Files
deb-python-taskflow/taskflow/engines/action_engine/task_action.py
Joshua Harlow ee1d583721 Add task state verification
Change-Id: I85abee2a1112ce1b9bb708cb9129f06c794f83b1
2013-10-14 12:22:23 -07:00

130 lines
5.0 KiB
Python

# -*- coding: utf-8 -*-
# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright (C) 2012 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.
import contextlib
import logging
from taskflow.engines.action_engine import base_action as base
from taskflow.openstack.common import excutils
from taskflow import states
from taskflow.utils import misc
LOG = logging.getLogger(__name__)
RESET_TASK_STATES = (states.PENDING,)
SAVE_RESULT_STATES = (states.SUCCESS, states.FAILURE)
ALREADY_FINISHED_STATES = (states.SUCCESS,)
NEVER_RAN_STATES = (states.PENDING,)
@contextlib.contextmanager
def _autobind(task, bind_name, bind_func, **kwargs):
try:
task.bind(bind_name, bind_func, **kwargs)
yield task
finally:
task.unbind(bind_name, bind_func)
class TaskAction(base.Action):
def __init__(self, task, task_id):
self._task = task
self._id = task_id
@property
def name(self):
return self._task.name
@property
def uuid(self):
return self._id
def _change_state(self, engine, state,
result=None, progress=None, force=False):
"""Update result and change state."""
old_state = engine.storage.get_task_state(self.uuid)
state_check = states.check_task_transition(old_state, state)
if not force and not state_check:
# NOTE(harlowja): if we are forcing this state change, we don't
# care if the state transition should be ignored, if it's not being
# forced then we just ignore this state change.
return
if state in RESET_TASK_STATES:
engine.storage.reset(self.uuid)
if state in SAVE_RESULT_STATES:
engine.storage.save(self.uuid, result, state)
else:
engine.storage.set_task_state(self.uuid, state)
if progress is not None:
engine.storage.set_task_progress(self.uuid, progress)
engine._on_task_state_change(self, state, result=result)
def _on_update_progress(self, task, event_data, progress, **kwargs):
"""Update task progress value that stored in engine."""
try:
engine = event_data['engine']
engine.storage.set_task_progress(self.uuid, progress, **kwargs)
except Exception:
# Update progress callbacks should never fail, so capture and log
# the emitted exception instead of raising it.
LOG.exception("Failed setting task progress for %s (%s) to %0.3f",
task, self.uuid, progress)
def _force_state(self, engine, state, progress, result=None):
self._change_state(engine, state,
result=result, progress=progress, force=True)
self._task.update_progress(progress)
def execute(self, engine):
if engine.storage.get_task_state(self.uuid) in ALREADY_FINISHED_STATES:
# Skip tasks that already finished.
return
self._force_state(engine, states.RUNNING, 0.0)
with _autobind(self._task,
'update_progress', self._on_update_progress,
engine=engine):
try:
kwargs = engine.storage.fetch_mapped_args(self._task.rebind)
result = self._task.execute(**kwargs)
except Exception:
failure = misc.Failure()
self._change_state(engine, states.FAILURE, result=failure)
failure.reraise()
self._force_state(engine, states.SUCCESS, 1.0, result=result)
def revert(self, engine):
if engine.storage.get_task_state(self.uuid) in NEVER_RAN_STATES:
# NOTE(imelnikov): in all the other states, the task
# execution was at least attempted, so we should give
# task a chance for cleanup
return
self._force_state(engine, states.REVERTING, 0.0)
with _autobind(self._task,
'update_progress', self._on_update_progress,
engine=engine):
kwargs = engine.storage.fetch_mapped_args(self._task.rebind)
try:
self._task.revert(result=engine.storage.get(self._id),
**kwargs)
except Exception:
with excutils.save_and_reraise_exception():
self._change_state(engine, states.FAILURE)
self._force_state(engine, states.REVERTED, 1.0)
self._force_state(engine, states.PENDING, 0.0)