71 lines
2.4 KiB
Python
71 lines
2.4 KiB
Python
# Copyright (c) 2010 OpenStack Foundation
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# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# 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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"""
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Scheduler base class that all Schedulers should inherit from
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"""
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import abc
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import six
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from stevedore import driver
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import nova.conf
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from nova import objects
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from nova import servicegroup
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CONF = nova.conf.CONF
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@six.add_metaclass(abc.ABCMeta)
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class Scheduler(object):
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"""The base class that all Scheduler classes should inherit from."""
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USES_ALLOCATION_CANDIDATES = True
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"""Indicates that the scheduler driver calls the Placement API for
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allocation candidates and uses those allocation candidates in its
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decision-making.
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"""
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def __init__(self):
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self.host_manager = driver.DriverManager(
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"nova.scheduler.host_manager",
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CONF.scheduler.host_manager,
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invoke_on_load=True).driver
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self.servicegroup_api = servicegroup.API()
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def run_periodic_tasks(self, context):
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"""Manager calls this so drivers can perform periodic tasks."""
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pass
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def hosts_up(self, context, topic):
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"""Return the list of hosts that have a running service for topic."""
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services = objects.ServiceList.get_by_topic(context, topic)
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return [service.host
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for service in services
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if self.servicegroup_api.service_is_up(service)]
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@abc.abstractmethod
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def select_destinations(self, context, spec_obj, instance_uuids,
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alloc_reqs_by_rp_uuid, provider_summaries,
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allocation_request_version=None, return_alternates=False):
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"""Returns a list of lists of Selection objects that have been chosen
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by the scheduler driver, one for each requested instance.
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"""
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return []
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