96 lines
3.1 KiB
Python
96 lines
3.1 KiB
Python
# -*- coding: utf-8 -*-
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (C) 2012 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 uuid
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from taskflow import exceptions as exc
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from taskflow import states
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class JobClaimer(object):
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"""A base class for objects that can attempt to claim a given claim a given
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job, so that said job can be worked on."""
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__metaclass__ = abc.ABCMeta
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@abc.abstractmethod
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def claim(self, job, owner):
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"""This method will attempt to claim said job and must
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either succeed at this or throw an exception signaling the job can not
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be claimed."""
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raise NotImplementedError()
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class Job(object):
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"""A job is connection to some set of work to be done by some agent. Basic
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information is provided about said work to be able to attempt to
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fullfill said work."""
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__metaclass__ = abc.ABCMeta
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def __init__(self, name, context, catalog, claimer):
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self.name = name
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self.context = context
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self.state = states.UNCLAIMED
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self.owner = None
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self.posted_on = []
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self._catalog = catalog
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self._claimer = claimer
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self._logbook = None
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self._id = str(uuid.uuid4().hex)
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@property
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def logbook(self):
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if self._logbook is None:
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if self in self._catalog:
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self._logbook = self._catalog.fetch(self)
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else:
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self._logbook = self._catalog.create(self)
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return self._logbook
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def claim(self, owner):
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""" This can be used to attempt transition this job from unclaimed
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to claimed.
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This must be done in a way that likely uses some type of locking or
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ownership transfer so that only a single entity gets this job to work
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on. This will avoid multi-job ownership, which can lead to
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inconsistent state."""
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if self.state != states.UNCLAIMED:
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raise exc.UnclaimableJobException("Unable to claim job when job is"
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" in state %s" % (self.state))
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self._claimer.claim(self, owner)
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self.owner = owner
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self._change_state(states.CLAIMED)
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def _change_state(self, new_state):
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self.state = new_state
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# TODO(harlowja): update the logbook
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def erase(self):
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"""Erases any traces of this job from its associated resources."""
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for b in self.posted_on:
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b.erase(self)
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self._catalog.erase(self)
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self._logbook = None
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@property
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def tracking_id(self):
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return "j-%s-%s" % (self.name, self._id)
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