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#

#

# Copyright (C) 2013 Google Inc.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful, but

# WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

# 02110-1301, USA.

"""Module for generic RPC clients.

"""

import logging

import ganeti.rpc.transport as t

from ganeti import constants

from ganeti import errors

from ganeti.rpc.errors import (ProtocolError, RequestError, LuxiError)

from ganeti import serializer

KEY_METHOD = constants.LUXI_KEY_METHOD

KEY_ARGS = constants.LUXI_KEY_ARGS

KEY_SUCCESS = constants.LUXI_KEY_SUCCESS

KEY_RESULT = constants.LUXI_KEY_RESULT

KEY_VERSION = constants.LUXI_KEY_VERSION

def ParseRequest(msg):

  """Parses a request message.

  """

  try:

    request = serializer.LoadJson(msg)

  except ValueError, err:

    raise ProtocolError("Invalid RPC request (parsing error): %s" % err)

  logging.debug("RPC request: %s", request)

  if not isinstance(request, dict):

    logging.error("RPC request not a dict: %r", msg)

    raise ProtocolError("Invalid RPC request (not a dict)")

  method = request.get(KEY_METHOD, None) # pylint: disable=E1103

  args = request.get(KEY_ARGS, None) # pylint: disable=E1103

  version = request.get(KEY_VERSION, None) # pylint: disable=E1103

  if method is None or args is None:

    logging.error("RPC request missing method or arguments: %r", msg)

    raise ProtocolError(("Invalid RPC request (no method or arguments"

                         " in request): %r") % msg)

  return (method, args, version)

def ParseResponse(msg):

  """Parses a response message.

  """

  # Parse the result

  try:

    data = serializer.LoadJson(msg)

  except KeyboardInterrupt:

    raise

  except Exception, err:

    raise ProtocolError("Error while deserializing response: %s" % str(err))

  # Validate response

  if not (isinstance(data, dict) and

          KEY_SUCCESS in data and

          KEY_RESULT in data):

    raise ProtocolError("Invalid response from server: %r" % data)

  return (data[KEY_SUCCESS], data[KEY_RESULT],

          data.get(KEY_VERSION, None)) # pylint: disable=E1103

def FormatResponse(success, result, version=None):

  """Formats a response message.

  """

  response = {

    KEY_SUCCESS: success,

    KEY_RESULT: result,

    }

  if version is not None:

    response[KEY_VERSION] = version

  logging.debug("RPC response: %s", response)

  return serializer.DumpJson(response)

def FormatRequest(method, args, version=None):

  """Formats a request message.

  """

  # Build request

  request = {

    KEY_METHOD: method,

    KEY_ARGS: args,

    }

  if version is not None:

    request[KEY_VERSION] = version

  # Serialize the request

  return serializer.DumpJson(request,

                             private_encoder=serializer.EncodeWithPrivateFields)

def CallRPCMethod(transport_cb, method, args, version=None):

  """Send a RPC request via a transport and return the response.

  """

  assert callable(transport_cb)

  request_msg = FormatRequest(method, args, version=version)

  # Send request and wait for response

  response_msg = transport_cb(request_msg)

  (success, result, resp_version) = ParseResponse(response_msg)

  # Verify version if there was one in the response

  if resp_version is not None and resp_version != version:

    raise LuxiError("RPC version mismatch, client %s, response %s" %

                    (version, resp_version))

  if success:

    return result

  errors.MaybeRaise(result)

  raise RequestError(result)

class AbstractClient(object):

  """High-level client abstraction.

  This uses a backing Transport-like class on top of which it

  implements data serialization/deserialization.

  """

  def __init__(self, timeouts=None, transport=t.Transport):

    """Constructor for the Client class.

    Arguments:

      - address: a valid address the the used transport class

      - timeout: a list of timeouts, to be used on connect and read/write

      - transport: a Transport-like class

    If timeout is not passed, the default timeouts of the transport

    class are used.

    """

    self.timeouts = timeouts

    self.transport_class = transport

    self.transport = None

    # The version used in RPC communication, by default unused:

    self.version = None

  def _GetAddress(self):

    """Returns the socket address

    """

    raise NotImplementedError

  def _InitTransport(self):

    """(Re)initialize the transport if needed.

    """

    if self.transport is None:

      self.transport = self.transport_class(self._GetAddress(),

                                            timeouts=self.timeouts)

  def _CloseTransport(self):

    """Close the transport, ignoring errors.

    """

    if self.transport is None:

      return

    try:

      old_transp = self.transport

      self.transport = None

      old_transp.Close()

    except Exception: # pylint: disable=W0703

      pass

  def _SendMethodCall(self, data):

    # Send request and wait for response

    def send(try_no):

      if try_no:

        logging.debug("RPC peer disconnected, retrying")

      self._InitTransport()

      return self.transport.Call(data)

    return t.Transport.RetryOnBrokenPipe(send, lambda _: self._CloseTransport())

  def Close(self):

    """Close the underlying connection.

    """

    self._CloseTransport()

  def close(self):

    """Same as L{Close}, to be used with contextlib.closing(...).

    """

    self.Close()

  def CallMethod(self, method, args):

    """Send a generic request and return the response.

    """

    if not isinstance(args, (list, tuple)):

      raise errors.ProgrammerError("Invalid parameter passed to CallMethod:"

                                   " expected list, got %s" % type(args))

    return CallRPCMethod(self._SendMethodCall, method, args,

                         version=self.version)

class AbstractStubClient(AbstractClient):

  """An abstract Client that connects a generated stub client to a L{Transport}.

  Subclasses should inherit from this class (first) as well and a designated

  stub (second).

  """

  def __init__(self, timeouts=None, transport=t.Transport):

    """Constructor for the class.

    Arguments are the same as for L{AbstractClient}. Checks that SOCKET_PATH

    attribute is defined (in the stub class).

    """

    super(AbstractStubClient, self).__init__(timeouts, transport)

  def _GenericInvoke(self, method, *args):

    return self.CallMethod(method, args)

  def _GetAddress(self):

    return self._GetSocketPath() # pylint: disable=E1101