/**
* the singleton pattern
*
* @return Felamimail_Backend_Cache_Imap_Folder or Felamimail_Backend_Cache_Sql_Folder
*/
public static function getInstance()
{
if (self::$_instance === NULL) {
$adapter = Tinebase_Core::getConfig()->messagecache;
$adapter = empty($adapter) ? 'sql' : $adapter;
$classname = 'Felamimail_Backend_Cache_' . ucfirst($adapter) . '_Folder';
self::$_instance = new $classname();
}
return self::$_instance;
}
