d873c0d8f5
Waiting on a threading.Event with eventlet can cause busy looping via epoll_wait, see related bug for more details. Change-Id: I007613058a2d21d1712c02fa6d1602b63705c1ab Related-bug: #1518430
288 lines
10 KiB
Python
288 lines
10 KiB
Python
# Copyright 2010 United States Government as represented by the
|
|
# Administrator of the National Aeronautics and Space Administration.
|
|
# All Rights Reserved.
|
|
# Copyright 2013 Red Hat, Inc.
|
|
# Copyright 2013 New Dream Network, LLC (DreamHost)
|
|
#
|
|
# 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.
|
|
|
|
from abc import ABCMeta
|
|
from abc import abstractmethod
|
|
import logging
|
|
import sys
|
|
import threading
|
|
|
|
import six
|
|
|
|
from oslo_utils import eventletutils
|
|
|
|
from oslo_messaging import _utils as utils
|
|
from oslo_messaging import dispatcher
|
|
from oslo_messaging import serializer as msg_serializer
|
|
from oslo_messaging import server as msg_server
|
|
from oslo_messaging import target as msg_target
|
|
|
|
__all__ = [
|
|
'NoSuchMethod',
|
|
'RPCAccessPolicyBase',
|
|
'LegacyRPCAccessPolicy',
|
|
'DefaultRPCAccessPolicy',
|
|
'ExplicitRPCAccessPolicy',
|
|
'RPCDispatcher',
|
|
'RPCDispatcherError',
|
|
'UnsupportedVersion',
|
|
'ExpectedException',
|
|
]
|
|
|
|
LOG = logging.getLogger(__name__)
|
|
|
|
|
|
class ExpectedException(Exception):
|
|
"""Encapsulates an expected exception raised by an RPC endpoint
|
|
|
|
Merely instantiating this exception records the current exception
|
|
information, which will be passed back to the RPC client without
|
|
exceptional logging.
|
|
"""
|
|
def __init__(self):
|
|
self.exc_info = sys.exc_info()
|
|
|
|
|
|
class RPCDispatcherError(msg_server.MessagingServerError):
|
|
"A base class for all RPC dispatcher exceptions."
|
|
|
|
|
|
class NoSuchMethod(RPCDispatcherError, AttributeError):
|
|
"Raised if there is no endpoint which exposes the requested method."
|
|
|
|
def __init__(self, method):
|
|
msg = "Endpoint does not support RPC method %s" % method
|
|
super(NoSuchMethod, self).__init__(msg)
|
|
self.method = method
|
|
|
|
|
|
class UnsupportedVersion(RPCDispatcherError):
|
|
"Raised if there is no endpoint which supports the requested version."
|
|
|
|
def __init__(self, version, method=None):
|
|
msg = "Endpoint does not support RPC version %s" % version
|
|
if method:
|
|
msg = "%s. Attempted method: %s" % (msg, method)
|
|
super(UnsupportedVersion, self).__init__(msg)
|
|
self.version = version
|
|
self.method = method
|
|
|
|
|
|
@six.add_metaclass(ABCMeta)
|
|
class RPCAccessPolicyBase(object):
|
|
"""Determines which endpoint methods may be invoked via RPC"""
|
|
|
|
@abstractmethod
|
|
def is_allowed(self, endpoint, method):
|
|
"""Applies an access policy to the rpc method
|
|
:param endpoint: the instance of a rpc endpoint
|
|
:param method: the method of the endpoint
|
|
:return: True if the method may be invoked via RPC, else False.
|
|
"""
|
|
|
|
|
|
class LegacyRPCAccessPolicy(RPCAccessPolicyBase):
|
|
"""The legacy access policy allows RPC access to all callable endpoint
|
|
methods including private methods (methods prefixed by '_')
|
|
"""
|
|
|
|
def is_allowed(self, endpoint, method):
|
|
return True
|
|
|
|
|
|
class DefaultRPCAccessPolicy(RPCAccessPolicyBase):
|
|
"""The default access policy prevents RPC calls to private methods
|
|
(methods prefixed by '_')
|
|
|
|
.. note::
|
|
|
|
LegacyRPCAdapterPolicy currently needs to be the default while we have
|
|
projects that rely on exposing private methods.
|
|
|
|
"""
|
|
|
|
def is_allowed(self, endpoint, method):
|
|
return not method.startswith('_')
|
|
|
|
|
|
class ExplicitRPCAccessPolicy(RPCAccessPolicyBase):
|
|
"""Policy which requires decorated endpoint methods to allow dispatch"""
|
|
|
|
def is_allowed(self, endpoint, method):
|
|
if hasattr(endpoint, method):
|
|
return hasattr(getattr(endpoint, method), 'exposed')
|
|
return False
|
|
|
|
|
|
class RPCDispatcher(dispatcher.DispatcherBase):
|
|
"""A message dispatcher which understands RPC messages.
|
|
|
|
A MessageHandlingServer is constructed by passing a callable dispatcher
|
|
which is invoked with context and message dictionaries each time a message
|
|
is received.
|
|
|
|
RPCDispatcher is one such dispatcher which understands the format of RPC
|
|
messages. The dispatcher looks at the namespace, version and method values
|
|
in the message and matches those against a list of available endpoints.
|
|
|
|
Endpoints may have a target attribute describing the namespace and version
|
|
of the methods exposed by that object.
|
|
|
|
The RPCDispatcher may have an access_policy attribute which determines
|
|
which of the endpoint methods are to be dispatched.
|
|
The default access_policy dispatches all public methods
|
|
on an endpoint object.
|
|
|
|
|
|
"""
|
|
def __init__(self, endpoints, serializer, access_policy=None):
|
|
"""Construct a rpc server dispatcher.
|
|
|
|
:param endpoints: list of endpoint objects for dispatching to
|
|
:param serializer: optional message serializer
|
|
"""
|
|
|
|
for ep in endpoints:
|
|
target = getattr(ep, 'target', None)
|
|
if target and not isinstance(target, msg_target.Target):
|
|
errmsg = "'target' is a reserved Endpoint attribute used" + \
|
|
" for namespace and version filtering. It must" + \
|
|
" be of type oslo_messaging.Target. Do not" + \
|
|
" define an Endpoint method named 'target'"
|
|
raise TypeError("%s: endpoint=%s" % (errmsg, ep))
|
|
|
|
self.endpoints = endpoints
|
|
self.serializer = serializer or msg_serializer.NoOpSerializer()
|
|
self._default_target = msg_target.Target()
|
|
if access_policy is not None:
|
|
if issubclass(access_policy, RPCAccessPolicyBase):
|
|
self.access_policy = access_policy()
|
|
else:
|
|
raise TypeError('access_policy must be a subclass of '
|
|
'RPCAccessPolicyBase')
|
|
else:
|
|
self.access_policy = DefaultRPCAccessPolicy()
|
|
|
|
@staticmethod
|
|
def _is_namespace(target, namespace):
|
|
return namespace in target.accepted_namespaces
|
|
|
|
@staticmethod
|
|
def _is_compatible(target, version):
|
|
endpoint_version = target.version or '1.0'
|
|
return utils.version_is_compatible(endpoint_version, version)
|
|
|
|
def _do_dispatch(self, endpoint, method, ctxt, args):
|
|
ctxt = self.serializer.deserialize_context(ctxt)
|
|
new_args = dict()
|
|
for argname, arg in args.items():
|
|
new_args[argname] = self.serializer.deserialize_entity(ctxt, arg)
|
|
func = getattr(endpoint, method)
|
|
result = func(ctxt, **new_args)
|
|
return self.serializer.serialize_entity(ctxt, result)
|
|
|
|
def _watchdog(self, event, incoming):
|
|
# NOTE(danms): If the client declared that they are going to
|
|
# time out after N seconds, send the call-monitor heartbeat
|
|
# every N/2 seconds to make sure there is plenty of time to
|
|
# account for inbound and outbound queuing delays. Client
|
|
# timeouts must be integral and positive, otherwise we log and
|
|
# ignore.
|
|
try:
|
|
client_timeout = int(incoming.client_timeout)
|
|
cm_heartbeat_interval = client_timeout / 2
|
|
except ValueError:
|
|
client_timeout = cm_heartbeat_interval = 0
|
|
|
|
if cm_heartbeat_interval < 1:
|
|
LOG.warning('Client provided an invalid timeout value of %r' % (
|
|
incoming.client_timeout))
|
|
return
|
|
|
|
while not event.wait(cm_heartbeat_interval):
|
|
LOG.debug(
|
|
'Sending call-monitor heartbeat for active call to %(method)s '
|
|
'(interval=%(interval)i)' % (
|
|
{'method': incoming.message.get('method'),
|
|
'interval': cm_heartbeat_interval}))
|
|
try:
|
|
incoming.heartbeat()
|
|
except Exception as exc:
|
|
# The heartbeat message failed to send. Likely the broker or
|
|
# client has died. Nothing to do here but exit the watchdog
|
|
# thread. If the client is still alive (dead broker) then its
|
|
# RPC will timeout as expected.
|
|
LOG.debug("Call-monitor heartbeat failed: %(exc)s"
|
|
% ({'exc': exc}))
|
|
break
|
|
|
|
def dispatch(self, incoming):
|
|
"""Dispatch an RPC message to the appropriate endpoint method.
|
|
|
|
:param incoming: incoming message
|
|
:type incoming: IncomingMessage
|
|
:raises: NoSuchMethod, UnsupportedVersion
|
|
"""
|
|
message = incoming.message
|
|
ctxt = incoming.ctxt
|
|
|
|
method = message.get('method')
|
|
args = message.get('args', {})
|
|
namespace = message.get('namespace')
|
|
version = message.get('version', '1.0')
|
|
|
|
# NOTE(danms): This event and watchdog thread are used to send
|
|
# call-monitoring heartbeats for this message while the call
|
|
# is executing if it runs for some time. The thread will wait
|
|
# for the event to be signaled, which we do explicitly below
|
|
# after dispatching the method call.
|
|
completion_event = eventletutils.Event()
|
|
watchdog_thread = threading.Thread(target=self._watchdog,
|
|
args=(completion_event, incoming))
|
|
if incoming.client_timeout:
|
|
# NOTE(danms): The client provided a timeout, so we start
|
|
# the watchdog thread. If the client is old or didn't send
|
|
# a timeout, we just never start the watchdog thread.
|
|
watchdog_thread.start()
|
|
|
|
found_compatible = False
|
|
for endpoint in self.endpoints:
|
|
target = getattr(endpoint, 'target', None)
|
|
if not target:
|
|
target = self._default_target
|
|
|
|
if not (self._is_namespace(target, namespace) and
|
|
self._is_compatible(target, version)):
|
|
continue
|
|
|
|
if hasattr(endpoint, method):
|
|
if self.access_policy.is_allowed(endpoint, method):
|
|
try:
|
|
return self._do_dispatch(endpoint, method, ctxt, args)
|
|
finally:
|
|
completion_event.set()
|
|
if incoming.client_timeout:
|
|
watchdog_thread.join()
|
|
|
|
found_compatible = True
|
|
|
|
if found_compatible:
|
|
raise NoSuchMethod(method)
|
|
else:
|
|
raise UnsupportedVersion(version, method=method)
|