101 lines
3.9 KiB
Python
101 lines
3.9 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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Chance (Random) Scheduler implementation
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"""
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import random
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from oslo.config import cfg
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from cinder import exception
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from cinder.scheduler import driver
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CONF = cfg.CONF
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class ChanceScheduler(driver.Scheduler):
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"""Implements Scheduler as a random node selector."""
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def _filter_hosts(self, request_spec, hosts, **kwargs):
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"""Filter a list of hosts based on request_spec."""
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filter_properties = kwargs.get('filter_properties', {})
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if not filter_properties:
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filter_properties = {}
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ignore_hosts = filter_properties.get('ignore_hosts', [])
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hosts = [host for host in hosts if host not in ignore_hosts]
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return hosts
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def _get_weighted_candidates(self, context, topic, request_spec, **kwargs):
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"""Returns a list of the available hosts."""
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elevated = context.elevated()
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hosts = self.hosts_up(elevated, topic)
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if not hosts:
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msg = _("Is the appropriate service running?")
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raise exception.NoValidHost(reason=msg)
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return self._filter_hosts(request_spec, hosts, **kwargs)
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def _schedule(self, context, topic, request_spec, **kwargs):
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"""Picks a host that is up at random."""
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hosts = self._get_weighted_candidates(context, topic,
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request_spec, **kwargs)
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if not hosts:
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msg = _("Could not find another host")
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raise exception.NoValidHost(reason=msg)
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return hosts[int(random.random() * len(hosts))]
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def schedule_create_volume(self, context, request_spec, filter_properties):
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"""Picks a host that is up at random."""
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topic = CONF.volume_topic
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host = self._schedule(context, topic, request_spec,
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filter_properties=filter_properties)
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volume_id = request_spec['volume_id']
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snapshot_id = request_spec['snapshot_id']
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image_id = request_spec['image_id']
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updated_volume = driver.volume_update_db(context, volume_id, host)
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self.volume_rpcapi.create_volume(context, updated_volume, host,
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request_spec, filter_properties,
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snapshot_id=snapshot_id,
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image_id=image_id)
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def host_passes_filters(self, context, host, request_spec,
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filter_properties):
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"""Check if the specified host passes the filters."""
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weighed_hosts = self._get_weighted_candidates(
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context,
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CONF.volume_topic,
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request_spec,
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filter_properties=filter_properties)
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for weighed_host in weighed_hosts:
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if weighed_host == host:
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elevated = context.elevated()
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host_states = self.host_manager.get_all_host_states(elevated)
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for host_state in host_states:
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if host_state.host == host:
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return host_state
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msg = (_('cannot place volume %(id)s on %(host)s')
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% {'id': request_spec['volume_id'], 'host': host})
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raise exception.NoValidHost(reason=msg)
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