Update from https://crrev.com/317530

testing/legion/discovery_server.py

-# Copyright 2015 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-"""The discovery server used to register clients.
-
-The discovery server is started by the host controller and allows the clients
-to register themselves when they start. Authentication of the client controllers
-is based on an OTP passed to the client controller binary on startup.
-"""
-
-import logging
-import threading
-import xmlrpclib
-import SimpleXMLRPCServer
-
-#pylint: disable=relative-import
-import common_lib
-
-
-class DiscoveryServer(object):
-  """Discovery server run on the host."""
-
-  def __init__(self):
-    self._expected_clients = {}
-    self._rpc_server = None
-    self._thread = None
-
-  def _RegisterClientRPC(self, otp, ip):
-    """The RPC used by a client to register with the discovery server."""
-    assert otp in self._expected_clients
-    cb = self._expected_clients.pop(otp)
-    cb(ip)
-
-  def RegisterClientCallback(self, otp, callback):
-    """Registers a callback associated with an OTP."""
-    assert callable(callback)
-    self._expected_clients[otp] = callback
-
-  def Start(self):
-    """Starts the discovery server."""
-    logging.debug('Starting discovery server')
-    self._rpc_server = SimpleXMLRPCServer.SimpleXMLRPCServer(
-        (common_lib.SERVER_ADDRESS, common_lib.SERVER_PORT),
-        allow_none=True, logRequests=False)
-    self._rpc_server.register_function(
-        self._RegisterClientRPC, 'RegisterClient')
-    self._thread = threading.Thread(target=self._rpc_server.serve_forever)
-    self._thread.start()
-
-  def Shutdown(self):
-    """Shuts the discovery server down."""
-    if self._thread and self._thread.is_alive():
-      logging.debug('Shutting down discovery server')
-      self._rpc_server.shutdown()