MessageCache.php

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<?php

# Message cache
# Performs various useful MediaWiki namespace-related functions

define( "MSG_LOAD_TIMEOUT", 60);
define( "MSG_LOCK_TIMEOUT", 10);
define( "MSG_WAIT_TIMEOUT", 10);

class MessageCache
{
        var $mCache, $mUseCache, $mDisable, $mExpiry;
        var $mMemcKey, $mKeys, $mParserOptions, $mParser;
        var $mExtensionMessages;

        var $mInitialised = false;

        function initialise( &$memCached, $useDB, $expiry, $memcPrefix ) {
                $this->mUseCache = !is_null( $memCached );
                $this->mMemc = &$memCached;
                $this->mDisable = !$useDB;
                $this->mExpiry = $expiry;
                $this->mDisableTransform = false;
                $this->mMemcKey = "$memcPrefix:messages";
                $this->mKeys = false; # initialised on demand
                $this->mInitialised = true;
                $this->mParserOptions = ParserOptions::newFromUser( $u=NULL );
                $this->mParser = new Parser;
                
                $this->load();
        }

        # Loads messages either from memcached or the database, if not disabled
        # On error, quietly switches to a fallback mode
        # Returns false for a reportable error, true otherwise
        function load() {
                global $wgAllMessagesEn;
                
                if ( $this->mDisable ) {
                        return true;
                }
                
                $success = true;
                
                if ( $this->mUseCache ) {
                        $this->mCache = $this->mMemc->get( $this->mMemcKey );
                        
                        # If there's nothing in memcached, load all the messages from the database
                        if ( !$this->mCache ) {
                                $this->lock();
                                # Other threads don't need to load the messages if another thread is doing it.
                                $this->mMemc->set( $this->mMemcKey, "loading", MSG_LOAD_TIMEOUT );
                                $this->loadFromDB();
                                # Save in memcached
                                if ( !$this->mMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry ) ) {
                                        # Hack for slabs reassignment problem
                                        $this->mMemc->set( $this->mMemcKey, "error" );
                                        wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
                                }
                                $this->unlock();
                        }
                        
                        if ( !is_array( $this->mCache ) ) {
                                # If it is 'loading' or 'error', switch to individual message mode, otherwise disable
                                if ( $this->mCache == "loading" ) {
                                        $this->mUseCache = false;
                                } elseif ( $this->mCache == "error" ) {
                                        $this->mUseCache = false;
                                        $success = false;
                                } else {
                                        $this->mDisable = true;
                                        $success = false;
                                }
                                $this->mCache = false;
                        }
                }
                return $success;
        }

        # Loads all cacheable messages from the database
        function loadFromDB()
        {
                $fname = "MessageCache::loadFromDB";
                $sql = "SELECT cur_title,cur_text FROM cur WHERE cur_is_redirect=0 AND cur_namespace=" . NS_MEDIAWIKI;
                $res = wfQuery( $sql, DB_READ, $fname );
                
                $this->mCache = array();
                for ( $row = wfFetchObject( $res ); $row; $row = wfFetchObject( $res ) ) {
                        $this->mCache[$row->cur_title] = $row->cur_text;
                }

                wfFreeResult( $res );
        }
        
        # Not really needed anymore
        function getKeys() {
                global $wgAllMessagesEn, $wgLang;
                if ( !$this->mKeys ) {
                        $this->mKeys = array();
                        foreach ( $wgAllMessagesEn as $key => $value ) {
                                array_push( $this->mKeys, $wgLang->ucfirst( $key ) );
                        }
                }
                return $this->mKeys;
        }
        
        # Obsolete
        function isCacheable( $key ) {
                return true;
                /*
                global $wgAllMessagesEn, $wgLang;
                return array_key_exists( $wgLang->lcfirst( $key ), $wgAllMessagesEn ) || 
                        array_key_exists( $key, $wgAllMessagesEn );
                */
        }

        function replace( $title, $text ) {
                $this->lock();
                $this->load();
                if ( is_array( $this->mCache ) ) {
                        $this->mCache[$title] = $text;
                        $this->mMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry );
                }
                $this->unlock();
        }

        # Returns success
        # Represents a write lock on the messages key
        function lock() {
                if ( !$this->mUseCache ) {
                        return true;
                }

                $lockKey = $this->mMemcKey . "lock";
                for ($i=0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
                        sleep(1);
                }
                
                return $i >= MSG_WAIT_TIMEOUT;
        }
        
        function unlock() {
                if ( !$this->mUseCache ) {
                        return;
                }

                $lockKey = $this->mMemcKey . "lock";
                $this->mMemc->delete( $lockKey );
        }
        
        function get( $key, $useDB ) {
                global $wgLang, $wgLanguageCode;
                
                # If uninitialised, someone is trying to call this halfway through Setup.php
                if ( !$this->mInitialised ) {
                        return "&lt;$key&gt;";
                }
                
                $message = false;
                if ( !$this->mDisable ) {
                        $title = $wgLang->ucfirst( $key );
                        

                        # Try the cache
                        if ( $this->mUseCache && $this->mCache && array_key_exists( $title, $this->mCache ) ) {
                                $message = $this->mCache[$title];
                        }
                        
                        # If it wasn't in the cache, load each message from the DB individually
                        if ( !$message && $useDB) {
                                $result = wfGetArray( "cur", array("cur_text"), 
                                  array( "cur_namespace" => NS_MEDIAWIKI, "cur_title" => $title ),
                                  "MessageCache::get" );
                                if ( $result ) {
                                        $message = $result->cur_text;
                                }
                        }
                }
                # Try the extension array
                if ( !$message ) {
                        $message = @$this->mExtensionMessages[$key];
                }

                # Try the array in $wgLang
                if ( !$message ) {
                        $message = $wgLang->getMessage( $key );
                } 

                # Try the English array
                if ( !$message && $wgLanguageCode != "en" ) {
                        $message = Language::getMessage( $key );
                }
                
                # Final fallback
                if ( !$message ) {
                        $message = "&lt;$key&gt;";
                }
                
                # Replace brace tags
                $message = $this->transform( $message );
                return $message;
        }

        function transform( $message ) {
                if( !$this->mDisableTransform ) { 
                        if ( strstr( $message, "{{" ) !== false ) {
                                $message = $this->mParser->transformMsg( $message, $this->mParserOptions );
                        }
                }
                return $message;
        }
        
        function disable() { $this->mDisable = true; }
        function enable() { $this->mDisable = false; }
        function disableTransform() { $this->mDisableTransform = true; }

        function addMessage( $key, $value ) {
                $this->mExtensionMessages[$key] = $value;
        }

        function addMessages( $messages ) {
                foreach ( $messages as $key => $value ) {
                        $this->mExtensionMessages[$key] = $value;
                }
        }
}
?>

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