do not bother fetching the whole cache blob to avoid I/O.
 294                                         # Instead, just try to get the non-blocking $statusKey lock
 295                                         # below, and use the local stale value if it was not acquired.
 296                                         $where[] = 'global cache is presumed expired';
 297                                 } else {
 298                                         $cache = $this->mMemc->get( $cacheKey );
 299                                         if ( !$cache ) {
 300                                                 $where[] = 'global cache is empty';
 301                                         } elseif ( $this->isCacheExpired( $cache ) ) {
 302                                                 $where[] = 'global cache is expired';
 303                                                 $staleCache = $cache;
 304                                         } elseif ( $hashVolatile ) {
 305                                                 # DB results are replica DB lag prone until the holdoff TTL passes.
 306                                                 # By then, updates should be reflected in loadFromDBWithLock().
 307                                                 # One thread renerates the cache while others use old values.
 308                                                 $where[] = 'global cache is expired/volatile';
 309                                                 $staleCache = $cache;
 310                                         } else {
 311                                                 $where[] = 'got from global cache';
 312                                                 $this->mCache[$code] = $cache;
 313                                                 $this->saveToCaches( $cache, 'local-only', $code );
 314                                                 $success = true;
 315                                         }
 316                                 }
 317
 318                                 if ( $success ) {
 319                                         # Done, no need to retry
 320                                         break;
 321                                 }
 322
 323                                 # We need to call loadFromDB. Limit the concurrency to one process.
 324                                 # This prevents the site from going down when the cache expires.
 325                                 # Note that the DB slam protection lock here is non-blocking.
 326                                 $loadStatus = $this->loadFromDBWithLock( $code, $where, $mode );
 327                                 if ( $loadStatus === true ) {
 328                                         $success = true;
 329                                         break;
 330                                 } elseif ( $staleCache ) {
 331                                         # Use the stale cache while some other thread constructs the new one
 332                                         $where[] = 'using stale cache';
 333                                         $this->mCache[$code] = $staleCache;
 334                                         $success = true;
 335                                         break;
 336                                 } elseif ( $failedAttempts > 0 ) {
 337                                         # Already blocked once, so avoid another lock/unlock cycle.
 338                                         # This case will typically be hit if memcached is down, or if
 339                                         # loadFromDB() takes longer than LOCK_WAIT.
 340                                         $where[] = "could not acquire status key.";
 341                                         break;
 342                                 } elseif ( $loadStatus === 'cantacquire' ) {
 343                                         # Wait for the other thread to finish, then retry. Normally,
 344                                         # the memcached get() will then yeild the other thread's result.
 345                                         $where[] = 'waited for other thread to complete';
 346                                         $this->getReentrantScopedLock( $cacheKey );
 347                                 } else {
 348                                         # Disable cache; $loadStatus is 'disabled'
 349                                         break;
 350                                 }
 351                         }
 352                 }
 353
 354                 if ( !$success ) {
 355                         $where[] = 'loading FAILED - cache is disabled';
 356                         $this->mDisable = true;
 357                         $this->mCache = false;
 358                         wfDebugLog( 'MessageCacheError', __METHOD__ . ": Failed to load $code\n" );
 359                         # This used to throw an exception, but that led to nasty side effects like
 360                         # the whole wiki being instantly down if the memcached server died
 361                 } else {
 362                         # All good, just record the success
 363                         $this->mLoadedLanguages[$code] = true;
 364                 }
 365
 366                 $info = implode( ', ', $where );
 367                 wfDebugLog( 'MessageCache', __METHOD__ . ": Loading $code... $info\n" );
 368
 369                 return $success;
 370         }
 371
 372         /**
 373          * @param string $code
 374          * @param array $where List of wfDebug() comments
 375          * @param integer $mode Use MessageCache::FOR_UPDATE to use DB_MASTER
 376          * @return bool|string True on success or one of ("cantacquire", "disabled")
 377          */
 378         protected function loadFromDBWithLock( $code, array &$where, $mode = null ) {
 379                 global $wgUseLocalMessageCache;
 380
 381                 # If cache updates on all levels fail, give up on message overrides.
 382                 # This is to avoid easy site outages; see $saveSuccess comments below.
 383                 $statusKey = wfMemcKey( 'messages', $code, 'status' );
 384                 $status = $this->mMemc->get( $statusKey );
 385                 if ( $status === 'error' ) {
 386                         $where[] = "could not load; method is still globally disabled";
 387                         return 'disabled';
 388                 }
 389
 390                 # Now let's regenerate
 391                 $where[] = 'loading from database';
 392
 393                 # Lock the cache to prevent conflicting writes.
 394                 # This lock is non-blocking so stale cache can quickly be used.
 395                 # Note that load() will call a blocking getReentrantScopedLock()
 396                 # after this if it really need to wait for any current thread.
 397                 $cacheKey = wfMemcKey( 'messages', $code );
 398                 $scopedLock = $this->getReentrantScopedLock( $cacheKey, 0 );
 399                 if ( !$scopedLock ) {
 400                         $where[] = 'could not acquire main lock';
 401                         return 'cantacquire';
 402                 }
 403
 404                 $cache = $this->loadFromDB( $code, $mode );
 405                 $this->mCache[$code] = $cache;
 406                 $saveSuccess = $this->saveToCaches( $cache, 'all', $code );
 407
 408                 if ( !$saveSuccess ) {
 409                         /**
 410                          * Cache save has failed.
 411                          *
 412                          * There are two main scenarios where this could be a problem:
 413                          * - The cache is more than the maximum size (typically 1MB compressed).
 414                          * - Memcached has no space remaining in the relevant slab class. This is
 415                          *   unlikely with recent versions of memcached.
 416                          *
 417                          * Either way, if there is a local cache, nothing bad will happen. If there
 418                          * is no local cache, disabling the message cache for all requests avoids
 419                          * incurring a loadFromDB() overhead on every request, and thus saves the
 420                          * wiki from complete downtime under moderate traffic conditions.
 421                          */
 422                         if ( !$wgUseLocalMessageCache ) {
 423                                 $this->mMemc->set( $statusKey, 'error', 60 * 5 );
 424                                 $where[] = 'could not save cache, disabled globally for 5 minutes';
 425                         } else {
 426                                 $where[] = "could not save global cache";
 427                         }
 428                 }
 429
 430                 return true;
 431         }
 432
 433         /**
 434          * Loads cacheable messages from the database. Messages bigger than
 435          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 436          * on-demand from the database later.
 437          *
 438          * @param string $code Language code
 439          * @param integer $mode Use MessageCache::FOR_UPDATE to skip process cache
 440          * @return array Loaded messages for storing in caches
 441          */
 442         function loadFromDB( $code, $mode = null ) {
 443                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 444
 445                 $dbr = wfGetDB( ( $mode == self::FOR_UPDATE ) ? DB_MASTER : DB_SLAVE );
 446
 447                 $cache = [];
 448
 449                 # Common conditions
 450                 $conds = [
 451                         'page_is_redirect' => 0,
 452                         'page_namespace' => NS_MEDIAWIKI,
 453                 ];
 454
 455                 $mostused = [];
 456                 if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
 457                         if ( !isset( $this->mCache[$wgLanguageCode] ) ) {
 458                                 $this->load( $wgLanguageCode );
 459                         }
 460                         $mostused = array_keys( $this->mCache[$wgLanguageCode] );
 461                         foreach ( $mostused as $key => $value ) {
 462                                 $mostused[$key] = "$value/$code";
 463                         }
 464                 }
 465
 466                 if ( count( $mostused ) ) {
 467                         $conds['page_title'] = $mostused;
 468                 } elseif ( $code !== $wgLanguageCode ) {
 469                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
 470                 } else {
 471                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 472                         # other than language code.
 473                         $conds[] = 'page_title NOT' . $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 474                 }
 475
 476                 # Conditions to fetch oversized pages to ignore them
 477                 $bigConds = $conds;
 478                 $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );
 479
 480                 # Load titles for all oversized pages in the MediaWiki namespace
 481                 $res = $dbr->select( 'page', 'page_title', $bigConds, __METHOD__ . "($code)-big" );
 482                 foreach ( $res as $row ) {
 483                         $cache[$row->page_title] = '!TOO BIG';
 484                 }
 485
 486                 # Conditions to load the remaining pages with their contents
 487                 $smallConds = $conds;
 488                 $smallConds[] = 'page_latest=rev_id';
 489                 $smallConds[] = 'rev_text_id=old_id';
 490                 $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );
 491
 492                 $res = $dbr->select(
 493                         [ 'page', 'revision', 'text' ],
 494                         [ 'page_title', 'old_text', 'old_flags' ],
 495                         $smallConds,
 496                         __METHOD__ . "($code)-small"
 497                 );
 498
 499                 foreach ( $res as $row ) {
 500                         $text = Revision::getRevisionText( $row );
 501                         if ( $text === false ) {
 502                                 // Failed to fetch data; possible ES errors?
 503                                 // Store a marker to fetch on-demand as a workaround...
 504                                 $entry = '!TOO BIG';
 505                                 wfDebugLog(
 506                                         'MessageCache',
 507                                         __METHOD__
 508                                                 . ": failed to load message page text for {$row->page_title} ($code)"
 509                                 );
 510                         } else {
 511                                 $entry = ' ' . $text;
 512                         }
 513                         $cache[$row->page_title] = $entry;
 514                 }
 515
 516                 $cache['VERSION'] = MSG_CACHE_VERSION;
 517                 ksort( $cache );
 518                 $cache['HASH'] = md5( serialize( $cache ) );
 519                 $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );
 520
 521                 return $cache;
 522         }
 523
 524         /**
 525          * Updates cache as necessary when message page is changed
 526          *
 527          * @param string|bool $title Name of the page changed (false if deleted)
 528          * @param mixed $text New contents of the page.
 529          */
 530         public function replace( $title, $text ) {
 531                 global $wgMaxMsgCacheEntrySize, $wgContLang, $wgLanguageCode;
 532
 533                 if ( $this->mDisable ) {
 534                         return;
 535                 }
 536
 537                 list( $msg, $code ) = $this->figureMessage( $title );
 538                 if ( strpos( $title, '/' ) !== false && $code === $wgLanguageCode ) {
 539                         // Content language overrides do not use the /<code> suffix
 540                         return;
 541                 }
 542
 543                 // Note that if the cache is volatile, load() may trigger a DB fetch.
 544                 // In that case we reenter/reuse the existing cache key lock to avoid
 545                 // a self-deadlock. This is safe as no reads happen *directly* in this
 546                 // method between getReentrantScopedLock() and load() below. There is
 547                 // no risk of data "changing under our feet" for replace().
 548                 $cacheKey = wfMemcKey( 'messages', $code );
 549                 $scopedLock = $this->getReentrantScopedLock( $cacheKey );
 550                 $this->load( $code, self::FOR_UPDATE );
 551
 552                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 553                 if ( $text === false ) {
 554                         // Article was deleted
 555                         $this->mCache[$code][$title] = '!NONEXISTENT';
 556                         $this->wanCache->delete( $titleKey );
 557                 } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 558                         // Check for size
 559                         $this->mCache[$code][$title] = '!TOO BIG';
 560                         $this->wanCache->set( $titleKey, ' ' . $text, $this->mExpiry );
 561                 } else {
 562                         $this->mCache[$code][$title] = ' ' . $text;
 563                         $this->wanCache->delete( $titleKey );
 564                 }
 565
 566                 // Mark this cache as definitely "latest" (non-volatile) so
 567                 // load() calls do try to refresh the cache with replica DB data
 568                 $this->mCache[$code]['LATEST'] = time();
 569
 570                 // Update caches if the lock was acquired
 571                 if ( $scopedLock ) {
 572                         $this->saveToCaches( $this->mCache[$code], 'all', $code );
 573                 }
 574
 575                 ScopedCallback::consume( $scopedLock );
 576                 // Relay the purge to APC and other DCs
 577                 $this->wanCache->touchCheckKey( wfMemcKey( 'messages', $code ) );
 578
 579                 // Also delete cached sidebar... just in case it is affected
 580                 $codes = [ $code ];
 581                 if ( $code === 'en' ) {
 582                         // Delete all sidebars, like for example on action=purge on the
 583                         // sidebar messages
 584                         $codes = array_keys( Language::fetchLanguageNames() );
 585                 }
 586
 587                 foreach ( $codes as $code ) {
 588                         $sidebarKey = wfMemcKey( 'sidebar', $code );
 589                         $this->wanCache->delete( $sidebarKey );
 590                 }
 591
 592                 // Update the message in the message blob store
 593                 $resourceloader = RequestContext::getMain()->getOutput()->getResourceLoader();
 594                 $blobStore = $resourceloader->getMessageBlobStore();
 595                 $blobStore->updateMessage( $wgContLang->lcfirst( $msg ) );
 596
 597                 Hooks::run( 'MessageCacheReplace', [ $title, $text ] );
 598         }
 599
 600         /**
 601          * Is the given cache array expired due to time passing or a version change?
 602          *
 603          * @param array $cache
 604          * @return bool
 605          */
 606         protected function isCacheExpired( $cache ) {
 607                 if ( !isset( $cache['VERSION'] ) || !isset( $cache['EXPIRY'] ) ) {
 608                         return true;
 609                 }
 610                 if ( $cache['VERSION'] != MSG_CACHE_VERSION ) {
 611                         return true;
 612                 }
 613                 if ( wfTimestampNow() >= $cache['EXPIRY'] ) {
 614                         return true;
 615                 }
 616
 617                 return false;
 618         }
 619
 620         /**
 621          * Shortcut to update caches.
 622          *
 623          * @param array $cache Cached messages with a version.
 624          * @param string $dest Either "local-only" to save to local caches only
 625          *   or "all" to save to all caches.
 626          * @param string|bool $code Language code (default: false)
 627          * @return bool
 628          */
 629         protected function saveToCaches( array $cache, $dest, $code = false ) {
 630                 if ( $dest === 'all' ) {
 631                         $cacheKey = wfMemcKey( 'messages', $code );
 632                         $success = $this->mMemc->set( $cacheKey, $cache );
 633                 } else {
 634                         $success = true;
 635                 }
 636
 637                 $this->setValidationHash( $code, $cache );
 638                 $this->saveToLocalCache( $code, $cache );
 639
 640                 return $success;
 641         }
 642
 643         /**
 644          * Get the md5 used to validate the local APC cache
 645          *
 646          * @param string $code
 647          * @return array (hash or false, bool expiry/volatility status)
 648          */
 649         protected function getValidationHash( $code ) {
 650                 $curTTL = null;
 651                 $value = $this->wanCache->get(
 652                         wfMemcKey( 'messages', $code, 'hash', 'v1' ),
 653                         $curTTL,
 654                         [ wfMemcKey( 'messages', $code ) ]
 655                 );
 656
 657                 if ( !$value ) {
 658                         // No hash found at all; cache must regenerate to be safe
 659                         $hash = false;
 660                         $expired = true;
 661                 } else {
 662                         $hash = $value['hash'];
 663                         if ( ( time() - $value['latest'] ) < WANObjectCache::HOLDOFF_TTL ) {
 664                                 // Cache was recently updated via replace() and should be up-to-date
 665                                 $expired = false;
 666                         } else {
 667                                 // See if the "check" key was bumped after the hash was generated
 668                                 $expired = ( $curTTL < 0 );
 669                         }
 670                 }
 671
 672                 return [ $hash, $expired ];
 673         }
 674
 675         /**
 676          * Set the md5 used to validate the local disk cache
 677          *
 678          * If $cache has a 'LATEST' UNIX timestamp key, then the hash will not
 679          * be treated as "volatile" by getValidationHash() for the next few seconds
 680          *
 681          * @param string $code
 682          * @param array $cache Cached messages with a version
 683          */
 684         protected function setValidationHash( $code, array $cache ) {
 685                 $this->wanCache->set(
 686                         wfMemcKey( 'messages', $code, 'hash', 'v1' ),
 687                         [
 688                                 'hash' => $cache['HASH'],
 689                                 'latest' => isset( $cache['LATEST'] ) ? $cache['LATEST'] : 0
 690                         ],
 691                         WANObjectCache::TTL_INDEFINITE
 692                 );
 693         }
 694
 695         /**
 696          * @param string $key A language message cache key that stores blobs
 697          * @param integer $timeout Wait timeout in seconds
 698          * @return null|ScopedCallback
 699          */
 700         protected function getReentrantScopedLock( $key, $timeout = self::WAIT_SEC ) {
 701                 return $this->mMemc->getScopedLock( $key, $timeout, self::LOCK_TTL, __METHOD__ );
 702         }
 703
 704         /**
 705          * Get a message from either the content language or the user language.
 706          *
 707          * First, assemble a list of languages to attempt getting the message from. This
 708          * chain begins with the requested language and its fallbacks and then continues with
 709          * the content language and its fallbacks. For each language in the chain, the following
 710          * process will occur (in this order):
 711          *  1. If a language-specific override, i.e., [[MW:msg/lang]], is available, use that.
 712          *     Note: for the content language, there is no /lang subpage.
 713          *  2. Fetch from the static CDB cache.
 714          *  3. If available, check the database for fallback language overrides.
 715          *
 716          * This process provides a number of guarantees. When changing this code, make sure all
 717          * of these guarantees are preserved.
 718          *  * If the requested language is *not* the content language, then the CDB cache for that
 719          *    specific language will take precedence over the root database page ([[MW:msg]]).
 720          *  * Fallbacks will be just that: fallbacks. A fallback language will never be reached if
 721          *    the message is available *anywhere* in the language for which it is a fallback.
 722          *
 723          * @param string $key The message key
 724          * @param bool $useDB If true, look for the message in the DB, false
 725          *   to use only the compiled l10n cache.
 726          * @param bool|string|object $langcode Code of the language to get the message for.
 727          *   - If string and a valid code, will create a standard language object
 728          *   - If string but not a valid code, will create a basic language object
 729          *   - If boolean and false, create object from the current users language
 730          *   - If boolean and true, create object from the wikis content language
 731          *   - If language object, use it as given
 732          * @param bool $isFullKey Specifies whether $key is a two part key "msg/lang".
 733          *
 734          * @throws MWException When given an invalid key
 735          * @return string|bool False if the message doesn't exist, otherwise the
 736          *   message (which can be empty)
 737          */
 738         function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
 739                 if ( is_int( $key ) ) {
 740                         // Fix numerical strings that somehow become ints
 741                         // on their way here
 742                         $key = (string)$key;
 743                 } elseif ( !is_string( $key ) ) {
 744                         throw new MWException( 'Non-string key given' );
 745                 } elseif ( $key === '' ) {
 746                         // Shortcut: the empty key is always missing
 747                         return false;
 748                 }
 749
 750                 // For full keys, get the language code from the key
 751                 $pos = strrpos( $key, '/' );
 752                 if ( $isFullKey && $pos !== false ) {
 753                         $langcode = substr( $key, $pos + 1 );
 754                         $key = substr( $key, 0, $pos );
 755                 }
 756
 757                 // Normalise title-case input (with some inlining)
 758                 $lckey = MessageCache::normalizeKey( $key );
 759
 760                 Hooks::run( 'MessageCache::get', [ &$lckey ] );
 761
 762                 // Loop through each language in the fallback list until we find something useful
 763                 $lang = wfGetLangObj( $langcode );
 764                 $message = $this->getMessageFromFallbackChain(
 765                         $lang,
 766                         $lckey,
 767                         !$this->mDisable && $useDB
 768                 );
 769
 770                 // If we still have no message, maybe the key was in fact a full key so try that
 771                 if ( $message === false ) {
 772                         $parts = explode( '/', $lckey );
 773                         // We may get calls for things that are http-urls from sidebar
 774                         // Let's not load nonexistent languages for those
 775                         // They usually have more than one slash.
 776                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 777                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 778                                 if ( $message === null ) {
 779                                         $message = false;
 780                                 }
 781                         }
 782                 }
 783
 784                 // Post-processing if the message exists
 785                 if ( $message !== false ) {
 786                         // Fix whitespace
 787                         $message = str_replace(
 788                                 [
 789                                         # Fix for trailing whitespace, removed by textarea
 790                                         '&#32;',
 791                                         # Fix for NBSP, converted to space by firefox
 792                                         '&nbsp;',
 793                                         '&#160;',
 794                                         '&shy;'
 795                                 ],
 796                                 [
 797                                         ' ',
 798                                         "\xc2\xa0",
 799                                         "\xc2\xa0",
 800                                         "\xc2\xad"
 801                                 ],
 802                                 $message
 803                         );
 804                 }
 805
 806                 return $message;
 807         }
 808
 809         /**
 810          * Given a language, try and fetch messages from that language.
 811          *
 812          * Will also consider fallbacks of that language, the site language, and fallbacks for
 813          * the site language.
 814          *
 815          * @see MessageCache::get
 816          * @param Language|StubObject $lang Preferred language
 817          * @param string $lckey Lowercase key for the message (as for localisation cache)
 818          * @param bool $useDB Whether to include messages from the wiki database
 819          * @return string|bool The message, or false if not found
 820          */
 821         protected function getMessageFromFallbackChain( $lang, $lckey, $useDB ) {
 822                 global $wgContLang;
 823
 824                 $alreadyTried = [];
 825
 826                  // First try the requested language.
 827                 $message = $this->getMessageForLang( $lang, $lckey, $useDB, $alreadyTried );
 828                 if ( $message !== false ) {
 829                         return $message;
 830                 }
 831
 832                 // Now try checking the site language.
 833                 $message = $this->getMessageForLang( $wgContLang, $lckey, $useDB, $alreadyTried );
 834                 return $message;
 835         }
 836
 837         /**
 838          * Given a language, try and fetch messages from that language and its fallbacks.
 839          *
 840          * @see MessageCache::get
 841          * @param Language|StubObject $lang Preferred language
 842          * @param string $lckey Lowercase key for the message (as for localisation cache)
 843          * @param bool $useDB Whether to include messages from the wiki database
 844          * @param bool[] $alreadyTried Contains true for each language that has been tried already
 845          * @return string|bool The message, or false if not found
 846          */
 847         private function getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried ) {
 848                 global $wgContLang;
 849                 $langcode = $lang->getCode();
 850
 851                 // Try checking the database for the requested language
 852                 if ( $useDB ) {
 853                         $uckey = $wgContLang->ucfirst( $lckey );
 854
 855                         if ( !isset( $alreadyTried[ $langcode ] ) ) {
 856                                 $message = $this->getMsgFromNamespace(
 857                                         $this->getMessagePageName( $langcode, $uckey ),
 858                                         $langcode
 859                                 );
 860
 861                                 if ( $message !== false ) {
 862                                         return $message;
 863                                 }
 864                                 $alreadyTried[ $langcode ] = true;
 865                         }
 866                 }
 867
 868                 // Check the CDB cache
 869                 $message = $lang->getMessage( $lckey );
 870                 if ( $message !== null ) {
 871                         return $message;
 872                 }
 873
 874                 // Try checking the database for all of the fallback languages
 875                 if ( $useDB ) {
 876                         $fallbackChain = Language::getFallbacksFor( $langcode );
 877
 878                         foreach ( $fallbackChain as $code ) {
 879                                 if ( isset( $alreadyTried[ $code ] ) ) {
 880                                         continue;
 881                                 }
 882
 883                                 $message = $this->getMsgFromNamespace( $this->getMessagePageName( $code, $uckey ), $code );
 884
 885                                 if ( $message !== false ) {
 886                                         return $message;
 887                                 }
 888                                 $alreadyTried[ $code ] = true;
 889                         }
 890                 }
 891
 892                 return false;
 893         }
 894
 895         /**
 896          * Get the message page name for a given language
 897          *
 898          * @param string $langcode
 899          * @param string $uckey Uppercase key for the message
 900          * @return string The page name
 901          */
 902         private function getMessagePageName( $langcode, $uckey ) {
 903                 global $wgLanguageCode;
 904                 if ( $langcode === $wgLanguageCode ) {
 905                         // Messages created in the content language will not have the /lang extension
 906                         return $uckey;
 907                 } else {
 908                         return "$uckey/$langcode";
 909                 }
 910         }
 911
 912         /**
 913          * Get a message from the MediaWiki namespace, with caching. The key must
 914          * first be converted to two-part lang/msg form if necessary.
 915          *
 916          * Unlike self::get(), this function doesn't resolve fallback chains, and
 917          * some callers require this behavior. LanguageConverter::parseCachedTable()
 918          * and self::get() are some examples in core.
 919          *
 920          * @param string $title Message cache key with initial uppercase letter.
 921          * @param string $code Code denoting the language to try.
 922          * @return string|bool The message, or false if it does not exist or on error
 923          */
 924         public function getMsgFromNamespace( $title, $code ) {
 925                 $this->load( $code );
 926                 if ( isset( $this->mCache[$code][$title] ) ) {
 927                         $entry = $this->mCache[$code][$title];
 928                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 929                                 // The message exists, so make sure a string
 930                                 // is returned.
 931                                 return (string)substr( $entry, 1 );
 932                         } elseif ( $entry === '!NONEXISTENT' ) {
 933                                 return false;
 934                         } elseif ( $entry === '!TOO BIG' ) {
 935                                 // Fall through and try invididual message cache below
 936                         }
 937                 } else {
 938                         // XXX: This is not cached in process cache, should it?
 939                         $message = false;
 940                         Hooks::run( 'MessagesPreLoad', [ $title, &$message ] );
 941                         if ( $message !== false ) {
 942                                 return $message;
 943                         }
 944
 945                         return false;
 946                 }
 947
 948                 # Try the individual message cache
 949                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 950                 $entry = $this->wanCache->get( $titleKey );
 951                 if ( $entry ) {
 952                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 953                                 $this->mCache[$code][$title] = $entry;
 954
 955                                 // The message exists, so make sure a string
 956                                 // is returned.
 957                                 return (string)substr( $entry, 1 );
 958                         } elseif ( $entry === '!NONEXISTENT' ) {
 959                                 $this->mCache[$code][$title] = '!NONEXISTENT';
 960
 961                                 return false;
 962                         } else {
 963                                 # Corrupt/obsolete entry, delete it
 964                                 $this->wanCache->delete( $titleKey );
 965                         }
 966                 }
 967
 968                 # Try loading it from the database
 969                 $revision = Revision::newFromTitle( Title::makeTitle( NS_MEDIAWIKI, $title ) );
 970                 if ( $revision ) {
 971                         $content = $revision->getContent();
 972                         if ( !$content ) {
 973                                 // A possibly temporary loading failure.
 974                                 wfDebugLog(
 975                                         'MessageCache',
 976                                         __METHOD__ . ": failed to load message page text for {$title} ($code)"
 977                                 );
 978                                 $message = null; // no negative caching
 979                         } else {
 980                                 // XXX: Is this the right way to turn a Content object into a message?
 981                                 // NOTE: $content is typically either WikitextContent, JavaScriptContent or
 982                                 //       CssContent. MessageContent is *not* used for storing messages, it's
 983                                 //       only used for wrapping them when needed.
 984                                 $message = $content->getWikitextForTransclusion();
 985
 986                                 if ( $message === false || $message === null ) {
 987                                         wfDebugLog(
 988                                                 'MessageCache',
 989                                                 __METHOD__ . ": message content doesn't provide wikitext "
 990                                                         . "(content model: " . $content->getModel() . ")"
 991                                         );
 992
 993                                         $message = false; // negative caching
 994                                 } else {
 995                                         $this->mCache[$code][$title] = ' ' . $message;
 996                                         $this->wanCache->set( $titleKey, ' ' . $message, $this->mExpiry );
 997                                 }
 998                         }
 999                 } else {
1000                         $message = false; // negative caching
1001                 }
1002
1003                 if ( $message === false ) { // negative caching
1004                         $this->mCache[$code][$title] = '!NONEXISTENT';
1005                         $this->wanCache->set( $titleKey, '!NONEXISTENT', $this->mExpiry );
1006                 }
1007
1008                 return $message;
1009         }
1010
1011         /**
1012          * @param string $message
1013          * @param bool $interface
1014          * @param string $language Language code
1015          * @param Title $title
1016          * @return string
1017          */
1018         function transform( $message, $interface = false, $language = null, $title = null ) {
1019                 // Avoid creating parser if nothing to transform
1020                 if ( strpos( $message, '{{' ) === false ) {
1021                         return $message;
1022                 }
1023
1024                 if ( $this->mInParser ) {
1025                         return $message;
1026                 }
1027
1028                 $parser = $this->getParser();
1029                 if ( $parser ) {
1030                         $popts = $this->getParserOptions();
1031                         $popts->setInterfaceMessage( $interface );
1032                         $popts->setTargetLanguage( $language );
1033
1034                         $userlang = $popts->setUserLang( $language );
1035                         $this->mInParser = true;
1036                         $message = $parser->transformMsg( $message, $popts, $title );
1037                         $this->mInParser = false;
1038                         $popts->setUserLang( $userlang );
1039                 }
1040
1041                 return $message;
1042         }
1043
1044         /**
1045          * @return Parser
1046          */
1047         function getParser() {
1048                 global $wgParser, $wgParserConf;
1049                 if ( !$this->mParser && isset( $wgParser ) ) {
1050                         # Do some initialisation so that we don't have to do it twice
1051                         $wgParser->firstCallInit();
1052                         # Clone it and store it
1053                         $class = $wgParserConf['class'];
1054                         if ( $class == 'ParserDiffTest' ) {
1055                                 # Uncloneable
1056                                 $this->mParser = new $class( $wgParserConf );
1057                         } else {
1058                                 $this->mParser = clone $wgParser;
1059                         }
1060                 }
1061
1062                 return $this->mParser;
1063         }
1064
1065         /**
1066          * @param string $text
1067          * @param Title $title
1068          * @param bool $linestart Whether or not this is at the start of a line
1069          * @param bool $interface Whether this is an interface message
1070          * @param Language|string $language Language code
1071          * @return ParserOutput|string
1072          */
1073         public function parse( $text, $title = null, $linestart = true,
1074                 $interface = false, $language = null
1075         ) {
1076                 if ( $this->mInParser ) {
1077                         return htmlspecialchars( $text );
1078                 }
1079
1080                 $parser = $this->getParser();
1081                 $popts = $this->getParserOptions();
1082                 $popts->setInterfaceMessage( $interface );
1083
1084                 if ( is_string( $language ) ) {
1085                         $language = Language::factory( $language );
1086                 }
1087                 $popts->setTargetLanguage( $language );
1088
1089                 if ( !$title || !$title instanceof Title ) {
1090                         global $wgTitle;
1091                         wfDebugLog( 'GlobalTitleFail', __METHOD__ . ' called by ' .
1092                                 wfGetAllCallers( 5 ) . ' with no title set.' );
1093                         $title = $wgTitle;
1094                 }
1095                 // Sometimes $wgTitle isn't set either...
1096                 if ( !$title ) {
1097                         # It's not uncommon having a null $wgTitle in scripts. See r80898
1098                         # Create a ghost title in such case
1099                         $title = Title::makeTitle( NS_SPECIAL, 'Badtitle/title not set in ' . __METHOD__ );
1100                 }
1101
1102                 $this->mInParser = true;
1103                 $res = $parser->parse( $text, $title, $popts, $linestart );
1104                 $this->mInParser = false;
1105
1106                 return $res;
1107         }
1108
1109         function disable() {
1110                 $this->mDisable = true;
1111         }
1112
1113         function enable() {
1114                 $this->mDisable = false;
1115         }
1116
1117         /**
1118          * Whether DB/cache usage is disabled for determining messages
1119          *
1120          * If so, this typically indicates either:
1121          *   - a) load() failed to find a cached copy nor query the DB
1122          *   - b) we are in a special context or error mode that cannot use the DB
1123          * If the DB is ignored, any derived HTML output or cached objects may be wrong.
1124          * To avoid long-term cache pollution, TTLs can be adjusted accordingly.
1125          *
1126          * @return bool
1127          * @since 1.27
1128          */
1129         public function isDisabled() {
1130                 return $this->mDisable;
1131         }
1132
1133         /**
1134          * Clear all stored messages. Mainly used after a mass rebuild.
1135          */
1136         function clear() {
1137                 $langs = Language::fetchLanguageNames( null, 'mw' );
1138                 foreach ( array_keys( $langs ) as $code ) {
1139                         # Global and local caches
1140                         $this->wanCache->touchCheckKey( wfMemcKey( 'messages', $code ) );
1141                 }
1142
1143                 $this->mLoadedLanguages = [];
1144         }
1145
1146         /**
1147          * @param string $key
1148          * @return array
1149          */
1150         public function figureMessage( $key ) {
1151                 global $wgLanguageCode;
1152
1153                 $pieces = explode( '/', $key );
1154                 if ( count( $pieces ) < 2 ) {
1155                         return [ $key, $wgLanguageCode ];
1156                 }
1157
1158                 $lang = array_pop( $pieces );
1159                 if ( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
1160                         return [ $key, $wgLanguageCode ];
1161                 }
1162
1163                 $message = implode( '/', $pieces );
1164
1165                 return [ $message, $lang ];
1166         }
1167
1168         /**
1169          * Get all message keys stored in the message cache for a given language.
1170          * If $code is the content language code, this will return all message keys
1171          * for which MediaWiki:msgkey exists. If $code is another language code, this
1172          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
1173          * @param string $code Language code
1174          * @return array Array of message keys (strings)
1175          */
1176         public function getAllMessageKeys( $code ) {
1177                 global $wgContLang;
1178                 $this->load( $code );
1179                 if ( !isset( $this->mCache[$code] ) ) {
1180                         // Apparently load() failed
1181                         return null;
1182                 }
1183                 // Remove administrative keys
1184                 $cache = $this->mCache[$code];
1185                 unset( $cache['VERSION'] );
1186                 unset( $cache['EXPIRY'] );
1187                 // Remove any !NONEXISTENT keys
1188                 $cache = array_diff( $cache, [ '!NONEXISTENT' ] );
1189
1190                 // Keys may appear with a capital first letter. lcfirst them.
1191                 return array_map( [ $wgContLang, 'lcfirst' ], array_keys( $cache ) );
1192         }
1193 }