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An initial implementation of an AMQP 1.0 based messaging driver

The key driver interfaces are implemented in the ProtonDriver class in  The logic for interfacing with Pyngus in order to
send/receive messages, manage AMQP connections and links, and handle
protocol events is in is a fairly generic
socket connection and I/O processor which runs in its own thread. uses the thread to schedule subscription
and message send requests from the driver, as well as handle all
protocol event callbacks coming from Pyngus.

Included in this patch are a set of functional tests that can be run
under tox (tox -eamqp1).  These tests fully exercise the new driver,
from the driver API down to the 'wire' - nothing in the driver is
mocked out.  The functional tests implement a simple loopback test
broker, which allows the driver to send and receive messages via the
local network.  All RPC call patterns, RPC timeouts, and even broker
failover are verified by the included functional tests.

This driver uses the Pyngus module, which is a pure-python client API
built on the Proton AMQP 1.0 protocol engine library from the Apache
Qpid project.  Pyngus is available via

This driver introduces a dependency on the Proton AMQP 1.0 protocol
library, which is a platform-dependent library that must be installed
in order to use this driver and run the functional tests.

Change-Id: I871703e4cdc04cee3e6c214e911c9df464ede2ed
Implements: blueprint amqp10-driver-implementation
Gordon Sim 8 years ago
committed by Kenneth Giusti
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# TODO(kgiusti) AMQP 1.0 support depends on the Qpid Proton AMQP 1.0
# development libraries. As these are not yet available from the
# Ubuntu repositories, do not require these packages by default. If
# you have installed the Proton development libraries, you can run the
# amqp1 driver tox tests this way:
# tox -e amqp1
pyngus>=1.0.0,<2.0.0 # Apache-2.0
python-qpid-proton>=0.7,<0.8 # Apache-2.0



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# Copyright 2014, 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
# 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.
from .driver import ProtonDriver


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# Copyright 2014, 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
# 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.
Controller that manages the interface between the driver and the messaging
This module defines a Controller class that is responsible for performing
messaging-related operations (Tasks) requested by the driver, and for managing
the connection to the messaging service. The Controller creates a background
thread which performs all messaging operations and socket I/O. The
Controller's messaging logic is executed in the background thread via lambda
functions scheduled by the Controller.
import abc
import collections
import logging
import threading
import uuid
import pyngus
from six import moves
from oslo.config import cfg
from oslo.messaging._drivers.protocols.amqp import eventloop
LOG = logging.getLogger(__name__)
_amqp1_opts = [
help="address prefix used when sending to a specific server"),
help="address prefix used when broadcasting to all servers"),
help="address prefix when sending to any server in group"),
help='Name for the AMQP container'),
default=0, # disabled
help='Timeout for inactive connections (in seconds)'),
help='Debug: dump AMQP frames to stdout'),
help="CA certificate PEM file for verifing server certificate"),
help='Identifying certificate PEM file to present to clients'),
help='Private key PEM file used to sign cert_file certificate'),
help='Password for decrypting ssl_key_file (if encrypted)'),
help='Accept clients using either SSL or plain TCP')
class Task(object):
"""Perform a messaging operation via the Controller."""
def execute(self, controller):
"""This method will be run on the eventloop thread."""
class Replies(pyngus.ReceiverEventHandler):
"""This is the receiving link for all reply messages. Messages are routed
to the proper Listener's incoming queue using the correlation-id header in
the message.
def __init__(self, connection, on_ready):
self._correlation = {} # map of correlation-id to response queue
self._ready = False
self._on_ready = on_ready
self._receiver = connection.create_receiver("replies",
# capacity determines the maximum number of reply messages this link
# can receive. As messages are received and credit is consumed, this
# driver will 'top up' the credit back to max capacity. This number
# should be large enough to avoid needlessly flow-controlling the
# replies.
self.capacity = 100 # TODO(kgiusti) guesstimate - make configurable
self._credit = 0
def ready(self):
return self._ready
def prepare_for_response(self, request, reply_queue):
"""Apply a unique message identifier to this request message. This will
be used to identify messages sent in reply. The identifier is placed
in the 'id' field of the request message. It is expected that the
identifier will appear in the 'correlation-id' field of the
corresponding response message.
""" = uuid.uuid4().hex
# reply is placed on reply_queue
self._correlation[] = reply_queue
request.reply_to = self._receiver.source_address
LOG.debug("Reply for msg id=%s expected on link %s",, request.reply_to)
# Pyngus ReceiverLink event callbacks:
def receiver_active(self, receiver_link):
"""This is a Pyngus callback, invoked by Pyngus when the receiver_link
has transitioned to the open state and is able to receive incoming
self._ready = True
LOG.debug("Replies expected on link %s",
def receiver_remote_closed(self, receiver, pn_condition):
"""This is a Pyngus callback, invoked by Pyngus when the peer of this
receiver link has initiated closing the connection.
# TODO(kgiusti) Unclear if this error will ever occur (as opposed to
# the Connection failing instead). Log for now, possibly implement a
# recovery strategy if necessary.
LOG.error("Reply subscription closed by peer: %s",
(pn_condition or "no error given"))
def message_received(self, receiver, message, handle):
"""This is a Pyngus callback, invoked by Pyngus when a new message
arrives on this receiver link from the peer.
self._credit = self._credit - 1
key = message.correlation_id
if key in self._correlation:
LOG.debug("Received response for msg id=%s", key)
# cleanup (only need one response per request)
del self._correlation[key]
LOG.warn("Can't find receiver for response msg id=%s, dropping!",
def _update_credit(self):
if self.capacity > self._credit:
self._receiver.add_capacity(self.capacity - self._credit)
self._credit = self.capacity
class Server(pyngus.ReceiverEventHandler):
"""A group of links that receive messages from a set of addresses derived
from a given target. Messages arriving on the links are placed on the
'incoming' queue.
def __init__(self, addresses, incoming):
self._incoming = incoming
self._addresses = addresses
def attach(self, connection):
"""Create receiver links over the given connection for all the
configured addresses.
self._receivers = []
for a in self._addresses:
props = {"snd-settle-mode": "settled"}
rname = "Consumer-%s:src=%s:tgt=%s" % (uuid.uuid4().hex, a, a)
r = connection.create_receiver(source_address=a,
# TODO(kgiusti) Hardcoding credit here is sub-optimal. A better
# approach would monitor for a back-up of inbound messages to be
# processed by the consuming application and backpressure the
# sender based on configured thresholds.
# Pyngus ReceiverLink event callbacks:
def receiver_remote_closed(self, receiver, pn_condition):
"""This is a Pyngus callback, invoked by Pyngus when the peer of this
receiver link has initiated closing the connection.
text = "Server subscription %(addr)s closed by peer: %(err_msg)s"
vals = {
"addr": receiver.source_address or receiver.target_address,
"err_msg": pn_condition or "no error given"
LOG.error(text % vals)
def message_received(self, receiver, message, handle):
"""This is a Pyngus callback, invoked by Pyngus when a new message
arrives on this receiver link from the peer.
# TODO(kgiusti) Sub-optimal to grant one credit each time a message
# arrives. A better approach would grant batches of credit on demand.
LOG.debug("message received: %s", message)
class Hosts(object):
"""An order list of peer addresses. Connection failover progresses from
one host to the next.
HostnamePort = collections.namedtuple('HostnamePort',
['hostname', 'port'])
def __init__(self, entries=None):
self._entries = [self.HostnamePort(h, p) for h, p in entries or []]
self._current = 0
def add(self, hostname, port=5672):
self._entries.append(self.HostnamePort(hostname, port))
def current(self):
if len(self._entries):
return self._entries[self._current]
return self.HostnamePort("localhost", 5672)
def next(self):
if len(self._entries) > 1:
self._current = (self._current + 1) % len(self._entries)
return self.current
def __repr__(self):
return '<Hosts ' + str(self) + '>'
def __str__(self):
return ", ".join(["%s:%i" % e for e in self._entries])
class Controller(pyngus.ConnectionEventHandler):
"""Controls the connection to the AMQP messaging service. This object is
the 'brains' of the driver. It maintains the logic for addressing, sending
and receiving messages, and managing the connection. All messaging and I/O
work is done on the Eventloop thread, allowing the driver to run
asynchronously from the messaging clients.
def __init__(self, hosts, default_exchange, config):
self.processor = None
# queue of Task() objects to execute on the eventloop once the
# connection is ready:
self._tasks = moves.queue.Queue(maxsize=500)
# limit the number of Task()'s to execute per call to _process_tasks().
# This allows the eventloop main thread to return to servicing socket
# I/O in a timely manner
self._max_task_batch = 50
# cache of sending links indexed by address:
self._senders = {}
# Servers (set of receiving links), indexed by target:
self._servers = {}
self.hosts = Hosts(hosts)
opt_group = cfg.OptGroup(name='amqp1',
title='AMQP 1.0 options')
config.register_opts(_amqp1_opts, group=opt_group)
self.server_request_prefix = config.amqp1.server_request_prefix
self.broadcast_prefix = config.amqp1.broadcast_prefix
self.group_request_prefix = config.amqp1.group_request_prefix
self._container_name = config.amqp1.container_name
if not self._container_name:
self._container_name = "container-%s" % uuid.uuid4().hex
self.idle_timeout = config.amqp1.idle_timeout
self.trace_protocol = config.amqp1.trace
self.ssl_ca_file = config.amqp1.ssl_ca_file
self.ssl_cert_file = config.amqp1.ssl_cert_file
self.ssl_key_file = config.amqp1.ssl_key_file
self.ssl_key_password = config.amqp1.ssl_key_password
self.ssl_allow_insecure = config.amqp1.allow_insecure_clients
self.separator = "."
self.fanout_qualifier = "all"
self.default_exchange = default_exchange
# can't handle a request until the replies link is active, as
# we need the peer assigned address, so need to delay any
# processing of task queue until this is done
self._replies = None
# Set True when the driver is shutting down
self._closing = False
# only schedule one outstanding reconnect attempt at a time
self._reconnecting = False
self._delay = 0 # seconds between retries
# prevent queuing up multiple requests to run _process_tasks()
self._process_tasks_scheduled = False
self._process_tasks_lock = threading.Lock()
def connect(self):
"""Connect to the messaging service."""
self.processor = eventloop.Thread(self._container_name)
self.processor.wakeup(lambda: self._do_connect())
def add_task(self, task):
"""Add a Task for execution on processor thread."""
def destroy(self):
"""Shutdown the messaging service."""
if self.processor:
self.processor.wakeup(lambda: self._start_shutdown())"Waiting for eventloop to exit")
self.processor = None"Eventloop exited, driver shut down")
# The remaining methods are reserved to run from the eventloop thread only!
# They must not be invoked directly!
# methods executed by Tasks created by the driver:
def request(self, target, request, reply_queue=None):
"""Send a request message to the given target, and arrange for a
response to be put on the optional reply_queue if specified
address = self._resolve(target)
LOG.debug("Sending request for %s to %s", target, address)
if reply_queue is not None:
self._replies.prepare_for_response(request, reply_queue)
self._send(address, request)
def response(self, address, response):
LOG.debug("Sending response to %s", address)
self._send(address, response)
def subscribe(self, target, in_queue):
"""Subscribe to messages sent to 'target', place received messages on
addresses = [
self._subscribe(target, addresses, in_queue)
def subscribe_notifications(self, target, in_queue):
"""Subscribe for notifications on 'target', place received messages on
addresses = [self._group_request_address(target)]
self._subscribe(target, addresses, in_queue)
def _subscribe(self, target, addresses, in_queue):
LOG.debug("Subscribing to %s (%s)", target, addresses)
self._servers[target] = Server(addresses, in_queue)
def _resolve(self, target):
"""Return a link address for a given target."""
if target.server:
return self._server_address(target)
elif target.fanout:
return self._broadcast_address(target)
return self._group_request_address(target)
def _sender(self, address):
# if we already have a sender for that address, use it
# else establish the sender and cache it
if address in self._senders:
sender = self._senders[address]
sname = "Producer-%s:src=%s:tgt=%s" % (uuid.uuid4().hex,
address, address)
conn = self._socket_connection.connection
sender = conn.create_sender(source_address=address,
self._senders[address] = sender
return sender
def _send(self, addr, message):
"""Send the message out the link addressed by 'addr'."""
address = str(addr)
message.address = address
def _server_address(self, target):
return self._concatenate([self.server_request_prefix, or self.default_exchange,
target.topic, target.server])
def _broadcast_address(self, target):
return self._concatenate([self.broadcast_prefix, or self.default_exchange,
target.topic, self.fanout_qualifier])
def _group_request_address(self, target):
return self._concatenate([self.group_request_prefix, or self.default_exchange,
def _concatenate(self, items):
return self.separator.join(filter(bool, items))
# commands executed on the processor (eventloop) via 'wakeup()':
def _do_connect(self):
"""Establish connection and reply subscription on processor thread."""
hostname = self.hosts.current.hostname
port = self.hosts.current.port
conn_props = {}
if self.idle_timeout:
conn_props["idle-time-out"] = float(self.idle_timeout)
if self.trace_protocol:
conn_props["x-trace-protocol"] = self.trace_protocol
if self.ssl_ca_file:
conn_props["x-ssl-ca-file"] = self.ssl_ca_file
if self.ssl_cert_file:
# assume this connection is for a server. If client authentication
# support is developed, we'll need an explict flag (server or
# client)
conn_props["x-ssl-server"] = True
conn_props["x-ssl-identity"] = (self.ssl_cert_file,
conn_props["x-ssl-allow-cleartext"] = self.ssl_allow_insecure
self._socket_connection = self.processor.connect(hostname, port,
LOG.debug("Connection initiated")
def _process_tasks(self):
"""Execute Task objects in the context of the processor thread."""
with self._process_tasks_lock:
self._process_tasks_scheduled = False
count = 0
while (not self._tasks.empty() and
count < self._max_task_batch and
except Exception as e:
LOG.exception("Error processing task: %s", e)
count += 1
# if we hit _max_task_batch, resume task processing later:
if not self._tasks.empty() and self._can_process_tasks:
def _schedule_task_processing(self):
"""_process_tasks() helper: prevent queuing up multiple requests for
task processing. This method is called both by the application thread
and the processing thread.
if self.processor:
with self._process_tasks_lock:
already_scheduled = self._process_tasks_scheduled
self._process_tasks_scheduled = True
if not already_scheduled:
self.processor.wakeup(lambda: self._process_tasks())
def _can_process_tasks(self):
"""_process_tasks helper(): indicates that the driver is ready to
process Tasks. In order to process messaging-related tasks, the reply
queue link must be active.
return (not self._closing and
self._replies and self._replies.ready())
def _start_shutdown(self):
"""Called when the driver destroys the controller, this method attempts
to cleanly close the AMQP connection to the peer.
""""Shutting down AMQP connection")
self._closing = True
# try a clean shutdown
# don't wait for a close from the remote, may never happen
# reply link active callback:
def _reply_link_ready(self):
"""Invoked when the Replies reply link has become active. At this
point, we are ready to send/receive messages (via Task processing).
""""Messaging is active (%s:%i)", self.hosts.current.hostname,
# callback from eventloop on socket error
def socket_error(self, error):
"""Called by eventloop when a socket error occurs."""
LOG.debug("Socket failure: %s", error)
# Pyngus connection event callbacks (and their helpers), all invoked from
# the eventloop thread:
def connection_failed(self, connection, error):
"""This is a Pyngus callback, invoked by Pyngus when a non-recoverable
error occurs on the connection.
if connection is not self._socket_connection.connection:
# pyngus bug: ignore failure callback on destroyed connections
LOG.debug("AMQP Connection failure: %s", error)
def connection_active(self, connection):
"""This is a Pyngus callback, invoked by Pyngus when the connection to
the peer is up. At this point, the driver will activate all subscriber
links (server) and the reply link.
LOG.debug("Connection active (%s:%i), subscribing...",
self.hosts.current.hostname, self.hosts.current.port)
for s in self._servers.itervalues():
self._replies = Replies(self._socket_connection.connection,
lambda: self._reply_link_ready())
self._delay = 0
def connection_closed(self, connection):
"""This is a Pyngus callback, invoked by Pyngus when the connection has
cleanly closed. This occurs after the driver closes the connection
locally, and the peer has acknowledged the close. At this point, the
shutdown of the driver's connection is complete.
LOG.debug("AMQP connection closed.")
# if the driver isn't being shutdown, failover and reconnect
def connection_remote_closed(self, connection, reason):
"""This is a Pyngus callback, invoked by Pyngus when the peer has
requested that the connection be closed.
if not self._closing:
# The messaging service/broker is trying to shut down the
# connection. Acknowledge the close, and try to reconnect/failover
# later once the connection has closed (connection_closed is
# called)."Connection closed by peer: %s",
reason or "no reason given")
def _complete_shutdown(self):
"""The AMQP Connection has closed, and the driver shutdown is complete.
Clean up controller resources and exit.
self.processor.shutdown()"Messaging has shutdown")
def _handle_connection_loss(self):
"""The connection to the messaging service has been lost. Try to
reestablish the connection/failover.
if self._closing:
# we're in the middle of shutting down the driver anyways,
# just consider it done:
# for some reason, we've lost the connection to the messaging
# service. Try to re-establish the connection:
if not self._reconnecting:
self._reconnecting = True
self._replies = None
if self._delay == 0:
self._delay = 1
d = self._delay"delaying reconnect attempt for %d seconds", d)
self.processor.schedule(lambda: self._do_reconnect(), d)
self._delay = min(d * 2, 60)
def _do_reconnect(self):
"""Invoked on connection/socket failure, failover and re-connect to the
messaging service.
if not self._closing:
self._reconnecting = False
self._senders = {}
hostname, port ="Reconnecting to: %s:%i", hostname, port)
self._socket_connection.connect(hostname, port)


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# Copyright 2014, 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
# 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.
Driver for the 'amqp' transport.
This module provides a transport driver that speaks version 1.0 of the AMQP
messaging protocol. The driver sends messages and creates subscriptions via
'tasks' that are performed on its behalf via the controller module.
import logging
import threading
import time
from six import moves
from oslo import messaging
from oslo.messaging._drivers import base
from oslo.messaging._drivers import common
from oslo.messaging.openstack.common import importutils
from oslo.messaging.openstack.common import jsonutils
from oslo.messaging import target as messaging_target
# TODO(kgiusti): this module depends on platform specific libraries (proton)
# which are not available on all systems (yet). The unittest loader will
# attempt to directly import this driver even if the dependent libraries are
# not installed. Since the default set of unit tests do not exercise this
# driver, we shouldn't cause them to fail due to the missing
# dependencies. These hacks allow the import to succeed without raising an
# import error and causing all the tests to fail. [Note: to run the set of test
# for this driver, use the 'amqp1' test environment - e.g. 'tox -eamqp1']
# Remove these hacks once the qpid-proton C libraries are available via Ubuntu
# base repos and can be added to the base test-requirements.txt [they are
# already available via EPEL]:
class _FakeController(object):
"""A mocked Controller to use if the controller module fails to import
due to missing dependencies. Stubs out the _amqp1_opts option list and
provides a fake 'Task' superclass so the sub-classes SendTask, ListenTask,
and ReplyTask defined by this module will parse correctly on import.
This allows the tests to import the module without failing even
if the proton libraries are not installed. Be aware that attempting to use
(instantiate) the PythonDriver will raise a NotImplementedError if the fake
controller is in use. This is by design since the driver really cannot
work without the real controller and its dependencies.
fake_controller = True
Task = type('Task', (object,), {})
_amqp1_opts = list()
proton = importutils.try_import("proton")
from oslo.messaging._drivers.protocols.amqp import controller
except ImportError:
controller = _FakeController()
def get_opts():
"""Provide access to the controller's configuration options."""
return controller._amqp1_opts
# TODO(kgiusti) End of hack
LOG = logging.getLogger(__name__)
class SendTask(controller.Task):
"""A task that sends a message to a target, and optionally allows for the
calling thread to wait for a reply.
def __init__(self, target, request, reply_expected, deadline):
super(SendTask, self).__init__()
self._target = target
self._request = request
self._deadline = deadline
if reply_expected:
self._reply_queue = moves.queue.Queue()
self._reply_queue = None
def execute(self, controller):
"""Runs on eventloop thread - sends request."""
if not self._deadline or self._deadline > time.time():
controller.request(self._target, self._request, self._reply_queue)
LOG.warn("Send request to %s aborted: TTL expired.", self._target)
def get_reply(self, timeout):
"""Retrieve the reply."""
if not self._reply_queue:
return None
return self._reply_queue.get(timeout=timeout)
except moves.queue.Empty:
raise messaging.MessagingTimeout('Timed out waiting for a reply')
class ListenTask(controller.Task):
"""A task that creates a subscription to the given target. Messages
arriving from the target are given to the listener.
def __init__(self, target, listener, notifications=False):
"""Create a subscription to the target."""
super(ListenTask, self).__init__()
self._target = target
self._listener = listener
self._notifications = notifications
def execute(self, controller):
"""Run on the eventloop thread - subscribes to target. Inbound messages
are queued to the listener's incoming queue.
if self._notifications:
controller.subscribe(self._target, self._listener.incoming)
class ReplyTask(controller.Task):
"""A task that sends 'response' message to address."""
def __init__(self, address, response, log_failure):
super(ReplyTask, self).__init__()
self._address = address
self._response = response
self._log_failure = log_failure
def execute(self, controller):
"""Run on the eventloop thread - send the response message."""
controller.response(self._address, self._response)
def marshal_response(reply=None, failure=None):
# TODO(grs): do replies have a context?
msg = proton.Message()
if failure:
failure = common.serialize_remote_exception(failure)
data = {"failure": failure}
data = {"response": reply}
msg.body = jsonutils.dumps(data)
return msg
def unmarshal_response(message, allowed):
# TODO(kgiusti) This may fail to unpack and raise an exception. Need to
# communicate this to the caller!
data = jsonutils.loads(message.body)
failure = data.get('failure')
if failure is not None:
raise common.deserialize_remote_exception(failure, allowed)
return data.get("response")
def marshal_request(request, context, envelope):
msg = proton.Message()
if envelope:
request = common.serialize_msg(request)
data = {
"request": request,
"context": context
msg.body = jsonutils.dumps(data)
return msg
def unmarshal_request(message):
data = jsonutils.loads(message.body)
return (data.get("request"), data.get("context"))
class ProtonIncomingMessage(base.IncomingMessage):
def __init__(self, listener, ctxt, request, message):
super(ProtonIncomingMessage, self).__init__(listener, ctxt, request)
self._reply_to = message.reply_to
self._correlation_id =
def reply(self, reply=None, failure=None, log_failure=True):
"""Schedule a ReplyTask to send the reply."""
if self._reply_to:
response = marshal_response(reply=reply, failure=failure)
response.correlation_id = self._correlation_id
LOG.debug("Replying to %s", self._correlation_id)
task = ReplyTask(self._reply_to, response, log_failure)
LOG.debug("Ignoring reply as no reply address available")
def acknowledge(self):
def requeue(self):
class ProtonListener(base.Listener):
def __init__(self, driver):
super(ProtonListener, self).__init__(driver)
self.incoming = moves.queue.Queue()
def poll(self):
message = self.incoming.get()
request, ctxt = unmarshal_request(message)
LOG.debug("Returning incoming message")
return ProtonIncomingMessage(self, ctxt, request, message)
class ProtonDriver(base.BaseDriver):
def __init__(self, conf, url,
default_exchange=None, allowed_remote_exmods=[]):
# TODO(kgiusti) Remove once driver fully stabilizes:
LOG.warning("Support for the 'amqp' transport is EXPERIMENTAL.")
if proton is None or hasattr(controller, "fake_controller"):
raise NotImplementedError("Proton AMQP C libraries not installed")
super(ProtonDriver, self).__init__(conf, url, default_exchange,
# TODO(grs): handle authentication etc
hosts = [(h.hostname, h.port or 5672) for h in url.hosts]
# Create a Controller that connects to the messaging service:
self._ctrl = controller.Controller(hosts, default_exchange, conf)
# lazy connection setup - don't cause the controller to connect until
# after the first messaging request:
self._connect_called = False
self._lock = threading.Lock()
def _ensure_connect_called(func):
"""Causes the controller to connect to the messaging service when it is
first used. It is safe to push tasks to it whether connected or not,
but those tasks won't be processed until connection completes.
def wrap(self, *args, **kws):
with self._lock:
connect_called = self._connect_called
self._connect_called = True
if not connect_called:
return func(self, *args, **kws)
return wrap
def send(self, target, ctxt, message,
wait_for_reply=None, timeout=None, envelope=False,
"""Send a message to the given target."""
# TODO(kgiusti) need to add support for retry
if retry is not None:
raise NotImplementedError('"retry" not implemented by'
'this transport driver')
request = marshal_request(message, ctxt, envelope)
expire = 0
if timeout:
expire = time.time() + timeout # when the caller times out
# amqp uses millisecond time values, timeout is seconds
request.ttl = int(timeout * 1000)
request.expiry_time = int(expire * 1000)
LOG.debug("Send to %s", target)
task = SendTask(target, request, wait_for_reply, expire)
result = None
if wait_for_reply:
# the following can raise MessagingTimeout if no reply received:
reply = task.get_reply(timeout)
# TODO(kgiusti) how to handle failure to un-marshal? Must log, and
# determine best way to communicate this failure back up to the
# caller
result = unmarshal_response(reply, self._allowed_remote_exmods)
LOG.debug("Send to %s returning", target)
return result
def send_notification(self, target, ctxt, message, version,
"""Send a notification message to the given target."""
# TODO(kgiusti) need to add support for retry
if retry is not None:
raise NotImplementedError('"retry" not implemented by'
'this transport driver')
return self.send(target, ctxt, message, envelope=(version == 2.0))
def listen(self, target):
"""Construct a Listener for the given target."""
LOG.debug("Listen to %s", target)
listener = ProtonListener(self)
self._ctrl.add_task(ListenTask(target, listener))
return listener
def listen_for_notifications(self, targets_and_priorities):
LOG.debug("Listen for notifications %s", targets_and_priorities)
listener = ProtonListener(self)
for target, priority in targets_and_priorities:
topic = '%s.%s' % (target.topic, priority)
t = messaging_target.Target(topic=topic)
self._ctrl.add_task(ListenTask(t, listener, True))
return listener
def cleanup(self):
"""Release all resources."""
LOG.debug("Cleaning up ProtonDriver")
self._ctrl = None


@ -0,0 +1,326 @@
# Copyright 2014, 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
# 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.
A thread that performs all messaging I/O and protocol event handling.
This module provides a background thread that handles messaging operations
scheduled via the Controller, and performs blocking socket I/O and timer
processing. This thread is designed to be as simple as possible - all the
protocol specific intelligence is provided by the Controller and executed on
the background thread via callables.
import errno
import heapq
import logging
import os
import select
import socket
import sys
import threading
import time
import uuid
import pyngus
from six import moves
LOG = logging.getLogger(__name__)
class _SocketConnection():
"""Associates a pyngus Connection with a python network socket,
and handles all connection-related I/O and timer events.
def __init__(self, name, container, properties, handler): = name
self.socket = None
self._properties = properties or {}
self._properties["properties"] = self._get_name_and_pid()
# The handler is a pyngus ConnectionEventHandler, which is invoked by
# pyngus on connection-related events (active, closed, error, etc).
# Currently it is the Controller object.
self._handler = handler
self._container = container
c = container.create_connection(name, handler, self._properties)
c.user_context = self
self.connection = c
def _get_name_and_pid(self):
# helps identify the process that is using the connection
return {u'process': os.path.basename(sys.argv[0]), u'pid': os.getpid()}
def fileno(self):
"""Allows use of a _SocketConnection in a select() call.
return self.socket.fileno()
def read(self):
"""Called when socket is read-ready."""
while True:
rc = pyngus.read_socket_input(self.connection, self.socket)
if rc > 0:
return rc
except socket.error as e:
if e.errno == errno.EAGAIN or e.errno == errno.EINTR:
elif e.errno == errno.EWOULDBLOCK:
return 0
return pyngus.Connection.EOS
def write(self):
"""Called when socket is write-ready."""
while True:
rc = pyngus.write_socket_output(self.connection, self.socket)
if rc > 0:
return rc
except socket.error as e:
if e.errno == errno.EAGAIN or e.errno == errno.EINTR:
elif e.errno == errno.EWOULDBLOCK:
return 0
return pyngus.Connection.EOS
def connect(self, hostname, port, sasl_mechanisms="ANONYMOUS"):
"""Connect to host:port and start the AMQP protocol."""
addr = socket.getaddrinfo(hostname, port,
socket.AF_INET, socket.SOCK_STREAM)
if not addr:
key = "%s:%i" % (hostname, port)
error = "Invalid peer address '%s'" % key
my_socket = socket.socket(addr[0][0], addr[0][1], addr[0][2])
my_socket.setblocking(0) # 0=non-blocking
my_socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
except socket.error as e:
if e.errno != errno.EINPROGRESS:
error = "Socket connect failure '%s'" % str(e)
self.socket = my_socket
if sasl_mechanisms:
pn_sasl = self.connection.pn_sasl
# TODO(kgiusti): server if accepting inbound connections
def reset(self, name=None):
"""Clean up the current state, expect 'connect()' to be recalled
if self.connection:
if name: = name
c = self._container.create_connection(, self._handler,
c.user_context = self
self.connection = c
def close(self):
if self.socket:
class Schedule(object):
"""A list of callables (requests). Each callable may have a delay (in
milliseconds) which causes the callable to be scheduled to run after the
delay passes.
def __init__(self):
self._entries = []
def schedule(self, request, delay):
"""Request a callable be executed after delay."""
entry = (time.time() + delay, request)
heapq.heappush(self._entries, entry)
def get_delay(self, max_delay=None):
"""Get the delay in milliseconds until the next callable needs to be
run, or 'max_delay' if no outstanding callables or the delay to the
next callable is > 'max_delay'.
due = self._entries[0][0] if self._entries else None
if due is None:
return max_delay
now = time.time()
if due < now:
return 0
return min(due - now, max_delay) if max_delay else due - now
def process(self):
"""Invoke all expired callables."""
while self._entries and self._entries[0][0] < time.time():
class Requests(object):
"""A queue of callables to execute from the eventloop thread's main
def __init__(self):
self._requests = moves.queue.Queue(maxsize=10)
self._wakeup_pipe = os.pipe()
def wakeup(self, request=None):
"""Enqueue a callable to be executed by the eventloop, and force the
eventloop thread to wake up from select().
if request:
os.write(self._wakeup_pipe[1], "!")
def fileno(self):
"""Allows this request queue to be used by select()."""
return self._wakeup_pipe[0]
def read(self):
"""Invoked by the eventloop thread, execute each queued callable."""[0], 512)
# first pop of all current tasks
requests = []
while not self._requests.empty():
# then process them, this allows callables to re-register themselves to
# be run on the next iteration of the I/O loop
for r in requests:
class Thread(threading.Thread):
"""Manages socket I/O and executes callables queued up by external
def __init__(self, container_name=None):
super(Thread, self).__init__()
# callables from other threads:
self._requests = Requests()
# delayed callables (only used on this thread for now):
self._schedule = Schedule()
# Configure a container
if container_name is None:
container_name = uuid.uuid4().hex
self._container = pyngus.Container(container_name) = "Thread for Proton container: %s" %
self._shutdown = False
self.daemon = True
def wakeup(self, request=None):
"""Wake up the eventloop thread, Optionally providing a callable to run
when the eventloop wakes up.
def schedule(self, request, delay):
"""Invoke request after delay seconds."""
self._schedule.schedule(request, delay)
def destroy(self):
"""Stop the processing thread, releasing all resources.
LOG.debug("Stopping Proton container %s",
self.wakeup(lambda: self.shutdown())
def shutdown(self):"eventloop shutdown requested")
self._shutdown = True
def connect(self, hostname, port, handler, properties=None, name=None,
"""Get a _SocketConnection to a peer represented by url."""
key = name or "%s:%i" % (hostname, port)
# return pre-existing
conn = self._container.get_connection(key)
if conn:
return conn.user_context
# create a new connection - this will be stored in the
# container, using the specified name as the lookup key, or if
# no name was provided, the host:port combination
sc = _SocketConnection(key, self._container,
properties, handler=handler)
sc.connect(hostname, port, sasl_mechanisms)
return sc
def run(self):
"""Run the proton event/timer loop."""
LOG.debug("Starting Proton thread, container=%s",
while not self._shutdown:
readers, writers, timers = self._container.need_processing()
readfds = [c.user_context for c in readers]
# additionally, always check for readability of pipe we
# are using to wakeup processing thread by other threads
writefds = [c.user_context for c in writers]
timeout = None
if timers:
deadline = timers[0].deadline # 0 == next expiring timer
now = time.time()
timeout = 0 if deadline <= now else deadline - now
# adjust timeout for any deferred requests
timeout = self._schedule.get_delay(timeout)
results =, writefds, [], timeout)
except select.error as serror:
if serror[0] == errno.EINTR:
LOG.warning("ignoring interrupt from select(): %s",
raise # assuming fatal...
readable, writable, ignore = results
for r in readable:
self._schedule.process() # run any deferred requests
for t in timers:
if t.deadline > time.time():
for w in writable:
w.write()"eventloop thread exiting, container=%s",


@ -27,6 +27,7 @@ from oslo.messaging._drivers import impl_zmq
from oslo.messaging._drivers import matchmaker
from oslo.messaging._drivers import matchmaker_redis
from oslo.messaging._drivers import matchmaker_ring
from oslo.messaging._drivers.protocols.amqp import driver as amqp1_driver
from oslo.messaging._executors import impl_eventlet
from oslo.messaging.notify import notifier
from oslo.messaging.rpc import client
@ -41,7 +42,8 @@ _global_opt_lists = [
_opts = [


@ -31,6 +31,7 @@ oslo.messaging.drivers =
rabbit = oslo.messaging._drivers.impl_rabbit:RabbitDriver
qpid = oslo.messaging._drivers.impl_qpid:QpidDriver
zmq = oslo.messaging._drivers.impl_zmq:ZmqDriver
amqp = oslo.messaging._drivers.protocols.amqp:ProtonDriver
# To avoid confusion
kombu = oslo.messaging._drivers.impl_rabbit:RabbitDriver


@ -0,0 +1,654 @@
# Copyright (C) 2014 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
# 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 logging
import os
import select
import socket
import threading
import time
import uuid
from six import moves
import testtools
from oslo import messaging
from oslo.messaging._drivers.protocols.amqp import driver as amqp_driver
from oslo.messaging.openstack.common import importutils
from tests import utils as test_utils
# TODO(kgiusti) Conditionally run these tests only if the necessary
# dependencies are installed. This should be removed once the proton libraries
# are available in the base repos for all supported platforms.
pyngus = importutils.try_import("pyngus")
LOG = logging.getLogger(__name__)
class _ListenerThread(threading.Thread):
"""Run a blocking listener in a thread."""
def __init__(self, listener, msg_count):
super(_ListenerThread, self).__init__()
self.listener = listener
self.msg_count = msg_count
self.messages = moves.queue.Queue()
self.daemon = True
def run(self):"Listener started")
while self.msg_count > 0:
in_msg = self.listener.poll()
self.msg_count -= 1
if in_msg.message.get('method') == 'echo':
in_msg.message.get('id')})"Listener stopped")
def get_messages(self):
"""Returns a list of all received messages."""
msgs = []
while True:
m = self.messages.get(False)
except moves.queue.Empty:
return msgs
@testtools.skipUnless(pyngus, "proton modules not present")
class TestProtonDriverLoad(test_utils.BaseTestCase):
def setUp(self):
super(TestProtonDriverLoad, self).setUp()
self.messaging_conf.transport_driver = 'amqp'
def test_driver_load(self):
transport = messaging.get_transport(self.conf)
class _AmqpBrokerTestCase(test_utils.BaseTestCase):
@testtools.skipUnless(pyngus, "proton modules not present")
def setUp(self):"Starting Broker Test")
super(_AmqpBrokerTestCase, self).setUp()
self._broker = FakeBroker()
self._broker_addr = "amqp://%s:%d" % (,
self._broker_url = messaging.TransportURL.parse(self.conf,
def tearDown(self):
super(_AmqpBrokerTestCase, self).tearDown()
self._broker.stop()"Broker Test Ended")
class TestAmqpSend(_AmqpBrokerTestCase):
"""Test sending and receiving messages."""
def test_driver_unconnected_cleanup(self):
"""Verify the driver can cleanly shutdown even if never connected."""
driver = amqp_driver.ProtonDriver(self.conf, self._broker_url)
def test_listener_cleanup(self):
"""Verify unused listener can cleanly shutdown."""
driver = amqp_driver.ProtonDriver(self.conf, self._broker_url)
target = messaging.Target(topic="test-topic")
listener = driver.listen(target)
self.assertIsInstance(listener, amqp_driver.ProtonListener)
def test_send_no_reply(self):
driver = amqp_driver.ProtonDriver(self.conf, self._broker_url)
target = messaging.Target(topic="test-topic")
listener = _ListenerThread(driver.listen(target), 1)
rc = driver.send(target, {"context": True},
{"msg": "value"}, wait_for_reply=False)
self.assertEqual(listener.messages.get().message, {"msg": "value"})
def test_send_exchange_with_reply(self):
driver = amqp_driver.ProtonDriver(self.conf, self._broker_url)
target1 = messaging.Target(topic="test-topic", exchange="e1")
listener1 = _ListenerThread(driver.listen(target1), 1)
target2 = messaging.Target(topic="test-topic", exchange="e2")
listener2 = _ListenerThread(driver.listen(target2), 1)
rc = driver.send(target1, {"context": "whatever"},
{"method": "echo", "id": "e1"},
self.assertEqual(rc.get('correlation-id'), 'e1')
rc = driver.send(target2, {"context": "whatever"},
{"method": "echo", "id": "e2"},
self.assertEqual(rc.get('correlation-id'), 'e2')
def test_messaging_patterns(self):
"""Verify the direct, shared, and fanout message patterns work."""
driver = amqp_driver.ProtonDriver(self.conf, self._broker_url)
target1 = messaging.Target(topic="test-topic", server="server1")
listener1 = _ListenerThread(driver.listen(target1), 4)
target2 = messaging.Target(topic="test-topic", server="server2")
listener2 = _ListenerThread(driver.listen(target2), 3)
shared_target = messaging.Target(topic="test-topic")
fanout_target = messaging.Target(topic="test-topic",
# this should go to only one server:
driver.send(shared_target, {"context": "whatever"},
{"method": "echo", "id": "either-1"},
self.assertEqual(self._broker.topic_count, 1)
self.assertEqual(self._broker.direct_count, 1) # reply
# this should go to the other server:
driver.send(shared_target, {"context": "whatever"},
{"method": "echo", "id": "either-2"},
self.assertEqual(self._broker.topic_count, 2)
self.assertEqual(self._broker.direct_count, 2) # reply
# these should only go to listener1:
driver.send(target1, {"context": "whatever"},
{"method": "echo", "id": "server1-1"},
driver.send(target1, {"context": "whatever"},
{"method": "echo", "id": "server1-2"},
self.assertEqual(self._broker.direct_count, 6) # 2X(send+reply)
# this should only go to listener2:
driver.send(target2, {"context": "whatever"},
{"method": "echo", "id": "server2"},
self.assertEqual(self._broker.direct_count, 8)
# both listeners should get a copy:
driver.send(fanout_target, {"context": "whatever"},
{"method": "echo", "id": "fanout"})
self.assertEqual(self._broker.fanout_count, 1)
listener1_ids = [x.message.get('id') for x in listener1.get_messages()]
listener2_ids = [x.message.get('id') for x in listener2.get_messages()]
self.assertTrue('fanout' in listener1_ids and
'fanout' in listener2_ids)
self.assertTrue('server1-1' in listener1_ids and
'server1-1' not in listener2_ids)