def subscribe(self, callback, resource, event):
"""Subscribe callback for a resource event.
The same callback may register for more than one event.
:param callback: the callback. It must raise or return a boolean.
:param resource: the resource. It must be a valid resource.
:param event: the event. It must be a valid event.
"""
LOG.debug("Subscribe: %(callback)s %(resource)s %(event)s", {
'callback': callback,
'resource': resource,
'event': event
})
if resource not in resources.VALID:
raise exceptions.Invalid(element='resource', value=resource)
if event not in events.VALID:
raise exceptions.Invalid(element='event', value=event)
callback_id = _get_id(callback)
self._callbacks[resource][event][callback_id] = callback
# We keep a copy of callbacks to speed the unsubscribe operation.
if callback_id not in self._index:
self._index[callback_id] = collections.defaultdict(set)
self._index[callback_id][resource].add(event)
def unsubscribe(self, callback, resource, event):
"""Unsubscribe callback from the registry.
:param callback: the callback.
:param resource: the resource.
:param event: the event.
"""
LOG.debug("Unsubscribe: %(callback)s %(resource)s %(event)s", {
'callback': callback,
'resource': resource,
'event': event
})
callback_id = self._find(callback)
if not callback_id:
LOG.debug("Callback %s not found", callback_id)
return
if resource and event:
del self._callbacks[resource][event][callback_id]
self._index[callback_id][resource].discard(event)
if not self._index[callback_id][resource]:
del self._index[callback_id][resource]
if not self._index[callback_id]:
del self._index[callback_id]
else:
value = '%s,%s' % (resource, event)
raise exceptions.Invalid(element='resource,event', value=value)
def _validate_resource_type(resource_type):
if not resources.is_valid_resource_type(resource_type):
raise exceptions.Invalid(element='resource', value=resource_type)