Use subprocess42 in recipe_engine to avoid threading madness.

recipe_engine/run.py

-# Copyright (c) 2013-2015 The Chromium Authors. All rights reserved.
+# Copyright 2016 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.
 
 """Entry point for fully-annotated builds.
 
 This script is part of the effort to move all builds to annotator-based
 systems. Any builder configured to use the AnnotatorFactory.BaseFactory()
 found in scripts/master/factory/annotator_factory.py executes a single
 AddAnnotatedScript step. That step (found in annotator_commands.py) calls
 this script with the build- and factory-properties passed on the command
@@ skipping 52 matching lines @@
 """
 
 import collections
 import os
 import sys
 import traceback
 
 from . import loader
 from . import recipe_api
 from . import recipe_test_api
+from . import step_runner as step_runner_module
 from . import types
 from . import util
 
 
 SCRIPT_PATH = os.path.dirname(os.path.abspath(__file__))
 
 BUILDBOT_MAGIC_ENV = set([
     'BUILDBOT_BLAMELIST',
     'BUILDBOT_BRANCH',
     'BUILDBOT_BUILDBOTURL',
@@ skipping 114 matching lines @@
   properties.pop('root', None)
 
   # TODO(iannucci): A much better way to do this would be to dynamically
   #   detect if the mirrors are actually available during the execution of the
   #   recipe.
   if ('use_mirror' not in properties and (
     'TESTING_MASTERNAME' in os.environ or
     'TESTING_SLAVENAME' in os.environ)):
     properties['use_mirror'] = False
 
-  engine = RecipeEngine(step_runner, properties, universe)
+  with stream_engine.new_step_stream('setup_build') as s:
+    engine = RecipeEngine(step_runner, properties, universe)
 
-  # Create all API modules and top level RunSteps function.  It doesn't launch
-  # any recipe code yet; RunSteps needs to be called.
-  api = None
-  with stream_engine.new_step_stream('setup_build') as s:
+    # Create all API modules and top level RunSteps function.  It doesn't launch
+    # any recipe code yet; RunSteps needs to be called.
+    api = None
+
     assert 'recipe' in properties
     recipe = properties['recipe']
 
     properties_to_print = properties.copy()
     if 'use_mirror' in properties:
       del properties_to_print['use_mirror']
 
     run_recipe_help_lines = [
         'To repro this locally, run the following line from a build checkout:',
         '',
@@ skipping 68 matching lines @@
     """See run_steps() for parameter meanings."""
     self._step_runner = step_runner
     self._properties = properties
     self._universe_view = universe_view
 
     # A stack of ActiveStep objects, holding the most recently executed step at
     # each nest level (objects deeper in the stack have lower nest levels).
     # When we pop from this stack, we close the corresponding step stream.
     self._step_stack = []
 
+    # TODO(iannucci): come up with a more structured way to advertise/set mode
+    # flags/options for the engine.
+    if '$recipe_engine' in properties:
+      options = properties['$recipe_engine']
+      try:
+        mode_flags = options.get('mode_flags')
+        if mode_flags:
+          if mode_flags.get('use_subprocess42'):
+            print "Setting MODE_SUBPROCESS42: True"
+            step_runner_module.MODE_SUBPROCESS42 = True
+      except Exception as e:
+        print "Failed to set recipe_engine options, got: %r: %s" % (options, e)
+
   @property
   def properties(self):
     return self._properties
 
   @property
   def universe(self):
     return self._universe_view.universe
 
   @property
   def previous_step_result(self):
@@ skipping 153 matching lines @@
         results.append(
           loader._invoke_with_properties(
             run_recipe, properties, recipe_script.PROPERTIES,
             properties.keys()))
       except TypeError as e:
         raise TypeError(
             "Got %r while trying to call recipe %s with properties %r" % (
               e, recipe, properties))
 
     return results