def __init__(self,
client,
subscription,
flow_control=types.FlowControl(),
executor=None,
queue=None):
"""Instantiate the policy.
Args:
client (~.pubsub_v1.subscriber.client): The subscriber client used
to create this instance.
subscription (str): The name of the subscription. The canonical
format for this is
``projects/{project}/subscriptions/{subscription}``.
flow_control (~google.cloud.pubsub_v1.types.FlowControl): The flow
control settings.
executor (~concurrent.futures.ThreadPoolExecutor): (Optional.) A
ThreadPoolExecutor instance, or anything duck-type compatible
with it.
queue (~queue.Queue): (Optional.) A Queue instance, appropriate
for crossing the concurrency boundary implemented by
``executor``.
"""
# Default the callback to a no-op; it is provided by `.open`.
self._callback = _do_nothing_callback
# Default the future to None; it is provided by `.open`.
self._future = None
# Create a queue for keeping track of shared state.
if queue is None:
queue = queue_mod.Queue()
self._request_queue = queue
# Call the superclass constructor.
super(Policy, self).__init__(
client=client,
flow_control=flow_control,
subscription=subscription,
)
# Also maintain a request queue and an executor.
if executor is None:
executor_kwargs = {}
if sys.version_info >= (3, 6):
executor_kwargs['thread_name_prefix'] = (
'ThreadPoolExecutor-SubscriberPolicy')
executor = futures.ThreadPoolExecutor(max_workers=10,
**executor_kwargs)
self._executor = executor
_LOGGER.debug('Creating callback requests thread (not starting).')
self._callback_requests = _helper_threads.QueueCallbackThread(
self._request_queue,
self.on_callback_request,
)
def test_queue_callback_thread():
queue_ = queue.Queue()
callback = mock.Mock(spec=())
qct = _helper_threads.QueueCallbackThread(queue_, callback)
# Set up an appropriate mock for the queue, and call the queue callback
# thread.
with mock.patch.object(queue.Queue, 'get') as get:
get.side_effect = (mock.sentinel.A, _helper_threads.STOP)
qct()
# Assert that we got the expected calls.
assert get.call_count == 2
callback.assert_called_once_with(mock.sentinel.A)