96e6d971a0
When a retry atom or a task atom changes state it is quite useful to know the prior state the atom was in; to make this easier pass that information along in the details about the state transition so that observers can inspect it if they desire to. This matches more closely with the flow notification which does include the prior state (under the details key 'old_state') so this also increases the uniformity of notifications in general. Change-Id: I7df1fcc60ba178198776ddaa2681caee5811c4ff
149 lines
6.0 KiB
Python
149 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, old_state, 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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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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old_state = self._storage.get_atom_state(task.name)
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if self._is_identity_transition(old_state, 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 = {
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'task_name': task.name,
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'task_uuid': task_uuid,
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'result': result,
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'old_state': old_state,
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}
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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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