Adding the initial code for Omnibot multi-machine support

testing/legion/client_rpc_methods.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.
+"""Client RPC Methods.

[Marc-Antoine Ruel (Google), 2015/01/30 21:58:39]

This is not informative. "client_rpc_methods.py" pretty much convey this
information. :)

[Mike Meade, 2015/02/03 01:18:08]

Done.

+
+The RPC methods made available on the client are all defined here in the
+RPCMethods class. This class is made separate for easy maintenance and
+method lookup.
+"""
+
+import logging
+import subprocess
+import threading
+
+
+class RPCMethods(object):
+  """The class exposing RPC methods."""
+
+  def __init__(self, server):
+    self.server = server
+
+  def Echo(self, message):
+    """Simple RPC method to print and return a message."""
+    logging.info('Echoing %s', message)
+    return 'echo ' + message
+
+  def Subprocess(self, cmd):
+    """Run the commands in a subprocess.
+
+    Note that stdout and stderr are passed to this process' stdout and stderr
+    and only the return code is returned.
+
+    Args:
+      cmd: A command list to pass to subprocess.call.
+    """
+    p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
+                         stderr=subprocess.PIPE)
+    p.wait()

[Marc-Antoine Ruel (Google), 2015/01/30 21:58:39]

This will hang. You need to use .communicate()

[Mike Meade, 2015/02/03 01:18:08]

Done.

+    return (p.returncode, p.stdout.read(), p.stderr.read())
+
+  def Quit(self):
+    """Call server.shutdown in another thread.
+
+    This is needed because server.shutdown waits for the server to actually
+    quit. However the server cannot shutdown until it completes handling this
+    call. Calling this in the same thread results in a deadlock.
+    """
+    t = threading.Thread(target=self.server.shutdown)
+    t.start()