1222bda50d
Implement dependency checks when adding items to flows: - retry can't be depended on tasks from it's subflow. - retry can't provide same values as tasks or other retries Change-Id: Iffa8e673fd2de39407ae22cd38ad523d484cbba7
95 lines
3.3 KiB
Python
95 lines
3.3 KiB
Python
# -*- coding: utf-8 -*-
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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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from taskflow import exceptions
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from taskflow import flow
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class Flow(flow.Flow):
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"""Linear Flow pattern.
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A linear (potentially nested) flow of *tasks/flows* that can be
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applied in order as one unit and rolled back as one unit using
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the reverse order that the *tasks/flows* have been applied in.
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NOTE(imelnikov): Tasks/flows contained in this linear flow must not
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depend on outputs (provided names/values) of tasks/flows that follow it.
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"""
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def __init__(self, name, retry=None):
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super(Flow, self).__init__(name, retry)
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self._children = []
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def add(self, *items):
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"""Adds a given task/tasks/flow/flows to this flow."""
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if not items:
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return self
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# NOTE(imelnikov): we add item to the end of flow, so it should
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# not provide anything previous items of the flow require.
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requires = self.requires
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provides = self.provides
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for item in items:
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requires |= item.requires
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out_of_order = requires & item.provides
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if out_of_order:
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raise exceptions.InvariantViolation(
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"%(item)s provides %(oo)s that are required "
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"by previous item(s) of linear flow %(flow)s"
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% dict(item=item.name, flow=self.name,
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oo=sorted(out_of_order)))
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same_provides = provides & item.provides
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if same_provides:
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raise exceptions.DependencyFailure(
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"%(item)s provides %(value)s but is already being"
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" provided by %(flow)s and duplicate producers"
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" are disallowed"
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% dict(item=item.name, flow=self.name,
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value=sorted(same_provides)))
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provides |= item.provides
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self._children.extend(items)
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return self
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def __len__(self):
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return len(self._children)
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def __iter__(self):
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for child in self._children:
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yield child
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def __getitem__(self, index):
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return self._children[index]
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@property
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def provides(self):
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provides = set()
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provides.update(self._retry_provides)
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for subflow in self._children:
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provides.update(subflow.provides)
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return provides
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@property
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def requires(self):
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requires = set()
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provides = set()
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requires.update(self._retry_requires)
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provides.update(self._retry_provides)
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for subflow in self._children:
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requires.update(subflow.requires - provides)
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provides.update(subflow.provides)
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return requires
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