如何在ProtoRPC中使用Memcache(Google App Engine - Python)

Question

我正在尝试使用ProtoRPC的memcache来加速某些过程(使用Python的Google App Engine).为了简化问题,我使用了Hello World示例,并对其进行了一些修改.这是我的版本:

from protorpc import messages
from protorpc import remote
from protorpc.wsgi import service

from google.appengine.api import memcache

class HelloRequest(messages.Message):
  my_name = messages.StringField(1, required=True)

class ElementOfArrayResponse(messages.Message):
  value=messages.IntegerField(1)

class HelloResponse(messages.Message):
  hello = messages.StringField(1, required=True)
  list = messages.MessageField(ElementOfArrayResponse, 2, repeated=True)

class HelloService(remote.Service):
  @remote.method(HelloRequest, HelloResponse)
  def hello(self, request):
    response = memcache.get(request.my_name)

    if response is None:
      list = []
      for i in range(7):
        list.append(SomeElementResponse(value=i))
      response = HelloResponse(hello='Hello there, %s!' % request.my_name, list=list)
      memcache.set(request.my_name,response)
    return response

app = service.service_mappings([('/hello.*', HelloService)])

但是,不幸的是,这段代码返回的错误是:ERROR 2013-01-12 17:17:31,081 service.py:196] Encountered unexpected error from ProtoRPC method implementation: PicklingError (Can't pickle <type 'weakref'>: attribute lookup __builtin__.weakref failed).

但是,当我使用与原始代码几乎相同的代码时HelloResponse,memcache工作得很好.

那么,我做错了什么？

Answer 1

两件事,看起来你的memcache键是一个List对象(想要确保你知道这一点).在你的代码旁边,你必须message在放入/退出memcacheapi 时序列化对象.

这是一个重写:

from protorpc import remote
from protorpc import messages
from protorpc import protojson
from protorpc.wsgi import service
from google.appengine.api import memcache


class HelloRequest(messages.Message):
  my_name = messages.StringField(1, required=True)

class ElementOfArrayResponse(messages.Message):
  value=messages.IntegerField(1)

class HelloResponse(messages.Message):
  hello = messages.StringField(1, required=True)
  list = messages.MessageField(ElementOfArrayResponse, 2, repeated=True)

class HelloService(remote.Service):
  @remote.method(HelloRequest, HelloResponse)
  def hello(self, request):
    response = memcache.get(request.my_name)
    if response:
      # decode the value to a message..
      response = protojson.decode_message(HelloResponse, response)
    else:
      list = []
      for i in range(7):
        list.append(SomeElementResponse(value=i))
      response = HelloResponse(hello='Hello there, %s!' % request.my_name, list=list)
      # encode the message to a serializable format..
      value = protojson.encode_message(message)
      memcache.set(request.my_name, value)
    return response

app = service.service_mappings([('/hello.*', HelloService)])