9d0b16e7fb
Most TaskFlow exception don't have 'Exception' suffix in their names, so we drop it from the few that have it, for sake of consistency and more concise and expressive code. MissingDependencies parent object is changed from InvalidState to InvariantViolation, which is more appropriate. Unused ClosedException is dropped. Breaking change: any client code that used renamed exceptions, ClosedException or relied on catching MissingDependencies as InvariantViolationException is affected. Change-Id: I649b7760d382ccb6df333bdffd667ba6b67a431e
91 lines
3.1 KiB
Python
91 lines
3.1 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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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):
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super(Flow, self).__init__(name)
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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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# 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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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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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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