[Predator] Add TouchCrashedDirectory feature.

appengine/findit/crash/loglinear/changelist_features/touch_crashed_directory.py

Index: appengine/findit/crash/loglinear/changelist_features/touch_crashed_directory.py
diff --git a/appengine/findit/crash/loglinear/changelist_features/touch_crashed_directory.py b/appengine/findit/crash/loglinear/changelist_features/touch_crashed_directory.py
new file mode 100644
index 0000000000000000000000000000000000000000..68faf97505f8c0debe5cf6b236e47901fdad9c03
--- /dev/null
+++ b/appengine/findit/crash/loglinear/changelist_features/touch_crashed_directory.py
@@ -0,0 +1,114 @@
+# Copyright 2017 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.
+
+from collections import defaultdict
+from collections import namedtuple
+import logging
+import math
+import os
+
+from crash import crash_util
+from crash.loglinear.feature import Feature
+from crash.loglinear.feature import FeatureValue
+import libs.math.logarithms as lmath
+
+
+class CrashedDirectory(namedtuple('CrashedDirectory', ['value'])):
+  """Represents a crashed directory.
+
+  ``CrashedDirectory`` is a crashed group which knows whether itself matches a
+  touched file(``FileChangeIno``) or not.
+  """
+  __slots__ = ()
+
+  def MatchTouchedFile(self, touched_file):
+    """Determines whether a touched_file matches this crashed directory or not.
+
+    Args:
+      touched_file (FileChangeInfo): touched file to examine.
+
+    Returns:
+      Boolean indicating whether it is a match or not.
+    """
+    touched_dir = (os.path.dirname(touched_file.new_path)
+                   if touched_file.new_path else None)
+    return crash_util.IsSameFilePath(self.value, touched_dir)
+
+  def __str__(self):  # pragma: no cover
+    return '%s(value = %s)' % (self.__class__.__name__, self.value)
+
+
+class TouchCrashedDirectoryFeature(Feature):
+  """Returns either log one or log zero.
+
+  When a suspect touched crashed file, we return the log-domain
+  value 0 (aka normal-domain value of 1). When the there is no file match,
+  we return log-domain value -inf (aka normal-domain value of 0).
+  """
+  @property
+  def name(self):
+    return 'TouchCrashedDirectory'
+
+  def CrashedDirectoryFactory(self, frame):
+    """Factory function to create ``CrashedDirectory``."""
+    return CrashedDirectory(os.path.dirname(frame.file_path) if frame else None)
+
+  def __call__(self, report):
+    """
+    Args:
+      report (CrashReport): the crash report being analyzed.
+
+    Returns:
+      A ``FeatureValue`` with name, log-domain value, reason and changed_files.
+    """
+    dep_to_grouped_frame_infos = crash_util.IndexFramesWithCrashedGroup(
+        report.stacktrace, self.CrashedDirectoryFactory, report.dependencies)
+
+    def FeatureValueGivenReport(suspect):  # pylint: disable=W0613
+      """Compute ``FeatureValue`` for a suspect.
+
+      Args:
+        suspect (Suspect): The suspected changelog and some meta information
+          about it.
+
+      Returns:
+        The ``FeatureValue`` of this feature.
+      """
+      grouped_frame_infos = dep_to_grouped_frame_infos.get(suspect.dep_path, {})
+      matches = crash_util.MatchSuspectWithFrameInfos(suspect,
+                                                      grouped_frame_infos)
+
+      if not matches:
+        return FeatureValue(name=self.name,
+                            value=lmath.LOG_ZERO,
+                            reason=None,
+                            changed_files=None)
+
+      def _ReasonForCrashMatch(match):
+        frame_file_path_to_index = defaultdict(list)
+        for frame_info in match.frame_infos:
+          frame_file_path_to_index[
+              frame_info.frame.file_path].append(frame_info.frame.index)
+
+        frame_file_path_to_index = {
+            file_path: ', '.join(['frame#%d' % indice for indice in index])
+            for file_path, index in frame_file_path_to_index.iteritems()
+        }
+        return (
+            'Changed files %s, which are under the same directory %s as %s') % (
+                ', '.join([touched_file.new_path
+                           for touched_file in match.touched_files]),
+                match.crashed_group.value,
+                ', '.join(['%s (in %s)' % (file_path, index)
+                           for file_path, index in
+                           frame_file_path_to_index.iteritems()]))
+
+      return FeatureValue(
+          name=self.name,
+          value=lmath.LOG_ONE,
+          reason='\n'.join([_ReasonForCrashMatch(match)
+                            for match in matches.itervalues()]),
+          changed_files=None)
+
+    return FeatureValueGivenReport