80 lines
2.2 KiB
Python
80 lines
2.2 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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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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@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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@abc.abstractproperty
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def requires(self):
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"""Browse flow requirements."""
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@abc.abstractproperty
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def provides(self):
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"""Browse values provided by the flow."""
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