Files
deb-python-taskflow/taskflow/listeners/base.py
Joshua Harlow 0abfe90eb3 Move toward python 3/2 compatible metaclass
Change-Id: Ia7e07a7530e26c388c5da3e362510233b6a65aa6
2013-10-09 17:39:05 -07:00

96 lines
3.6 KiB
Python

# -*- coding: utf-8 -*-
# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
from __future__ import absolute_import
import abc
import logging
import six
from taskflow import states
from taskflow.utils import misc
LOG = logging.getLogger(__name__)
# NOTE(harlowja): on these states will results be useable, all other states
# do not produce results.
FINISH_STATES = (states.FAILURE, states.SUCCESS)
class LoggingBase(six.with_metaclass(abc.ABCMeta)):
"""This provides a simple listener that can be attached to an engine which
can be derived from to log the received actions to some logging backend. It
provides a useful context manager access to be able to register and
unregister with a given engine automatically when a context is entered and
when it is exited.
"""
def __init__(self, engine,
listen_for=misc.TransitionNotifier.ANY):
self._listen_for = listen_for
self._engine = engine
self._registered = False
@abc.abstractmethod
def _log(self, message, *args, **kwargs):
raise NotImplementedError()
def _flow_receiver(self, state, details):
self._log("%s has moved flow '%s' (%s) into state '%s'",
details['engine'], details['flow_name'],
details['flow_uuid'], state)
def _task_receiver(self, state, details):
if state in FINISH_STATES:
result = details.get('result')
exc_info = None
was_failure = False
if isinstance(result, misc.Failure):
if result.exc_info:
exc_info = tuple(result.exc_info)
was_failure = True
self._log("%s has moved task '%s' (%s) into state '%s'"
" with result '%s' (failure=%s)",
details['engine'], details['task_name'],
details['task_uuid'], state, result, was_failure,
exc_info=exc_info)
else:
self._log("%s has moved task '%s' (%s) into state '%s'",
details['engine'], details['task_name'],
details['task_uuid'], state)
def __enter__(self):
if not self._registered:
self._engine.notifier.register(self._listen_for,
self._flow_receiver)
self._engine.task_notifier.register(self._listen_for,
self._task_receiver)
self._registered = True
def __exit__(self, type, value, tb):
try:
self._engine.notifier.deregister(self._listen_for,
self._flow_receiver)
self._engine.task_notifier.deregister(self._listen_for,
self._task_receiver)
self._registered = False
except Exception:
# Don't let deregistering throw exceptions
LOG.exception("Failed deregistering listeners from engine %s",
self._engine)