Safe XML RPC calls in multiple gevent tasks

xmlrpclib_gevent.py

"""
Safe XML RPC calls in multiple gevent tasks. Basically, it serializes calls.

Assuming you are running a server like this::

  import time
  from SimpleXMLRPCServer import SimpleXMLRPCServer

  def is_even(n):
      time.sleep(3)
      return n % 2 == 0

  server = SimpleXMLRPCServer(("localhost", 8000))
  print "Listening on port 8000..."
  server.register_function(is_even, "toto.is_even")
  server.serve_forever()

Usage::

  # You need to monkey patch to force xmlrpclib to use gevent socket
  from gevent.monkey import patch_all
  patch_all(thread=False)
  
  from xmlrpclib_gevent import ServerProxy
  
  proxy = ServerProxy('http://localhost:8000')
  
  def is_even(proxy, number):
      result = proxy.toto.is_even(number)
      print('Is {0} even? {1}'.format(number, result))

  task1 = gevent.spawn(is_even, proxy, 55)
  task2 = gevent.spawn(is_even, proxy, 44)

  gevent.joinall((task1, task2))
"""

from xmlrpclib import ServerProxy as _ServerProxy

from gevent.lock import RLock


class Wrap(object):

    def __init__(self, lock, method):
        self.__lock = lock
        self.__method = method

    def __getattr__(self, name):
        return Wrap(self.__lock, getattr(self.__method, name))

    def __call__(self, *args):
        with self.__lock:
            return self.__method(*args)


class ServerProxy(_ServerProxy):

    def __init__(self, *args, **kwargs):
        self.__lock = RLock()
        _ServerProxy.__init__(self, *args, **kwargs)

    def __getattr__(self, name):
        method = _ServerProxy.__getattr__(self, name)
        return Wrap(self.__lock, method)