exonerator/gerrit_precq.py

# Copyright 2018 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Functions for forgiving false Pre-CQ rejections."""

from __future__ import print_function
from __future__ import absolute_import
from __future__ import division

from chromite.lib import cros_logging as logging

from exonerator import gerrit_cq
from exonerator import constants


_TRYBOT_READY_LABEL = 'Trybot-Ready'
_EXONERATOR_PRECQ_MESSAGE = """\
CL-Exonerator has triggered a Pre-CQ retry on this CL due to a Pre-CQ sanity
failure.
"""
_REPOSITORY_WHITELIST = frozenset(['infra/dummies/general-sandbox'])


def MaybeExonerate(change, build_id):
  """Mark a CL as Trybot-Ready only if it hasn't already been.

  Args:
    change: A GerritPatchTuple.
    build_id: The CIDB id for the build which the change was kicked out of.
  """
  helper = gerrit_cq.GetHelper(internal=change.internal)
  details = helper.GetChangeDetail(change.gerrit_number)
  if not details:
    logging.warning('Change details was None for %s', str(change))
    return False

  if not _ShouldBeMarkedPreCQReady(details, change.patch_number):
    logging.info(
        "Change %s was not ready to exonerate %d", str(change), build_id)
    return False

  if not details['project'] in _REPOSITORY_WHITELIST:
    logging.info(
        'Change %s has project %s, which is not whitelisted.',
        details, details['project'])

  try:
    helper.SetReview(
        change.gerrit_number,
        msg=_EXONERATOR_PRECQ_MESSAGE,
        labels={_TRYBOT_READY_LABEL: 1})
    return True
  # Network errors or permission errors won't get retried. That's ok for now.
  except Exception:
    logging.exception('Encountered an exception while marking %s with CQ+1',
                      str(change))
    return False


def CanBeMarkedReady(change):
  """Whether a change is ready to be exonerated.

  Args:
    change: A GerritPatchTuple to test.
  """
  helper = gerrit_cq.GetHelper(internal=change.internal)
  details = helper.GetChangeDetail(change.gerrit_number)
  if details:
    return _ShouldBeMarkedPreCQReady(details, change.patch_number)
  else:
    logging.warning('Change details was None for %s', str(change))
    return False


def _ShouldBeMarkedPreCQReady(change_details, known_patch_number):
  """Whether a CL should be re-marked as Trybot-Ready.

  We only want to send CLs back into the pre-cq if they haven't already been
  marked Trybot-Ready+1, CQ+1, and it's not already on a newer patchset.

  Args:
    change_details: The change details response from Gerrit.
    known_patch_number: The revision number which we want to forgive.
  """
  return (
      gerrit_cq.SanityCheckChange(change_details, known_patch_number)
      # It shouldn't already have Trybot-Ready+1, CQ+1 or CQ-1
      and not (gerrit_cq.LabelValues(
          change_details, gerrit_cq.COMMIT_QUEUE_LABEL) - {0})
      and not (gerrit_cq.LabelValues(
          change_details, _TRYBOT_READY_LABEL) - {0})
      # Don't exonerate CLs with Code-Review-1 or Code-Review-2
      and all(label >= 0
              for label in gerrit_cq.LabelValues(
                  change_details, gerrit_cq.CODE_REVIEW_LABEL))
      and _PreCQApprovalWasRemovedByBot(change_details)
  )


def _PreCQApprovalWasRemovedByBot(change_details):
  """Whether the latest Pre-CQ Approval was removed by a bot.

  Either Trybot-Ready+1 or Commit-Queue+1 labels can kick off pre-cq. To
  check whether the change was kicked out by a bot, check the latest message
  which removes either Trybot-Ready or CQ+1, and see whether it was made by
  chromeos-commit-bot@chromium.org.

  Args:
    change_details: The response from gerrit with the change's details.
  """
  for message in reversed(change_details['messages']):
    if (('-' + _TRYBOT_READY_LABEL) in message['message']
        or '-Commit-Queue' in message['message']):
      return (message['real_author']['email']
              == constants.CHROMEOS_COMMIT_BOT_EMAIL)
  return False