Add dependency_manager initialization to binary_manager

tools/telemetry/telemetry/internal/util/binary_manager.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.
 
+#TODO(aiolos): Remove the debug logging once the entire Dependency Manager
+#system has landed.
+import logging
+import os
+
 from catapult_base import support_binaries
+from catapult_base import dependency_manager
+from telemetry.core import util
 
 
+class InitializationError(Exception):
+  def __init__(self, string):
+    super(InitializationError, self).__init__(string)
+
+
+TELEMETRY_PROJECT_CONFIG = os.path.join(
+    util.GetTelemetryDir(), 'telemetry', 'internal', 'binary_dependencies.json')

[nednguyen, 2015/08/10 17:01:10]

Did you already add this file?

[aiolos (Not reviewing), 2015/08/10 20:37:27]

Not yet. We don't actually do anything with the file yet, so I was going to add
it in the CL that included the dependency_manager's actual initialization code.
But thought knowing how it was getting passed in was useful for this CL. I can
easily add an empty json file if you'd prefer.

+
+_dependency_manager = None
+
+def InitDependencyManagerForUnittests():
+  if not _dependency_manager:
+    InitDependencyManager(None)
+
+def InitDependencyManager(environment_config):

[eakuefner, 2015/08/10 17:07:03]

nit: two newlines between top-level definitions.

[aiolos (Not reviewing), 2015/08/10 20:37:27]

Done.

+  global _dependency_manager
+  if _dependency_manager:
+    raise InitializationError('Trying to re-initialize the binary manager with '
+                              'config %s' % environment_config)
+  config_files = [TELEMETRY_PROJECT_CONFIG]
+  if environment_config:
+    config_files.append(environment_config)
+  _dependency_manager = dependency_manager.DependencyManager(config_files)
+  logging.debug('Initialized the dependency manager.')

[nednguyen, 2015/08/10 17:01:10]

This log should come before the dependency_manager.DependencyManager in case of
failure?
Also maybe add the content of config_files in the debug message?

[aiolos (Not reviewing), 2015/08/10 20:37:27]

That's actually why I wanted it after. I've cared less about whether we tried to
initialize it and more that we succeeded in my debugging thus far, although that
may not always be the case. I'm going to add a log before hand instead of moving
it.
Done.

+
 def FetchPath(binary_name, platform, arch):
   """ Return a path to the appropriate executable for <binary_name>, downloading
       from cloud storage if needed, or None if it cannot be found.
   """
+  logging.debug('Called FetchPath for binary: %s on platform: %s and arch: '
+                '%s' % (binary_name, platform, arch))
+  if _dependency_manager is None:
+    raise InitializationError(
+        'Called FetchPath with uninitialized binary manager.')
   return support_binaries.FindPath(binary_name, platform, arch)
 
 def LocalPath(binary_name, platform, arch):
   """ Return a local path to the given binary name, or None if an executable
       cannot be found. Will not download the executable.
       """
+  logging.debug('Called LocalPath for binary: %s on platform: %s and arch: '
+                '%s' % (binary_name, platform, arch))
+  if _dependency_manager is None:
+    raise InitializationError(
+        'Called LocalPath with uninitialized binary manager.')
   del platform, arch
   return support_binaries.FindLocallyBuiltPath(binary_name)