diff --git a/oslo/messaging/_drivers/base.py b/oslo/messaging/_drivers/base.py
index dcf08287e..82b36412e 100644
--- a/oslo/messaging/_drivers/base.py
+++ b/oslo/messaging/_drivers/base.py
@@ -67,6 +67,11 @@ class BaseDriver(object):
self._default_exchange = default_exchange
self._allowed_remote_exmods = allowed_remote_exmods
+ def require_features(self, requeue=False):
+ if requeue:
+ raise NotImplementedError('Message requeueing not supported by '
+ 'this transport driver')
+
@abc.abstractmethod
def send(self, target, ctxt, message,
wait_for_reply=None, timeout=None, envelope=False):
diff --git a/oslo/messaging/_drivers/impl_fake.py b/oslo/messaging/_drivers/impl_fake.py
index 2bfbe16b3..564dc21ce 100644
--- a/oslo/messaging/_drivers/impl_fake.py
+++ b/oslo/messaging/_drivers/impl_fake.py
@@ -112,6 +112,9 @@ class FakeDriver(base.BaseDriver):
self._exchanges_lock = threading.Lock()
self._exchanges = {}
+ def require_features(self, requeue=True):
+ pass
+
@staticmethod
def _check_serialize(message):
"""Make sure a message intended for rpc can be serialized.
diff --git a/oslo/messaging/_drivers/impl_qpid.py b/oslo/messaging/_drivers/impl_qpid.py
index c53ad8946..f9b275f70 100644
--- a/oslo/messaging/_drivers/impl_qpid.py
+++ b/oslo/messaging/_drivers/impl_qpid.py
@@ -100,8 +100,7 @@ class QpidMessage(dict):
self._session.acknowledge(self._raw_message)
def requeue(self):
- raise NotImplementedError('The QPID driver does not yet support '
- 'requeuing messages')
+ pass
class ConsumerBase(object):
diff --git a/oslo/messaging/_drivers/impl_rabbit.py b/oslo/messaging/_drivers/impl_rabbit.py
index be41a4ec1..4df6964b5 100644
--- a/oslo/messaging/_drivers/impl_rabbit.py
+++ b/oslo/messaging/_drivers/impl_rabbit.py
@@ -744,3 +744,6 @@ class RabbitDriver(amqpdriver.AMQPDriverBase):
connection_pool,
default_exchange,
allowed_remote_exmods)
+
+ def require_features(self, requeue=True):
+ pass
diff --git a/oslo/messaging/_drivers/impl_zmq.py b/oslo/messaging/_drivers/impl_zmq.py
index 6b2b53957..af5b612b2 100644
--- a/oslo/messaging/_drivers/impl_zmq.py
+++ b/oslo/messaging/_drivers/impl_zmq.py
@@ -844,8 +844,7 @@ class ZmqIncomingMessage(base.IncomingMessage):
self.condition.notify()
def requeue(self):
- raise NotImplementedError('The ZeroMQ driver does not yet support '
- 'requeuing messages')
+ pass
class ZmqListener(base.Listener):
diff --git a/oslo/messaging/notify/dispatcher.py b/oslo/messaging/notify/dispatcher.py
index 87deee854..ca8a2f01e 100644
--- a/oslo/messaging/notify/dispatcher.py
+++ b/oslo/messaging/notify/dispatcher.py
@@ -44,10 +44,11 @@ class NotificationDispatcher(object):
message to the endpoints
"""
- def __init__(self, targets, endpoints, serializer):
+ def __init__(self, targets, endpoints, serializer, allow_requeue):
self.targets = targets
self.endpoints = endpoints
self.serializer = serializer or msg_serializer.NoOpSerializer()
+ self.allow_requeue = allow_requeue
self._callbacks_by_priority = {}
for endpoint, prio in itertools.product(endpoints, PRIORITIES):
@@ -114,7 +115,7 @@ class NotificationDispatcher(object):
try:
ret = callback(ctxt, publisher_id, event_type, payload)
ret = NotificationResult.HANDLED if ret is None else ret
- if ret != NotificationResult.HANDLED:
+ if self.allow_requeue and ret == NotificationResult.REQUEUE:
return ret
finally:
localcontext.clear_local_context()
diff --git a/oslo/messaging/notify/listener.py b/oslo/messaging/notify/listener.py
index 06a2e24ce..c6c17df8b 100644
--- a/oslo/messaging/notify/listener.py
+++ b/oslo/messaging/notify/listener.py
@@ -73,26 +73,20 @@ priority
Parameters to endpoint methods are the request context supplied by the client,
the publisher_id of the notification message, the event_type, the payload.
-An endpoint method can return explicitly messaging.NotificationResult.HANDLED
+By supplying a serializer object, a listener can deserialize a request context
+and arguments from - and serialize return values to - primitive types.
+
+An endpoint method can explicitly return messaging.NotificationResult.HANDLED
to acknowledge a message or messaging.NotificationResult.REQUEUE to requeue the
message.
-The message is acknowledge only if all endpoints return
-messaging.NotificationResult.HANDLED
+The message is acknowledged only if all endpoints either return
+messaging.NotificationResult.HANDLED or None.
-If nothing is returned by an endpoint, this is considered like
-messaging.NotificationResult.HANDLED
-
-messaging.NotificationResult values needs to be handled by drivers:
-
-* HANDLED: supported by all drivers
-* REQUEUE: supported by drivers: fake://, rabbit://
-
-In case of an unsupported driver nothing is done to the message and a
-NotImplementedError is raised and logged.
-
-By supplying a serializer object, a listener can deserialize a request context
-and arguments from - and serialize return values to - primitive types.
+Note that not all transport drivers implement support for requeueing. In order
+to use this feature, applications should assert that the feature is available
+by passing allow_requeue=True to get_notification_listener(). If the driver
+does not support requeueing, it will raise NotImplementedError at this point.
"""
from oslo.messaging.notify import dispatcher as notify_dispatcher
@@ -100,7 +94,8 @@ from oslo.messaging import server as msg_server
def get_notification_listener(transport, targets, endpoints,
- executor='blocking', serializer=None):
+ executor='blocking', serializer=None,
+ allow_requeue=False):
"""Construct a notification listener
The executor parameter controls how incoming messages will be received and
@@ -117,7 +112,12 @@ def get_notification_listener(transport, targets, endpoints,
:type executor: str
:param serializer: an optional entity serializer
:type serializer: Serializer
+ :param allow_requeue: whether NotificationResult.REQUEUE support is needed
+ :type allow_requeue: bool
+ :raises: NotImplementedError
"""
+ transport._require_driver_features(requeue=allow_requeue)
dispatcher = notify_dispatcher.NotificationDispatcher(targets, endpoints,
- serializer)
+ serializer,
+ allow_requeue)
return msg_server.MessageHandlingServer(transport, dispatcher, executor)
diff --git a/oslo/messaging/transport.py b/oslo/messaging/transport.py
index 7c8a3be97..16e6f49bd 100644
--- a/oslo/messaging/transport.py
+++ b/oslo/messaging/transport.py
@@ -78,6 +78,9 @@ class Transport(object):
self.conf = driver.conf
self._driver = driver
+ def _require_driver_features(self, requeue=False):
+ self._driver.require_features(requeue=requeue)
+
def _send(self, target, ctxt, message, wait_for_reply=None, timeout=None):
if not target.topic:
raise exceptions.InvalidTarget('A topic is required to send',
diff --git a/tests/test_notify_dispatcher.py b/tests/test_notify_dispatcher.py
index 3e2c966a1..7b3531374 100644
--- a/tests/test_notify_dispatcher.py
+++ b/tests/test_notify_dispatcher.py
@@ -97,9 +97,8 @@ class TestDispatcher(test_utils.BaseTestCase):
msg['priority'] = self.priority
targets = [messaging.Target(topic='notifications')]
- dispatcher = notify_dispatcher.NotificationDispatcher(targets,
- endpoints,
- None)
+ dispatcher = notify_dispatcher.NotificationDispatcher(
+ targets, endpoints, None, allow_requeue=True)
# check it listen on wanted topics
self.assertEqual(sorted(dispatcher._targets_priorities),
@@ -138,9 +137,8 @@ class TestDispatcher(test_utils.BaseTestCase):
def test_dispatcher_unknown_prio(self, mylog):
msg = notification_msg.copy()
msg['priority'] = 'what???'
- dispatcher = notify_dispatcher.NotificationDispatcher([mock.Mock()],
- [mock.Mock()],
- None)
+ dispatcher = notify_dispatcher.NotificationDispatcher(
+ [mock.Mock()], [mock.Mock()], None, allow_requeue=True)
with dispatcher(mock.Mock(ctxt={}, message=msg)) as callback:
callback()
mylog.warning.assert_called_once_with('Unknown priority "what???"')
diff --git a/tests/test_notify_listener.py b/tests/test_notify_listener.py
index 3b35a3bb1..0cf5f5405 100644
--- a/tests/test_notify_listener.py
+++ b/tests/test_notify_listener.py
@@ -35,7 +35,7 @@ class ListenerSetupMixin(object):
self._expect_messages = expect_messages
self._received_msgs = 0
self._listener = messaging.get_notification_listener(
- transport, targets, endpoints + [self])
+ transport, targets, endpoints + [self], allow_requeue=True)
def info(self, ctxt, publisher_id, event_type, payload):
self._received_msgs += 1