f0de22c18a
Instead of only storing injected atom arguments in memory allow for specifying those to be persisted; so that users who desire this feature can persist them (it defaults to being transient to retain the old API behavior). This also reworks the validating of engine dependencies to be more correct. It removes the validation of these dependencies from the prepare() method and moves them to a new engine validate() method; this allows users to prepare() the engine, then inject there atom non-transient arguments and then validate(); the validation would fail prior to this at preparation time since no injected arguments would exist and the user would not have the ability to inject any that target a specific atom, since the atom detail would not have been created yet (since that is populated in the prepartion method). Change-Id: I2846d0334db32a115592f850d85b206d9e6a3f07
127 lines
4.2 KiB
Python
127 lines
4.2 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2013 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 debtcollector import moves
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import six
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from taskflow import storage
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from taskflow.types import notifier
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from taskflow.utils import misc
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@six.add_metaclass(abc.ABCMeta)
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class Engine(object):
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"""Base for all engines implementations.
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:ivar notifier: A notification object that will dispatch events that
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occur related to the flow the engine contains.
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:ivar task_notifier: A notification object that will dispatch events that
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occur related to the tasks the engine contains.
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occur related to the tasks the engine
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contains (deprecated).
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:ivar atom_notifier: A notification object that will dispatch events that
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occur related to the atoms the engine contains.
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"""
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def __init__(self, flow, flow_detail, backend, options):
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self._flow = flow
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self._flow_detail = flow_detail
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self._backend = backend
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if not options:
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self._options = {}
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else:
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self._options = dict(options)
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self._notifier = notifier.Notifier()
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self._atom_notifier = notifier.Notifier()
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@property
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def notifier(self):
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"""The flow notifier."""
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return self._notifier
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@property
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@moves.moved_property('atom_notifier', version="0.6",
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removal_version="?")
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def task_notifier(self):
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"""The task notifier."""
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return self._atom_notifier
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@property
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def atom_notifier(self):
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"""The atom notifier."""
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return self._atom_notifier
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@property
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def options(self):
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"""The options that were passed to this engine on construction."""
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return self._options
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@misc.cachedproperty
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def storage(self):
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"""The storage unit for this flow."""
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return storage.Storage(self._flow_detail, backend=self._backend)
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@abc.abstractmethod
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def compile(self):
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"""Compiles the contained flow into a internal representation.
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This internal representation is what the engine will *actually* use to
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run. If this compilation can not be accomplished then an exception
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is expected to be thrown with a message indicating why the compilation
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could not be achieved.
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"""
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@abc.abstractmethod
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def prepare(self):
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"""Performs any pre-run, but post-compilation actions.
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NOTE(harlowja): During preparation it is currently assumed that the
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underlying storage will be initialized, the atoms will be reset and
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the engine will enter the PENDING state.
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"""
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@abc.abstractmethod
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def validate(self):
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"""Performs any pre-run, post-prepare validation actions.
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NOTE(harlowja): During validation all final dependencies
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will be verified and ensured. This will by default check that all
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atoms have satisfiable requirements (satisfied by some other
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provider).
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"""
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@abc.abstractmethod
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def run(self):
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"""Runs the flow in the engine to completion (or die trying)."""
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@abc.abstractmethod
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def suspend(self):
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"""Attempts to suspend the engine.
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If the engine is currently running atoms then this will attempt to
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suspend future work from being started (currently active atoms can
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not currently be preempted) and move the engine into a suspend state
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which can then later be resumed from.
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"""
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# TODO(harlowja): remove in 0.7 or later...
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EngineBase = moves.moved_class(Engine, 'EngineBase', __name__,
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version="0.6", removal_version="?")
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