1.23.16/php/MessageCache_8php_source.html

<?php

define( 'MSG_CACHE_VERSION', 1 );


define( 'MSG_LOAD_TIMEOUT', 60 );


define( 'MSG_LOCK_TIMEOUT', 30 );

define( 'MSG_WAIT_TIMEOUT', 30 );


class MessageCache {

    protected $mCache;


    protected $mDisable;


    protected $mExpiry;


    protected $mParserOptions, $mParser;


    protected $mLoadedLanguages = array();


    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;

            $this->mParserOptions->setEditSection( false );

            // 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;

    }


    function getLocalCache( $hash, $code ) {

        global $wgCacheDirectory;


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


        # Check file existence

        wfSuppressWarnings();

        $file = fopen( $filename, 'r' );

        wfRestoreWarnings();

        if ( !$file ) {

            return false; // No cache file

        }


        // 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 unserialize( $serialized );

        } else {

            fclose( $file );


            return false; // Wrong hash

        }

    }


    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 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

        $staleCache = false; # a cache array with expired data, or false if none has been loaded

        $where = array(); # Debug info, delayed to avoid spamming debug log too much

        $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages


        # Local cache

        # Hash of the contents is stored in memcache, to detect if local cache goes

        # out of date (e.g. due to replace() on some other server)

        if ( $wgUseLocalMessageCache ) {

            wfProfileIn( __METHOD__ . '-fromlocal' );


            $hash = $this->mMemc->get( wfMemcKey( 'messages', $code, 'hash' ) );

            if ( $hash ) {

                $cache = $this->getLocalCache( $hash, $code );

                if ( !$cache ) {

                    $where[] = 'local cache is empty or has the wrong hash';

                } elseif ( $this->isCacheExpired( $cache ) ) {

                    $where[] = 'local cache is expired';

                    $staleCache = $cache;

                } else {

                    $where[] = 'got from local cache';

                    $success = true;

                    $this->mCache[$code] = $cache;

                }

            }

            wfProfileOut( __METHOD__ . '-fromlocal' );

        }


        if ( !$success ) {

            # 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 < 2; $failedAttempts++ ) {

                wfProfileIn( __METHOD__ . '-fromcache' );

                $cache = $this->mMemc->get( $cacheKey );

                if ( !$cache ) {

                    $where[] = 'global cache is empty';

                } elseif ( $this->isCacheExpired( $cache ) ) {

                    $where[] = 'global cache is expired';

                    $staleCache = $cache;

                } else {

                    $where[] = 'got from global cache';

                    $this->mCache[$code] = $cache;

                    $this->saveToCaches( $cache, 'local-only', $code );

                    $success = true;

                }


                wfProfileOut( __METHOD__ . '-fromcache' );


                if ( $success ) {

                    # Done, no need to retry

                    break;

                }


                # We need to call loadFromDB. Limit the concurrency to a single

                # process. This prevents the site from going down when the cache

                # expires.

                $statusKey = wfMemcKey( 'messages', $code, 'status' );

                $acquired = $this->mMemc->add( $statusKey, 'loading', MSG_LOAD_TIMEOUT );

                if ( $acquired ) {

                    # Unlock the status key if there is an exception

                    $that = $this;

                    $statusUnlocker = new ScopedCallback( function () use ( $that, $statusKey ) {

                        $that->mMemc->delete( $statusKey );

                    } );


                    # Now let's regenerate

                    $where[] = 'loading from database';


                    # Lock the cache to prevent conflicting writes

                    # If this lock fails, it doesn't really matter, it just means the

                    # write is potentially non-atomic, e.g. the results of a replace()

                    # may be discarded.

                    if ( $this->lock( $cacheKey ) ) {

                        $mainUnlocker = new ScopedCallback( function () use ( $that, $cacheKey ) {

                            $that->unlock( $cacheKey );

                        } );

                    } else {

                        $mainUnlocker = null;

                        $where[] = 'could not acquire main lock';

                    }


                    $cache = $this->loadFromDB( $code );

                    $this->mCache[$code] = $cache;

                    $success = true;

                    $saveSuccess = $this->saveToCaches( $cache, 'all', $code );


                    # Unlock

                    ScopedCallback::consume( $mainUnlocker );

                    ScopedCallback::consume( $statusUnlocker );


                    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 ( !$wgUseLocalMessageCache ) {

                            $this->mMemc->set( $statusKey, 'error', 60 * 5 );

                            $where[] = 'could not save cache, disabled globally for 5 minutes';

                        } else {

                            $where[] = "could not save global cache";

                        }

                    }


                    # Load from DB complete, no need to retry

                    break;

                } elseif ( $staleCache ) {

                    # Use the stale cache while some other thread constructs the new one

                    $where[] = 'using stale cache';

                    $this->mCache[$code] = $staleCache;

                    $success = true;

                    break;

                } elseif ( $failedAttempts > 0 ) {

                    # Already retried once, still failed, so don't do another lock/unlock cycle

                    # This case will typically be hit if memcached is down, or if

                    # loadFromDB() takes longer than MSG_WAIT_TIMEOUT

                    $where[] = "could not acquire status key.";

                    break;

                } else {

                    $status = $this->mMemc->get( $statusKey );

                    if ( $status === 'error' ) {

                        # Disable cache

                        break;

                    } else {

                        # Wait for the other thread to finish, then retry

                        $where[] = 'waited for other thread to complete';

                        $this->lock( $cacheKey );

                        $this->unlock( $cacheKey );

                    }

                }

            }

        }


        if ( !$success ) {

            $where[] = 'loading FAILED - cache is disabled';

            $this->mDisable = true;

            $this->mCache = false;

            # 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

        } else {

            # All good, just record the success

            $this->mLoadedLanguages[$code] = true;

        }

        $info = implode( ', ', $where );

        wfDebug( __METHOD__ . ": Loading $code... $info\n" );

        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 && $code !== $wgLanguageCode ) {

            if ( !isset( $this->mCache[$wgLanguageCode] ) ) {

                $this->load( $wgLanguageCode );

            }

            $mostused = array_keys( $this->mCache[$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;

        }


        $cache['VERSION'] = MSG_CACHE_VERSION;

        $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );

        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], 'all', $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::fetchLanguageNames() );

        }


        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 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;

    }


    protected function saveToCaches( $cache, $dest, $code = false ) {

        wfProfileIn( __METHOD__ );

        global $wgUseLocalMessageCache;


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


        if ( $dest === 'all' ) {

            $success = $this->mMemc->set( $cacheKey, $cache );

        } else {

            $success = true;

        }


        # Save to local cache

        if ( $wgUseLocalMessageCache ) {

            $serialized = serialize( $cache );

            $hash = md5( $serialized );

            $this->mMemc->set( wfMemcKey( 'messages', $code, 'hash' ), $hash );

            $this->saveToLocal( $serialized, $hash, $code );

        }


        wfProfileOut( __METHOD__ );


        return $success;

    }


    function lock( $key ) {

        $lockKey = $key . ':lock';

        $acquired = false;

        $testDone = false;

        for ( $i = 0; $i < MSG_WAIT_TIMEOUT && !$acquired; $i++ ) {

            $acquired = $this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT );

            if ( $acquired ) {

                break;

            }


            # Fail fast if memcached is totally down

            if ( !$testDone ) {

                $testDone = true;

                if ( !$this->mMemc->set( wfMemcKey( 'test' ), 'test', 1 ) ) {

                    break;

                }

            }

            sleep( 1 );

        }


        return $acquired;

    }


    function unlock( $key ) {

        $lockKey = $key . ':lock';

        $this->mMemc->delete( $lockKey );

    }


    function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {

        global $wgContLang;


        $section = new ProfileSection( __METHOD__ );


        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;

        }


        // For full keys, get the language code from the key

        $pos = strrpos( $key, '/' );

        if ( $isFullKey && $pos !== false ) {

            $langcode = substr( $key, $pos + 1 );

            $key = substr( $key, 0, $pos );

        }


        // Normalise title-case input (with some inlining)

        $lckey = strtr( $key, ' ', '_' );

        if ( ord( $lckey ) < 128 ) {

            $lckey[0] = strtolower( $lckey[0] );

        } else {

            $lckey = $wgContLang->lcfirst( $lckey );

        }


        wfRunHooks( 'MessageCache::get', array( &$lckey ) );


        if ( ord( $lckey ) < 128 ) {

            $uckey = ucfirst( $lckey );

        } else {

            $uckey = $wgContLang->ucfirst( $lckey );

        }


        // Loop through each language in the fallback list until we find something useful

        $lang = wfGetLangObj( $langcode );

        $message = $this->getMessageFromFallbackChain(

            $lang,

            $lckey,

            $uckey,

            !$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(

                array(

                    # Fix for trailing whitespace, removed by textarea

                    '&#32;',

                    # Fix for NBSP, converted to space by firefox

                    '&nbsp;',

                    '&#160;',

                ),

                array(

                    ' ',

                    "\xc2\xa0",

                    "\xc2\xa0"

                ),

                $message

            );

        }


        return $message;

    }


    protected function getMessageFromFallbackChain( $lang, $lckey, $uckey, $useDB ) {

        global $wgLanguageCode, $wgContLang;


        $langcode = $lang->getCode();

        $message = false;


        // First try the requested language.

        if ( $useDB ) {

            if ( $langcode === $wgLanguageCode ) {

                // Messages created in the content language will not have the /lang extension

                $message = $this->getMsgFromNamespace( $uckey, $langcode );

            } else {

                $message = $this->getMsgFromNamespace( "$uckey/$langcode", $langcode );

            }

        }


        if ( $message !== false ) {

            return $message;

        }


        // Check the CDB cache

        $message = $lang->getMessage( $lckey );

        if ( $message !== null ) {

            return $message;

        }


        list( $fallbackChain, $siteFallbackChain ) =

            Language::getFallbacksIncludingSiteLanguage( $langcode );


        // Next try checking the database for all of the fallback languages of the requested language.

        if ( $useDB ) {

            foreach ( $fallbackChain as $code ) {

                if ( $code === $wgLanguageCode ) {

                    // Messages created in the content language will not have the /lang extension

                    $message = $this->getMsgFromNamespace( $uckey, $code );

                } else {

                    $message = $this->getMsgFromNamespace( "$uckey/$code", $code );

                }


                if ( $message !== false ) {

                    // Found the message.

                    return $message;

                }

            }

        }


        // Now try checking the site language.

        if ( $useDB ) {

            $message = $this->getMsgFromNamespace( $uckey, $wgLanguageCode );

            if ( $message !== false ) {

                return $message;

            }

        }


        $message = $wgContLang->getMessage( $lckey );

        if ( $message !== null ) {

            return $message;

        }


        // Finally try the DB for the site language's fallbacks.

        if ( $useDB ) {

            foreach ( $siteFallbackChain as $code ) {

                $message = $this->getMsgFromNamespace( "$uckey/$code", $code );

                if ( $message === false && $code === $wgLanguageCode ) {

                    // Messages created in the content language will not have the /lang extension

                    $message = $this->getMsgFromNamespace( $uckey, $code );

                }


                if ( $message !== false ) {

                    // Found the message.

                    return $message;

                }

            }

        }


        return false;

    }


    function getMsgFromNamespace( $title, $code ) {

        $this->load( $code );

        if ( isset( $this->mCache[$code][$title] ) ) {

            $entry = $this->mCache[$code][$title];

            if ( substr( $entry, 0, 1 ) === ' ' ) {

                // The message exists, so make sure a string

                // is returned.

                return (string)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;

            }


            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;


                // The message exists, so make sure a string

                // is returned.

                return (string)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 ), false, Revision::READ_LATEST

        );

        if ( $revision ) {

            $content = $revision->getContent();

            if ( !$content ) {

                // A possibly temporary loading failure.

                wfDebugLog(

                    'MessageCache',

                    __METHOD__ . ": failed to load message page text for {$title} ($code)"

                );

                $message = null; // no negative caching

            } else {

                // 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.

                $message = $content->getWikitextForTransclusion();


                if ( $message === false || $message === null ) {

                    wfDebugLog(

                        'MessageCache',

                        __METHOD__ . ": message content doesn't provide wikitext "

                            . "(content model: " . $content->getContentHandler() . ")"

                    );


                    $message = false; // negative caching

                } else {

                    $this->mCache[$code][$title] = ' ' . $message;

                    $this->mMemc->set( $titleKey, ' ' . $message, $this->mExpiry );

                }

            }

        } else {

            $message = false; // negative caching

        }


        if ( $message === false ) { // negative caching

            $this->mCache[$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::fetchLanguageNames( null, 'mw' );

        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 );

        if ( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {

            return array( $key, $wgLanguageCode );

        }


        $message = implode( '/', $pieces );


        return array( $message, $lang );

    }


    public function getAllMessageKeys( $code ) {

        global $wgContLang;

        $this->load( $code );

        if ( !isset( $this->mCache[$code] ) ) {

            // Apparently load() failed

            return null;

        }

        // Remove administrative keys

        $cache = $this->mCache[$code];

        unset( $cache['VERSION'] );

        unset( $cache['EXPIRY'] );

        // Remove any !NONEXISTENT keys

        $cache = array_diff( $cache, array( '!NONEXISTENT' ) );


        // Keys may appear with a capital first letter. lcfirst them.

        return array_map( array( $wgContLang, 'lcfirst' ), array_keys( $cache ) );

    }

}