oslo.messaging/oslo_messaging/_drivers/zmq_driver/server/consumers/zmq_sub_consumer.py

#    Copyright 2015 Mirantis, 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 logging
import threading
import uuid

import six

from oslo_messaging._drivers import base
from oslo_messaging._drivers.zmq_driver.server.consumers\
    import zmq_consumer_base
from oslo_messaging._drivers.zmq_driver import zmq_address
from oslo_messaging._drivers.zmq_driver import zmq_async
from oslo_messaging._drivers.zmq_driver import zmq_names
from oslo_messaging._drivers.zmq_driver import zmq_socket
from oslo_messaging._i18n import _LE

LOG = logging.getLogger(__name__)

zmq = zmq_async.import_zmq()


class SubIncomingMessage(base.IncomingMessage):

    def __init__(self, listener, request, socket, poller):
        super(SubIncomingMessage, self).__init__(
            listener, request.context, request.message)
        self.socket = socket
        self.msg_id = request.message_id
        poller.resume_polling(socket)

    def reply(self, reply=None, failure=None, log_failure=True):
        """Reply is not needed for non-call messages"""

    def acknowledge(self):
        LOG.debug("Not sending acknowledge for %s", self.msg_id)

    def requeue(self):
        """Requeue is not supported"""


class SubConsumer(zmq_consumer_base.ConsumerBase):

    def __init__(self, conf, poller, server):
        super(SubConsumer, self).__init__(conf, poller, server)
        self.matchmaker = server.matchmaker
        self.subscriptions = set()
        self.targets = []
        self._socket_lock = threading.Lock()
        self.socket = zmq_socket.ZmqSocket(self.context, zmq.SUB)
        self.sockets.append(self.socket)
        self.id = uuid.uuid4()
        self.publishers_poller = MatchmakerPoller(
            self.matchmaker, on_result=self.on_publishers)

    def _subscribe_on_target(self, target):
        topic_filter = zmq_address.target_to_subscribe_filter(target)
        if target.topic:
            self.socket.setsockopt(zmq.SUBSCRIBE, six.b(target.topic))
            self.subscriptions.add(six.b(target.topic))
        if target.server:
            self.socket.setsockopt(zmq.SUBSCRIBE, six.b(target.server))
            self.subscriptions.add(six.b(target.server))
        if target.topic and target.server:
            self.socket.setsockopt(zmq.SUBSCRIBE, topic_filter)
            self.subscriptions.add(topic_filter)

        LOG.debug("[%(host)s] Subscribing to topic %(filter)s",
                  {"host": self.id, "filter": topic_filter})

    def on_publishers(self, publishers):
        with self._socket_lock:
            for host, sync in publishers:
                self.socket.connect(zmq_address.get_tcp_direct_address(host))

            self.poller.register(self.socket, self.receive_message)
        LOG.debug("[%s] SUB consumer connected to publishers %s",
                  (self.id, publishers))

    def listen(self, target):
        LOG.debug("Listen to target %s", target)
        with self._socket_lock:
            self._subscribe_on_target(target)

    def _receive_request(self, socket):
        topic_filter = socket.recv()
        LOG.debug("[%(id)s] Received %(topict_filter)s topic",
                  {'id': self.id, 'topic_filter': topic_filter})
        assert topic_filter in self.subscriptions
        request = socket.recv_pyobj()
        return request

    def receive_message(self, socket):
        try:
            request = self._receive_request(socket)
            if not request:
                return None
            LOG.debug("Received %(type)s, %(id)s, %(target)s",
                      {"type": request.msg_type,
                       "id": request.message_id,
                       "target": request.target})

            if request.msg_type not in zmq_names.MULTISEND_TYPES:
                LOG.error(_LE("Unknown message type: %s"), request.msg_type)
            else:
                return SubIncomingMessage(self.server, request, socket,
                                          self.poller)
        except zmq.ZMQError as e:
            LOG.error(_LE("Receiving message failed: %s"), str(e))


class MatchmakerPoller(object):
    """This entity performs periodical async polling
    to the matchmaker if no hosts were registered for
    specified target before.
    """

    def __init__(self, matchmaker, on_result):
        self.matchmaker = matchmaker
        self.executor = zmq_async.get_executor(
            method=self._poll_for_publishers)
        self.on_result = on_result
        self.executor.execute()

    def _poll_for_publishers(self):
        publishers = self.matchmaker.get_publishers_retrying()
        if publishers:
            self.on_result(publishers)
            self.executor.done()


class BackChatter(object):

    def __init__(self, context):
        self.socket = zmq_socket.ZmqSocket(context, zmq.PUSH)

    def connect(self, address):
        self.socket.connect(address)

    def send_ready(self):
        for i in range(self.socket.connections_count()):
            self.socket.send(zmq_names.ACK_TYPE)

    def close(self):
        self.socket.setsockopt(zmq.LINGER, 5)
        self.socket.close()