thirdparty/google_appengine/google/appengine/api/apiproxy_stub.py
author Sverre Rabbelier <srabbelier@gmail.com>
Sun, 19 Apr 2009 17:42:44 +0000
changeset 2246 c29272f640b0
parent 828 f5fd65cc3bf3
permissions -rwxr-xr-x
Tweak the 'load balancing' algorithm In order to reduce contention we randomly skipped jobs, but this caused many jobs to end up stopping early. Now instead we keep on going until we time out (also increased the chance of doing work). Patch by: Sverre Rabbelier

#!/usr/bin/env python
#
# Copyright 2007 Google Inc.
#
# 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.
#

"""Base class for implementing API proxy stubs."""





from google.appengine.api import apiproxy_rpc
from google.appengine.runtime import apiproxy_errors


MAX_REQUEST_SIZE = 1 << 20


class APIProxyStub(object):
  """Base class for implementing API proxy stub classes.

  To implement an API proxy stub:
    - Extend this class.
    - Override __init__ to pass in appropriate default service name.
    - Implement service methods as _Dynamic_<method>(request, response).
  """

  def __init__(self, service_name, max_request_size=MAX_REQUEST_SIZE):
    """Constructor.

    Args:
      service_name: Service name expected for all calls.
      max_request_size: int, maximum allowable size of the incoming request.  A
        apiproxy_errors.RequestTooLargeError will be raised if the inbound
        request exceeds this size.  Default is 1 MB.
    """
    self.__service_name = service_name
    self.__max_request_size = max_request_size

  def CreateRPC(self):
    """Creates RPC object instance.

    Returns:
      a instance of RPC.
    """
    return apiproxy_rpc.RPC(stub=self)

  def MakeSyncCall(self, service, call, request, response):
    """The main RPC entry point.

    Args:
      service: Must be name as provided to service_name of constructor.
      call: A string representing the rpc to make.  Must be part of
        the underlying services methods and impemented by _Dynamic_<call>.
      request: A protocol buffer of the type corresponding to 'call'.
      response: A protocol buffer of the type corresponding to 'call'.
    """
    assert service == self.__service_name, ('Expected "%s" service name, '
                                            'was "%s"' % (self.__service_name,
                                                          service))
    if request.ByteSize() > self.__max_request_size:
      raise apiproxy_errors.RequestTooLargeError(
          'The request to API call %s.%s() was too large.' % (service, call))
    messages = []
    assert request.IsInitialized(messages), messages

    method = getattr(self, '_Dynamic_' + call)
    method(request, response)