[Findit] Initial code of findit for crash. Add scorers to apply heuristic rules.

appengine/findit/crash/crash_util.py

Index: appengine/findit/crash/crash_util.py
diff --git a/appengine/findit/crash/crash_util.py b/appengine/findit/crash/crash_util.py
new file mode 100644
index 0000000000000000000000000000000000000000..1456ff8e7a0d017a44fc18166f29974187afefb8
--- /dev/null
+++ b/appengine/findit/crash/crash_util.py
@@ -0,0 +1,27 @@
+# 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.
+
+
+def IsSameFilePath(path1, path2):
+  """Determines if two paths represent same path.

[Martin Barbella, 2016/04/15 06:05:24]

What's the use case for this? Just trying to understand the rationale for the 3
directory intersection.

[Sharu, 2016/04/15 22:59:46]

If a file moved directory, like from 'a/b/c/file.cc' to 'a/b/file.cc', as long
as it's new location is not too far from the old one (more than 3), we guess
it's the same file. 

+
+  Compares the name of the folders in the path (by split('/')), and checks
+  if they match either more than 3 or min of path lengths.

[stgao, 2016/04/15 18:35:18]

How about adding the reason behind this comparison?

[Sharu, 2016/04/15 22:59:46]

I just port over this method which is the method we use in clusterfuzz. I
thought we already had agreement on this as others? We can discuss this if you
have concerns here. 

+
+  Args:
+    path1 (str): First path.
+    path2 (str): Second path to compare.
+
+  Returns:
+    Boolean, True if it they are thought to be a same path, False otherwise.
+  """
+  path_parts1 = path1.split('/')

[Martin Barbella, 2016/04/15 06:05:24]

Nit: _1. Ditto for the other.

[Sharu, 2016/04/15 22:59:46]

Done.

+  path_parts2 = path2.split('/')
+
+  if path_parts1[-1] != path_parts2[-1]:
+    return False
+
+  intersection = set(path_parts1).intersection(set(path_parts2))
+  return len(intersection) >= (min(3, min(len(path_parts1),

[stgao, 2016/04/15 18:35:18]

min(3, 2, 1) == 1

[Sharu, 2016/04/15 22:59:46]

I think this is the intended behavior of this method. However it may be
problematic. like two files:
DEPS
a/b/c/d/e/f/g/DEPS 
would be treated as the same file.

+                                          len(path_parts2))))