oslo.messaging/oslo_messaging/_drivers/base.py
Davanum Srinivas fb73297112 Fix Notification listener blocking behavior
Add a sleep() to allow other threads (like the one collecting
the stats) to run.

Closes-Bug: #1555632
Change-Id: I6fcb63c10acd76f2815e23fbd303f08974feb993
2016-03-11 12:15:52 -05:00

153 lines
4.5 KiB
Python

# Copyright 2013 Red Hat, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import abc
import time
from oslo_config import cfg
from oslo_utils import timeutils
import six
from six.moves import range as compat_range
from oslo_messaging import exceptions
base_opts = [
cfg.IntOpt('rpc_conn_pool_size',
default=30,
deprecated_group='DEFAULT',
help='Size of RPC connection pool.'),
]
def batch_poll_helper(func):
"""Decorator to poll messages in batch
This decorator helps driver that polls message one by one,
to returns a list of message.
"""
def wrapper(in_self, timeout=None, prefetch_size=1):
incomings = []
driver_prefetch = in_self.prefetch_size
if driver_prefetch > 0:
prefetch_size = min(prefetch_size, driver_prefetch)
watch = timeutils.StopWatch(duration=timeout)
with watch:
for __ in compat_range(prefetch_size):
msg = func(in_self, timeout=watch.leftover(return_none=True))
if msg is not None:
incomings.append(msg)
else:
# timeout reached or listener stopped
break
time.sleep(0)
return incomings
return wrapper
class TransportDriverError(exceptions.MessagingException):
"""Base class for transport driver specific exceptions."""
@six.add_metaclass(abc.ABCMeta)
class IncomingMessage(object):
def __init__(self, ctxt, message):
self.ctxt = ctxt
self.message = message
def acknowledge(self):
"Acknowledge the message."
@abc.abstractmethod
def requeue(self):
"Requeue the message."
@six.add_metaclass(abc.ABCMeta)
class RpcIncomingMessage(IncomingMessage):
@abc.abstractmethod
def reply(self, reply=None, failure=None, log_failure=True):
"Send a reply or failure back to the client."
@six.add_metaclass(abc.ABCMeta)
class Listener(object):
def __init__(self, prefetch_size=-1):
self.prefetch_size = prefetch_size
@abc.abstractmethod
def poll(self, timeout=None, prefetch_size=1):
"""Blocking until 'prefetch_size' message is pending and return
[IncomingMessage].
Return None after timeout seconds if timeout is set and no message is
ending or if the listener have been stopped.
"""
def stop(self):
"""Stop listener.
Stop the listener message polling
"""
pass
def cleanup(self):
"""Cleanup listener.
Close connection (socket) used by listener if any.
As this is listener specific method, overwrite it in to derived class
if cleanup of listener required.
"""
pass
@six.add_metaclass(abc.ABCMeta)
class BaseDriver(object):
prefetch_size = 0
def __init__(self, conf, url,
default_exchange=None, allowed_remote_exmods=None):
self.conf = conf
self._url = url
self._default_exchange = default_exchange
self._allowed_remote_exmods = allowed_remote_exmods or []
def require_features(self, requeue=False):
if requeue:
raise NotImplementedError('Message requeueing not supported by '
'this transport driver')
@abc.abstractmethod
def send(self, target, ctxt, message,
wait_for_reply=None, timeout=None, envelope=False):
"""Send a message to the given target."""
@abc.abstractmethod
def send_notification(self, target, ctxt, message, version):
"""Send a notification message to the given target."""
@abc.abstractmethod
def listen(self, target):
"""Construct a Listener for the given target."""
@abc.abstractmethod
def listen_for_notifications(self, targets_and_priorities, pool):
"""Construct a notification Listener for the given list of
tuple of (target, priority).
"""
@abc.abstractmethod
def cleanup(self):
"""Release all resources."""