# Copyright (c) 2015 OpenStack Foundation
# 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

The default is to spread instances across all hosts evenly.  If you prefer
stacking, you can set the 'disk_weight_multiplier' option (by configuration
or aggregate metadata) to a negative number and the weighing has the opposite
effect of the default.
"""

import nova.conf
from nova.scheduler import utils
from nova.scheduler import weights

CONF = nova.conf.CONF


class DiskWeigher(weights.BaseHostWeigher):
    minval = 0

    def weight_multiplier(self, host_state):
        """Override the weight multiplier."""
        return utils.get_weight_multiplier(
            host_state, 'disk_weight_multiplier',
            CONF.filter_scheduler.disk_weight_multiplier)

    def _weigh_object(self, host_state, weight_properties):
        """Higher weights win.  We want spreading to be the default."""
        return host_state.free_disk_mb
#    under the License.
"""
Disk Weigher.  Weigh hosts by their disk usage.