23dfff4105
In order to move away from the existing flows having their own implementation of running, start moving the existing flows to be patterns that only structure tasks (and impose constraints about how the group of tasks can run) in useful ways. Let the concept of running those patterns be handled by an engine instead of being handled by the flow itself. This will allow for varying engines to be able to run flows in whichever way the engine chooses (as long as the constraints set up by the flow are observed). Currently threaded flow and graph flow are broken by this commit, since they have not been converted to being a structure of tasks + constraints. The existing engine has not yet been modified to run those structures either, work is underway to remediate this. Part of: blueprint patterns-and-engines Followup bugs that must be addressed: Bug: 1221448 Bug: 1221505 Change-Id: I3a8b96179f336d1defe269728ebae0caa3d832d7
84 lines
2.4 KiB
Python
84 lines
2.4 KiB
Python
# -*- coding: utf-8 -*-
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (C) 2012 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 abc
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from taskflow.openstack.common import uuidutils
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from taskflow import task
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from taskflow import utils
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def _class_name(obj):
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return ".".join([obj.__class__.__module__, obj.__class__.__name__])
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class Flow(object):
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"""The base abstract class of all flow implementations.
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It provides a name and an identifier (uuid or other) to the flow so that
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it can be uniquely identifed among many flows.
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Flows are expected to provide the following methods:
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- add
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- __len__
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"""
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__metaclass__ = abc.ABCMeta
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def __init__(self, name, uuid=None):
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self._name = str(name)
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if uuid:
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self._id = str(uuid)
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else:
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self._id = uuidutils.generate_uuid()
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@property
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def name(self):
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"""A non-unique name for this flow (human readable)"""
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return self._name
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@property
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def uuid(self):
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return self._id
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@abc.abstractmethod
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def __len__(self):
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"""Returns how many items are in this flow."""
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raise NotImplementedError()
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def __str__(self):
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lines = ["%s: %s" % (_class_name(self), self.name)]
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lines.append("%s" % (self.uuid))
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lines.append("%s" % (len(self)))
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return "; ".join(lines)
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def _extract_item(self, item):
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if isinstance(item, (task.BaseTask, Flow)):
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return item
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if issubclass(item, task.BaseTask):
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return item()
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task_factory = getattr(item, utils.TASK_FACTORY_ATTRIBUTE, None)
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if task_factory:
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return self._extract_item(task_factory(item))
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raise TypeError("Invalid item %r: it's not task and not flow" % item)
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@abc.abstractmethod
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def add(self, *items):
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"""Adds a given item/items to this flow."""
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raise NotImplementedError()
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