125 lines
4.0 KiB
Python
125 lines
4.0 KiB
Python
# -*- coding: utf-8 -*-
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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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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from taskflow import exceptions as exc
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# Job states.
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CLAIMED = 'CLAIMED'
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FAILURE = 'FAILURE'
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PENDING = 'PENDING'
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RUNNING = 'RUNNING'
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SUCCESS = 'SUCCESS'
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UNCLAIMED = 'UNCLAIMED'
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# Flow states.
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FAILURE = FAILURE
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PENDING = 'PENDING'
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REVERTING = 'REVERTING'
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REVERTED = 'REVERTED'
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RUNNING = RUNNING
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SUCCESS = SUCCESS
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SUSPENDING = 'SUSPENDING'
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SUSPENDED = 'SUSPENDED'
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RESUMING = 'RESUMING'
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# Task states.
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FAILURE = FAILURE
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SUCCESS = SUCCESS
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REVERTED = REVERTED
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REVERTING = REVERTING
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# TODO(harlowja): use when we can timeout tasks??
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TIMED_OUT = 'TIMED_OUT'
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## Flow state transitions
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# https://wiki.openstack.org/wiki/TaskFlow/States_of_Task_and_Flow#Flow_States
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_ALLOWED_FLOW_TRANSITIONS = frozenset((
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(PENDING, RUNNING), # run it!
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(RUNNING, SUCCESS), # all tasks finished successfully
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(RUNNING, FAILURE), # some of task failed
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(RUNNING, SUSPENDING), # engine.suspend was called
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(SUCCESS, RUNNING), # see note below
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(FAILURE, RUNNING), # see note below
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(FAILURE, REVERTING), # flow failed, do cleanup now
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(REVERTING, REVERTED), # revert done
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(REVERTING, FAILURE), # revert failed
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(REVERTING, SUSPENDING), # engine.suspend was called
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(REVERTED, RUNNING), # try again
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(SUSPENDING, SUSPENDED), # suspend finished
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(SUSPENDING, SUCCESS), # all tasks finished while we were waiting
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(SUSPENDING, FAILURE), # some tasks failed while we were waiting
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(SUSPENDING, REVERTED), # all tasks were reverted while we were waiting
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(SUSPENDED, RUNNING), # restart from suspended
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(SUSPENDED, REVERTING), # revert from suspended
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(RESUMING, SUSPENDED), # after flow resumed, it is suspended
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))
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# NOTE(imelnikov) SUCCESS->RUNNING and FAILURE->RUNNING transitions are
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# useful when flow or flowdetails backing it were altered after the flow
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# was finished; then, client code may want to run through flow again
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# to ensure all tasks from updated flow had a chance to run.
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# NOTE(imelnikov): Engine cannot transition flow from SUSPENDING to
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# SUSPENDED while some tasks from the flow are running and some results
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# from them are not retrieved and saved properly, so while flow is
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# in SUSPENDING state it may wait for some of the tasks to stop. Then,
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# flow can go to SUSPENDED, SUCCESS, FAILURE or REVERTED state depending
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# of actual state of the tasks -- e.g. if all tasks were finished
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# successfully while we were waiting, flow can be transitioned from
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# SUSPENDING to SUCCESS state.
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_IGNORED_FLOW_TRANSITIONS = frozenset(
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(a, b)
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for a in (PENDING, FAILURE, SUCCESS, SUSPENDED, REVERTED)
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for b in (SUSPENDING, SUSPENDED, RESUMING)
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if a != b
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)
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def check_flow_transition(old_state, new_state):
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"""Check that flow can transition from old_state to new_state.
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If transition can be performed, it returns True. If transition
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should be ignored, it returns False. If transition is not
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valid, it raises InvalidStateException.
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"""
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if old_state == new_state:
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return False
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pair = (old_state, new_state)
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if pair in _ALLOWED_FLOW_TRANSITIONS:
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return True
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if pair in _IGNORED_FLOW_TRANSITIONS:
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return False
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if new_state == RESUMING:
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return True
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raise exc.InvalidStateException(
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"Flow transition from %s to %s is not allowed" % pair)
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