def METHOD_NAME(future):
    """
    Canceller of _DoAcquisition task.
    """
    logging.debug("Cancelling acquisition...")
    with _acq_lock:
        if future._acq_state == FINISHED:
            logging.debug("Acquisition already finished.")
            return False
        future._acq_state = CANCELLED
        _sem_done.set()
        logging.debug("Acquisition cancelled.")
    return True