c1f37e5fa3
To allow compilation into an execution graph to be done via other methods than our pattern flattening concept create a module that defines what a compiler should do and what the expected return type from compilation of a atom/flow is and how it will be used by our existing engine types. Part of blueprint plug-engine Change-Id: I324172571f36a574195bcdeac71c6ec14cb11944
50 lines
2.2 KiB
Python
50 lines
2.2 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2014 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 collections
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from taskflow import exceptions as exc
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from taskflow.utils import flow_utils
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# The result of a compilers compile() is this tuple (for now it is just a
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# execution graph but in the future it may grow to include more attributes
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# that help the runtime units execute in a more optimal/featureful manner).
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Compilation = collections.namedtuple("Compilation", ["execution_graph"])
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class PatternCompiler(object):
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"""Compiles patterns & atoms (potentially nested) into an compilation
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unit with a *logically* equivalent directed acyclic graph representation.
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NOTE(harlowja): during this pattern translation process any nested flows
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will be converted into there equivalent subgraphs. This currently implies
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that contained atoms in those nested flows, post-translation will no longer
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be associated with there previously containing flow but instead will lose
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this identity and what will remain is the logical constraints that there
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contained flow mandated. In the future this may be changed so that this
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association is not lost via the compilation process (since it is sometime
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useful to retain part of this relationship).
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"""
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def compile(self, root):
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graph = flow_utils.flatten(root)
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if graph.number_of_nodes() == 0:
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# Try to get a name attribute, otherwise just use the object
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# string representation directly if that attribute does not exist.
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name = getattr(root, 'name', root)
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raise exc.Empty("Root container '%s' (%s) is empty."
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% (name, type(root)))
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return Compilation(graph)
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