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