/usr/lib/python2.7/dist-packages/oslo_messaging/notify/dispatcher.py is in python-oslo.messaging 4.6.1-2ubuntu1.
This file is owned by root:root, with mode 0o644.
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# All Rights Reserved.
# Copyright 2013 eNovance
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import itertools
import logging
import six
from oslo_messaging._i18n import _LE, _LW
from oslo_messaging import dispatcher
from oslo_messaging import localcontext
from oslo_messaging import serializer as msg_serializer
LOG = logging.getLogger(__name__)
PRIORITIES = ['audit', 'debug', 'info', 'warn', 'error', 'critical', 'sample']
class NotificationResult(object):
HANDLED = 'handled'
REQUEUE = 'requeue'
class _NotificationDispatcherBase(dispatcher.DispatcherBase):
def __init__(self, targets, endpoints, serializer, allow_requeue,
pool=None):
self.targets = targets
self.endpoints = endpoints
self.serializer = serializer or msg_serializer.NoOpSerializer()
self.allow_requeue = allow_requeue
self.pool = pool
self._callbacks_by_priority = {}
for endpoint, prio in itertools.product(endpoints, PRIORITIES):
if hasattr(endpoint, prio):
method = getattr(endpoint, prio)
screen = getattr(endpoint, 'filter_rule', None)
self._callbacks_by_priority.setdefault(prio, []).append(
(screen, method))
priorities = self._callbacks_by_priority.keys()
self._targets_priorities = set(itertools.product(self.targets,
priorities))
def _listen(self, transport):
transport._require_driver_features(requeue=self.allow_requeue)
return transport._listen_for_notifications(self._targets_priorities,
pool=self.pool)
def __call__(self, incoming):
return dispatcher.DispatcherExecutorContext(
incoming, self._dispatch_and_handle_error,
post=self._post_dispatch)
def _post_dispatch(self, incoming, requeues):
for m in incoming:
try:
if requeues and m in requeues:
m.requeue()
else:
m.acknowledge()
except Exception:
LOG.error(_LE("Fail to ack/requeue message"), exc_info=True)
def _dispatch_and_handle_error(self, incoming):
"""Dispatch a notification message to the appropriate endpoint method.
:param incoming: the incoming notification message
:type ctxt: IncomingMessage
"""
try:
return self._dispatch(incoming)
except Exception:
LOG.error(_LE('Exception during message handling'), exc_info=True)
def _dispatch(self, incoming):
"""Dispatch notification messages to the appropriate endpoint method.
"""
messages_grouped = itertools.groupby((
self._extract_user_message(m)
for m in incoming), lambda x: x[0])
requeues = set()
for priority, messages in messages_grouped:
__, raw_messages, messages = six.moves.zip(*messages)
raw_messages = list(raw_messages)
messages = list(messages)
if priority not in PRIORITIES:
LOG.warning(_LW('Unknown priority "%s"'), priority)
continue
for screen, callback in self._callbacks_by_priority.get(priority,
[]):
if screen:
filtered_messages = [message for message in messages
if screen.match(
message["ctxt"],
message["publisher_id"],
message["event_type"],
message["metadata"],
message["payload"])]
else:
filtered_messages = messages
if not filtered_messages:
continue
ret = self._exec_callback(callback, filtered_messages)
if self.allow_requeue and ret == NotificationResult.REQUEUE:
requeues.update(raw_messages)
break
return requeues
def _exec_callback(self, callback, *args):
ret = callback(*args)
return NotificationResult.HANDLED if ret is None else ret
def _extract_user_message(self, incoming):
ctxt = self.serializer.deserialize_context(incoming.ctxt)
message = incoming.message
publisher_id = message.get('publisher_id')
event_type = message.get('event_type')
metadata = {
'message_id': message.get('message_id'),
'timestamp': message.get('timestamp')
}
priority = message.get('priority', '').lower()
payload = self.serializer.deserialize_entity(ctxt,
message.get('payload'))
return priority, incoming, dict(ctxt=ctxt,
publisher_id=publisher_id,
event_type=event_type,
payload=payload,
metadata=metadata)
class NotificationDispatcher(_NotificationDispatcherBase):
"""A message dispatcher which understands Notification messages.
A MessageHandlingServer is constructed by passing a callable dispatcher
which is invoked with context and message dictionaries each time a message
is received.
"""
def _exec_callback(self, callback, messages):
localcontext._set_local_context(
messages[0]["ctxt"])
try:
return super(NotificationDispatcher, self)._exec_callback(
callback,
messages[0]["ctxt"],
messages[0]["publisher_id"],
messages[0]["event_type"],
messages[0]["payload"],
messages[0]["metadata"])
finally:
localcontext._clear_local_context()
class BatchNotificationDispatcher(_NotificationDispatcherBase):
"""A message dispatcher which understands Notification messages.
A MessageHandlingServer is constructed by passing a callable dispatcher
which is invoked with a list of message dictionaries each time 'batch_size'
messages are received or 'batch_timeout' seconds is reached.
"""
def __init__(self, targets, endpoints, serializer, allow_requeue,
pool=None, batch_size=None, batch_timeout=None):
super(BatchNotificationDispatcher, self).__init__(targets, endpoints,
serializer,
allow_requeue,
pool)
self.batch_size = batch_size
self.batch_timeout = batch_timeout
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