]> scripts.mit.edu Git - autoinstallsdev/mediawiki.git/blobdiff - includes/MessageCache.php
MediaWiki 1.17.1
[autoinstallsdev/mediawiki.git] / includes / MessageCache.php
index 7f94cc9d7a23719cea48bf66a64db7052cf098fd..a111211f884f4f8c0631b7e2bba830bf1a29b010 100644 (file)
 <?php
 /**
- *
- * @package MediaWiki
- * @subpackage Cache
+ * @file
+ * @ingroup Cache
  */
 
-/** */
-require_once( 'Revision.php' );
-
 /**
  *
  */
 define( 'MSG_LOAD_TIMEOUT', 60);
 define( 'MSG_LOCK_TIMEOUT', 10);
 define( 'MSG_WAIT_TIMEOUT', 10);
+define( 'MSG_CACHE_VERSION', 1 );
 
 /**
  * Message cache
- * Performs various useful MediaWiki namespace-related functions
- *
- * @package MediaWiki
+ * Performs various MediaWiki namespace-related functions
+ * @ingroup Cache
  */
-class MessageCache
-{
-       var $mCache, $mUseCache, $mDisable, $mExpiry;
-       var $mMemcKey, $mKeys, $mParserOptions, $mParser;
-       var $mExtensionMessages = array();
-       var $mInitialised = false;
-       var $mDeferred = true;
-
-       function initialise( &$memCached, $useDB, $expiry, $memcPrefix) {
-               $fname = 'MessageCache::initialise';
-               wfProfileIn( $fname );
-
-               $this->mUseCache = !is_null( $memCached );
-               $this->mMemc = &$memCached;
+class MessageCache {
+       /**
+        * Process local cache of loaded messages that are defined in
+        * MediaWiki namespace. First array level is a language code,
+        * second level is message key and the values are either message
+        * content prefixed with space, or !NONEXISTENT for negative
+        * caching.
+        */
+       protected $mCache;
+
+       // Should  mean that database cannot be used, but check
+       protected $mDisable;
+
+       /// Lifetime for cache, used by object caching
+       protected $mExpiry;
+
+       /**
+        * Message cache has it's own parser which it uses to transform
+        * messages.
+        */
+       protected $mParserOptions, $mParser;
+
+       /// Variable for tracking which variables are already loaded
+       protected $mLoadedLanguages = array();
+
+       function __construct( $memCached, $useDB, $expiry ) {
+               if ( !$memCached ) {
+                       $memCached = wfGetCache( CACHE_NONE );
+               }
+
+               $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;
-
-               wfProfileIn( $fname.'-parseropt' );
-               $this->mParserOptions = ParserOptions::newFromUser( $u=NULL );
-               wfProfileOut( $fname.'-parseropt' );
-               wfProfileIn( $fname.'-parser' );
-               $this->mParser = new Parser;
-               wfProfileOut( $fname.'-parser' );
-
-               # When we first get asked for a message,
-               # then we'll fill up the cache. If we
-               # can return a cache hit, this saves
-               # some extra milliseconds
-               $this->mDeferred = true;
-
-               wfProfileOut( $fname );
+       }
+
+
+       /**
+        * ParserOptions is lazy initialised.
+        */
+       function getParserOptions() {
+               if ( !$this->mParserOptions ) {
+                       $this->mParserOptions = new ParserOptions;
+               }
+               return $this->mParserOptions;
+       }
+
+       /**
+        * Try to load the cache from a local file.
+        * Actual format of the file depends on the $wgLocalMessageCacheSerialized
+        * setting.
+        *
+        * @param $hash String: the hash of contents, to check validity.
+        * @param $code Mixed: Optional language code, see documenation of load().
+        * @return false on failure.
+        */
+       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 );
+               }
+       }
+
+       /**
+        * Save the cache to a local file.
+        */
+       function saveToLocal( $serialized, $hash, $code ) {
+               global $wgCacheDirectory;
+
+               $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
+               wfMkdirParents( $wgCacheDirectory ); // 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 );
+               @chmod( $filename, 0666 );
+       }
+
+       function saveToScript( $array, $hash, $code ) {
+               global $wgCacheDirectory;
+
+               $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
+               $tempFilename = $filename . '.tmp';
+               wfMkdirParents( $wgCacheDirectory ); // 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;
        }
 
        /**
-        * 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
+        * Set the cache to $cache, if it is valid. Otherwise set the cache to false.
         */
-       function load() {
-               global $wgAllMessagesEn;
+       function setCache( $cache, $code ) {
+               if ( isset( $cache['VERSION'] ) && $cache['VERSION'] == MSG_CACHE_VERSION ) {
+                       $this->mCache[$code] = $cache;
+                       return true;
+               } else {
+                       return false;
+               }
+       }
 
+       /**
+        * 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 succesfully 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 succesfully populated,
+        * or false if populating empty cache fails. Also returns true if MessageCache
+        * is disabled.
+        *
+        * @param $code String: language to which load messages
+        */
+       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( "MessageCache::load(): disabled\n" );
+                               wfDebug( __METHOD__ . ": disabled\n" );
                                $shownDisabled = true;
                        }
                        return true;
                }
-               $fname = 'MessageCache::load';
-               wfProfileIn( $fname );
-               $success = true;
-
-               if ( $this->mUseCache ) {
-                       wfProfileIn( $fname.'-fromcache' );
-                       $this->mCache = $this->mMemc->get( $this->mMemcKey );
-                       wfProfileOut( $fname.'-fromcache' );
-
-                       # If there's nothing in memcached, load all the messages from the database
-                       if ( !$this->mCache ) {
-                               wfDebug( "MessageCache::load(): loading all messages\n" );
-                               $this->lock();
-                               # Other threads don't need to load the messages if another thread is doing it.
-                               $success = $this->mMemc->add( $this->mMemcKey.'-status', "loading", MSG_LOAD_TIMEOUT );
-                               if ( $success ) {
-                                       wfProfileIn( $fname.'-load' );
-                                       $this->loadFromDB();
-                                       wfProfileOut( $fname.'-load' );
-                                       # Save in memcached
-                                       # Keep trying if it fails, this is kind of important
-                                       wfProfileIn( $fname.'-save' );
-                                       for ($i=0; $i<20 &&
-                                                  !$this->mMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry );
-                                            $i++ ) {
-                                               usleep(mt_rand(500000,1500000));
-                                       }
-                                       wfProfileOut( $fname.'-save' );
-                                       if ( $i == 20 ) {
-                                               $this->mMemc->set( $this->mMemcKey.'-status', 'error', 60*5 );
-                                               wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
-                                       }
-                               }
-                               $this->unlock();
+
+               # 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' );
+               }
+
 
-                       if ( !is_array( $this->mCache ) ) {
-                               wfDebug( "MessageCache::load(): individual message mode\n" );
-                               # If it is 'loading' or 'error', switch to individual message mode, otherwise disable
-                               # Causing too much DB load, disabling -- TS
-                               $this->mDisable = true;
-                               /*
-                               if ( $this->mCache == "loading" ) {
-                                       $this->mUseCache = false;
-                               } elseif ( $this->mCache == "error" ) {
-                                       $this->mUseCache = false;
-                                       $success = false;
+               # (3)
+               # Nothing in caches... so we need create one and store it in caches
+               if ( !$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->mDisable = true;
-                                       $success = false;
-                               }*/
-                               $this->mCache = false;
+                                       $this->mMemc->set( $statusKey, 'error', 60*5 );
+                                       wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
+                               }
                        }
+                       $this->unlock($cacheKey);
                }
-               wfProfileOut( $fname );
-               $this->mDeferred = false;
+
+               if ( !$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;
        }
 
        /**
-        * Loads all or main part of cacheable messages from the database
+        * 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 $code Optional language code, see documenation of load().
+        * @return Array: Loaded messages for storing in caches.
         */
-       function loadFromDB() {
-               $fname = 'MessageCache::loadFromDB';
-               $dbr =& wfGetDB( DB_SLAVE );
-               $conditions = array( 'page_is_redirect' => 0,
-                                       'page_namespace' => NS_MEDIAWIKI);
+       function loadFromDB( $code = false ) {
+               wfProfileIn( __METHOD__ );
+               global $wgMaxMsgCacheEntrySize, $wgContLanguageCode;
+               $dbr = wfGetDB( DB_SLAVE );
+               $cache = array();
+
+               # Common conditions
+               $conds = array(
+                       'page_is_redirect' => 0,
+                       'page_namespace' => NS_MEDIAWIKI,
+               );
+
+               if ( $code ) {
+                       # Is this fast enough. Should not matter if the filtering is done in the
+                       # database or in code.
+                       if ( $code !== $wgContLanguageCode ) {
+                               # Messages for particular language
+                               $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' ),
-                       'page_is_redirect=0 AND page_namespace='.NS_MEDIAWIKI.' AND page_latest=rev_id AND rev_text_id=old_id',
-                       $fname
-               );
+                       $smallConds, __METHOD__ . "($code)-small" );
 
-               $this->mCache = array();
-               for ( $row = $dbr->fetchObject( $res ); $row; $row = $dbr->fetchObject( $res ) ) {
-                       $this->mCache[$row->page_title] = Revision::getRevisionText( $row );
+               foreach ( $res as $row ) {
+                       $cache[$row->page_title] = ' ' . Revision::getRevisionText( $row );
                }
 
-               $dbr->freeResult( $res );
-               /*
-               # FIXME: This is too slow currently.
-               # We need to bulk-fetch revisions, but in a portable way...
-               $resultSet = Revision::fetchFromConds( $dbr, array(
-                       'page_namespace'   => NS_MEDIAWIKI,
-                       'page_is_redirect' => 0,
-                       'page_id=rev_page' ) );
-               while( $row = $resultSet->fetchObject() ) {
-                       $revision = new Revision( $row );
-                       $title = $revision->getTitle();
-                       $this->mCache[$title->getDBkey()] = $revision->getText();
-               }
-               $resultSet->free();
-               */
+               $cache['VERSION'] = MSG_CACHE_VERSION;
+               wfProfileOut( __METHOD__ );
+               return $cache;
        }
 
        /**
-        * Not really needed anymore
+        * Updates cache as necessary when message page is changed
+        *
+        * @param $title String: name of the page changed.
+        * @param $text Mixed: new contents of the page.
         */
-       function getKeys() {
-               global $wgAllMessagesEn, $wgContLang;
-               if ( !$this->mKeys ) {
-                       $this->mKeys = array();
-                       foreach ( $wgAllMessagesEn as $key => $value ) {
-                               $title = $wgContLang->ucfirst( $key );
-                               array_push( $this->mKeys, $title );
+       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);
+
+               if ( is_array($this->mCache[$code]) ) {
+                       $titleKey = wfMemcKey( 'messages', 'individual', $title );
+
+                       if ( $text === false ) {
+                               # Article was deleted
+                               unset( $this->mCache[$code][$title] );
+                               $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
+               global $parserMemc;
+               $codes = array( $code );
+               if ( $code === 'en'  ) {
+                       // Delete all sidebars, like for example on action=purge on the
+                       // sidebar messages
+                       $codes = array_keys( Language::getLanguageNames() );
                }
-               return $this->mKeys;
+
+               foreach ( $codes as $code ) {
+                       $sidebarKey = wfMemcKey( 'sidebar', $code );
+                       $parserMemc->delete( $sidebarKey );
+               }
+               
+               // Update the message in the message blob store
+               global $wgContLang;
+               MessageBlobStore::updateMessage( $wgContLang->lcfirst( $msg ) );
+
+               wfRunHooks( "MessageCacheReplace", array( $title, $text ) );
+
+               wfProfileOut( __METHOD__ );
        }
 
        /**
-        * @deprecated
+        * Shortcut to update caches.
+        *
+        * @param $cache Array: cached messages with a version.
+        * @param $memc Bool: Wether to update or not memcache.
+        * @param $code String: Language code.
+        * @return False on somekind of error.
         */
-       function isCacheable( $key ) {
-               return true;
-       }
+       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;
+               }
 
-       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 );
+               # 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 );
+                       }
                }
-               $this->unlock();
+
+               wfProfileOut( __METHOD__ );
+               return $success;
        }
 
        /**
-        * Returns success
         * Represents a write lock on the messages key
+        *
+        * @return Boolean: success
         */
-       function lock() {
-               if ( !$this->mUseCache ) {
-                       return true;
-               }
-
-               $lockKey = $this->mMemcKey . 'lock';
+       function lock($key) {
+               $lockKey = $key . ':lock';
                for ($i=0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
                        sleep(1);
                }
@@ -218,157 +483,310 @@ class MessageCache
                return $i >= MSG_WAIT_TIMEOUT;
        }
 
-       function unlock() {
-               if ( !$this->mUseCache ) {
-                       return;
-               }
-
-               $lockKey = $this->mMemcKey . 'lock';
+       function unlock($key) {
+               $lockKey = $key . ':lock';
                $this->mMemc->delete( $lockKey );
        }
 
-       function get( $key, $useDB, $forcontent=true, $isfullkey = false ) {
-               global $wgContLanguageCode;
-               if( $forcontent ) {
-                       global $wgContLang;
-                       $lang =& $wgContLang;
-                       $langcode = $wgContLanguageCode;
-               } else {
-                       global $wgLang, $wgLanguageCode;
-                       $lang =& $wgLang;
-                       $langcode = $wgLanguageCode;
+       /**
+        * Get a message from either the content language or the user language.
+        *
+        * @param $key String: the message cache key
+        * @param $useDB Boolean: get the message from the DB, false to use only
+        *               the localisation
+        * @param $langcode String: code of the language to get the message for, if
+        *                  it is a valid code create a language for that language,
+        *                  if it is a string but not a valid code then make a basic
+        *                  language object, if it is a false boolean then use the
+        *                  current users language (as a fallback for the old
+        *                  parameter functionality), or if it is a true boolean
+        *                  then use the wikis content language (also as a
+        *                  fallback).
+        * @param $isFullKey Boolean: specifies whether $key is a two part key
+        *                   "msg/lang".
+        */
+       function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
+               global $wgLanguageCode, $wgContLang;
+
+               if ( !is_string( $key ) ) {
+                       throw new MWException( "Non-string key given" );
                }
-               # If uninitialised, someone is trying to call this halfway through Setup.php
-               if( !$this->mInitialised ) {
-                       return '&lt;' . htmlspecialchars($key) . '&gt;';
+
+               if ( strval( $key ) === '' ) {
+                       # Shortcut: the empty key is always missing
+                       return false;
                }
-               # If cache initialization was deferred, start it now.
-               if( $this->mDeferred ) {
-                       $this->load();
+
+               $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( $lckey );
+               }
+
+               # Try the MediaWiki namespace
                if( !$this->mDisable && $useDB ) {
-                       $title = $lang->ucfirst( $key );
-                       if(!$isfullkey && ($langcode != $wgContLanguageCode) ) {
+                       $title = $uckey;
+                       if(!$isFullKey && ( $langcode != $wgLanguageCode ) ) {
                                $title .= '/' . $langcode;
                        }
-                       $message = $this->getFromCache( $title );
-               }
-               # Try the extension array
-               if( !$message ) {
-                       $message = @$this->mExtensionMessages[$key];
+                       $message = $this->getMsgFromNamespace( $title, $langcode );
                }
 
                # Try the array in the language object
-               if( !$message ) {
-                       wfSuppressWarnings();
-                       $message = $lang->getMessage( $key );
-                       wfRestoreWarnings();
+               if ( $message === false ) {
+                       $message = $lang->getMessage( $lckey );
+                       if ( is_null( $message ) ) {
+                               $message = false;
+                       }
                }
 
-               # Try the English array
-               if( !$message && $langcode != 'en' ) {
-                       wfSuppressWarnings();
-                       $message = Language::getMessage( $key );
-                       wfRestoreWarnings();
+               # 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( !$message &&
+               if( ($message === false || $message === '-' ) &&
                        !$this->mDisable && $useDB &&
-                       !$isfullkey && ($langcode != $wgContLanguageCode) ) {
-                       $message = $this->getFromCache( $lang->ucfirst( $key ) );
+                       !$isFullKey && ($langcode != $wgLanguageCode) ) {
+                       $message = $this->getMsgFromNamespace( $uckey, $wgLanguageCode );
                }
 
                # Final fallback
-               if( !$message ) {
-                       return '&lt;' . htmlspecialchars($key) . '&gt;';
+               if( $message === false ) {
+                       return false;
                }
 
-               # Replace brace tags
-               $message = $this->transform( $message );
+               # 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 getFromCache( $title ) {
+       /**
+        * Get a message from the MediaWiki namespace, with caching. The key must
+        * first be converted to two-part lang/msg form if necessary.
+        *
+        * @param $title String: Message cache key with initial uppercase letter.
+        * @param $code String: code denoting the language to try.
+        */
+       function getMsgFromNamespace( $title, $code ) {
+               $type = false;
                $message = false;
 
-               # Try the cache
-               if( $this->mUseCache && is_array( $this->mCache ) && array_key_exists( $title, $this->mCache ) ) {
-                       $message = $this->mCache[$title];
+               $this->load( $code );
+               if ( isset( $this->mCache[$code][$title] ) ) {
+                       $entry = $this->mCache[$code][$title];
+                       $type = substr( $entry, 0, 1 );
+                       if ( $type == ' ' ) {
+                               return substr( $entry, 1 );
+                       }
                }
 
-               if ( !$message && $this->mUseCache ) {
-                       $message = $this->mMemc->get( $this->mMemcKey . ':' . $title );
-                       if( $message ) {
-                               $this->mCache[$title] = $message;
-                       }
+               # Call message hooks, in case they are defined
+               wfRunHooks('MessagesPreLoad', array( $title, &$message ) );
+               if ( $message !== false ) {
+                       return $message;
                }
 
-               # Call message Hooks, in case they are defined
-               wfRunHooks('MessagesPreLoad',array($title,&$message));
-
-               # If it wasn't in the cache, load each message from the DB individually
-               if ( !$message ) {
-                       $revision = Revision::newFromTitle( Title::makeTitle( NS_MEDIAWIKI, $title ) );
-                       if( $revision ) {
-                               $message = $revision->getText();
-                               if ($this->mUseCache) {
-                                       $this->mCache[$title]=$message;
-                                       /* individual messages may be often
-                                          recached until proper purge code exists
-                                       */
-                                       $this->mMemc->set( $this->mMemcKey . ':' . $title, $message, 300 );
-                               }
+               $titleKey = wfMemcKey( 'messages', 'individual', $title );
+
+               # Try the individual message cache
+               $entry = $this->mMemc->get( $titleKey );
+               if ( $entry ) {
+                       $type = substr( $entry, 0, 1 );
+
+                       if ( $type === ' ' ) {
+                               # Ok!
+                               $message = substr( $entry, 1 );
+                               $this->mCache[$code][$title] = $entry;
+                               return $message;
+                       } elseif ( $entry === '!NONEXISTENT' ) {
+                               return false;
+                       } else {
+                               # Corrupt/obsolete entry, delete it
+                               $this->mMemc->delete( $titleKey );
                        }
                }
 
+               # Try loading it from the DB
+               $revision = Revision::newFromTitle( Title::makeTitle( NS_MEDIAWIKI, $title ) );
+               if( $revision ) {
+                       $message = $revision->getText();
+                       $this->mCache[$code][$title] = ' ' . $message;
+                       $this->mMemc->set( $titleKey, ' ' . $message, $this->mExpiry );
+               } else {
+                       # Negative caching
+                       # Use some special text instead of false, because false gets converted to '' somewhere
+                       $this->mMemc->set( $titleKey, '!NONEXISTENT', $this->mExpiry );
+                       $this->mCache[$code][$title] = false;
+               }
                return $message;
        }
 
-       function transform( $message ) {
-               if( !$this->mDisableTransform ) {
-                       if( strpos( $message, '{{' ) !== false ) {
-                               $message = $this->mParser->transformMsg( $message, $this->mParserOptions );
+       function transform( $message, $interface = false, $language = null ) {
+               // Avoid creating parser if nothing to transform
+               if( strpos( $message, '{{' ) === false ) {
+                       return $message;
+               }
+
+               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;
                        }
+                       #wfDebug( __METHOD__ . ": following contents triggered transform: $message\n" );
+               }
+               if ( $this->mParser ) {
+                       $popts = $this->getParserOptions();
+                       $popts->setInterfaceMessage( $interface );
+                       $popts->setTargetLanguage( $language );
+                       $userlang = $popts->setUserLang( $language );
+                       $message = $this->mParser->transformMsg( $message, $popts );
+                       $popts->setUserLang( $userlang );
                }
                return $message;
        }
 
        function disable() { $this->mDisable = true; }
        function enable() { $this->mDisable = false; }
-       function disableTransform() { $this->mDisableTransform = true; }
-       function enableTransform() { $this->mDisableTransform = false; }
+
+       /** @deprecated */
+       function disableTransform(){
+               wfDeprecated( __METHOD__ );
+       }
+       function enableTransform() {
+               wfDeprecated( __METHOD__ );
+       }
+       function setTransform( $x ) {
+               wfDeprecated( __METHOD__ );
+       }
+       function getTransform() {
+               wfDeprecated( __METHOD__ );
+               return false;
+       }
 
        /**
+        * Clear all stored messages. Mainly used after a mass rebuild.
+        */
+       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();
+       }
+
+       /**
         * Add a message to the cache
+        * @deprecated Use $wgExtensionMessagesFiles
         *
-        * @param mixed $key
-        * @param mixed $value
+        * @param $key Mixed
+        * @param $value Mixed
+        * @param $lang String: the messages language, English by default
         */
-       function addMessage( $key, $value ) {
-               $this->mExtensionMessages[$key] = $value;
+       function addMessage( $key, $value, $lang = 'en' ) {
+               wfDeprecated( __METHOD__ );
+               $lc = Language::getLocalisationCache();
+               $lc->addLegacyMessages( array( $lang => array( $key => $value ) ) );
        }
 
        /**
         * Add an associative array of message to the cache
+        * @deprecated Use $wgExtensionMessagesFiles
         *
-        * @param array $messages An associative array of key => values to be added
+        * @param $messages Array: an associative array of key => values to be added
+        * @param $lang String: the messages language, English by default
         */
-       function addMessages( $messages ) {
-               foreach ( $messages as $key => $value ) {
-                       $this->addMessage( $key, $value );
-               }
+       function addMessages( $messages, $lang = 'en' ) {
+               wfDeprecated( __METHOD__ );
+               $lc = Language::getLocalisationCache();
+               $lc->addLegacyMessages( array( $lang => $messages ) );
        }
 
        /**
-        * Clear all stored messages. Mainly used after a mass rebuild.
+        * Add a 2-D array of messages by lang. Useful for extensions.
+        * @deprecated Use $wgExtensionMessagesFiles
+        *
+        * @param $messages Array: the array to be added
         */
-       function clear() {
-               if( $this->mUseCache ) {
-                       $this->mMemc->delete( $this->mMemcKey );
-               }
+       function addMessagesByLang( $messages ) {
+               wfDeprecated( __METHOD__ );
+               $lc = Language::getLocalisationCache();
+               $lc->addLegacyMessages( $messages );
        }
+
+       /**
+        * Set a hook for addMessagesByLang()
+        */
+       function setExtensionMessagesHook( $callback ) {
+               $this->mAddMessagesHook = $callback;
+       }
+
+       /**
+        * @deprecated
+        */
+       function loadAllMessages( $lang = false ) {
+       }
+
+       /**
+        * @deprecated
+        */
+       function loadMessagesFile( $filename, $langcode = false ) {
+       }
+
+       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 );
+       }
+
 }
-?>