Allow for the notifier to provide a 'details_filter'
When a notifier is being used for retry atoms and for task atoms it is useful to allow a filter callback to be provided that will skip notification depending on whether the details matches or not (so that task or retry notifications can proceed). Part of fix for bug 1395966 Change-Id: If03005c253c3f540d2c33faf7a7474a5fde9dcdd
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a57c811922
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taskflow
@ -91,11 +91,16 @@ class NotifierTest(test.TestCase):
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call_counts[registered_state].append((state, details))
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notifier = nt.Notifier()
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notifier.register(states.SUCCESS,
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functools.partial(call_me_on, states.SUCCESS))
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notifier.register(nt.Notifier.ANY,
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functools.partial(call_me_on,
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nt.Notifier.ANY))
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call_me_on_success = functools.partial(call_me_on, states.SUCCESS)
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notifier.register(states.SUCCESS, call_me_on_success)
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self.assertTrue(notifier.is_registered(states.SUCCESS,
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call_me_on_success))
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call_me_on_any = functools.partial(call_me_on, nt.Notifier.ANY)
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notifier.register(nt.Notifier.ANY, call_me_on_any)
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self.assertTrue(notifier.is_registered(nt.Notifier.ANY,
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call_me_on_any))
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self.assertEqual(2, len(notifier))
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notifier.notify(states.SUCCESS, {})
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@ -107,3 +112,62 @@ class NotifierTest(test.TestCase):
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self.assertEqual(2, len(call_counts[nt.Notifier.ANY]))
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self.assertEqual(1, len(call_counts[states.SUCCESS]))
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self.assertEqual(2, len(call_counts))
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def test_details_filter(self):
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call_counts = collections.defaultdict(list)
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def call_me_on(registered_state, state, details):
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call_counts[registered_state].append((state, details))
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def when_red(details):
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return details.get('color') == 'red'
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notifier = nt.Notifier()
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call_me_on_success = functools.partial(call_me_on, states.SUCCESS)
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notifier.register(states.SUCCESS, call_me_on_success,
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details_filter=when_red)
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self.assertEqual(1, len(notifier))
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self.assertTrue(notifier.is_registered(
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states.SUCCESS, call_me_on_success, details_filter=when_red))
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notifier.notify(states.SUCCESS, {})
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self.assertEqual(0, len(call_counts[states.SUCCESS]))
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notifier.notify(states.SUCCESS, {'color': 'red'})
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self.assertEqual(1, len(call_counts[states.SUCCESS]))
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notifier.notify(states.SUCCESS, {'color': 'green'})
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self.assertEqual(1, len(call_counts[states.SUCCESS]))
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def test_different_details_filter(self):
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call_counts = collections.defaultdict(list)
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def call_me_on(registered_state, state, details):
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call_counts[registered_state].append((state, details))
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def when_red(details):
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return details.get('color') == 'red'
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def when_blue(details):
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return details.get('color') == 'blue'
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notifier = nt.Notifier()
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call_me_on_success = functools.partial(call_me_on, states.SUCCESS)
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notifier.register(states.SUCCESS, call_me_on_success,
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details_filter=when_red)
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notifier.register(states.SUCCESS, call_me_on_success,
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details_filter=when_blue)
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self.assertEqual(2, len(notifier))
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self.assertTrue(notifier.is_registered(
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states.SUCCESS, call_me_on_success, details_filter=when_blue))
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self.assertTrue(notifier.is_registered(
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states.SUCCESS, call_me_on_success, details_filter=when_red))
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notifier.notify(states.SUCCESS, {})
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self.assertEqual(0, len(call_counts[states.SUCCESS]))
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notifier.notify(states.SUCCESS, {'color': 'red'})
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self.assertEqual(1, len(call_counts[states.SUCCESS]))
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notifier.notify(states.SUCCESS, {'color': 'blue'})
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self.assertEqual(2, len(call_counts[states.SUCCESS]))
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notifier.notify(states.SUCCESS, {'color': 'green'})
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self.assertEqual(2, len(call_counts[states.SUCCESS]))
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@ -15,7 +15,6 @@
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# under the License.
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import collections
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import copy
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import logging
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import six
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@ -25,6 +24,56 @@ from taskflow.utils import reflection
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LOG = logging.getLogger(__name__)
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class _Listener(object):
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"""Internal helper that represents a notification listener/target."""
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def __init__(self, callback, args=None, kwargs=None, details_filter=None):
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self._callback = callback
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self._details_filter = details_filter
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if not args:
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self._args = ()
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else:
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self._args = args[:]
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if not kwargs:
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self._kwargs = {}
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else:
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self._kwargs = kwargs.copy()
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def __call__(self, event_type, details):
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if self._details_filter is not None:
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if not self._details_filter(details):
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return
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kwargs = self._kwargs.copy()
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kwargs['details'] = details
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self._callback(event_type, *self._args, **kwargs)
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def __repr__(self):
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repr_msg = "%s object at 0x%x calling into '%r'" % (
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reflection.get_class_name(self), id(self), self._callback)
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if self._details_filter is not None:
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repr_msg += " using details filter '%r'" % self._details_filter
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return "<%s>" % repr_msg
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def is_equivalent(self, callback, details_filter=None):
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if not reflection.is_same_callback(self._callback, callback):
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return False
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if details_filter is not None:
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if self._details_filter is None:
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return False
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else:
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return reflection.is_same_callback(self._details_filter,
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details_filter)
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else:
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return self._details_filter is None
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def __eq__(self, other):
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if isinstance(other, _Listener):
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return self.is_equivalent(other._callback,
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details_filter=other._details_filter)
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else:
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return NotImplemented
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class Notifier(object):
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"""A notification helper class.
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@ -34,7 +83,7 @@ class Notifier(object):
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notification occurs.
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"""
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#: Keys that can not be used in callbacks arguments
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#: Keys that can *not* be used in callbacks arguments
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RESERVED_KEYS = ('details',)
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#: Kleene star constant that is used to recieve all notifications
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@ -46,15 +95,14 @@ class Notifier(object):
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def __len__(self):
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"""Returns how many callbacks are registered."""
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count = 0
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for (_event_type, callbacks) in six.iteritems(self._listeners):
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count += len(callbacks)
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for (_event_type, listeners) in six.iteritems(self._listeners):
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count += len(listeners)
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return count
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def is_registered(self, event_type, callback):
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def is_registered(self, event_type, callback, details_filter=None):
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"""Check if a callback is registered."""
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listeners = list(self._listeners.get(event_type, []))
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for (cb, _args, _kwargs) in listeners:
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if reflection.is_same_callback(cb, callback):
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for listener in self._listeners.get(event_type, []):
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if listener.is_equivalent(callback, details_filter=details_filter):
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return True
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return False
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@ -72,52 +120,55 @@ class Notifier(object):
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:param details: addition event details
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"""
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listeners = list(self._listeners.get(self.ANY, []))
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for i in self._listeners[event_type]:
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if i not in listeners:
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listeners.append(i)
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for listener in self._listeners[event_type]:
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if listener not in listeners:
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listeners.append(listener)
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if not listeners:
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return
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for (callback, args, kwargs) in listeners:
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if args is None:
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args = []
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if kwargs is None:
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kwargs = {}
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kwargs['details'] = details
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for listener in listeners:
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try:
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callback(event_type, *args, **kwargs)
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listener(event_type, details)
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except Exception:
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LOG.warn("Failure calling callback %s to notify about event"
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" %s, details: %s", callback, event_type,
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LOG.warn("Failure calling listener %s to notify about event"
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" %s, details: %s", listener, event_type,
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details, exc_info=True)
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def register(self, event_type, callback, args=None, kwargs=None):
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def register(self, event_type, callback,
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args=None, kwargs=None, details_filter=None):
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"""Register a callback to be called when event of a given type occurs.
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Callback will be called with provided ``args`` and ``kwargs`` and
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when event type occurs (or on any event if ``event_type`` equals to
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:attr:`.ANY`). It will also get additional keyword argument,
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``details``, that will hold event details provided to the
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:meth:`.notify` method.
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:meth:`.notify` method (if a details filter callback is provided then
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the target callback will *only* be triggered if the details filter
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callback returns a truthy value).
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"""
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if not six.callable(callback):
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raise ValueError("Notification callback must be callable")
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if self.is_registered(event_type, callback):
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raise ValueError("Notification callback already registered")
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raise ValueError("Event callback must be callable")
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if details_filter is not None:
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if not six.callable(details_filter):
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raise ValueError("Details filter must be callable")
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if self.is_registered(event_type, callback,
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details_filter=details_filter):
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raise ValueError("Event callback already registered with"
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" equivalent details filter")
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if kwargs:
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for k in self.RESERVED_KEYS:
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if k in kwargs:
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raise KeyError(("Reserved key '%s' not allowed in "
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"kwargs") % k)
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kwargs = copy.copy(kwargs)
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if args:
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args = copy.copy(args)
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self._listeners[event_type].append((callback, args, kwargs))
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raise KeyError("Reserved key '%s' not allowed in "
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"kwargs" % k)
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self._listeners[event_type].append(
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_Listener(callback,
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args=args, kwargs=kwargs,
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details_filter=details_filter))
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def deregister(self, event_type, callback):
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def deregister(self, event_type, callback, details_filter=None):
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"""Remove a single callback from listening to event ``event_type``."""
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if event_type not in self._listeners:
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return
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for i, (cb, args, kwargs) in enumerate(self._listeners[event_type]):
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if reflection.is_same_callback(cb, callback):
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for i, listener in enumerate(self._listeners[event_type]):
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if listener.is_equivalent(callback, details_filter=details_filter):
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self._listeners[event_type].pop(i)
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break
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