Current File : /www/varak.net/wiki.varak.net/includes/cache/MessageCache.php
<?php
/**
* Localisation messages cache.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup Cache
*/
use MediaWiki\MediaWikiServices;
use Wikimedia\ScopedCallback;
use MediaWiki\Logger\LoggerFactory;
use Wikimedia\Rdbms\Database;
/**
* MediaWiki message cache structure version.
* Bump this whenever the message cache format has changed.
*/
define( 'MSG_CACHE_VERSION', 2 );
/**
* Cache of messages that are defined by MediaWiki namespace pages or by hooks
*
* Performs various MediaWiki namespace-related functions
* @ingroup Cache
*/
class MessageCache {
const FOR_UPDATE = 1; // force message reload
/** How long to wait for memcached locks */
const WAIT_SEC = 15;
/** How long memcached locks last */
const LOCK_TTL = 30;
/**
* Process cache of loaded messages that are defined in MediaWiki namespace
*
* @var MapCacheLRU Map of (language code => key => " <MESSAGE>" or "!TOO BIG")
*/
protected $cache;
/**
* Map of (lowercase message key => index) for all software defined messages
*
* @var array
*/
protected $overridable;
/**
* @var bool[] Map of (language code => boolean)
*/
protected $cacheVolatile = [];
/**
* Should mean that database cannot be used, but check
* @var bool $mDisable
*/
protected $mDisable;
/**
* Lifetime for cache, used by object caching.
* Set on construction, see __construct().
*/
protected $mExpiry;
/**
* Message cache has its own parser which it uses to transform messages
* @var ParserOptions
*/
protected $mParserOptions;
/** @var Parser */
protected $mParser;
/**
* @var bool $mInParser
*/
protected $mInParser = false;
/** @var WANObjectCache */
protected $wanCache;
/** @var BagOStuff */
protected $clusterCache;
/** @var BagOStuff */
protected $srvCache;
/** @var Language */
protected $contLang;
/**
* Singleton instance
*
* @var MessageCache $instance
*/
private static $instance;
/**
* Get the signleton instance of this class
*
* @since 1.18
* @return MessageCache
*/
public static function singleton() {
if ( self::$instance === null ) {
global $wgUseDatabaseMessages, $wgMsgCacheExpiry, $wgUseLocalMessageCache;
$services = MediaWikiServices::getInstance();
self::$instance = new self(
$services->getMainWANObjectCache(),
wfGetMessageCacheStorage(),
$wgUseLocalMessageCache
? $services->getLocalServerObjectCache()
: new EmptyBagOStuff(),
$wgUseDatabaseMessages,
$wgMsgCacheExpiry,
$services->getContentLanguage()
);
}
return self::$instance;
}
/**
* Destroy the singleton instance
*
* @since 1.18
*/
public static function destroyInstance() {
self::$instance = null;
}
/**
* Normalize message key input
*
* @param string $key Input message key to be normalized
* @return string Normalized message key
*/
public static function normalizeKey( $key ) {
$lckey = strtr( $key, ' ', '_' );
if ( ord( $lckey ) < 128 ) {
$lckey[0] = strtolower( $lckey[0] );
} else {
$lckey = MediaWikiServices::getInstance()->getContentLanguage()->lcfirst( $lckey );
}
return $lckey;
}
/**
* @param WANObjectCache $wanCache
* @param BagOStuff $clusterCache
* @param BagOStuff $serverCache
* @param bool $useDB Whether to look for message overrides (e.g. MediaWiki: pages)
* @param int $expiry Lifetime for cache. @see $mExpiry.
* @param Language|null $contLang Content language of site
*/
public function __construct(
WANObjectCache $wanCache,
BagOStuff $clusterCache,
BagOStuff $serverCache,
$useDB,
$expiry,
Language $contLang = null
) {
$this->wanCache = $wanCache;
$this->clusterCache = $clusterCache;
$this->srvCache = $serverCache;
$this->cache = new MapCacheLRU( 5 ); // limit size for sanity
$this->mDisable = !$useDB;
$this->mExpiry = $expiry;
$this->contLang = $contLang ?? MediaWikiServices::getInstance()->getContentLanguage();
}
/**
* ParserOptions is lazy initialised.
*
* @return ParserOptions
*/
function getParserOptions() {
global $wgUser;
if ( !$this->mParserOptions ) {
if ( !$wgUser->isSafeToLoad() ) {
// $wgUser isn't unstubbable yet, so don't try to get a
// ParserOptions for it. And don't cache this ParserOptions
// either.
$po = ParserOptions::newFromAnon();
$po->setAllowUnsafeRawHtml( false );
return $po;
}
$this->mParserOptions = new ParserOptions;
// Messages may take parameters that could come
// from malicious sources. As a precaution, disable
// the <html> parser tag when parsing messages.
$this->mParserOptions->setAllowUnsafeRawHtml( false );
}
return $this->mParserOptions;
}
/**
* Try to load the cache from APC.
*
* @param string $code Optional language code, see documenation of load().
* @return array|bool The cache array, or false if not in cache.
*/
protected function getLocalCache( $code ) {
$cacheKey = $this->srvCache->makeKey( __CLASS__, $code );
return $this->srvCache->get( $cacheKey );
}
/**
* Save the cache to APC.
*
* @param string $code
* @param array $cache The cache array
*/
protected function saveToLocalCache( $code, $cache ) {
$cacheKey = $this->srvCache->makeKey( __CLASS__, $code );
$this->srvCache->set( $cacheKey, $cache );
}
/**
* Loads messages from caches or from database in this order:
* (1) local message cache (if $wgUseLocalMessageCache is enabled)
* (2) memcached
* (3) from the database.
*
* When successfully loading from (2) or (3), all higher level caches are
* updated for the newest version.
*
* Nothing is loaded if member variable mDisable is true, either manually
* set by calling code or if message loading fails (is this possible?).
*
* Returns true if cache is already populated or it was successfully populated,
* or false if populating empty cache fails. Also returns true if MessageCache
* is disabled.
*
* @param string $code Language to which load messages
* @param int|null $mode Use MessageCache::FOR_UPDATE to skip process cache [optional]
* @throws InvalidArgumentException
* @return bool
*/
protected function load( $code, $mode = null ) {
if ( !is_string( $code ) ) {
throw new InvalidArgumentException( "Missing language code" );
}
# Don't do double loading...
if ( $this->cache->has( $code ) && $mode != self::FOR_UPDATE ) {
return true;
}
$this->overridable = array_flip( Language::getMessageKeysFor( $code ) );
# 8 lines of code just to say (once) that message cache is disabled
if ( $this->mDisable ) {
static $shownDisabled = false;
if ( !$shownDisabled ) {
wfDebug( __METHOD__ . ": disabled\n" );
$shownDisabled = true;
}
return true;
}
# Loading code starts
$success = false; # Keep track of success
$staleCache = false; # a cache array with expired data, or false if none has been loaded
$where = []; # Debug info, delayed to avoid spamming debug log too much
# Hash of the contents is stored in memcache, to detect if data-center cache
# or local cache goes out of date (e.g. due to replace() on some other server)
list( $hash, $hashVolatile ) = $this->getValidationHash( $code );
$this->cacheVolatile[$code] = $hashVolatile;
# Try the local cache and check against the cluster hash key...
$cache = $this->getLocalCache( $code );
if ( !$cache ) {
$where[] = 'local cache is empty';
} elseif ( !isset( $cache['HASH'] ) || $cache['HASH'] !== $hash ) {
$where[] = 'local cache has the wrong hash';
$staleCache = $cache;
} elseif ( $this->isCacheExpired( $cache ) ) {
$where[] = 'local cache is expired';
$staleCache = $cache;
} elseif ( $hashVolatile ) {
$where[] = 'local cache validation key is expired/volatile';
$staleCache = $cache;
} else {
$where[] = 'got from local cache';
$this->cache->set( $code, $cache );
$success = true;
}
if ( !$success ) {
$cacheKey = $this->clusterCache->makeKey( 'messages', $code );
# Try the global cache. If it is empty, try to acquire a lock. If
# the lock can't be acquired, wait for the other thread to finish
# and then try the global cache a second time.
for ( $failedAttempts = 0; $failedAttempts <= 1; $failedAttempts++ ) {
if ( $hashVolatile && $staleCache ) {
# Do not bother fetching the whole cache blob to avoid I/O.
# Instead, just try to get the non-blocking $statusKey lock
# below, and use the local stale value if it was not acquired.
$where[] = 'global cache is presumed expired';
} else {
$cache = $this->clusterCache->get( $cacheKey );
if ( !$cache ) {
$where[] = 'global cache is empty';
} elseif ( $this->isCacheExpired( $cache ) ) {
$where[] = 'global cache is expired';
$staleCache = $cache;
} elseif ( $hashVolatile ) {
# DB results are replica DB lag prone until the holdoff TTL passes.
# By then, updates should be reflected in loadFromDBWithLock().
# One thread renerates the cache while others use old values.
$where[] = 'global cache is expired/volatile';
$staleCache = $cache;
} else {
$where[] = 'got from global cache';
$this->cache->set( $code, $cache );
$this->saveToCaches( $cache, 'local-only', $code );
$success = true;
}
}
if ( $success ) {
# Done, no need to retry
break;
}
# We need to call loadFromDB. Limit the concurrency to one process.
# This prevents the site from going down when the cache expires.
# Note that the DB slam protection lock here is non-blocking.
$loadStatus = $this->loadFromDBWithLock( $code, $where, $mode );
if ( $loadStatus === true ) {
$success = true;
break;
} elseif ( $staleCache ) {
# Use the stale cache while some other thread constructs the new one
$where[] = 'using stale cache';
$this->cache->set( $code, $staleCache );
$success = true;
break;
} elseif ( $failedAttempts > 0 ) {
# Already blocked once, so avoid another lock/unlock cycle.
# This case will typically be hit if memcached is down, or if
# loadFromDB() takes longer than LOCK_WAIT.
$where[] = "could not acquire status key.";
break;
} elseif ( $loadStatus === 'cantacquire' ) {
# Wait for the other thread to finish, then retry. Normally,
# the memcached get() will then yeild the other thread's result.
$where[] = 'waited for other thread to complete';
$this->getReentrantScopedLock( $cacheKey );
} else {
# Disable cache; $loadStatus is 'disabled'
break;
}
}
}
if ( !$success ) {
$where[] = 'loading FAILED - cache is disabled';
$this->mDisable = true;
$this->cache->set( $code, [] );
wfDebugLog( 'MessageCacheError', __METHOD__ . ": Failed to load $code\n" );
# This used to throw an exception, but that led to nasty side effects like
# the whole wiki being instantly down if the memcached server died
}
if ( !$this->cache->has( $code ) ) { // sanity
throw new LogicException( "Process cache for '$code' should be set by now." );
}
$info = implode( ', ', $where );
wfDebugLog( 'MessageCache', __METHOD__ . ": Loading $code... $info\n" );
return $success;
}
/**
* @param string $code
* @param array &$where List of wfDebug() comments
* @param int|null $mode Use MessageCache::FOR_UPDATE to use DB_MASTER
* @return bool|string True on success or one of ("cantacquire", "disabled")
*/
protected function loadFromDBWithLock( $code, array &$where, $mode = null ) {
# If cache updates on all levels fail, give up on message overrides.
# This is to avoid easy site outages; see $saveSuccess comments below.
$statusKey = $this->clusterCache->makeKey( 'messages', $code, 'status' );
$status = $this->clusterCache->get( $statusKey );
if ( $status === 'error' ) {
$where[] = "could not load; method is still globally disabled";
return 'disabled';
}
# Now let's regenerate
$where[] = 'loading from database';
# Lock the cache to prevent conflicting writes.
# This lock is non-blocking so stale cache can quickly be used.
# Note that load() will call a blocking getReentrantScopedLock()
# after this if it really need to wait for any current thread.
$cacheKey = $this->clusterCache->makeKey( 'messages', $code );
$scopedLock = $this->getReentrantScopedLock( $cacheKey, 0 );
if ( !$scopedLock ) {
$where[] = 'could not acquire main lock';
return 'cantacquire';
}
$cache = $this->loadFromDB( $code, $mode );
$this->cache->set( $code, $cache );
$saveSuccess = $this->saveToCaches( $cache, 'all', $code );
if ( !$saveSuccess ) {
/**
* Cache save has failed.
*
* There are two main scenarios where this could be a problem:
* - The cache is more than the maximum size (typically 1MB compressed).
* - Memcached has no space remaining in the relevant slab class. This is
* unlikely with recent versions of memcached.
*
* Either way, if there is a local cache, nothing bad will happen. If there
* is no local cache, disabling the message cache for all requests avoids
* incurring a loadFromDB() overhead on every request, and thus saves the
* wiki from complete downtime under moderate traffic conditions.
*/
if ( $this->srvCache instanceof EmptyBagOStuff ) {
$this->clusterCache->set( $statusKey, 'error', 60 * 5 );
$where[] = 'could not save cache, disabled globally for 5 minutes';
} else {
$where[] = "could not save global cache";
}
}
return true;
}
/**
* Loads cacheable messages from the database. Messages bigger than
* $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
* on-demand from the database later.
*
* @param string $code Language code
* @param int|null $mode Use MessageCache::FOR_UPDATE to skip process cache
* @return array Loaded messages for storing in caches
*/
protected function loadFromDB( $code, $mode = null ) {
global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
// (T164666) The query here performs really poorly on WMF's
// contributions replicas. We don't have a way to say "any group except
// contributions", so for the moment let's specify 'api'.
// @todo: Get rid of this hack.
$dbr = wfGetDB( ( $mode == self::FOR_UPDATE ) ? DB_MASTER : DB_REPLICA, 'api' );
$cache = [];
$mostused = []; // list of "<cased message key>/<code>"
if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {
if ( !$this->cache->has( $wgLanguageCode ) ) {
$this->load( $wgLanguageCode );
}
$mostused = array_keys( $this->cache->get( $wgLanguageCode ) );
foreach ( $mostused as $key => $value ) {
$mostused[$key] = "$value/$code";
}
}
// Get the list of software-defined messages in core/extensions
$overridable = array_flip( Language::getMessageKeysFor( $wgLanguageCode ) );
// Common conditions
$conds = [
'page_is_redirect' => 0,
'page_namespace' => NS_MEDIAWIKI,
];
if ( count( $mostused ) ) {
$conds['page_title'] = $mostused;
} elseif ( $code !== $wgLanguageCode ) {
$conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );
} else {
# Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
# other than language code.
$conds[] = 'page_title NOT' .
$dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
}
// Set the stubs for oversized software-defined messages in the main cache map
$res = $dbr->select(
'page',
[ 'page_title', 'page_latest' ],
array_merge( $conds, [ 'page_len > ' . intval( $wgMaxMsgCacheEntrySize ) ] ),
__METHOD__ . "($code)-big"
);
foreach ( $res as $row ) {
$name = $this->contLang->lcfirst( $row->page_title );
// Include entries/stubs for all keys in $mostused in adaptive mode
if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $name, $overridable ) ) {
$cache[$row->page_title] = '!TOO BIG';
}
// At least include revision ID so page changes are reflected in the hash
$cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
}
// Set the text for small software-defined messages in the main cache map
$res = $dbr->select(
[ 'page', 'revision', 'text' ],
[ 'page_title', 'page_latest', 'old_id', 'old_text', 'old_flags' ],
array_merge( $conds, [ 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize ) ] ),
__METHOD__ . "($code)-small",
[],
[
'revision' => [ 'JOIN', 'page_latest=rev_id' ],
'text' => [ 'JOIN', 'rev_text_id=old_id' ],
]
);
foreach ( $res as $row ) {
$name = $this->contLang->lcfirst( $row->page_title );
// Include entries/stubs for all keys in $mostused in adaptive mode
if ( $wgAdaptiveMessageCache || $this->isMainCacheable( $name, $overridable ) ) {
$text = Revision::getRevisionText( $row );
if ( $text === false ) {
// Failed to fetch data; possible ES errors?
// Store a marker to fetch on-demand as a workaround...
// TODO Use a differnt marker
$entry = '!TOO BIG';
wfDebugLog(
'MessageCache',
__METHOD__
. ": failed to load message page text for {$row->page_title} ($code)"
);
} else {
$entry = ' ' . $text;
}
$cache[$row->page_title] = $entry;
} else {
// T193271: cache object gets too big and slow to generate.
// At least include revision ID so page changes are reflected in the hash.
$cache['EXCESSIVE'][$row->page_title] = $row->page_latest;
}
}
$cache['VERSION'] = MSG_CACHE_VERSION;
ksort( $cache );
# Hash for validating local cache (APC). No need to take into account
# messages larger than $wgMaxMsgCacheEntrySize, since those are only
# stored and fetched from memcache.
$cache['HASH'] = md5( serialize( $cache ) );
$cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );
unset( $cache['EXCESSIVE'] ); // only needed for hash
return $cache;
}
/**
* @param string $name Message name with lowercase first letter
* @param array $overridable Map of (key => unused) for software-defined messages
* @return bool
*/
private function isMainCacheable( $name, array $overridable ) {
// Include common conversion table pages. This also avoids problems with
// Installer::parse() bailing out due to disallowed DB queries (T207979).
return ( isset( $overridable[$name] ) || strpos( $name, 'conversiontable/' ) === 0 );
}
/**
* Updates cache as necessary when message page is changed
*
* @param string $title Message cache key with initial uppercase letter
* @param string|bool $text New contents of the page (false if deleted)
*/
public function replace( $title, $text ) {
global $wgLanguageCode;
if ( $this->mDisable ) {
return;
}
list( $msg, $code ) = $this->figureMessage( $title );
if ( strpos( $title, '/' ) !== false && $code === $wgLanguageCode ) {
// Content language overrides do not use the /<code> suffix
return;
}
// (a) Update the process cache with the new message text
if ( $text === false ) {
// Page deleted
$this->cache->setField( $code, $title, '!NONEXISTENT' );
} else {
// Ignore $wgMaxMsgCacheEntrySize so the process cache is up to date
$this->cache->setField( $code, $title, ' ' . $text );
}
// (b) Update the shared caches in a deferred update with a fresh DB snapshot
DeferredUpdates::addUpdate(
new MessageCacheUpdate( $code, $title, $msg ),
DeferredUpdates::PRESEND
);
}
/**
* @param string $code
* @param array[] $replacements List of (title, message key) pairs
* @throws MWException
*/
public function refreshAndReplaceInternal( $code, array $replacements ) {
global $wgMaxMsgCacheEntrySize;
// Allow one caller at a time to avoid race conditions
$scopedLock = $this->getReentrantScopedLock(
$this->clusterCache->makeKey( 'messages', $code )
);
if ( !$scopedLock ) {
foreach ( $replacements as list( $title ) ) {
LoggerFactory::getInstance( 'MessageCache' )->error(
__METHOD__ . ': could not acquire lock to update {title} ({code})',
[ 'title' => $title, 'code' => $code ] );
}
return;
}
// Load the existing cache to update it in the local DC cache.
// The other DCs will see a hash mismatch.
if ( $this->load( $code, self::FOR_UPDATE ) ) {
$cache = $this->cache->get( $code );
} else {
// Err? Fall back to loading from the database.
$cache = $this->loadFromDB( $code, self::FOR_UPDATE );
}
// Check if individual cache keys should exist and update cache accordingly
$newTextByTitle = []; // map of (title => content)
$newBigTitles = []; // map of (title => latest revision ID), like EXCESSIVE in loadFromDB()
foreach ( $replacements as list( $title ) ) {
$page = WikiPage::factory( Title::makeTitle( NS_MEDIAWIKI, $title ) );
$page->loadPageData( $page::READ_LATEST );
$text = $this->getMessageTextFromContent( $page->getContent() );
// Remember the text for the blob store update later on
$newTextByTitle[$title] = $text;
// Note that if $text is false, then $cache should have a !NONEXISTANT entry
if ( !is_string( $text ) ) {
$cache[$title] = '!NONEXISTENT';
} elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
$cache[$title] = '!TOO BIG';
$newBigTitles[$title] = $page->getLatest();
} else {
$cache[$title] = ' ' . $text;
}
}
// Update HASH for the new key. Incorporates various administrative keys,
// including the old HASH (and thereby the EXCESSIVE value from loadFromDB()
// and previous replace() calls), but that doesn't really matter since we
// only ever compare it for equality with a copy saved by saveToCaches().
$cache['HASH'] = md5( serialize( $cache + [ 'EXCESSIVE' => $newBigTitles ] ) );
// Update the too-big WAN cache entries now that we have the new HASH
foreach ( $newBigTitles as $title => $id ) {
// Match logic of loadCachedMessagePageEntry()
$this->wanCache->set(
$this->bigMessageCacheKey( $cache['HASH'], $title ),
' ' . $newTextByTitle[$title],
$this->mExpiry
);
}
// Mark this cache as definitely being "latest" (non-volatile) so
// load() calls do not try to refresh the cache with replica DB data
$cache['LATEST'] = time();
// Update the process cache
$this->cache->set( $code, $cache );
// Pre-emptively update the local datacenter cache so things like edit filter and
// blacklist changes are reflected immediately; these often use MediaWiki: pages.
// The datacenter handling replace() calls should be the same one handling edits
// as they require HTTP POST.
$this->saveToCaches( $cache, 'all', $code );
// Release the lock now that the cache is saved
ScopedCallback::consume( $scopedLock );
// Relay the purge. Touching this check key expires cache contents
// and local cache (APC) validation hash across all datacenters.
$this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
// Purge the messages in the message blob store and fire any hook handlers
$resourceloader = RequestContext::getMain()->getOutput()->getResourceLoader();
$blobStore = $resourceloader->getMessageBlobStore();
foreach ( $replacements as list( $title, $msg ) ) {
$blobStore->updateMessage( $this->contLang->lcfirst( $msg ) );
Hooks::run( 'MessageCacheReplace', [ $title, $newTextByTitle[$title] ] );
}
}
/**
* Is the given cache array expired due to time passing or a version change?
*
* @param array $cache
* @return bool
*/
protected function isCacheExpired( $cache ) {
if ( !isset( $cache['VERSION'] ) || !isset( $cache['EXPIRY'] ) ) {
return true;
}
if ( $cache['VERSION'] != MSG_CACHE_VERSION ) {
return true;
}
if ( wfTimestampNow() >= $cache['EXPIRY'] ) {
return true;
}
return false;
}
/**
* Shortcut to update caches.
*
* @param array $cache Cached messages with a version.
* @param string $dest Either "local-only" to save to local caches only
* or "all" to save to all caches.
* @param string|bool $code Language code (default: false)
* @return bool
*/
protected function saveToCaches( array $cache, $dest, $code = false ) {
if ( $dest === 'all' ) {
$cacheKey = $this->clusterCache->makeKey( 'messages', $code );
$success = $this->clusterCache->set( $cacheKey, $cache );
$this->setValidationHash( $code, $cache );
} else {
$success = true;
}
$this->saveToLocalCache( $code, $cache );
return $success;
}
/**
* Get the md5 used to validate the local APC cache
*
* @param string $code
* @return array (hash or false, bool expiry/volatility status)
*/
protected function getValidationHash( $code ) {
$curTTL = null;
$value = $this->wanCache->get(
$this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
$curTTL,
[ $this->getCheckKey( $code ) ]
);
if ( $value ) {
$hash = $value['hash'];
if ( ( time() - $value['latest'] ) < WANObjectCache::TTL_MINUTE ) {
// Cache was recently updated via replace() and should be up-to-date.
// That method is only called in the primary datacenter and uses FOR_UPDATE.
// Also, it is unlikely that the current datacenter is *now* secondary one.
$expired = false;
} else {
// See if the "check" key was bumped after the hash was generated
$expired = ( $curTTL < 0 );
}
} else {
// No hash found at all; cache must regenerate to be safe
$hash = false;
$expired = true;
}
return [ $hash, $expired ];
}
/**
* Set the md5 used to validate the local disk cache
*
* If $cache has a 'LATEST' UNIX timestamp key, then the hash will not
* be treated as "volatile" by getValidationHash() for the next few seconds.
* This is triggered when $cache is generated using FOR_UPDATE mode.
*
* @param string $code
* @param array $cache Cached messages with a version
*/
protected function setValidationHash( $code, array $cache ) {
$this->wanCache->set(
$this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),
[
'hash' => $cache['HASH'],
'latest' => $cache['LATEST'] ?? 0
],
WANObjectCache::TTL_INDEFINITE
);
}
/**
* @param string $key A language message cache key that stores blobs
* @param int $timeout Wait timeout in seconds
* @return null|ScopedCallback
*/
protected function getReentrantScopedLock( $key, $timeout = self::WAIT_SEC ) {
return $this->clusterCache->getScopedLock( $key, $timeout, self::LOCK_TTL, __METHOD__ );
}
/**
* Get a message from either the content language or the user language.
*
* First, assemble a list of languages to attempt getting the message from. This
* chain begins with the requested language and its fallbacks and then continues with
* the content language and its fallbacks. For each language in the chain, the following
* process will occur (in this order):
* 1. If a language-specific override, i.e., [[MW:msg/lang]], is available, use that.
* Note: for the content language, there is no /lang subpage.
* 2. Fetch from the static CDB cache.
* 3. If available, check the database for fallback language overrides.
*
* This process provides a number of guarantees. When changing this code, make sure all
* of these guarantees are preserved.
* * If the requested language is *not* the content language, then the CDB cache for that
* specific language will take precedence over the root database page ([[MW:msg]]).
* * Fallbacks will be just that: fallbacks. A fallback language will never be reached if
* the message is available *anywhere* in the language for which it is a fallback.
*
* @param string $key The message key
* @param bool $useDB If true, look for the message in the DB, false
* to use only the compiled l10n cache.
* @param bool|string|object $langcode Code of the language to get the message for.
* - If string and a valid code, will create a standard language object
* - If string but not a valid code, will create a basic language object
* - If boolean and false, create object from the current users language
* - If boolean and true, create object from the wikis content language
* - If language object, use it as given
*
* @throws MWException When given an invalid key
* @return string|bool False if the message doesn't exist, otherwise the
* message (which can be empty)
*/
function get( $key, $useDB = true, $langcode = true ) {
if ( is_int( $key ) ) {
// Fix numerical strings that somehow become ints
// on their way here
$key = (string)$key;
} elseif ( !is_string( $key ) ) {
throw new MWException( 'Non-string key given' );
} elseif ( $key === '' ) {
// Shortcut: the empty key is always missing
return false;
}
// Normalise title-case input (with some inlining)
$lckey = self::normalizeKey( $key );
Hooks::run( 'MessageCache::get', [ &$lckey ] );
// Loop through each language in the fallback list until we find something useful
$message = $this->getMessageFromFallbackChain(
wfGetLangObj( $langcode ),
$lckey,
!$this->mDisable && $useDB
);
// If we still have no message, maybe the key was in fact a full key so try that
if ( $message === false ) {
$parts = explode( '/', $lckey );
// We may get calls for things that are http-urls from sidebar
// Let's not load nonexistent languages for those
// They usually have more than one slash.
if ( count( $parts ) == 2 && $parts[1] !== '' ) {
$message = Language::getMessageFor( $parts[0], $parts[1] );
if ( $message === null ) {
$message = false;
}
}
}
// Post-processing if the message exists
if ( $message !== false ) {
// Fix whitespace
$message = str_replace(
[
# Fix for trailing whitespace, removed by textarea
' ',
# Fix for NBSP, converted to space by firefox
' ',
' ',
'­'
],
[
' ',
"\u{00A0}",
"\u{00A0}",
"\u{00AD}"
],
$message
);
}
return $message;
}
/**
* Given a language, try and fetch messages from that language.
*
* Will also consider fallbacks of that language, the site language, and fallbacks for
* the site language.
*
* @see MessageCache::get
* @param Language|StubObject $lang Preferred language
* @param string $lckey Lowercase key for the message (as for localisation cache)
* @param bool $useDB Whether to include messages from the wiki database
* @return string|bool The message, or false if not found
*/
protected function getMessageFromFallbackChain( $lang, $lckey, $useDB ) {
$alreadyTried = [];
// First try the requested language.
$message = $this->getMessageForLang( $lang, $lckey, $useDB, $alreadyTried );
if ( $message !== false ) {
return $message;
}
// Now try checking the site language.
$message = $this->getMessageForLang( $this->contLang, $lckey, $useDB, $alreadyTried );
return $message;
}
/**
* Given a language, try and fetch messages from that language and its fallbacks.
*
* @see MessageCache::get
* @param Language|StubObject $lang Preferred language
* @param string $lckey Lowercase key for the message (as for localisation cache)
* @param bool $useDB Whether to include messages from the wiki database
* @param bool[] $alreadyTried Contains true for each language that has been tried already
* @return string|bool The message, or false if not found
*/
private function getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried ) {
$langcode = $lang->getCode();
// Try checking the database for the requested language
if ( $useDB ) {
$uckey = $this->contLang->ucfirst( $lckey );
if ( !isset( $alreadyTried[$langcode] ) ) {
$message = $this->getMsgFromNamespace(
$this->getMessagePageName( $langcode, $uckey ),
$langcode
);
if ( $message !== false ) {
return $message;
}
$alreadyTried[$langcode] = true;
}
} else {
$uckey = null;
}
// Check the CDB cache
$message = $lang->getMessage( $lckey );
if ( $message !== null ) {
return $message;
}
// Try checking the database for all of the fallback languages
if ( $useDB ) {
$fallbackChain = Language::getFallbacksFor( $langcode );
foreach ( $fallbackChain as $code ) {
if ( isset( $alreadyTried[$code] ) ) {
continue;
}
$message = $this->getMsgFromNamespace(
$this->getMessagePageName( $code, $uckey ), $code );
if ( $message !== false ) {
return $message;
}
$alreadyTried[$code] = true;
}
}
return false;
}
/**
* Get the message page name for a given language
*
* @param string $langcode
* @param string $uckey Uppercase key for the message
* @return string The page name
*/
private function getMessagePageName( $langcode, $uckey ) {
global $wgLanguageCode;
if ( $langcode === $wgLanguageCode ) {
// Messages created in the content language will not have the /lang extension
return $uckey;
} else {
return "$uckey/$langcode";
}
}
/**
* Get a message from the MediaWiki namespace, with caching. The key must
* first be converted to two-part lang/msg form if necessary.
*
* Unlike self::get(), this function doesn't resolve fallback chains, and
* some callers require this behavior. LanguageConverter::parseCachedTable()
* and self::get() are some examples in core.
*
* @param string $title Message cache key with initial uppercase letter
* @param string $code Code denoting the language to try
* @return string|bool The message, or false if it does not exist or on error
*/
public function getMsgFromNamespace( $title, $code ) {
// Load all MediaWiki page definitions into cache. Note that individual keys
// already loaded into cache during this request remain in the cache, which
// includes the value of hook-defined messages.
$this->load( $code );
$entry = $this->cache->getField( $code, $title );
if ( $entry !== null ) {
// Message page exists as an override of a software messages
if ( substr( $entry, 0, 1 ) === ' ' ) {
// The message exists and is not '!TOO BIG'
return (string)substr( $entry, 1 );
} elseif ( $entry === '!NONEXISTENT' ) {
// The text might be '-' or missing due to some data loss
return false;
}
// Load the message page, utilizing the individual message cache.
// If the page does not exist, there will be no hook handler fallbacks.
$entry = $this->loadCachedMessagePageEntry(
$title,
$code,
$this->cache->getField( $code, 'HASH' )
);
} else {
// Message page either does not exist or does not override a software message
$name = $this->contLang->lcfirst( $title );
if ( !$this->isMainCacheable( $name, $this->overridable ) ) {
// Message page does not override any software-defined message. A custom
// message might be defined to have content or settings specific to the wiki.
// Load the message page, utilizing the individual message cache as needed.
$entry = $this->loadCachedMessagePageEntry(
$title,
$code,
$this->cache->getField( $code, 'HASH' )
);
}
if ( $entry === null || substr( $entry, 0, 1 ) !== ' ' ) {
// Message does not have a MediaWiki page definition; try hook handlers
$message = false;
Hooks::run( 'MessagesPreLoad', [ $title, &$message, $code ] );
if ( $message !== false ) {
$this->cache->setField( $code, $title, ' ' . $message );
} else {
$this->cache->setField( $code, $title, '!NONEXISTENT' );
}
return $message;
}
}
if ( $entry !== false && substr( $entry, 0, 1 ) === ' ' ) {
if ( $this->cacheVolatile[$code] ) {
// Make sure that individual keys respect the WAN cache holdoff period too
LoggerFactory::getInstance( 'MessageCache' )->debug(
__METHOD__ . ': loading volatile key \'{titleKey}\'',
[ 'titleKey' => $title, 'code' => $code ] );
} else {
$this->cache->setField( $code, $title, $entry );
}
// The message exists, so make sure a string is returned
return (string)substr( $entry, 1 );
}
$this->cache->setField( $code, $title, '!NONEXISTENT' );
return false;
}
/**
* @param string $dbKey
* @param string $code
* @param string $hash
* @return string Either " <MESSAGE>" or "!NONEXISTANT"
*/
private function loadCachedMessagePageEntry( $dbKey, $code, $hash ) {
$fname = __METHOD__;
return $this->srvCache->getWithSetCallback(
$this->srvCache->makeKey( 'messages-big', $hash, $dbKey ),
IExpiringStore::TTL_MINUTE,
function () use ( $code, $dbKey, $hash, $fname ) {
return $this->wanCache->getWithSetCallback(
$this->bigMessageCacheKey( $hash, $dbKey ),
$this->mExpiry,
function ( $oldValue, &$ttl, &$setOpts ) use ( $dbKey, $code, $fname ) {
// Try loading the message from the database
$dbr = wfGetDB( DB_REPLICA );
$setOpts += Database::getCacheSetOptions( $dbr );
// Use newKnownCurrent() to avoid querying revision/user tables
$title = Title::makeTitle( NS_MEDIAWIKI, $dbKey );
$revision = Revision::newKnownCurrent( $dbr, $title );
if ( !$revision ) {
// The wiki doesn't have a local override page. Cache absence with normal TTL.
// When overrides are created, self::replace() takes care of the cache.
return '!NONEXISTENT';
}
$content = $revision->getContent();
if ( $content ) {
$message = $this->getMessageTextFromContent( $content );
} else {
LoggerFactory::getInstance( 'MessageCache' )->warning(
$fname . ': failed to load page text for \'{titleKey}\'',
[ 'titleKey' => $dbKey, 'code' => $code ]
);
$message = null;
}
if ( !is_string( $message ) ) {
// Revision failed to load Content, or Content is incompatible with wikitext.
// Possibly a temporary loading failure.
$ttl = 5;
return '!NONEXISTENT';
}
return ' ' . $message;
}
);
}
);
}
/**
* @param string $message
* @param bool $interface
* @param Language|null $language
* @param Title|null $title
* @return string
*/
public function transform( $message, $interface = false, $language = null, $title = null ) {
// Avoid creating parser if nothing to transform
if ( strpos( $message, '{{' ) === false ) {
return $message;
}
if ( $this->mInParser ) {
return $message;
}
$parser = $this->getParser();
if ( $parser ) {
$popts = $this->getParserOptions();
$popts->setInterfaceMessage( $interface );
$popts->setTargetLanguage( $language );
$userlang = $popts->setUserLang( $language );
$this->mInParser = true;
$message = $parser->transformMsg( $message, $popts, $title );
$this->mInParser = false;
$popts->setUserLang( $userlang );
}
return $message;
}
/**
* @return Parser
*/
public function getParser() {
global $wgParser, $wgParserConf;
if ( !$this->mParser && isset( $wgParser ) ) {
# Do some initialisation so that we don't have to do it twice
$wgParser->firstCallInit();
# Clone it and store it
$class = $wgParserConf['class'];
if ( $class == ParserDiffTest::class ) {
# Uncloneable
$this->mParser = new $class( $wgParserConf );
} else {
$this->mParser = clone $wgParser;
}
}
return $this->mParser;
}
/**
* @param string $text
* @param Title|null $title
* @param bool $linestart Whether or not this is at the start of a line
* @param bool $interface Whether this is an interface message
* @param Language|string|null $language Language code
* @return ParserOutput|string
*/
public function parse( $text, $title = null, $linestart = true,
$interface = false, $language = null
) {
global $wgTitle;
if ( $this->mInParser ) {
return htmlspecialchars( $text );
}
$parser = $this->getParser();
$popts = $this->getParserOptions();
$popts->setInterfaceMessage( $interface );
if ( is_string( $language ) ) {
$language = Language::factory( $language );
}
$popts->setTargetLanguage( $language );
if ( !$title || !$title instanceof Title ) {
wfDebugLog( 'GlobalTitleFail', __METHOD__ . ' called by ' .
wfGetAllCallers( 6 ) . ' with no title set.' );
$title = $wgTitle;
}
// Sometimes $wgTitle isn't set either...
if ( !$title ) {
# It's not uncommon having a null $wgTitle in scripts. See r80898
# Create a ghost title in such case
$title = Title::makeTitle( NS_SPECIAL, 'Badtitle/title not set in ' . __METHOD__ );
}
$this->mInParser = true;
$res = $parser->parse( $text, $title, $popts, $linestart );
$this->mInParser = false;
return $res;
}
public function disable() {
$this->mDisable = true;
}
public function enable() {
$this->mDisable = false;
}
/**
* Whether DB/cache usage is disabled for determining messages
*
* If so, this typically indicates either:
* - a) load() failed to find a cached copy nor query the DB
* - b) we are in a special context or error mode that cannot use the DB
* If the DB is ignored, any derived HTML output or cached objects may be wrong.
* To avoid long-term cache pollution, TTLs can be adjusted accordingly.
*
* @return bool
* @since 1.27
*/
public function isDisabled() {
return $this->mDisable;
}
/**
* Clear all stored messages in global and local cache
*
* Mainly used after a mass rebuild
*/
public function clear() {
$langs = Language::fetchLanguageNames( null, 'mw' );
foreach ( array_keys( $langs ) as $code ) {
$this->wanCache->touchCheckKey( $this->getCheckKey( $code ) );
}
$this->cache->clear();
}
/**
* @param string $key
* @return array
*/
public function figureMessage( $key ) {
global $wgLanguageCode;
$pieces = explode( '/', $key );
if ( count( $pieces ) < 2 ) {
return [ $key, $wgLanguageCode ];
}
$lang = array_pop( $pieces );
if ( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {
return [ $key, $wgLanguageCode ];
}
$message = implode( '/', $pieces );
return [ $message, $lang ];
}
/**
* Get all message keys stored in the message cache for a given language.
* If $code is the content language code, this will return all message keys
* for which MediaWiki:msgkey exists. If $code is another language code, this
* will ONLY return message keys for which MediaWiki:msgkey/$code exists.
* @param string $code Language code
* @return array Array of message keys (strings)
*/
public function getAllMessageKeys( $code ) {
$this->load( $code );
if ( !$this->cache->has( $code ) ) {
// Apparently load() failed
return null;
}
// Remove administrative keys
$cache = $this->cache->get( $code );
unset( $cache['VERSION'] );
unset( $cache['EXPIRY'] );
unset( $cache['EXCESSIVE'] );
// Remove any !NONEXISTENT keys
$cache = array_diff( $cache, [ '!NONEXISTENT' ] );
// Keys may appear with a capital first letter. lcfirst them.
return array_map( [ $this->contLang, 'lcfirst' ], array_keys( $cache ) );
}
/**
* Purge message caches when a MediaWiki: page is created, updated, or deleted
*
* @param Title $title Message page title
* @param Content|null $content New content for edit/create, null on deletion
* @since 1.29
*/
public function updateMessageOverride( Title $title, Content $content = null ) {
$msgText = $this->getMessageTextFromContent( $content );
if ( $msgText === null ) {
$msgText = false; // treat as not existing
}
$this->replace( $title->getDBkey(), $msgText );
if ( $this->contLang->hasVariants() ) {
$this->contLang->updateConversionTable( $title );
}
}
/**
* @param string $code Language code
* @return string WAN cache key usable as a "check key" against language page edits
*/
public function getCheckKey( $code ) {
return $this->wanCache->makeKey( 'messages', $code );
}
/**
* @param Content|null $content Content or null if the message page does not exist
* @return string|bool|null Returns false if $content is null and null on error
*/
private function getMessageTextFromContent( Content $content = null ) {
// @TODO: could skip pseudo-messages like js/css here, based on content model
if ( $content ) {
// Message page exists...
// XXX: Is this the right way to turn a Content object into a message?
// NOTE: $content is typically either WikitextContent, JavaScriptContent or
// CssContent. MessageContent is *not* used for storing messages, it's
// only used for wrapping them when needed.
$msgText = $content->getWikitextForTransclusion();
if ( $msgText === false || $msgText === null ) {
// This might be due to some kind of misconfiguration...
$msgText = null;
LoggerFactory::getInstance( 'MessageCache' )->warning(
__METHOD__ . ": message content doesn't provide wikitext "
. "(content model: " . $content->getModel() . ")" );
}
} else {
// Message page does not exist...
$msgText = false;
}
return $msgText;
}
/**
* @param string $hash Hash for this version of the entire key/value overrides map
* @param string $title Message cache key with initial uppercase letter
* @return string
*/
private function bigMessageCacheKey( $hash, $title ) {
return $this->wanCache->makeKey( 'messages-big', $hash, $title );
}
}
Mini Shell