c95bf4165d
This reverts commit 42ca240e81 which
was a breaking change in a library consumed by other OpenStack
projects with no deprecation or backwards compatibility
considerations. It was able to merge because openstack/taskflow is
apparently not yet part of the integrated gate via the proposed
I202f4809afd689155e2cc4a00fc704fd772a0e92 change.
Change-Id: I96cf36dc317499df91e43502efc85221f8177395
Closes-Bug: #1300161
134 lines
4.7 KiB
Python
134 lines
4.7 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 time
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logging.basicConfig(level=logging.ERROR)
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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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import taskflow.engines
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from taskflow import exceptions
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from taskflow.patterns import unordered_flow as uf
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from taskflow import task
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from taskflow.tests import utils
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from taskflow.utils import misc
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# INTRO: In this example we create two tasks which can trigger exceptions
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# based on various inputs to show how to analyze the thrown exceptions for
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# which types were thrown and handle the different types in different ways.
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#
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# This is especially important if a set of tasks run in parallel and each of
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# those tasks may fail while running. This creates a scenario where multiple
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# exceptions have been thrown and those exceptions need to be handled in a
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# unified manner. Since an engine does not currently know how to resolve
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# those exceptions (someday it could) the code using that engine and activating
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# the flows and tasks using that engine will currently have to deal with
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# catching those exceptions (and silencing them if this is desired).
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#
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# NOTE(harlowja): The engine *will* trigger rollback even under multiple
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# exceptions being thrown, but at the end of that rollback the engine will
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# rethrow these exceptions to the code that called the run() method; allowing
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# that code to do further cleanups (if desired).
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def print_wrapped(text):
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print("-" * (len(text)))
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print(text)
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print("-" * (len(text)))
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class FirstException(Exception):
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"""Exception that first task raises."""
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class SecondException(Exception):
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"""Exception that second task raises."""
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class FirstTask(task.Task):
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def execute(self, sleep1, raise1):
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time.sleep(sleep1)
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if not isinstance(raise1, bool):
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raise TypeError('Bad raise1 value: %r' % raise1)
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if raise1:
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raise FirstException('First task failed')
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class SecondTask(task.Task):
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def execute(self, sleep2, raise2):
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time.sleep(sleep2)
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if not isinstance(raise2, bool):
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raise TypeError('Bad raise2 value: %r' % raise2)
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if raise2:
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raise SecondException('Second task failed')
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def run(**store):
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# Creates a flow, each task in the flow will examine the kwargs passed in
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# here and based on those kwargs it will behave in a different manner
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# while executing; this allows for the calling code (see below) to show
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# different usages of the failure catching and handling mechanism.
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flow = uf.Flow('flow').add(
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FirstTask(),
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SecondTask()
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)
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try:
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with utils.wrap_all_failures():
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taskflow.engines.run(flow, store=store,
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engine_conf='parallel')
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except exceptions.WrappedFailure as ex:
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unknown_failures = []
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for failure in ex:
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if failure.check(FirstException):
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print("Got FirstException: %s" % failure.exception_str)
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elif failure.check(SecondException):
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print("Got SecondException: %s" % failure.exception_str)
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else:
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print("Unknown failure: %s" % failure)
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unknown_failures.append(failure)
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misc.Failure.reraise_if_any(unknown_failures)
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print_wrapped("Raise and catch first exception only")
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run(sleep1=0.0, raise1=True,
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sleep2=0.0, raise2=False)
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# NOTE(imelnikov): in general, sleeping does not guarantee that we'll have both
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# task running before one of them fails, but with current implementation this
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# works most of times, which is enough for our purposes here (as an example).
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print_wrapped("Raise and catch both exceptions")
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run(sleep1=1.0, raise1=True,
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sleep2=1.0, raise2=True)
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print_wrapped("Handle one exception, and re-raise another")
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try:
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run(sleep1=1.0, raise1=True,
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sleep2=1.0, raise2='boom')
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except TypeError as ex:
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print("As expected, TypeError is here: %s" % ex)
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else:
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assert False, "TypeError expected"
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