fbee94170f
The key driver interfaces are implemented in the ProtonDriver class in driver.py. The logic for interfacing with Pyngus in order to send/receive messages, manage AMQP connections and links, and handle protocol events is in controller.py. eventloop.py is a fairly generic socket connection and I/O processor which runs in its own thread. controller.py uses the eventloop.py 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 pypi.python.org. 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
622 lines
25 KiB
Python
622 lines
25 KiB
Python
# Copyright 2014, Red Hat, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Controller that manages the interface between the driver and the messaging
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service.
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This module defines a Controller class that is responsible for performing
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messaging-related operations (Tasks) requested by the driver, and for managing
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the connection to the messaging service. The Controller creates a background
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thread which performs all messaging operations and socket I/O. The
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Controller's messaging logic is executed in the background thread via lambda
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functions scheduled by the Controller.
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"""
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import abc
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import collections
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import logging
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import threading
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import uuid
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import pyngus
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from six import moves
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from oslo.config import cfg
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from oslo.messaging._drivers.protocols.amqp import eventloop
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LOG = logging.getLogger(__name__)
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_amqp1_opts = [
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cfg.StrOpt('server_request_prefix',
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default='exclusive',
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help="address prefix used when sending to a specific server"),
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cfg.StrOpt('broadcast_prefix',
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default='broadcast',
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help="address prefix used when broadcasting to all servers"),
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cfg.StrOpt('group_request_prefix',
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default='unicast',
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help="address prefix when sending to any server in group"),
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cfg.StrOpt('container_name',
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default=None,
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help='Name for the AMQP container'),
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cfg.IntOpt('idle_timeout',
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default=0, # disabled
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help='Timeout for inactive connections (in seconds)'),
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cfg.BoolOpt('trace',
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default=False,
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help='Debug: dump AMQP frames to stdout'),
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cfg.StrOpt('ssl_ca_file',
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default='',
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help="CA certificate PEM file for verifing server certificate"),
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cfg.StrOpt('ssl_cert_file',
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default='',
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help='Identifying certificate PEM file to present to clients'),
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cfg.StrOpt('ssl_key_file',
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default='',
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help='Private key PEM file used to sign cert_file certificate'),
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cfg.StrOpt('ssl_key_password',
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default=None,
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help='Password for decrypting ssl_key_file (if encrypted)'),
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cfg.BoolOpt('allow_insecure_clients',
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default=False,
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help='Accept clients using either SSL or plain TCP')
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]
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class Task(object):
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"""Perform a messaging operation via the Controller."""
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@abc.abstractmethod
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def execute(self, controller):
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"""This method will be run on the eventloop thread."""
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class Replies(pyngus.ReceiverEventHandler):
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"""This is the receiving link for all reply messages. Messages are routed
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to the proper Listener's incoming queue using the correlation-id header in
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the message.
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"""
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def __init__(self, connection, on_ready):
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self._correlation = {} # map of correlation-id to response queue
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self._ready = False
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self._on_ready = on_ready
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self._receiver = connection.create_receiver("replies",
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event_handler=self)
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# capacity determines the maximum number of reply messages this link
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# can receive. As messages are received and credit is consumed, this
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# driver will 'top up' the credit back to max capacity. This number
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# should be large enough to avoid needlessly flow-controlling the
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# replies.
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self.capacity = 100 # TODO(kgiusti) guesstimate - make configurable
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self._credit = 0
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self._receiver.open()
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def ready(self):
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return self._ready
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def prepare_for_response(self, request, reply_queue):
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"""Apply a unique message identifier to this request message. This will
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be used to identify messages sent in reply. The identifier is placed
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in the 'id' field of the request message. It is expected that the
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identifier will appear in the 'correlation-id' field of the
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corresponding response message.
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"""
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request.id = uuid.uuid4().hex
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# reply is placed on reply_queue
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self._correlation[request.id] = reply_queue
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request.reply_to = self._receiver.source_address
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LOG.debug("Reply for msg id=%s expected on link %s",
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request.id, request.reply_to)
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# Pyngus ReceiverLink event callbacks:
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def receiver_active(self, receiver_link):
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"""This is a Pyngus callback, invoked by Pyngus when the receiver_link
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has transitioned to the open state and is able to receive incoming
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messages.
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"""
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self._ready = True
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self._update_credit()
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self._on_ready()
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LOG.debug("Replies expected on link %s",
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self._receiver.source_address)
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def receiver_remote_closed(self, receiver, pn_condition):
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"""This is a Pyngus callback, invoked by Pyngus when the peer of this
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receiver link has initiated closing the connection.
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"""
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# TODO(kgiusti) Unclear if this error will ever occur (as opposed to
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# the Connection failing instead). Log for now, possibly implement a
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# recovery strategy if necessary.
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LOG.error("Reply subscription closed by peer: %s",
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(pn_condition or "no error given"))
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def message_received(self, receiver, message, handle):
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"""This is a Pyngus callback, invoked by Pyngus when a new message
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arrives on this receiver link from the peer.
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"""
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self._credit = self._credit - 1
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self._update_credit()
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key = message.correlation_id
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if key in self._correlation:
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LOG.debug("Received response for msg id=%s", key)
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self._correlation[key].put(message)
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# cleanup (only need one response per request)
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del self._correlation[key]
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else:
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LOG.warn("Can't find receiver for response msg id=%s, dropping!",
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key)
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receiver.message_accepted(handle)
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def _update_credit(self):
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if self.capacity > self._credit:
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self._receiver.add_capacity(self.capacity - self._credit)
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self._credit = self.capacity
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class Server(pyngus.ReceiverEventHandler):
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"""A group of links that receive messages from a set of addresses derived
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from a given target. Messages arriving on the links are placed on the
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'incoming' queue.
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"""
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def __init__(self, addresses, incoming):
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self._incoming = incoming
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self._addresses = addresses
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def attach(self, connection):
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"""Create receiver links over the given connection for all the
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configured addresses.
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"""
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self._receivers = []
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for a in self._addresses:
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props = {"snd-settle-mode": "settled"}
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rname = "Consumer-%s:src=%s:tgt=%s" % (uuid.uuid4().hex, a, a)
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r = connection.create_receiver(source_address=a,
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target_address=a,
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event_handler=self,
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name=rname,
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properties=props)
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# TODO(kgiusti) Hardcoding credit here is sub-optimal. A better
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# approach would monitor for a back-up of inbound messages to be
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# processed by the consuming application and backpressure the
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# sender based on configured thresholds.
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r.add_capacity(500)
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r.open()
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self._receivers.append(r)
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# Pyngus ReceiverLink event callbacks:
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def receiver_remote_closed(self, receiver, pn_condition):
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"""This is a Pyngus callback, invoked by Pyngus when the peer of this
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receiver link has initiated closing the connection.
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"""
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text = "Server subscription %(addr)s closed by peer: %(err_msg)s"
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vals = {
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"addr": receiver.source_address or receiver.target_address,
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"err_msg": pn_condition or "no error given"
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}
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LOG.error(text % vals)
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def message_received(self, receiver, message, handle):
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"""This is a Pyngus callback, invoked by Pyngus when a new message
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arrives on this receiver link from the peer.
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"""
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# TODO(kgiusti) Sub-optimal to grant one credit each time a message
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# arrives. A better approach would grant batches of credit on demand.
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receiver.add_capacity(1)
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self._incoming.put(message)
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LOG.debug("message received: %s", message)
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receiver.message_accepted(handle)
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class Hosts(object):
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"""An order list of peer addresses. Connection failover progresses from
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one host to the next.
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"""
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HostnamePort = collections.namedtuple('HostnamePort',
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['hostname', 'port'])
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def __init__(self, entries=None):
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self._entries = [self.HostnamePort(h, p) for h, p in entries or []]
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self._current = 0
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def add(self, hostname, port=5672):
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self._entries.append(self.HostnamePort(hostname, port))
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@property
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def current(self):
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if len(self._entries):
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return self._entries[self._current]
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else:
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return self.HostnamePort("localhost", 5672)
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def next(self):
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if len(self._entries) > 1:
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self._current = (self._current + 1) % len(self._entries)
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return self.current
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def __repr__(self):
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return '<Hosts ' + str(self) + '>'
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def __str__(self):
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return ", ".join(["%s:%i" % e for e in self._entries])
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class Controller(pyngus.ConnectionEventHandler):
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"""Controls the connection to the AMQP messaging service. This object is
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the 'brains' of the driver. It maintains the logic for addressing, sending
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and receiving messages, and managing the connection. All messaging and I/O
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work is done on the Eventloop thread, allowing the driver to run
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asynchronously from the messaging clients.
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"""
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def __init__(self, hosts, default_exchange, config):
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self.processor = None
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# queue of Task() objects to execute on the eventloop once the
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# connection is ready:
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self._tasks = moves.queue.Queue(maxsize=500)
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# limit the number of Task()'s to execute per call to _process_tasks().
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# This allows the eventloop main thread to return to servicing socket
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# I/O in a timely manner
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self._max_task_batch = 50
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# cache of sending links indexed by address:
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self._senders = {}
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# Servers (set of receiving links), indexed by target:
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self._servers = {}
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self.hosts = Hosts(hosts)
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opt_group = cfg.OptGroup(name='amqp1',
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title='AMQP 1.0 options')
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config.register_group(opt_group)
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config.register_opts(_amqp1_opts, group=opt_group)
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self.server_request_prefix = config.amqp1.server_request_prefix
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self.broadcast_prefix = config.amqp1.broadcast_prefix
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self.group_request_prefix = config.amqp1.group_request_prefix
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self._container_name = config.amqp1.container_name
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if not self._container_name:
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self._container_name = "container-%s" % uuid.uuid4().hex
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self.idle_timeout = config.amqp1.idle_timeout
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self.trace_protocol = config.amqp1.trace
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self.ssl_ca_file = config.amqp1.ssl_ca_file
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self.ssl_cert_file = config.amqp1.ssl_cert_file
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self.ssl_key_file = config.amqp1.ssl_key_file
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self.ssl_key_password = config.amqp1.ssl_key_password
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self.ssl_allow_insecure = config.amqp1.allow_insecure_clients
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self.separator = "."
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self.fanout_qualifier = "all"
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self.default_exchange = default_exchange
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# can't handle a request until the replies link is active, as
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# we need the peer assigned address, so need to delay any
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# processing of task queue until this is done
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self._replies = None
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# Set True when the driver is shutting down
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self._closing = False
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# only schedule one outstanding reconnect attempt at a time
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self._reconnecting = False
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self._delay = 0 # seconds between retries
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# prevent queuing up multiple requests to run _process_tasks()
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self._process_tasks_scheduled = False
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self._process_tasks_lock = threading.Lock()
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def connect(self):
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"""Connect to the messaging service."""
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self.processor = eventloop.Thread(self._container_name)
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self.processor.wakeup(lambda: self._do_connect())
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def add_task(self, task):
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"""Add a Task for execution on processor thread."""
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self._tasks.put(task)
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self._schedule_task_processing()
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def destroy(self):
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"""Shutdown the messaging service."""
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if self.processor:
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self.processor.wakeup(lambda: self._start_shutdown())
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LOG.info("Waiting for eventloop to exit")
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self.processor.join()
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self.processor = None
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LOG.info("Eventloop exited, driver shut down")
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# The remaining methods are reserved to run from the eventloop thread only!
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# They must not be invoked directly!
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# methods executed by Tasks created by the driver:
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def request(self, target, request, reply_queue=None):
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"""Send a request message to the given target, and arrange for a
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response to be put on the optional reply_queue if specified
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"""
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address = self._resolve(target)
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LOG.debug("Sending request for %s to %s", target, address)
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if reply_queue is not None:
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self._replies.prepare_for_response(request, reply_queue)
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self._send(address, request)
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def response(self, address, response):
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LOG.debug("Sending response to %s", address)
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self._send(address, response)
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def subscribe(self, target, in_queue):
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"""Subscribe to messages sent to 'target', place received messages on
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'in_queue'.
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"""
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addresses = [
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self._server_address(target),
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self._broadcast_address(target),
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self._group_request_address(target)
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]
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self._subscribe(target, addresses, in_queue)
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def subscribe_notifications(self, target, in_queue):
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"""Subscribe for notifications on 'target', place received messages on
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'in_queue'.
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"""
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addresses = [self._group_request_address(target)]
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self._subscribe(target, addresses, in_queue)
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def _subscribe(self, target, addresses, in_queue):
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LOG.debug("Subscribing to %s (%s)", target, addresses)
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self._servers[target] = Server(addresses, in_queue)
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self._servers[target].attach(self._socket_connection.connection)
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def _resolve(self, target):
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"""Return a link address for a given target."""
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if target.server:
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return self._server_address(target)
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elif target.fanout:
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return self._broadcast_address(target)
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else:
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return self._group_request_address(target)
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def _sender(self, address):
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# if we already have a sender for that address, use it
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# else establish the sender and cache it
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if address in self._senders:
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sender = self._senders[address]
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else:
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sname = "Producer-%s:src=%s:tgt=%s" % (uuid.uuid4().hex,
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address, address)
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conn = self._socket_connection.connection
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sender = conn.create_sender(source_address=address,
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target_address=address,
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name=sname)
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sender.open()
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self._senders[address] = sender
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return sender
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def _send(self, addr, message):
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"""Send the message out the link addressed by 'addr'."""
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address = str(addr)
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message.address = address
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self._sender(address).send(message)
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def _server_address(self, target):
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return self._concatenate([self.server_request_prefix,
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target.exchange or self.default_exchange,
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target.topic, target.server])
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def _broadcast_address(self, target):
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return self._concatenate([self.broadcast_prefix,
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target.exchange or self.default_exchange,
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target.topic, self.fanout_qualifier])
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def _group_request_address(self, target):
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return self._concatenate([self.group_request_prefix,
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target.exchange or self.default_exchange,
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target.topic])
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def _concatenate(self, items):
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return self.separator.join(filter(bool, items))
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# commands executed on the processor (eventloop) via 'wakeup()':
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def _do_connect(self):
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"""Establish connection and reply subscription on processor thread."""
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hostname = self.hosts.current.hostname
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port = self.hosts.current.port
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conn_props = {}
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if self.idle_timeout:
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conn_props["idle-time-out"] = float(self.idle_timeout)
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if self.trace_protocol:
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conn_props["x-trace-protocol"] = self.trace_protocol
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if self.ssl_ca_file:
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conn_props["x-ssl-ca-file"] = self.ssl_ca_file
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if self.ssl_cert_file:
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# assume this connection is for a server. If client authentication
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# support is developed, we'll need an explict flag (server or
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# client)
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conn_props["x-ssl-server"] = True
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conn_props["x-ssl-identity"] = (self.ssl_cert_file,
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self.ssl_key_file,
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self.ssl_key_password)
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conn_props["x-ssl-allow-cleartext"] = self.ssl_allow_insecure
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self._socket_connection = self.processor.connect(hostname, port,
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handler=self,
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properties=conn_props)
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LOG.debug("Connection initiated")
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def _process_tasks(self):
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"""Execute Task objects in the context of the processor thread."""
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with self._process_tasks_lock:
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self._process_tasks_scheduled = False
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count = 0
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while (not self._tasks.empty() and
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count < self._max_task_batch and
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self._can_process_tasks):
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try:
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self._tasks.get(False).execute(self)
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except Exception as e:
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LOG.exception("Error processing task: %s", e)
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count += 1
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# if we hit _max_task_batch, resume task processing later:
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if not self._tasks.empty() and self._can_process_tasks:
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self._schedule_task_processing()
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def _schedule_task_processing(self):
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"""_process_tasks() helper: prevent queuing up multiple requests for
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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())
|
|
|
|
@property
|
|
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.
|
|
"""
|
|
LOG.info("Shutting down AMQP connection")
|
|
self._closing = True
|
|
if self._socket_connection.connection.active:
|
|
# try a clean shutdown
|
|
self._socket_connection.connection.close()
|
|
else:
|
|
# don't wait for a close from the remote, may never happen
|
|
self._complete_shutdown()
|
|
|
|
# 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).
|
|
"""
|
|
LOG.info("Messaging is active (%s:%i)", self.hosts.current.hostname,
|
|
self.hosts.current.port)
|
|
self._schedule_task_processing()
|
|
|
|
# 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)
|
|
self._handle_connection_loss()
|
|
|
|
# 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
|
|
return
|
|
LOG.debug("AMQP Connection failure: %s", error)
|
|
self._handle_connection_loss()
|
|
|
|
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():
|
|
s.attach(self._socket_connection.connection)
|
|
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
|
|
self._handle_connection_loss()
|
|
|
|
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).
|
|
LOG.info("Connection closed by peer: %s",
|
|
reason or "no reason given")
|
|
self._socket_connection.connection.close()
|
|
|
|
def _complete_shutdown(self):
|
|
"""The AMQP Connection has closed, and the driver shutdown is complete.
|
|
Clean up controller resources and exit.
|
|
"""
|
|
self._socket_connection.close()
|
|
self.processor.shutdown()
|
|
LOG.info("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:
|
|
self._complete_shutdown()
|
|
else:
|
|
# 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
|
|
self._do_reconnect()
|
|
else:
|
|
d = self._delay
|
|
LOG.info("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 = {}
|
|
self._socket_connection.reset()
|
|
hostname, port = self.hosts.next()
|
|
LOG.info("Reconnecting to: %s:%i", hostname, port)
|
|
self._socket_connection.connect(hostname, port)
|