08a1846396
Instead of having a nominally useful single-threaded storage unit that uses a dummy r/w lock and a multi-threaded storage unit just have the storage unit by default protect itself from multi-threading calls being used on it (with the appropriate reader/writer locks being activated to make this work correctly). Change-Id: Ib6879edb465156a8e54fd5b4002550d1cec49137
120 lines
4.1 KiB
Python
120 lines
4.1 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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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 deprecation
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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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@deprecation.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, all final dependencies
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will be verified, the tasks will be reset and the engine will enter
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the PENDING state.
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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 tasks then this will attempt to
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suspend future work from being started (currently active tasks 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 = deprecation.moved_inheritable_class(Engine,
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'EngineBase', __name__,
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version="0.6",
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removal_version="?")
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