def _init_futures(self):
"""Build futures for results and output; hook up callbacks"""
if not self._children:
for msg_id in self.msg_ids:
future = self._client._futures.get(msg_id, None)
if not future:
result = self._client.results.get(msg_id, _default)
# result resides in local cache, construct already-resolved Future
if result is not _default:
future = Future()
future.msg_id = msg_id
future.output = Future()
future.output.metadata = self.client.metadata[msg_id]
future.set_result(result)
future.output.set_result(None)
if not future:
raise KeyError("No Future or result for msg_id: %s" % msg_id)
self._children.append(future)
self._result_future = multi_future(self._children)
self._output_future = multi_future([self._result_future] + [
f.output for f in self._children
])
# on completion of my constituents, trigger my own resolution
self._result_future.add_done_callback(self._resolve_result)
self._output_future.add_done_callback(self._resolve_output)
