a134930dd5
Create a base implementation of a jobboard which serves as a place to post work to be done, a place to get notified of new work, and a place which can be used to atomically acquire that work (so that it can be worked on) as well as transfer that work from one entity (say when that entity fails) to another entity (for further resumption or other policy/code driven recovery processes). Implements: blueprint job-reference-impl Change-Id: I1de1525df0deee612fb14ca36f0415ea7d2f707c
103 lines
3.9 KiB
Python
103 lines
3.9 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2013 Rackspace Hosting Inc. All Rights Reserved.
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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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@six.add_metaclass(abc.ABCMeta)
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class JobBoard(object):
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"""A jobboard is an abstract representation of a place where jobs
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can be posted, reposted, claimed and transferred. There can be multiple
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implementations of this job board, depending on the desired semantics and
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capabilities of the underlying jobboard implementation.
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"""
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def __init__(self, name):
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self._name = name
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@abc.abstractmethod
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def iterjobs(self, only_unclaimed=False):
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"""Yields back jobs that are currently on this jobboard (claimed
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or not claimed).
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"""
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@abc.abstractproperty
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def job_count(self):
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"""Returns how many jobs are on this jobboard."""
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@abc.abstractmethod
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def find_owner(self, job):
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"""Gets the owner of the job if one exists."""
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@property
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def name(self):
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"""The non-uniquely identifying name of this jobboard."""
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return self._name
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@abc.abstractmethod
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def consume(self, job, who):
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"""Permanently (and atomically) removes a job from the jobboard,
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signaling that this job has been completed by the entity assigned
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to that job.
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Only the entity that has claimed that job is able to consume a job.
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A job that has been consumed can not be reclaimed or reposted by
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another entity (job postings are immutable). Any entity consuming
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a unclaimed job (or a job they do not own) will cause an exception.
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"""
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@abc.abstractmethod
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def post(self, name, book, details=None):
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"""Atomically creates and posts a job to the jobboard, allowing others
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to attempt to claim that job (and subsequently work on that job). The
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contents of the provided logbook must provide enough information for
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others to reference to construct & work on the desired entries that
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are contained in that logbook.
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Once a job has been posted it can only be removed by consuming that
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job (after that job is claimed). Any entity can post/propose jobs
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to the jobboard (in the future this may be restricted).
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Returns a job object representing the information that was posted.
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"""
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@abc.abstractmethod
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def claim(self, job, who):
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"""Atomically attempts to claim the given job for the entity and either
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succeeds or fails at claiming by throwing corresponding exceptions.
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If a job is claimed it is expected that the entity that claims that job
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will at sometime in the future work on that jobs flows and either fail
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at completing them (resulting in a reposting) or consume that job from
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the jobboard (signaling its completion).
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"""
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@abc.abstractmethod
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def abandon(self, job, who):
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"""Atomically abandons the given job on the jobboard, allowing that job
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to be reclaimed by others. This would typically occur if the entity
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that has claimed the job has failed or is unable to complete the job
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or jobs it has claimed.
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Only the entity that has claimed that job can abandon a job. Any entity
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abandoning a unclaimed job (or a job they do not own) will cause an
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exception.
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"""
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