WIP: Add auto-sheriff.appspot.com code to Blink

Tools/AutoSheriff/analysis.py

+# 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 json
+import collections
+import operator
+
+
+# Git ready, but only implemented for SVN atm.

[ojan, 2014/07/22 02:01:23]

I think we should only operate on monotonically increasing integer values. My
understanding is that even after the git migration, we'll have such a value for
each commit. We should make it the job of the infrastructure that this is built
upon to expose those values in addition to or instead of the git hash.

+def ids_after_first_including_second(first, second):
+    if not first or not second:
+        return []
+    try:
+        return range(int(first) + 1, int(second) + 1)
+    except ValueError, e:
+        # likely passed a git hash
+        return []
+
+
+# Git ready, but only implemented for SVN atm.
+def is_ancestor_of(older, younger):
+    return int(older) < int(younger)
+
+
+def is_decendant_of(younger, older):
+    return is_ancestor_of(older, younger)
+
+
+def commit_compare(one, two):
+    if is_decendant_of(one, two):
+        return -1
+    if is_ancestor_of(one, two):
+        return 1
+    return 0 # This is technically not right, since commits can be non-comparable.
+
+
+def flatten_to_commit_list(passing, failing):
+    # Flatten two commit dicts to a list of 'name:commit'
+    if not passing or not failing:
+        return []
+    all_commits = []
+    for name in passing.keys():
+        commits = ids_after_first_including_second(passing[name], failing[name])
+        all_commits.extend(['%s:%s' % (name, commit) for commit in commits])
+    return all_commits
+
+
+# FIXME: Perhaps this should be done by the feeder?
+def assign_keys(alerts):
+    for key, alert in enumerate(alerts):
+        # We could come up with something more sophisticated if necessary.
+        alert['key'] = 'f%s' % key # Just something so it doesn't look like a number.
+    return alerts
+
+
+def _make_merge_dicts(reducer):
+    def merge_dicts(one, two):
+        if not one or not two:
+            return None
+        reduction = {}
+        for key in set(one.keys() + two.keys()):
+            one_value = one.get(key)
+            two_value = two.get(key)
+            reduction[key] = reducer(one_value, two_value)
+        return reduction
+    return merge_dicts
+
+
+def merge_regression_ranges(alerts):
+    def make_compare(compare_func):
+        def compare(one, two):
+            if one and two and compare_func(one, two):
+                return one
+            # Treat None is 'infinite' so always return the more limiting.
+            # FIXME: 'passing' may wish to prefer None over a value?
+            return two or one
+        return compare
+
+    # These don't handle the case where commits can't be compared (git branches)
+    younger_commit = make_compare(is_decendant_of)
+    passing_dicts = map(operator.itemgetter('passing_revisions'), alerts)
+    last_passing = reduce(_make_merge_dicts(younger_commit), passing_dicts)
+
+    older_commit = make_compare(is_ancestor_of)
+    failing_dicts = map(operator.itemgetter('failing_revisions'), alerts)
+    first_failing = reduce(_make_merge_dicts(older_commit), failing_dicts)
+
+    return last_passing, first_failing
+
+
+def reason_key_for_alert(alert):
+    # FIXME: May need something smarter for reason_key.
+    reason_key = alert['step_name']
+    if alert['reason']:
+        reason_key += ':%s' % alert['reason']
+    else:
+        # If we don't understand the alert, just make it builder-unique.
+        reason_key += ':%s' % alert['builder_name']
+    return reason_key
+
+
+def group_by_reason(alerts):
+    by_reason = collections.defaultdict(list)
+    for alert in alerts:
+        by_reason[reason_key_for_alert(alert)].append(alert)
+
+    reason_groups = []
+    for reason_key, alerts in by_reason.items():
+        last_passing, first_failing = merge_regression_ranges(alerts)
+        blame_list = flatten_to_commit_list(last_passing, first_failing)
+        # FIXME: blame_list isn't filtered yet, but should be.
+        reason_groups.append({
+            'sort_key': reason_key,
+            'merged_last_passing': last_passing,
+            'merged_first_failing': first_failing,
+            'likely_revisions': blame_list,
+            'failure_keys': map(operator.itemgetter('key'), alerts),
+        })
+    return reason_groups
+
+# http://stackoverflow.com/questions/18715688/find-common-substring-between-two-strings
+def longestSubstringFinder(string1, string2):

[ojan, 2014/07/22 02:01:23]

s/camelCase/camel_case

+    answer = ""
+    len1, len2 = len(string1), len(string2)
+    for i in range(len1):
+        match = ""
+        for j in range(len2):
+            if (i + j < len1 and string1[i + j] == string2[j]):
+                match += string2[j]
+            else:
+                if (len(match) > len(answer)): answer = match
+                match = ""
+    return answer
+
+
+def range_key_for_group(group):
+    last_passing = group['merged_last_passing']
+    first_failing = group['merged_first_failing']
+    if last_passing:
+        range_key = ' '.join(flatten_to_commit_list(last_passing, first_failing))
+    else:
+        # Even regressions where we don't know when they started can be
+        # merged by our earliest known failure.
+        parts = ['<=%s:%s' % (name, commit) for name, commit in first_failing.items()]
+        range_key = ' '.join(parts)
+    # sort_key is a heuristic to avoid merging failiures like
+    # gclient revert + webkit_tests which just happened to pull
+    # exact matching revisions when failing.

[ojan, 2014/07/22 02:01:23]

I'm not sure it's wrong to group these together in this case. They have the same
regression range. I guess you eventually want to be able to associate a "note"
with each group for when the sheriff wants to annotate, in which case, not
grouping makes sense.

+    return group['sort_key'][:3] + range_key
+
+
+def merge_by_range(reason_groups):
+    if not reason_groups:
+        return []
+    expected_keys = sorted(reason_groups[0].keys())
+    by_range = {}
+    for group in reason_groups:
+        range_key = range_key_for_group(group)
+        existing = by_range.get(range_key)
+        if not existing:
+            # Shallow copy of group.
+            by_range[range_key] = dict(group)
+            continue
+
+        # FIXME: It's possible we don't want to merge two keys with nothing in common.
+        # e.g. bot_update and
+        # We only care about these two keys, the rest should be the same between all groups.
+        # I guess we could assert that...
+        by_range[range_key].update({
+            'sort_key': longestSubstringFinder(existing['sort_key'], group['sort_key']),
+            'failure_keys': sorted(set(existing['failure_keys'] + group['failure_keys'])),
+        })
+
+    return sorted(by_range.values(), key=operator.itemgetter('sort_key'))