MessageCache.php

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<?php
define( 'MSG_LOAD_TIMEOUT', 60 );
define( 'MSG_LOCK_TIMEOUT', 10 );
define( 'MSG_WAIT_TIMEOUT', 10 );
define( 'MSG_CACHE_VERSION', 1 );

class MessageCache {
        protected $mCache;

        // Should  mean that database cannot be used, but check
        protected $mDisable;

        protected $mExpiry;

        protected $mParserOptions, $mParser;

        protected $mLoadedLanguages = array();

        protected $mRequestedMessages = array();

        protected static $mAdaptiveDataAge = 604800; // Is 7*24*3600

        protected static $mAdaptiveInclusionThreshold = 0.05;

        private static $instance;

        protected $mInParser = false;

        public static function singleton() {
                if ( is_null( self::$instance ) ) {
                        global $wgUseDatabaseMessages, $wgMsgCacheExpiry;
                        self::$instance = new self( wfGetMessageCacheStorage(), $wgUseDatabaseMessages, $wgMsgCacheExpiry );
                }
                return self::$instance;
        }

        public static function destroyInstance() {
                self::$instance = null;
        }

        function __construct( $memCached, $useDB, $expiry ) {
                if ( !$memCached ) {
                        $memCached = wfGetCache( CACHE_NONE );
                }

                $this->mMemc = $memCached;
                $this->mDisable = !$useDB;
                $this->mExpiry = $expiry;
        }

        function getParserOptions() {
                if ( !$this->mParserOptions ) {
                        $this->mParserOptions = new ParserOptions;
                }
                return $this->mParserOptions;
        }

        function loadFromLocal( $hash, $code ) {
                global $wgCacheDirectory, $wgLocalMessageCacheSerialized;

                $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";

                # Check file existence
                wfSuppressWarnings();
                $file = fopen( $filename, 'r' );
                wfRestoreWarnings();
                if ( !$file ) {
                        return false; // No cache file
                }

                if ( $wgLocalMessageCacheSerialized ) {
                        // Check to see if the file has the hash specified
                        $localHash = fread( $file, 32 );
                        if ( $hash === $localHash ) {
                                // All good, get the rest of it
                                $serialized = '';
                                while ( !feof( $file ) ) {
                                        $serialized .= fread( $file, 100000 );
                                }
                                fclose( $file );
                                return $this->setCache( unserialize( $serialized ), $code );
                        } else {
                                fclose( $file );
                                return false; // Wrong hash
                        }
                } else {
                        $localHash = substr( fread( $file, 40 ), 8 );
                        fclose( $file );
                        if ( $hash != $localHash ) {
                                return false; // Wrong hash
                        }

                        # Require overwrites the member variable or just shadows it?
                        require( $filename );
                        return $this->setCache( $this->mCache, $code );
                }
        }

        function saveToLocal( $serialized, $hash, $code ) {
                global $wgCacheDirectory;

                $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
                wfMkdirParents( $wgCacheDirectory, null, __METHOD__ ); // might fail

                wfSuppressWarnings();
                $file = fopen( $filename, 'w' );
                wfRestoreWarnings();

                if ( !$file ) {
                        wfDebug( "Unable to open local cache file for writing\n" );
                        return;
                }

                fwrite( $file, $hash . $serialized );
                fclose( $file );
                wfSuppressWarnings();
                chmod( $filename, 0666 );
                wfRestoreWarnings();
        }

        function saveToScript( $array, $hash, $code ) {
                global $wgCacheDirectory;

                $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
                $tempFilename = $filename . '.tmp';
                wfMkdirParents( $wgCacheDirectory, null, __METHOD__ ); // might fail

                wfSuppressWarnings();
                $file = fopen( $tempFilename, 'w' );
                wfRestoreWarnings();

                if ( !$file ) {
                        wfDebug( "Unable to open local cache file for writing\n" );
                        return;
                }

                fwrite( $file, "<?php\n//$hash\n\n \$this->mCache = array(" );

                foreach ( $array as $key => $message ) {
                        $key = $this->escapeForScript( $key );
                        $message = $this->escapeForScript( $message );
                        fwrite( $file, "'$key' => '$message',\n" );
                }

                fwrite( $file, ");\n?>" );
                fclose( $file);
                rename( $tempFilename, $filename );
        }

        function escapeForScript( $string ) {
                $string = str_replace( '\\', '\\\\', $string );
                $string = str_replace( '\'', '\\\'', $string );
                return $string;
        }

        function setCache( $cache, $code ) {
                if ( isset( $cache['VERSION'] ) && $cache['VERSION'] == MSG_CACHE_VERSION ) {
                        $this->mCache[$code] = $cache;
                        return true;
                } else {
                        return false;
                }
        }

        function load( $code = false ) {
                global $wgUseLocalMessageCache;

                if( !is_string( $code ) ) {
                        # This isn't really nice, so at least make a note about it and try to
                        # fall back
                        wfDebug( __METHOD__ . " called without providing a language code\n" );
                        $code = 'en';
                }

                # Don't do double loading...
                if ( isset( $this->mLoadedLanguages[$code] ) ) {
                        return true;
                }

                # 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
                wfProfileIn( __METHOD__ );
                $success = false; # Keep track of success
                $where = array(); # Debug info, delayed to avoid spamming debug log too much
                $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages

                # (1) local cache
                # Hash of the contents is stored in memcache, to detect if local cache goes
                # out of date (due to update in other thread?)
                if ( $wgUseLocalMessageCache ) {
                        wfProfileIn( __METHOD__ . '-fromlocal' );

                        $hash = $this->mMemc->get( wfMemcKey( 'messages', $code, 'hash' ) );
                        if ( $hash ) {
                                $success = $this->loadFromLocal( $hash, $code );
                                if ( $success ) $where[] = 'got from local cache';
                        }
                        wfProfileOut( __METHOD__ . '-fromlocal' );
                }

                # (2) memcache
                # Fails if nothing in cache, or in the wrong version.
                if ( !$success ) {
                        wfProfileIn( __METHOD__ . '-fromcache' );
                        $cache = $this->mMemc->get( $cacheKey );
                        $success = $this->setCache( $cache, $code );
                        if ( $success ) {
                                $where[] = 'got from global cache';
                                $this->saveToCaches( $cache, false, $code );
                        }
                        wfProfileOut( __METHOD__ . '-fromcache' );
                }

                # (3)
                # Nothing in caches... so we need create one and store it in caches
                if ( !$success ) {
                        $where[] = 'cache is empty';
                        $where[] = 'loading from database';

                        $this->lock( $cacheKey );

                        # Limit the concurrency of loadFromDB to a single process
                        # This prevents the site from going down when the cache expires
                        $statusKey = wfMemcKey( 'messages', $code, 'status' );
                        $success = $this->mMemc->add( $statusKey, 'loading', MSG_LOAD_TIMEOUT );
                        if ( $success ) {
                                $cache = $this->loadFromDB( $code );
                                $success = $this->setCache( $cache, $code );
                        }
                        if ( $success ) {
                                $success = $this->saveToCaches( $cache, true, $code );
                                if ( $success ) {
                                        $this->mMemc->delete( $statusKey );
                                } else {
                                        $this->mMemc->set( $statusKey, 'error', 60 * 5 );
                                        wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
                                }
                        }
                        $this->unlock($cacheKey);
                }

                if ( !$success ) {
                        # Bad luck... this should not happen
                        $where[] = 'loading FAILED - cache is disabled';
                        $info = implode( ', ', $where );
                        wfDebug( __METHOD__ . ": Loading $code... $info\n" );
                        $this->mDisable = true;
                        $this->mCache = false;
                } else {
                        # All good, just record the success
                        $info = implode( ', ', $where );
                        wfDebug( __METHOD__ . ": Loading $code... $info\n" );
                        $this->mLoadedLanguages[$code] = true;
                }
                wfProfileOut( __METHOD__ );
                return $success;
        }

        function loadFromDB( $code ) {
                wfProfileIn( __METHOD__ );
                global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
                $dbr = wfGetDB( DB_SLAVE );
                $cache = array();

                # Common conditions
                $conds = array(
                        'page_is_redirect' => 0,
                        'page_namespace' => NS_MEDIAWIKI,
                );

                $mostused = array();
                if ( $wgAdaptiveMessageCache ) {
                        $mostused = $this->getMostUsedMessages();
                        if ( $code !== $wgLanguageCode ) {
                                foreach ( $mostused as $key => $value ) {
                                        $mostused[$key] = "$value/$code";
                                }
                        }
                }

                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() );
                }

                # Conditions to fetch oversized pages to ignore them
                $bigConds = $conds;
                $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );

                # Load titles for all oversized pages in the MediaWiki namespace
                $res = $dbr->select( 'page', 'page_title', $bigConds, __METHOD__ . "($code)-big" );
                foreach ( $res as $row ) {
                        $cache[$row->page_title] = '!TOO BIG';
                }

                # Conditions to load the remaining pages with their contents
                $smallConds = $conds;
                $smallConds[] = 'page_latest=rev_id';
                $smallConds[] = 'rev_text_id=old_id';
                $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );

                $res = $dbr->select(
                        array( 'page', 'revision', 'text' ),
                        array( 'page_title', 'old_text', 'old_flags' ),
                        $smallConds,
                        __METHOD__ . "($code)-small"
                );

                foreach ( $res as $row ) {
                        $text = Revision::getRevisionText( $row );
                        if( $text === false ) {
                                // Failed to fetch data; possible ES errors?
                                // Store a marker to fetch on-demand as a workaround...
                                $entry = '!TOO BIG';
                                wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$row->page_title} ($code)" );
                        } else {
                                $entry = ' ' . $text;
                        }
                        $cache[$row->page_title] = $entry;
                }

                foreach ( $mostused as $key ) {
                        if ( !isset( $cache[$key] ) ) {
                                $cache[$key] = '!NONEXISTENT';
                        }
                }

                $cache['VERSION'] = MSG_CACHE_VERSION;
                wfProfileOut( __METHOD__ );
                return $cache;
        }

        public function replace( $title, $text ) {
                global $wgMaxMsgCacheEntrySize;
                wfProfileIn( __METHOD__ );

                if ( $this->mDisable ) {
                        wfProfileOut( __METHOD__ );
                        return;
                }

                list( $msg, $code ) = $this->figureMessage( $title );

                $cacheKey = wfMemcKey( 'messages', $code );
                $this->load( $code );
                $this->lock( $cacheKey );

                $titleKey = wfMemcKey( 'messages', 'individual', $title );

                if ( $text === false ) {
                        # Article was deleted
                        $this->mCache[$code][$title] = '!NONEXISTENT';
                        $this->mMemc->delete( $titleKey );
                } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
                        # Check for size
                        $this->mCache[$code][$title] = '!TOO BIG';
                        $this->mMemc->set( $titleKey, ' ' . $text, $this->mExpiry );
                } else {
                        $this->mCache[$code][$title] = ' ' . $text;
                        $this->mMemc->delete( $titleKey );
                }

                # Update caches
                $this->saveToCaches( $this->mCache[$code], true, $code );
                $this->unlock( $cacheKey );

                // Also delete cached sidebar... just in case it is affected
                $codes = array( $code );
                if ( $code === 'en'  ) {
                        // Delete all sidebars, like for example on action=purge on the
                        // sidebar messages
                        $codes = array_keys( Language::getLanguageNames() );
                }

                global $wgMemc;
                foreach ( $codes as $code ) {
                        $sidebarKey = wfMemcKey( 'sidebar', $code );
                        $wgMemc->delete( $sidebarKey );
                }

                // Update the message in the message blob store
                global $wgContLang;
                MessageBlobStore::updateMessage( $wgContLang->lcfirst( $msg ) );

                wfRunHooks( 'MessageCacheReplace', array( $title, $text ) );

                wfProfileOut( __METHOD__ );
        }

        protected function saveToCaches( $cache, $memc = true, $code = false ) {
                wfProfileIn( __METHOD__ );
                global $wgUseLocalMessageCache, $wgLocalMessageCacheSerialized;

                $cacheKey = wfMemcKey( 'messages', $code );

                if ( $memc ) {
                        $success = $this->mMemc->set( $cacheKey, $cache, $this->mExpiry );
                } else {
                        $success = true;
                }

                # Save to local cache
                if ( $wgUseLocalMessageCache ) {
                        $serialized = serialize( $cache );
                        $hash = md5( $serialized );
                        $this->mMemc->set( wfMemcKey( 'messages', $code, 'hash' ), $hash, $this->mExpiry );
                        if ($wgLocalMessageCacheSerialized) {
                                $this->saveToLocal( $serialized, $hash, $code );
                        } else {
                                $this->saveToScript( $cache, $hash, $code );
                        }
                }

                wfProfileOut( __METHOD__ );
                return $success;
        }

        function lock( $key ) {
                $lockKey = $key . ':lock';
                for ( $i = 0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
                        sleep( 1 );
                }

                return $i >= MSG_WAIT_TIMEOUT;
        }

        function unlock( $key ) {
                $lockKey = $key . ':lock';
                $this->mMemc->delete( $lockKey );
        }

        function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
                global $wgLanguageCode, $wgContLang;

                if ( is_int( $key ) ) {
                        // "Non-string key given" exception sometimes happens for numerical strings that become ints somewhere on their way here
                        $key = strval( $key );
                }

                if ( !is_string( $key ) ) {
                        throw new MWException( 'Non-string key given' );
                }

                if ( strval( $key ) === '' ) {
                        # Shortcut: the empty key is always missing
                        return false;
                }

                $lang = wfGetLangObj( $langcode );
                if ( !$lang ) {
                        throw new MWException( "Bad lang code $langcode given" );
                }

                $langcode = $lang->getCode();

                $message = false;

                # Normalise title-case input (with some inlining)
                $lckey = str_replace( ' ', '_', $key );
                if ( ord( $key ) < 128 ) {
                        $lckey[0] = strtolower( $lckey[0] );
                        $uckey = ucfirst( $lckey );
                } else {
                        $lckey = $wgContLang->lcfirst( $lckey );
                        $uckey = $wgContLang->ucfirst( $lckey );
                }

                $this->mRequestedMessages[$uckey] = true;

                # Try the MediaWiki namespace
                if( !$this->mDisable && $useDB ) {
                        $title = $uckey;
                        if( !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
                                $title .= '/' . $langcode;
                        }
                        $message = $this->getMsgFromNamespace( $title, $langcode );
                }

                # Try the array in the language object
                if ( $message === false ) {
                        $message = $lang->getMessage( $lckey );
                        if ( is_null( $message ) ) {
                                $message = false;
                        }
                }

                # Try the array of another language
                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 ( is_null( $message ) ) {
                                        $message = false;
                                }
                        }
                }

                # Is this a custom message? Try the default language in the db...
                if( ( $message === false || $message === '-' ) &&
                        !$this->mDisable && $useDB &&
                        !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
                        $message = $this->getMsgFromNamespace( $uckey, $wgLanguageCode );
                }

                # Final fallback
                if( $message === false ) {
                        return false;
                }

                # Fix whitespace
                $message = strtr( $message,
                        array(
                                # Fix for trailing whitespace, removed by textarea
                                '&#32;' => ' ',
                                # Fix for NBSP, converted to space by firefox
                                '&nbsp;' => "\xc2\xa0",
                                '&#160;' => "\xc2\xa0",
                        ) );

                return $message;
        }

        function getMsgFromNamespace( $title, $code ) {
                global $wgAdaptiveMessageCache;

                $this->load( $code );
                if ( isset( $this->mCache[$code][$title] ) ) {
                        $entry = $this->mCache[$code][$title];
                        if ( substr( $entry, 0, 1 ) === ' ' ) {
                                return substr( $entry, 1 );
                        } elseif ( $entry === '!NONEXISTENT' ) {
                                return false;
                        } elseif( $entry === '!TOO BIG' ) {
                                // Fall through and try invididual message cache below
                        }
                } else {
                        // XXX: This is not cached in process cache, should it?
                        $message = false;
                        wfRunHooks( 'MessagesPreLoad', array( $title, &$message ) );
                        if ( $message !== false ) {
                                return $message;
                        }

                        if ( !$wgAdaptiveMessageCache ) {
                                return false;
                        }
                }

                # Try the individual message cache
                $titleKey = wfMemcKey( 'messages', 'individual', $title );
                $entry = $this->mMemc->get( $titleKey );
                if ( $entry ) {
                        if ( substr( $entry, 0, 1 ) === ' ' ) {
                                $this->mCache[$code][$title] = $entry;
                                return substr( $entry, 1 );
                        } elseif ( $entry === '!NONEXISTENT' ) {
                                $this->mCache[$code][$title] = '!NONEXISTENT';
                                return false;
                        } else {
                                # Corrupt/obsolete entry, delete it
                                $this->mMemc->delete( $titleKey );
                        }
                }

                # Try loading it from the database
                $revision = Revision::newFromTitle( Title::makeTitle( NS_MEDIAWIKI, $title ) );
                if ( $revision ) {
                        $message = $revision->getText();
                        if ($message === false) {
                                // A possibly temporary loading failure.
                                wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$title->getDbKey()} ($code)" );
                        } else {
                                $this->mCache[$code][$title] = ' ' . $message;
                                $this->mMemc->set( $titleKey, ' ' . $message, $this->mExpiry );
                        }
                } else {
                        $message = false;
                        $this->mCache[$code][$title] = '!NONEXISTENT';
                        $this->mMemc->set( $titleKey, '!NONEXISTENT', $this->mExpiry );
                }

                return $message;
        }

        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;
        }

        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 == 'Parser_DiffTest' ) {
                                # Uncloneable
                                $this->mParser = new $class( $wgParserConf );
                        } else {
                                $this->mParser = clone $wgParser;
                        }
                }
                return $this->mParser;
        }

        public function parse( $text, $title = null, $linestart = true, $interface = false, $language = null  ) {
                if ( $this->mInParser ) {
                        return htmlspecialchars( $text );
                }

                $parser = $this->getParser();
                $popts = $this->getParserOptions();
                $popts->setInterfaceMessage( $interface );
                $popts->setTargetLanguage( $language );

                wfProfileIn( __METHOD__ );
                if ( !$title || !$title instanceof Title ) {
                        global $wgTitle;
                        $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::newFromText( 'Dwimmerlaik' );
                }

                $this->mInParser = true;
                $res = $parser->parse( $text, $title, $popts, $linestart );
                $this->mInParser = false;

                wfProfileOut( __METHOD__ );
                return $res;
        }

        function disable() {
                $this->mDisable = true;
        }

        function enable() {
                $this->mDisable = false;
        }

        function clear() {
                $langs = Language::getLanguageNames( false );
                foreach ( array_keys($langs) as $code ) {
                        # Global cache
                        $this->mMemc->delete( wfMemcKey( 'messages', $code ) );
                        # Invalidate all local caches
                        $this->mMemc->delete( wfMemcKey( 'messages', $code, 'hash' ) );
                }
                $this->mLoadedLanguages = array();
        }

        public function figureMessage( $key ) {
                global $wgLanguageCode;
                $pieces = explode( '/', $key );
                if( count( $pieces ) < 2 ) {
                        return array( $key, $wgLanguageCode );
                }

                $lang = array_pop( $pieces );
                $validCodes = Language::getLanguageNames();
                if( !array_key_exists( $lang, $validCodes ) ) {
                        return array( $key, $wgLanguageCode );
                }

                $message = implode( '/', $pieces );
                return array( $message, $lang );
        }

        public static function logMessages() {
                wfProfileIn( __METHOD__ );
                global $wgAdaptiveMessageCache;
                if ( !$wgAdaptiveMessageCache || !self::$instance instanceof MessageCache ) {
                        wfProfileOut( __METHOD__ );
                        return;
                }

                $cachekey = wfMemckey( 'message-profiling' );
                $cache = wfGetCache( CACHE_DB );
                $data = $cache->get( $cachekey );

                if ( !$data ) {
                        $data = array();
                }

                $age = self::$mAdaptiveDataAge;
                $filterDate = substr( wfTimestamp( TS_MW, time() - $age ), 0, 8 );
                foreach ( array_keys( $data ) as $key ) {
                        if ( $key < $filterDate ) {
                                unset( $data[$key] );
                        }
                }

                $index = substr( wfTimestampNow(), 0, 8 );
                if ( !isset( $data[$index] ) ) {
                        $data[$index] = array();
                }

                foreach ( self::$instance->mRequestedMessages as $message => $_ ) {
                        if ( !isset( $data[$index][$message] ) ) {
                                $data[$index][$message] = 0;
                        }
                        $data[$index][$message]++;
                }

                $cache->set( $cachekey, $data );
                wfProfileOut( __METHOD__ );
        }

        public function getMostUsedMessages() {
                wfProfileIn( __METHOD__ );
                $cachekey = wfMemcKey( 'message-profiling' );
                $cache = wfGetCache( CACHE_DB );
                $data = $cache->get( $cachekey );
                if ( !$data ) {
                        wfProfileOut( __METHOD__ );
                        return array();
                }

                $list = array();

                foreach( $data as $messages ) {
                        foreach( $messages as $message => $count ) {
                                $key = $message;
                                if ( !isset( $list[$key] ) ) {
                                        $list[$key] = 0;
                                }
                                $list[$key] += $count;
                        }
                }

                $max = max( $list );
                foreach ( $list as $message => $count ) {
                        if ( $count < intval( $max * self::$mAdaptiveInclusionThreshold ) ) {
                                unset( $list[$message] );
                        }
                }

                wfProfileOut( __METHOD__ );
                return array_keys( $list );
        }

        public function getAllMessageKeys( $code ) {
                global $wgContLang;
                $this->load( $code );
                if ( !isset( $this->mCache[$code] ) ) {
                        // Apparently load() failed
                        return null;
                }
                $cache = $this->mCache[$code]; // Copy the cache
                unset( $cache['VERSION'] ); // Remove the VERSION key
                $cache = array_diff( $cache, array( '!NONEXISTENT' ) ); // Remove any !NONEXISTENT keys
                // Keys may appear with a capital first letter. lcfirst them.
                return array_map( array( $wgContLang, 'lcfirst' ), array_keys( $cache ) );
        }
}