205 lines
7.3 KiB
Python
205 lines
7.3 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from __future__ import absolute_import
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import abc
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from oslo_utils import excutils
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import six
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from taskflow import logging
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from taskflow import states
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from taskflow.types import failure
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from taskflow.types import notifier
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LOG = logging.getLogger(__name__)
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#: These states will results be usable, other states do not produce results.
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FINISH_STATES = (states.FAILURE, states.SUCCESS,
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states.REVERTED, states.REVERT_FAILURE)
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#: What is listened for by default...
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DEFAULT_LISTEN_FOR = (notifier.Notifier.ANY,)
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def _task_matcher(details):
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"""Matches task details emitted."""
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if not details:
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return False
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if 'task_name' in details and 'task_uuid' in details:
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return True
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return False
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def _retry_matcher(details):
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"""Matches retry details emitted."""
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if not details:
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return False
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if 'retry_name' in details and 'retry_uuid' in details:
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return True
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return False
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def _bulk_deregister(notifier, registered, details_filter=None):
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"""Bulk deregisters callbacks associated with many states."""
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while registered:
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state, cb = registered.pop()
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notifier.deregister(state, cb,
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details_filter=details_filter)
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def _bulk_register(watch_states, notifier, cb, details_filter=None):
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"""Bulk registers a callback associated with many states."""
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registered = []
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try:
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for state in watch_states:
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if not notifier.is_registered(state, cb,
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details_filter=details_filter):
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notifier.register(state, cb,
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details_filter=details_filter)
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registered.append((state, cb))
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except ValueError:
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with excutils.save_and_reraise_exception():
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_bulk_deregister(notifier, registered,
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details_filter=details_filter)
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else:
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return registered
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class Listener(object):
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"""Base class for listeners.
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A listener can be attached to an engine to do various actions on flow and
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atom state transitions. It implements the context manager protocol to be
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able to register and unregister with a given engine automatically when a
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context is entered and when it is exited.
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To implement a listener, derive from this class and override
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``_flow_receiver`` and/or ``_task_receiver`` and/or ``_retry_receiver``
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methods (in this class, they do nothing).
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"""
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def __init__(self, engine,
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task_listen_for=DEFAULT_LISTEN_FOR,
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flow_listen_for=DEFAULT_LISTEN_FOR,
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retry_listen_for=DEFAULT_LISTEN_FOR):
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if not task_listen_for:
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task_listen_for = []
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if not retry_listen_for:
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retry_listen_for = []
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if not flow_listen_for:
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flow_listen_for = []
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self._listen_for = {
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'task': list(task_listen_for),
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'retry': list(retry_listen_for),
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'flow': list(flow_listen_for),
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}
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self._engine = engine
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self._registered = {}
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def _flow_receiver(self, state, details):
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pass
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def _task_receiver(self, state, details):
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pass
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def _retry_receiver(self, state, details):
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pass
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def deregister(self):
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if 'task' in self._registered:
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_bulk_deregister(self._engine.atom_notifier,
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self._registered['task'],
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details_filter=_task_matcher)
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del self._registered['task']
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if 'retry' in self._registered:
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_bulk_deregister(self._engine.atom_notifier,
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self._registered['retry'],
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details_filter=_retry_matcher)
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del self._registered['retry']
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if 'flow' in self._registered:
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_bulk_deregister(self._engine.notifier,
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self._registered['flow'])
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del self._registered['flow']
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def register(self):
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if 'task' not in self._registered:
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self._registered['task'] = _bulk_register(
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self._listen_for['task'], self._engine.atom_notifier,
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self._task_receiver, details_filter=_task_matcher)
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if 'retry' not in self._registered:
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self._registered['retry'] = _bulk_register(
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self._listen_for['retry'], self._engine.atom_notifier,
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self._retry_receiver, details_filter=_retry_matcher)
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if 'flow' not in self._registered:
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self._registered['flow'] = _bulk_register(
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self._listen_for['flow'], self._engine.notifier,
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self._flow_receiver)
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def __enter__(self):
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self.register()
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return self
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def __exit__(self, type, value, tb):
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try:
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self.deregister()
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except Exception:
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# Don't let deregistering throw exceptions
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LOG.warn("Failed deregistering listeners from engine %s",
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self._engine, exc_info=True)
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@six.add_metaclass(abc.ABCMeta)
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class DumpingListener(Listener):
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"""Abstract base class for dumping listeners.
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This provides a simple listener that can be attached to an engine which can
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be derived from to dump task and/or flow state transitions to some target
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backend.
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To implement your own dumping listener derive from this class and
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override the ``_dump`` method.
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"""
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@abc.abstractmethod
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def _dump(self, message, *args, **kwargs):
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"""Dumps the provided *templated* message to some output."""
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def _flow_receiver(self, state, details):
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self._dump("%s has moved flow '%s' (%s) into state '%s'"
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" from state '%s'", self._engine, details['flow_name'],
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details['flow_uuid'], state, details['old_state'])
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def _task_receiver(self, state, details):
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if state in FINISH_STATES:
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result = details.get('result')
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exc_info = None
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was_failure = False
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if isinstance(result, failure.Failure):
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if result.exc_info:
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exc_info = tuple(result.exc_info)
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was_failure = True
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self._dump("%s has moved task '%s' (%s) into state '%s'"
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" from state '%s' with result '%s' (failure=%s)",
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self._engine, details['task_name'],
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details['task_uuid'], state, details['old_state'],
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result, was_failure, exc_info=exc_info)
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else:
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self._dump("%s has moved task '%s' (%s) into state '%s'"
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" from state '%s'", self._engine, details['task_name'],
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details['task_uuid'], state, details['old_state'])
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