public function clean($mode = \Zend_Cache::CLEANING_MODE_ALL, $tags = array()) 
    {
    	if ($mode == \Zend_Cache::CLEANING_MODE_MATCHING_TAG) {
            if ($tags) {
                if (!method_exists($this->_handle, 'tag_delete')) {
                    \Zend_Cache::throwException('Method tag_delete() is not supported by the PHP memcached extension!');
                }
                foreach ($tags as $tag) {
                    $this->_handle->tag_delete($tag);
                }
            }
        } else {
            return parent::clean($mode, $tags); 
        }
    }