1 files changed, 56 insertions, 0 deletions
diff --git a/catapult/telemetry/telemetry/internal/util/external_modules.py b/catapult/telemetry/telemetry/internal/util/external_modules.py
new file mode 100644
index 00000000..92faf593
--- /dev/null
+++ b/catapult/telemetry/telemetry/internal/util/external_modules.py
@@ -0,0 +1,56 @@
+# Copyright 2014 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.
+
+import importlib
+
+from distutils import version
+
+MODULES = {
+  'cv2': (version.StrictVersion('2.4.8'), version.StrictVersion('3.0.0')),
+  'numpy': (version.StrictVersion('1.6.1'), None),
+  'psutil': (version.StrictVersion('0.5.0'), None),
+}
+
+def ImportRequiredModule(module):
+  """Tries to import the desired module.
+
+  Returns:
+    The module on success, raises error on failure.
+  Raises:
+    ImportError: The import failed."""
+  versions = MODULES.get(module)
+  if versions is None:
+    raise NotImplementedError('Please teach telemetry about module %s.' %
+                              module)
+  min_version, max_version = versions
+
+  module = importlib.import_module(module)
+  try:
+    if ((min_version is not None and
+            version.StrictVersion(module.__version__) < min_version) or
+        (max_version is not None and
+            version.StrictVersion(module.__version__) >= max_version)):
+      raise ImportError(('Incorrect {0} version found, expected {1} <= version '
+                         '< {2}, found version {3}').format(
+          module, min_version, max_version, module.__version__))
+  except ValueError as e:
+    # This error is raised when a module returns and incorrectly formatted
+    # version string. ex. '$build 1456a'
+    if 'invalid version number' in str(e):
+      raise ImportError(('Incorrectly formatted {0} version found, expected '
+                         '{1} <= version < {2}, found version {3}').format(
+          module, min_version, max_version, module.__version__))
+    else:
+      raise
+  return module
+
+def ImportOptionalModule(module):
+  """Tries to import the desired module.
+
+  Returns:
+    The module if successful, None if not."""
+  try:
+    return ImportRequiredModule(module)
+  except ImportError:
+    return None