root / lib / rpc / client.py @ c4071978
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# Copyright (C) 2013 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""Module for generic RPC clients.
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"""
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import logging |
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import ganeti.rpc.transport as t |
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from ganeti import constants |
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from ganeti import errors |
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from ganeti.rpc.errors import (ProtocolError, RequestError, LuxiError) |
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from ganeti import serializer |
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KEY_METHOD = constants.LUXI_KEY_METHOD |
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KEY_ARGS = constants.LUXI_KEY_ARGS |
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KEY_SUCCESS = constants.LUXI_KEY_SUCCESS |
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KEY_RESULT = constants.LUXI_KEY_RESULT |
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KEY_VERSION = constants.LUXI_KEY_VERSION |
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def ParseRequest(msg): |
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"""Parses a request message.
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"""
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try:
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request = serializer.LoadJson(msg) |
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except ValueError, err: |
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raise ProtocolError("Invalid RPC request (parsing error): %s" % err) |
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logging.debug("RPC request: %s", request)
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if not isinstance(request, dict): |
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logging.error("RPC request not a dict: %r", msg)
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raise ProtocolError("Invalid RPC request (not a dict)") |
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method = request.get(KEY_METHOD, None) # pylint: disable=E1103 |
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args = request.get(KEY_ARGS, None) # pylint: disable=E1103 |
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version = request.get(KEY_VERSION, None) # pylint: disable=E1103 |
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if method is None or args is None: |
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logging.error("RPC request missing method or arguments: %r", msg)
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raise ProtocolError(("Invalid RPC request (no method or arguments" |
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" in request): %r") % msg)
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return (method, args, version)
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def ParseResponse(msg): |
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"""Parses a response message.
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"""
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# Parse the result
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try:
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data = serializer.LoadJson(msg) |
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except KeyboardInterrupt: |
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raise
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except Exception, err: |
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raise ProtocolError("Error while deserializing response: %s" % str(err)) |
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# Validate response
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if not (isinstance(data, dict) and |
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KEY_SUCCESS in data and |
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KEY_RESULT in data):
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raise ProtocolError("Invalid response from server: %r" % data) |
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return (data[KEY_SUCCESS], data[KEY_RESULT],
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data.get(KEY_VERSION, None)) # pylint: disable=E1103 |
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def FormatResponse(success, result, version=None): |
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"""Formats a response message.
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"""
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response = { |
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KEY_SUCCESS: success, |
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KEY_RESULT: result, |
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} |
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if version is not None: |
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response[KEY_VERSION] = version |
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logging.debug("RPC response: %s", response)
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return serializer.DumpJson(response)
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def FormatRequest(method, args, version=None): |
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"""Formats a request message.
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"""
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# Build request
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request = { |
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KEY_METHOD: method, |
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KEY_ARGS: args, |
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} |
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if version is not None: |
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request[KEY_VERSION] = version |
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# Serialize the request
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return serializer.DumpJson(request,
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private_encoder=serializer.EncodeWithPrivateFields) |
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def CallRPCMethod(transport_cb, method, args, version=None): |
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"""Send a RPC request via a transport and return the response.
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"""
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assert callable(transport_cb) |
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request_msg = FormatRequest(method, args, version=version) |
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# Send request and wait for response
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response_msg = transport_cb(request_msg) |
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(success, result, resp_version) = ParseResponse(response_msg) |
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# Verify version if there was one in the response
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if resp_version is not None and resp_version != version: |
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raise LuxiError("RPC version mismatch, client %s, response %s" % |
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(version, resp_version)) |
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if success:
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return result
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errors.MaybeRaise(result) |
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raise RequestError(result)
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class AbstractClient(object): |
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"""High-level client abstraction.
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This uses a backing Transport-like class on top of which it
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implements data serialization/deserialization.
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"""
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def __init__(self, timeouts=None, transport=t.Transport): |
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"""Constructor for the Client class.
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Arguments:
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- address: a valid address the the used transport class
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- timeout: a list of timeouts, to be used on connect and read/write
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- transport: a Transport-like class
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If timeout is not passed, the default timeouts of the transport
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class are used.
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"""
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self.timeouts = timeouts
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self.transport_class = transport
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self.transport = None |
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# The version used in RPC communication, by default unused:
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self.version = None |
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def _GetAddress(self): |
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"""Returns the socket address
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"""
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raise NotImplementedError |
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def _InitTransport(self): |
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"""(Re)initialize the transport if needed.
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"""
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if self.transport is None: |
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self.transport = self.transport_class(self._GetAddress(), |
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timeouts=self.timeouts)
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def _CloseTransport(self): |
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"""Close the transport, ignoring errors.
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"""
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if self.transport is None: |
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return
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try:
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old_transp = self.transport
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self.transport = None |
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old_transp.Close() |
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except Exception: # pylint: disable=W0703 |
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pass
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def _SendMethodCall(self, data): |
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# Send request and wait for response
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try:
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self._InitTransport()
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return self.transport.Call(data) |
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except Exception: |
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self._CloseTransport()
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raise
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def Close(self): |
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"""Close the underlying connection.
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"""
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self._CloseTransport()
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def close(self): |
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"""Same as L{Close}, to be used with contextlib.closing(...).
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"""
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self.Close()
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def CallMethod(self, method, args): |
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"""Send a generic request and return the response.
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"""
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if not isinstance(args, (list, tuple)): |
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raise errors.ProgrammerError("Invalid parameter passed to CallMethod:" |
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" expected list, got %s" % type(args)) |
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return CallRPCMethod(self._SendMethodCall, method, args, |
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version=self.version)
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class AbstractStubClient(AbstractClient): |
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"""An abstract Client that connects a generated stub client to a L{Transport}.
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Subclasses should inherit from this class (first) as well and a designated
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stub (second).
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"""
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def __init__(self, timeouts=None, transport=t.Transport): |
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"""Constructor for the class.
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Arguments are the same as for L{AbstractClient}. Checks that SOCKET_PATH
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attribute is defined (in the stub class).
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"""
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super(AbstractStubClient, self).__init__(timeouts, transport) |
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def _GenericInvoke(self, method, *args): |
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return self.CallMethod(method, args) |
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def _GetAddress(self): |
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return self._GetSocketPath() # pylint: disable=E1101 |