def METHOD_NAME(self, file_delta, byte_delta):
    """
    Update transfer info.
    :param file_delta: number of files transferred
    :type file_delta: int
    :param byte_delta: number of bytes transferred
    :type byte_delta: int
    """
    with self.lock:
        self.transfer_files += file_delta
        self.transfer_bytes += byte_delta
        self._update_progress()