oslo.messaging/oslo/messaging/_drivers/base.py

100 lines
2.9 KiB
Python

# Copyright 2013 Red Hat, Inc.
#
# 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 abc
import six
from oslo.messaging import exceptions
class TransportDriverError(exceptions.MessagingException):
"""Base class for transport driver specific exceptions."""
@six.add_metaclass(abc.ABCMeta)
class IncomingMessage(object):
def __init__(self, listener, ctxt, message):
self.conf = listener.conf
self.listener = listener
self.ctxt = ctxt
self.message = message
@abc.abstractmethod
def reply(self, reply=None, failure=None, log_failure=True):
"Send a reply or failure back to the client."
def acknowledge(self):
"Acknowledge the message."
@abc.abstractmethod
def requeue(self):
"Requeue the message."
@six.add_metaclass(abc.ABCMeta)
class Listener(object):
def __init__(self, driver):
self.conf = driver.conf
self.driver = driver
@abc.abstractmethod
def poll(self, timeout=None):
"""Blocking until a message is pending and return IncomingMessage.
Return None after timeout seconds if timeout is set and no message is
ending.
"""
@six.add_metaclass(abc.ABCMeta)
class BaseDriver(object):
def __init__(self, conf, url,
default_exchange=None, allowed_remote_exmods=None):
self.conf = conf
self._url = url
self._default_exchange = default_exchange
self._allowed_remote_exmods = allowed_remote_exmods or []
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):
"""Send a message to the given target."""
@abc.abstractmethod
def send_notification(self, target, ctxt, message, version):
"""Send a notification message to the given target."""
@abc.abstractmethod
def listen(self, target):
"""Construct a Listener for the given target."""
@abc.abstractmethod
def listen_for_notifications(self, targets_and_priorities):
"""Construct a notification Listener for the given list of
tuple of (target, priority).
"""
@abc.abstractmethod
def cleanup(self):
"""Release all resources."""