1f4dd72e6e
Instead of having code that is some what like the notifier
code we already have, but is duplicated and is slightly different
in the task class just move the code that was in the task class (and
doing similar actions) to instead now use a notifier that is directly
contained in the task base class for internal task triggering of
internal task events.
Breaking change: alters the capabilities of the task to process
notifications itself, most actions now must go through the task
notifier property and instead use that (update_progress still exists
as a common utility method, since it's likely the most common type
of notification that will be used).
Removes the following methods from task base class (as they are
no longer needed with a notifier attribute):
- trigger (replaced with notifier.notify)
- autobind (removed, not replaced, can be created by the user
of taskflow in a simple manner, without requiring
functionality in taskflow)
- bind (replaced with notifier.register)
- unbind (replaced with notifier.unregister)
- listeners_iter (replaced with notifier.listeners_iter)
Due to this change we can now also correctly proxy back events from
remote tasks to the engine for correct proxying back to the original
task.
Fixes bug 1370766
Change-Id: Ic9dfef516d72e6e32e71dda30a1cb3522c9e0be6
146 lines
6.0 KiB
Python
146 lines
6.0 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2012-2013 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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import functools
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from taskflow import logging
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from taskflow import states
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from taskflow import task as task_atom
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from taskflow.types import failure
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LOG = logging.getLogger(__name__)
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SAVE_RESULT_STATES = (states.SUCCESS, states.FAILURE)
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class TaskAction(object):
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"""An action that handles scheduling, state changes, ... of task atoms."""
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def __init__(self, storage, task_executor, notifier, walker_factory):
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self._storage = storage
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self._task_executor = task_executor
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self._notifier = notifier
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self._walker_factory = walker_factory
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@staticmethod
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def handles(atom):
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return isinstance(atom, task_atom.BaseTask)
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def _is_identity_transition(self, state, task, progress):
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if state in SAVE_RESULT_STATES:
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# saving result is never identity transition
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return False
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old_state = self._storage.get_atom_state(task.name)
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if state != old_state:
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# changing state is not identity transition by definition
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return False
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# NOTE(imelnikov): last thing to check is that the progress has
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# changed, which means progress is not None and is different from
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# what is stored in the database.
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if progress is None:
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return False
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old_progress = self._storage.get_task_progress(task.name)
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if old_progress != progress:
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return False
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return True
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def change_state(self, task, state, result=None, progress=None):
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if self._is_identity_transition(state, task, progress):
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# NOTE(imelnikov): ignore identity transitions in order
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# to avoid extra write to storage backend and, what's
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# more important, extra notifications
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return
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if state in SAVE_RESULT_STATES:
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self._storage.save(task.name, result, state)
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else:
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self._storage.set_atom_state(task.name, state)
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if progress is not None:
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self._storage.set_task_progress(task.name, progress)
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task_uuid = self._storage.get_atom_uuid(task.name)
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details = dict(task_name=task.name,
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task_uuid=task_uuid,
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result=result)
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self._notifier.notify(state, details)
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if progress is not None:
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task.update_progress(progress)
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def _on_update_progress(self, task, event_type, details):
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"""Should be called when task updates its progress."""
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try:
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progress = details.pop('progress')
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except KeyError:
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pass
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else:
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try:
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self._storage.set_task_progress(task.name, progress,
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details=details)
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except Exception:
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# Update progress callbacks should never fail, so capture and
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# log the emitted exception instead of raising it.
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LOG.exception("Failed setting task progress for %s to %0.3f",
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task, progress)
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def schedule_execution(self, task):
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self.change_state(task, states.RUNNING, progress=0.0)
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scope_walker = self._walker_factory(task)
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arguments = self._storage.fetch_mapped_args(task.rebind,
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atom_name=task.name,
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scope_walker=scope_walker)
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if task.notifier.can_be_registered(task_atom.EVENT_UPDATE_PROGRESS):
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progress_callback = functools.partial(self._on_update_progress,
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task)
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else:
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progress_callback = None
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task_uuid = self._storage.get_atom_uuid(task.name)
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return self._task_executor.execute_task(
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task, task_uuid, arguments,
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progress_callback=progress_callback)
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def complete_execution(self, task, result):
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if isinstance(result, failure.Failure):
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self.change_state(task, states.FAILURE, result=result)
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else:
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self.change_state(task, states.SUCCESS,
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result=result, progress=1.0)
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def schedule_reversion(self, task):
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self.change_state(task, states.REVERTING, progress=0.0)
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scope_walker = self._walker_factory(task)
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arguments = self._storage.fetch_mapped_args(task.rebind,
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atom_name=task.name,
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scope_walker=scope_walker)
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task_uuid = self._storage.get_atom_uuid(task.name)
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task_result = self._storage.get(task.name)
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failures = self._storage.get_failures()
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if task.notifier.can_be_registered(task_atom.EVENT_UPDATE_PROGRESS):
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progress_callback = functools.partial(self._on_update_progress,
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task)
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else:
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progress_callback = None
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future = self._task_executor.revert_task(
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task, task_uuid, arguments, task_result, failures,
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progress_callback=progress_callback)
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return future
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def complete_reversion(self, task, rev_result):
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if isinstance(rev_result, failure.Failure):
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self.change_state(task, states.FAILURE)
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else:
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self.change_state(task, states.REVERTED, progress=1.0)
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def wait_for_any(self, fs, timeout):
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return self._task_executor.wait_for_any(fs, timeout)
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