Synnefo » snf-ganeti

import logging

from ganeti import serializer

from ganeti import errors

from ganeti import pathutils

from ganeti.rpc import transport as t

  "ParseRequest",

  "ParseResponse",

  "FormatRequest",

  "FormatResponse",

  "CallLuxiMethod",

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 LUXI request message.

  """

  try:

    request = serializer.LoadJson(msg)

  except ValueError, err:

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

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

  if not isinstance(request, dict):

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

    raise ProtocolError("Invalid LUXI 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("LUXI request missing method or arguments: %r", msg)

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

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

  return (method, args, version)

def ParseResponse(msg):

  """Parses a LUXI 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 LUXI response message.

  """

  response = {

    KEY_SUCCESS: success,

    KEY_RESULT: result,

    }

  if version is not None:

    response[KEY_VERSION] = version

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

  return serializer.DumpJson(response)

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

  """Formats a LUXI 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)

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

  """Send a LUXI 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 errors.LuxiError("LUXI version mismatch, client %s, response %s" %

                           (version, resp_version))

  if success:

    return result

  errors.MaybeRaise(result)

  raise RequestError(result)

class Client(object):

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

    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.

    """

    if address is None:

      address = pathutils.MASTER_SOCKET

    self.address = address

    self.timeouts = timeouts

    self.transport_class = transport

    self.transport = None

    self._InitTransport()

  def _InitTransport(self):

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

    """

    if self.transport is None:

      self.transport = self.transport_class(self.address,

                                            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

    try:

      self._InitTransport()

      return self.transport.Call(data)

    except Exception:

      self._CloseTransport()

      raise

  def Close(self):

    """Close the underlying connection.

    """

    self._CloseTransport()

  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 CallLuxiMethod(self._SendMethodCall, method, args,

                          version=constants.LUXI_VERSION)