nova/nova/scheduler/weights/affinity.py

91 lines
3.2 KiB
Python

# Copyright (c) 2015 Ericsson AB
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Affinity Weighers. Weigh hosts by the number of instances from a given host.
AffinityWeigher implements the soft-affinity policy for server groups by
preferring the hosts that has more instances from the given group.
AntiAffinityWeigher implements the soft-anti-affinity policy for server groups
by preferring the hosts that has less instances from the given group.
"""
from oslo_config import cfg
from oslo_log import log as logging
from nova.i18n import _LW
from nova.scheduler import weights
CONF = cfg.CONF
LOG = logging.getLogger(__name__)
class _SoftAffinityWeigherBase(weights.BaseHostWeigher):
policy_name = None
def _weigh_object(self, host_state, request_spec):
"""Higher weights win."""
if not request_spec.instance_group:
return 0
policies = request_spec.instance_group.policies
if self.policy_name not in policies:
return 0
instances = set(host_state.instances.keys())
members = set(request_spec.instance_group.members)
member_on_host = instances.intersection(members)
return len(member_on_host)
class ServerGroupSoftAffinityWeigher(_SoftAffinityWeigherBase):
policy_name = 'soft-affinity'
warning_sent = False
def weight_multiplier(self):
if (CONF.soft_affinity_weight_multiplier < 0 and
not self.warning_sent):
LOG.warning(_LW('For the soft_affinity_weight_multiplier only a '
'positive value is meaningful as a negative value '
'would mean that the affinity weigher would '
'prefer non-collocating placement.'))
self.warning_sent = True
return CONF.soft_affinity_weight_multiplier
class ServerGroupSoftAntiAffinityWeigher(_SoftAffinityWeigherBase):
policy_name = 'soft-anti-affinity'
warning_sent = False
def weight_multiplier(self):
if (CONF.soft_anti_affinity_weight_multiplier < 0 and
not self.warning_sent):
LOG.warning(_LW('For the soft_anti_affinity_weight_multiplier '
'only a positive value is meaningful as a '
'negative value would mean that the anti-affinity '
'weigher would prefer collocating placement.'))
self.warning_sent = True
return CONF.soft_anti_affinity_weight_multiplier
def _weigh_object(self, host_state, request_spec):
weight = super(ServerGroupSoftAntiAffinityWeigher, self)._weigh_object(
host_state, request_spec)
return -1 * weight