__init__.py 文件源码

def add_done_callback(self, fn):  # pylint: disable=invalid-name
        """Enters a polling loop on OperationsClient.get_operation, and once the
        operation is done or cancelled, calls the function with this
        _OperationFuture. Added callables are called in the order that they were
        added.
        """
        if self._operation.done:
            _try_callback(self, fn)
        else:
            self._queue.put(dill.dumps(fn))
            if self._process is None:
                self._process = mp.Process(target=self._execute_tasks)
                self._process.start()