[Findit] Plain objects to represent the returned result from running the algorithm,

tools/findit/matchset.py

Index: tools/findit/matchset.py
diff --git a/tools/findit/matchset.py b/tools/findit/matchset.py
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+# Copyright (c) 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 logging
+import re
+from threading import Lock
+
+import crash_utils
+
+LINE_CHANGE_PRIORITY = 1
+FILE_CHANGE_PRIORITY = 2
+
+
+class Match(object):
+  """Represents a match entry.
+
+  A match is a CL that is suspected to have caused the crash. A match object
+  contains information about files it changes, their owners, etc.
+
+  Attributes:
+    line_of_crash: The list of lines that caused crash for this CL.
+    function: The list of functions that caused the crash.
+    min_distance: The minimum difference between the lines that CL changed and
+              lines that caused the crash.
+    files: The list of files that the CL changed.
+    file_urls: The list of URLs for the file.
+    owner: The owner of the CL.
+    component: The component that this CL belongs to.
+    stack_frame_indices: For files that caused crash, list of where in the
+                       stackframe they occur.
+    rank: The highest priority among the files the CL changes.
+    priorities: For each files, whether it changes the crashed line
+                (priority = 1) or is a simple file change (priority = 2).
+    url: URL of the CL.
+    review_url: The codereview address that reviews this CL.
+    reviewers: The list of people that reviewed this CL.
+    reason: The reason why this CL is suspected.
+  """
+  REVERT_PATTERN = re.compile(r'(revert\w*) r?(\d+)', re.I)
+
+  def __init__(self, revision, component):
+    self.isrevert = False
+    self.revert_of = None
+    self.line_of_crash = []
+    self.function = []
+    self.min_distance = float('inf')
+    self.files = []
+    self.file_urls = []
+    self.owner = revision['author']
+    self.component = component
+    self.stack_frame_indices = []
+    self.rank = float('inf')
+    self.priorities = []
+    self.url = revision['url']
+    self.review_url = 'N/A'
+    self.reviewers = ['N/A']
+    self.reason = None
+
+  def ParseMessage(self, message, codereview_api_url):
+    """Parses the message.
+
+    It checks the message to extract the code review website and list of
+    reviewers, and it also checks if the CL is a revert of another CL.
+
+    Args:
+      message: The message to parse.
+      codereview_api_url: URL to retrieve codereview data from.
+    """
+    for line in message.splitlines():
+      line = line.strip()
+
+      # Check if the line has the code review information.
+      if line.startswith('Review URL: '):
+
+        # Get review number for the code review site from the line.
+        parts = line.split('Review URL: ')
+        self.review_url = parts[1].strip()
+        issue_number = self.review_url.split('/')[-1]
+
+        # Get JSON from the code review site, ignore the line if it fails.
+        url = codereview_api_url % issue_number
+        json_string = crash_utils.GetDataFromURL(url)
+        if not json_string:
+          logging.warning('Failed to retrieve code review information from %s',
+                          url)
+          continue
+
+        # Load the JSON from the string, and get the list of reviewers.
+        code_review = crash_utils.LoadJSON(json_string)
+        if code_review:
+          self.reviewers = code_review['reviewers']
+
+      # Check if this CL is a revert of other CL.
+      if line.lower().startswith('revert'):
+        self.isrevert = True
+
+        # Check if the line says what CL this CL is a revert of.
+        revert = self.REVERT_PATTERN.match(line)
+        if revert:
+          self.revert_of = revert.group(2)
+        return
+
+
+class MatchSet(object):
+  """Represents a set of matches."""
+
+  def __init__(self, codereview_api_url):
+    self.codereview_api_url = codereview_api_url
+    self.matches = {}
+    self.cls_to_ignore = set()
+    self.matches_lock = Lock()
+
+  def GenerateMatchEntry(
+      self, revisions, cl, file_path, file_name, function, component,
+      crashed_lines, stack_frame_indices, file_action, repository_parser):
+    """Generates a match object.
+
+    Args:
+      revisions: The dictionary mapping cl's number to the revision information,
+                 as returned from a function ParseRevisions in parser.
+      cl: The SVN revision number or git hash.
+      file_path: The path of the file.
+      file_name: The name of the file that this CL might be the culprit cl.
+      function: The function that caused an crash.
+      component: The component the file is from.
+      crashed_lines: The list of the lines in the file that caused the crash.
+      stack_frame_indices: The list of positions of this file within a stack.
+      file_action: Whether file is modified, added or deleted.
+      repository_parser: The parser object to parse line diff.
+    """
+    # Check if this CL should be avoided.
+    with self.matches_lock:
+      if cl in self.cls_to_ignore:
+        return
+
+      # If this CL is not already identified as suspected, create a new entry.
+      if cl not in self.matches:
+        revision = revisions[cl]
+        match = Match(revision, component)
+        message = revisions[cl]['message']
+        # TODO(jeun): Don't hold lock while issuing http request.
+        match.ParseMessage(message, self.codereview_api_url)
+
+        # If this match is a revert, add to the set of CLs to be avoided.
+        if match.isrevert:

[stgao, 2014/08/09 19:51:02]

|isrevert| -> |is_reverted|?

+          self.cls_to_ignore.add(cl)
+
+          # If this match has info on what CL it is reverted from, add that CL.
+          if match.revert_of:
+            self.cls_to_ignore.add(match.revert_of)
+
+          # Return because we do not need to look at this CL anymore.
+          return
+
+        # Add this CL to the set of matches.
+        self.matches[cl] = match
+
+      # Else, bring in the existing result.
+      else:
+        match = self.matches[cl]
+
+    # Parse line diff information for this file.
+    (diff_url, changed_line_numbers, changed_line_contents) = (
+        repository_parser.ParseLineDiff(file_path, component, file_action, cl))
+
+    # Find the intersection between the lines that this file crashed on and
+    # the changed lines.
+    (line_intersection, stack_frame_index_intersection) = (
+        crash_utils.Intersection(
+            crashed_lines, stack_frame_indices, changed_line_numbers))
+
+    # Find the minimum distance between the changed lines and crashed lines.
+    min_distance = crash_utils.FindMinLineDistance(crashed_lines,
+                                                   changed_line_numbers)
+
+    # Check whether this CL changes the crashed lines or not.
+    if line_intersection:
+      priority = LINE_CHANGE_PRIORITY
+    else:
+      priority = FILE_CHANGE_PRIORITY
+
+    # Add the parsed information to the object.
+    with self.matches_lock:
+      match.line_of_crash.append(line_intersection)
+      match.files.append(file_name)
+
+      # Update the min distance only if it is less than the current one.
+      if min_distance < match.min_distance:
+        match.min_distance = min_distance
+
+      # If this CL does not change the crashed line, all occurrence of this
+      # file in the stack has the same significance.
+      if not stack_frame_index_intersection:
+        stack_frame_index_intersection = stack_frame_indices
+      match.stack_frame_indices.append(stack_frame_index_intersection)
+      match.file_urls.append(diff_url)
+
+      # Only record the highest rank of this CL.
+      if priority < match.rank:
+        match.rank = priority
+      match.priorities.append(priority)
+      match.function.append(function)
+
+  def RemoveReverts(self):
+    """Removes CLs that are revert."""
+    for cl in self.matches:
+      if cl in self.cls_to_ignore:
+        del self.matches[cl]