Adding the initial code for Omnibot multi-machine support

testing/legion/host_controller.py

Index: testing/legion/host_controller.py
diff --git a/testing/legion/host_controller.py b/testing/legion/host_controller.py
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+++ b/testing/legion/host_controller.py
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+# 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 host controller base library.
+
+This module is the basis on which host controllers are built and executed.
+"""
+import json
+import logging
+import sys
+
+#pylint: disable=relative-import
+import client_lib
+import common_lib
+import discovery_server
+
+
+class HostController(object):
+  """The base host controller class."""
+
+  clients = []
+
+  def __init__(self):
+    self._discovery_server = discovery_server.DiscoveryServer()
+
+  def _SetUp(self):
+    """Perform private internal setup operations."""
+    common_lib.InitLogging()
+    common_lib.LogCommandLine()
+    self._discovery_server.Start()
+
+  def SetUp(self):
+    """Setup method used by the subclass."""
+    pass
+
+  def Test(self):
+    """Main test method used by the subclass."""
+    pass
+
+  def TearDown(self):
+    """Teardown method used by the subclass."""
+    pass
+
+  def _TearDown(self):
+    """Private internal teardown method."""
+    self._discovery_server.Shutdown()
+    for client in self.clients:
+      client.Release()
+
+  def NewClient(self, isolate_file):
+    """Creates a new client object given an isolate file.
+
+    Args:
+      isolate_file: The path to an isolate file for the client machine.
+
+    Returns:
+      A new client_lib.Client object.
+    """
+    client = client_lib.Client(isolate_file, self._discovery_server)
+    self.clients.append(client)
+    return client
+
+  def RunController(self):
+    """Main entry point for the controller."""
+    error = None
+    tb = None
+    try:
+      self._SetUp()
+      self.SetUp()
+      self.Test()
+    except Exception, e:
+      # Defer raising exceptions until after TearDown and _TearDown are called.
+      error = e
+      tb = sys.exc_info()[-1]
+    try:
+      self.TearDown()
+    except Exception, e:
+      # Defer raising exceptions until after _TearDown is called.
+      # Note that an error raised here will obscure any errors raised
+      # previously.
+      error = e
+      tb = sys.exc_info()[-1]
+
+    self._TearDown()
+    if error:
+      raise error, None, tb  #pylint: disable=raising-bad-type