095650653d
Code that calculates provides and requires for flow is almost identical for all patterns, so this change makes it completely identical and puts it to the base class. Other patterns are still allowed to override these properties for sake of customization or optimization. Change-Id: I6e875e863047b5287ec727fc9a491f252f144ecf
95 lines
3.6 KiB
Python
95 lines
3.6 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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"""Unordered Flow pattern.
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A unordered (potentially nested) flow of *tasks/flows* that can be
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executed in any order as one unit and rolled back as one unit.
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NOTE(harlowja): Since the flow is unordered there can *not* be any
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dependency between task/flow inputs (requirements) and
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task/flow outputs (provided names/values).
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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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# NOTE(imelnikov): A unordered flow is unordered, so we use
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# set instead of list to save children, children so that
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# people using it don't depend on the ordering
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self._children = set()
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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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# check that items don't provide anything that other
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# part of flow provides or requires
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provides = self.provides
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old_requires = self.requires
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for item in items:
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item_provides = item.provides
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bad_provs = item_provides & old_requires
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if bad_provs:
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raise exceptions.DependencyFailure(
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"%(item)s provides %(oo)s that are required "
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"by other item(s) of unordered flow %(flow)s"
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% dict(item=item.name, flow=self.name,
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oo=sorted(bad_provs)))
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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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# check that items don't require anything other children provides
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if self.retry:
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# NOTE(imelnikov): it is allowed to depend on value provided
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# by retry controller of the flow
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provides -= self.retry.provides
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for item in items:
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bad_reqs = provides & item.requires
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if bad_reqs:
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raise exceptions.DependencyFailure(
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"%(item)s requires %(oo)s that are provided "
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"by other item(s) of unordered flow %(flow)s"
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% dict(item=item.name, flow=self.name,
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oo=sorted(bad_reqs)))
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self._children.update(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 iter_links(self):
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# NOTE(imelnikov): children in unordered flow have no dependencies
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# between each other due to invariants retained during construction.
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return iter(())
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