Files
deb-python-taskflow/taskflow/engines/action_engine/scheduler.py
Joshua Harlow 08c0bbc3e3 Cache the individual atom schedulers at compile time
These do not need to be re-fetched/re-examined each time.

Change-Id: Ie48100caa12575c725530911ad3d1dc9046e9d26
2015-06-18 10:18:01 -07:00

101 lines
3.7 KiB
Python

# -*- coding: utf-8 -*-
# Copyright (C) 2014 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 weakref
from taskflow import exceptions as excp
from taskflow import states as st
from taskflow.types import failure
class RetryScheduler(object):
"""Schedules retry atoms."""
def __init__(self, runtime):
self._runtime = weakref.proxy(runtime)
self._retry_action = runtime.retry_action
self._storage = runtime.storage
def schedule(self, retry):
"""Schedules the given retry atom for *future* completion.
Depending on the atoms stored intention this may schedule the retry
atom for reversion or execution.
"""
intention = self._storage.get_atom_intention(retry.name)
if intention == st.EXECUTE:
return self._retry_action.execute(retry)
elif intention == st.REVERT:
return self._retry_action.revert(retry)
elif intention == st.RETRY:
self._retry_action.change_state(retry, st.RETRYING)
self._runtime.retry_subflow(retry)
return self._retry_action.execute(retry)
else:
raise excp.ExecutionFailure("Unknown how to schedule retry with"
" intention: %s" % intention)
class TaskScheduler(object):
"""Schedules task atoms."""
def __init__(self, runtime):
self._storage = runtime.storage
self._task_action = runtime.task_action
def schedule(self, task):
"""Schedules the given task atom for *future* completion.
Depending on the atoms stored intention this may schedule the task
atom for reversion or execution.
"""
intention = self._storage.get_atom_intention(task.name)
if intention == st.EXECUTE:
return self._task_action.schedule_execution(task)
elif intention == st.REVERT:
return self._task_action.schedule_reversion(task)
else:
raise excp.ExecutionFailure("Unknown how to schedule task with"
" intention: %s" % intention)
class Scheduler(object):
"""Safely schedules atoms using a runtime ``fetch_scheduler`` routine."""
def __init__(self, runtime):
self._fetch_scheduler = runtime.fetch_scheduler
def schedule(self, atoms):
"""Schedules the provided atoms for *future* completion.
This method should schedule a future for each atom provided and return
a set of those futures to be waited on (or used for other similar
purposes). It should also return any failure objects that represented
scheduling failures that may have occurred during this scheduling
process.
"""
futures = set()
for atom in atoms:
scheduler = self._fetch_scheduler(atom)
try:
futures.add(scheduler.schedule(atom))
except Exception:
# Immediately stop scheduling future work so that we can
# exit execution early (rather than later) if a single atom
# fails to schedule correctly.
return (futures, [failure.Failure()])
return (futures, [])