5544d71bc8
Some things that popped out while reading the comments/documentation. Change-Id: I0ccecae3381447ede44bb855d91f997349be1562
114 lines
3.9 KiB
Python
114 lines
3.9 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2012-2013 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 logging
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import os
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import sys
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import tempfile
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import traceback
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logging.basicConfig(level=logging.ERROR)
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self_dir = os.path.abspath(os.path.dirname(__file__))
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top_dir = os.path.abspath(os.path.join(os.path.dirname(__file__),
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os.pardir,
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os.pardir))
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sys.path.insert(0, top_dir)
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sys.path.insert(0, self_dir)
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from taskflow import engines
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from taskflow.patterns import linear_flow as lf
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from taskflow.persistence import logbook
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from taskflow import task
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from taskflow.utils import persistence_utils as p_utils
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import example_utils as eu # noqa
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# INTRO: In this example we create two tasks, one that will say hi and one
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# that will say bye with optional capability to raise an error while
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# executing. During execution if a later task fails, the reverting that will
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# occur in the hi task will undo this (in a ~funny~ way).
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#
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# To also show the effect of task persistence we create a temporary database
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# that will track the state transitions of this hi + bye workflow, this
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# persistence allows for you to examine what is stored (using a sqlite client)
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# as well as shows you what happens during reversion and what happens to
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# the database during both of these modes (failing or not failing).
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class HiTask(task.Task):
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def execute(self):
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print("Hi!")
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def revert(self, **kwargs):
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print("Whooops, said hi too early, take that back!")
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class ByeTask(task.Task):
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def __init__(self, blowup):
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super(ByeTask, self).__init__()
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self._blowup = blowup
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def execute(self):
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if self._blowup:
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raise Exception("Fail!")
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print("Bye!")
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# This generates your flow structure (at this stage nothing is run).
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def make_flow(blowup=False):
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flow = lf.Flow("hello-world")
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flow.add(HiTask(), ByeTask(blowup))
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return flow
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# Persist the flow and task state here, if the file/dir exists already blow up
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# if not don't blow up, this allows a user to see both the modes and to see
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# what is stored in each case.
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if eu.SQLALCHEMY_AVAILABLE:
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persist_path = os.path.join(tempfile.gettempdir(), "persisting.db")
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backend_uri = "sqlite:///%s" % (persist_path)
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else:
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persist_path = os.path.join(tempfile.gettempdir(), "persisting")
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backend_uri = "file:///%s" % (persist_path)
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if os.path.exists(persist_path):
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blowup = False
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else:
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blowup = True
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with eu.get_backend(backend_uri) as backend:
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# Make a flow that will blow up if the file didn't exist previously, if it
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# did exist, assume we won't blow up (and therefore this shows the undo
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# and redo that a flow will go through).
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book = logbook.LogBook("my-test")
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flow = make_flow(blowup=blowup)
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eu.print_wrapped("Running")
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try:
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eng = engines.load(flow, engine='serial',
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backend=backend, book=book)
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eng.run()
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if not blowup:
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eu.rm_path(persist_path)
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except Exception:
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# NOTE(harlowja): don't exit with non-zero status code, so that we can
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# print the book contents, as well as avoiding exiting also makes the
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# unit tests (which also runs these examples) pass.
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traceback.print_exc(file=sys.stdout)
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eu.print_wrapped("Book contents")
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print(p_utils.pformat(book))
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