533 lines
18 KiB
Python
533 lines
18 KiB
Python
# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# All Rights Reserved.
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# Copyright 2011 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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import collections
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import copy
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import logging
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import sys
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import traceback
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from oslo_serialization import jsonutils
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from oslo_utils import timeutils
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import six
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import oslo_messaging
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from oslo_messaging._i18n import _
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from oslo_messaging._i18n import _LE, _LW
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from oslo_messaging import _utils as utils
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LOG = logging.getLogger(__name__)
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_EXCEPTIONS_MODULE = 'exceptions' if six.PY2 else 'builtins'
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_EXCEPTIONS_MODULES = ['exceptions', 'builtins']
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'''RPC Envelope Version.
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This version number applies to the top level structure of messages sent out.
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It does *not* apply to the message payload, which must be versioned
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independently. For example, when using rpc APIs, a version number is applied
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for changes to the API being exposed over rpc. This version number is handled
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in the rpc proxy and dispatcher modules.
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This version number applies to the message envelope that is used in the
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serialization done inside the rpc layer. See serialize_msg() and
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deserialize_msg().
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The current message format (version 2.0) is very simple. It is:
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{
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'oslo.version': <RPC Envelope Version as a String>,
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'oslo.message': <Application Message Payload, JSON encoded>
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}
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Message format version '1.0' is just considered to be the messages we sent
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without a message envelope.
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So, the current message envelope just includes the envelope version. It may
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eventually contain additional information, such as a signature for the message
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payload.
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We will JSON encode the application message payload. The message envelope,
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which includes the JSON encoded application message body, will be passed down
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to the messaging libraries as a dict.
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'''
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_RPC_ENVELOPE_VERSION = '2.0'
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_VERSION_KEY = 'oslo.version'
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_MESSAGE_KEY = 'oslo.message'
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_REMOTE_POSTFIX = '_Remote'
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class RPCException(Exception):
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msg_fmt = _("An unknown RPC related exception occurred.")
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def __init__(self, message=None, **kwargs):
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self.kwargs = kwargs
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if not message:
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try:
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message = self.msg_fmt % kwargs
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except Exception:
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# kwargs doesn't match a variable in the message
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# log the issue and the kwargs
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LOG.exception(_LE('Exception in string format operation, '
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'kwargs are:'))
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for name, value in kwargs.items():
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LOG.error("%s: %s", name, value)
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# at least get the core message out if something happened
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message = self.msg_fmt
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super(RPCException, self).__init__(message)
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class Timeout(RPCException):
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"""Signifies that a timeout has occurred.
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This exception is raised if the rpc_response_timeout is reached while
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waiting for a response from the remote side.
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"""
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msg_fmt = _('Timeout while waiting on RPC response - '
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'topic: "%(topic)s", RPC method: "%(method)s" '
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'info: "%(info)s"')
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def __init__(self, info=None, topic=None, method=None):
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"""Initiates Timeout object.
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:param info: Extra info to convey to the user
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:param topic: The topic that the rpc call was sent to
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:param method: The name of the rpc method being
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called
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"""
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self.info = info
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self.topic = topic
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self.method = method
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super(Timeout, self).__init__(
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None,
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info=info or _('<unknown>'),
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topic=topic or _('<unknown>'),
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method=method or _('<unknown>'))
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class DuplicateMessageError(RPCException):
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msg_fmt = _("Found duplicate message(%(msg_id)s). Skipping it.")
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class InvalidRPCConnectionReuse(RPCException):
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msg_fmt = _("Invalid reuse of an RPC connection.")
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class UnsupportedRpcVersion(RPCException):
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msg_fmt = _("Specified RPC version, %(version)s, not supported by "
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"this endpoint.")
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class UnsupportedRpcEnvelopeVersion(RPCException):
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msg_fmt = _("Specified RPC envelope version, %(version)s, "
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"not supported by this endpoint.")
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class RpcVersionCapError(RPCException):
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msg_fmt = _("Specified RPC version cap, %(version_cap)s, is too low")
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class Connection(object):
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"""A connection, returned by rpc.create_connection().
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This class represents a connection to the message bus used for rpc.
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An instance of this class should never be created by users of the rpc API.
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Use rpc.create_connection() instead.
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"""
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def close(self):
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"""Close the connection.
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This method must be called when the connection will no longer be used.
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It will ensure that any resources associated with the connection, such
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as a network connection, and cleaned up.
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"""
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raise NotImplementedError()
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def serialize_remote_exception(failure_info):
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"""Prepares exception data to be sent over rpc.
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Failure_info should be a sys.exc_info() tuple.
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"""
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tb = traceback.format_exception(*failure_info)
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failure = failure_info[1]
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kwargs = {}
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if hasattr(failure, 'kwargs'):
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kwargs = failure.kwargs
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# NOTE(matiu): With cells, it's possible to re-raise remote, remote
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# exceptions. Lets turn it back into the original exception type.
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cls_name = six.text_type(failure.__class__.__name__)
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mod_name = six.text_type(failure.__class__.__module__)
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if (cls_name.endswith(_REMOTE_POSTFIX) and
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mod_name.endswith(_REMOTE_POSTFIX)):
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cls_name = cls_name[:-len(_REMOTE_POSTFIX)]
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mod_name = mod_name[:-len(_REMOTE_POSTFIX)]
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data = {
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'class': cls_name,
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'module': mod_name,
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'message': six.text_type(failure),
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'tb': tb,
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'args': failure.args,
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'kwargs': kwargs
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}
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json_data = jsonutils.dumps(data)
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return json_data
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def deserialize_remote_exception(data, allowed_remote_exmods):
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failure = jsonutils.loads(six.text_type(data))
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trace = failure.get('tb', [])
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message = failure.get('message', "") + "\n" + "\n".join(trace)
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name = failure.get('class')
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module = failure.get('module')
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# the remote service which raised the given exception might have a
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# different python version than the caller. For example, the caller might
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# run python 2.7, while the remote service might run python 3.4. Thus,
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# the exception module will be "builtins" instead of "exceptions".
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if module in _EXCEPTIONS_MODULES:
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module = _EXCEPTIONS_MODULE
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# NOTE(ameade): We DO NOT want to allow just any module to be imported, in
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# order to prevent arbitrary code execution.
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if module != _EXCEPTIONS_MODULE and module not in allowed_remote_exmods:
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return oslo_messaging.RemoteError(name, failure.get('message'), trace)
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try:
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__import__(module)
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mod = sys.modules[module]
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klass = getattr(mod, name)
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if not issubclass(klass, Exception):
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raise TypeError("Can only deserialize Exceptions")
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failure = klass(*failure.get('args', []), **failure.get('kwargs', {}))
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except (AttributeError, TypeError, ImportError) as error:
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LOG.warning(_LW("Failed to rebuild remote exception due to error: %s"),
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six.text_type(error))
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return oslo_messaging.RemoteError(name, failure.get('message'), trace)
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ex_type = type(failure)
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str_override = lambda self: message
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new_ex_type = type(ex_type.__name__ + _REMOTE_POSTFIX, (ex_type,),
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{'__str__': str_override, '__unicode__': str_override})
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new_ex_type.__module__ = '%s%s' % (module, _REMOTE_POSTFIX)
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try:
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# NOTE(ameade): Dynamically create a new exception type and swap it in
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# as the new type for the exception. This only works on user defined
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# Exceptions and not core Python exceptions. This is important because
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# we cannot necessarily change an exception message so we must override
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# the __str__ method.
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failure.__class__ = new_ex_type
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except TypeError:
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# NOTE(ameade): If a core exception then just add the traceback to the
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# first exception argument.
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failure.args = (message,) + failure.args[1:]
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return failure
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class CommonRpcContext(object):
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def __init__(self, **kwargs):
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self.values = kwargs
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def __getattr__(self, key):
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try:
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return self.values[key]
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except KeyError:
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raise AttributeError(key)
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def to_dict(self):
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return copy.deepcopy(self.values)
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@classmethod
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def from_dict(cls, values):
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return cls(**values)
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def deepcopy(self):
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return self.from_dict(self.to_dict())
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def update_store(self):
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# local.store.context = self
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pass
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class ClientException(Exception):
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"""Encapsulates actual exception expected to be hit by a RPC proxy object.
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Merely instantiating it records the current exception information, which
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will be passed back to the RPC client without exceptional logging.
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"""
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def __init__(self):
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self._exc_info = sys.exc_info()
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def serialize_msg(raw_msg):
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# NOTE(russellb) See the docstring for _RPC_ENVELOPE_VERSION for more
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# information about this format.
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msg = {_VERSION_KEY: _RPC_ENVELOPE_VERSION,
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_MESSAGE_KEY: jsonutils.dumps(raw_msg)}
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return msg
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def deserialize_msg(msg):
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# NOTE(russellb): Hang on to your hats, this road is about to
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# get a little bumpy.
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#
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# Robustness Principle:
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# "Be strict in what you send, liberal in what you accept."
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#
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# At this point we have to do a bit of guessing about what it
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# is we just received. Here is the set of possibilities:
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#
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# 1) We received a dict. This could be 2 things:
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#
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# a) Inspect it to see if it looks like a standard message envelope.
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# If so, great!
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#
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# b) If it doesn't look like a standard message envelope, it could either
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# be a notification, or a message from before we added a message
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# envelope (referred to as version 1.0).
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# Just return the message as-is.
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#
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# 2) It's any other non-dict type. Just return it and hope for the best.
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# This case covers return values from rpc.call() from before message
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# envelopes were used. (messages to call a method were always a dict)
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if not isinstance(msg, dict):
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# See #2 above.
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return msg
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base_envelope_keys = (_VERSION_KEY, _MESSAGE_KEY)
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if not all(map(lambda key: key in msg, base_envelope_keys)):
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# See #1.b above.
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return msg
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# At this point we think we have the message envelope
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# format we were expecting. (#1.a above)
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if not utils.version_is_compatible(_RPC_ENVELOPE_VERSION,
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msg[_VERSION_KEY]):
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raise UnsupportedRpcEnvelopeVersion(version=msg[_VERSION_KEY])
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raw_msg = jsonutils.loads(msg[_MESSAGE_KEY])
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return raw_msg
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class DecayingTimer(object):
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def __init__(self, duration=None):
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self._watch = timeutils.StopWatch(duration=duration)
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def start(self):
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self._watch.start()
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def restart(self):
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self._watch.restart()
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def check_return(self, timeout_callback=None, *args, **kwargs):
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maximum = kwargs.pop('maximum', None)
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left = self._watch.leftover(return_none=True)
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if left is None:
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return maximum
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if left <= 0 and timeout_callback is not None:
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timeout_callback(*args, **kwargs)
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return left if maximum is None else min(left, maximum)
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# NOTE(sileht): Even if rabbit has only one Connection class,
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# this connection can be used for two purposes:
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# * wait and receive amqp messages (only do read stuffs on the socket)
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# * send messages to the broker (only do write stuffs on the socket)
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# The code inside a connection class is not concurrency safe.
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# Using one Connection class instance for doing both, will result
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# of eventlet complaining of multiple greenthreads that read/write the
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# same fd concurrently... because 'send' and 'listen' run in different
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# greenthread.
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# So, a connection cannot be shared between thread/greenthread and
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# this two variables permit to define the purpose of the connection
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# to allow drivers to add special handling if needed (like heatbeat).
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# amqp drivers create 3 kind of connections:
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# * driver.listen*(): each call create a new 'PURPOSE_LISTEN' connection
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# * driver.send*(): a pool of 'PURPOSE_SEND' connections is used
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# * driver internally have another 'PURPOSE_LISTEN' connection dedicated
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# to wait replies of rpc call
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PURPOSE_LISTEN = 'listen'
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PURPOSE_SEND = 'send'
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class ConnectionContext(Connection):
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"""The class that is actually returned to the create_connection() caller.
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This is essentially a wrapper around Connection that supports 'with'.
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It can also return a new Connection, or one from a pool.
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The function will also catch when an instance of this class is to be
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deleted. With that we can return Connections to the pool on exceptions
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and so forth without making the caller be responsible for catching them.
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If possible the function makes sure to return a connection to the pool.
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"""
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def __init__(self, connection_pool, purpose):
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"""Create a new connection, or get one from the pool."""
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self.connection = None
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self.connection_pool = connection_pool
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pooled = purpose == PURPOSE_SEND
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if pooled:
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self.connection = connection_pool.get()
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else:
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# a non-pooled connection is requested, so create a new connection
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self.connection = connection_pool.create(purpose)
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self.pooled = pooled
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self.connection.pooled = pooled
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def __enter__(self):
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"""When with ConnectionContext() is used, return self."""
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return self
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def _done(self):
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"""If the connection came from a pool, clean it up and put it back.
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If it did not come from a pool, close it.
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"""
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if self.connection:
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if self.pooled:
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# Reset the connection so it's ready for the next caller
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# to grab from the pool
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try:
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self.connection.reset()
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except Exception:
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LOG.exception(_LE("Fail to reset the connection, drop it"))
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try:
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self.connection.close()
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except Exception as exc:
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LOG.debug("pooled conn close failure (ignored): %s",
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str(exc))
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self.connection = self.connection_pool.create()
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finally:
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self.connection_pool.put(self.connection)
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else:
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try:
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self.connection.close()
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except Exception as exc:
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LOG.debug("pooled conn close failure (ignored): %s",
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str(exc))
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self.connection = None
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def __exit__(self, exc_type, exc_value, tb):
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"""End of 'with' statement. We're done here."""
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self._done()
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def __del__(self):
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"""Caller is done with this connection. Make sure we cleaned up."""
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self._done()
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def close(self):
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"""Caller is done with this connection."""
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self._done()
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def __getattr__(self, key):
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"""Proxy all other calls to the Connection instance."""
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if self.connection:
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return getattr(self.connection, key)
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else:
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raise InvalidRPCConnectionReuse()
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class ConfigOptsProxy(collections.Mapping):
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"""Proxy for oslo_config.cfg.ConfigOpts.
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Values from the query part of the transport url (if they are both present
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and valid) override corresponding values from the configuration.
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"""
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def __init__(self, conf, url, group):
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self._conf = conf
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self._url = url
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self._group = group
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self._validate_query()
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def _validate_query(self):
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for name in self._url.query:
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self.GroupAttrProxy(self._conf, self._group,
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self._conf[self._group],
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self._url)[name]
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def __getattr__(self, name):
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value = getattr(self._conf, name)
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if isinstance(value, self._conf.GroupAttr) and name == self._group:
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return self.GroupAttrProxy(self._conf, name, value, self._url)
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return value
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def __getitem__(self, name):
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return self.__getattr__(name)
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def __contains__(self, name):
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return name in self._conf
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def __iter__(self):
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return iter(self._conf)
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def __len__(self):
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return len(self._conf)
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class GroupAttrProxy(collections.Mapping):
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"""Internal helper proxy for oslo_config.cfg.ConfigOpts.GroupAttr."""
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_VOID_MARKER = object()
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def __init__(self, conf, group_name, group, url):
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self._conf = conf
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self._group_name = group_name
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self._group = group
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self._url = url
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def __getattr__(self, opt_name):
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# Make sure that the group has this specific option
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opt_value_conf = getattr(self._group, opt_name)
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# If the option is also present in the url and has a valid
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# (i.e. convertible) value type, then try to override it
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opt_value_url = self._url.query.get(opt_name, self._VOID_MARKER)
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if opt_value_url is self._VOID_MARKER:
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return opt_value_conf
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opt_info = self._conf._get_opt_info(opt_name, self._group_name)
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return opt_info['opt'].type(opt_value_url)
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def __getitem__(self, opt_name):
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return self.__getattr__(opt_name)
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def __contains__(self, opt_name):
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return opt_name in self._group
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def __iter__(self):
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return iter(self._group)
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def __len__(self):
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return len(self._group)
|