public function getRemainingLifetime( $id, $attributes = array() )
    {
        foreach ( $this->storageStack as $storageConf )
        {
            $lifetime = $storageConf->storage->getRemainingLifetime(
                $id,
                $attributes
            );
            if ( $lifetime > 0 )
            {
                return $lifetime;
            }
        }
        return 0;
    }