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# Copyright (c) 2011 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
# under the License.
"""
Scheduler host filters
"""
from nova import filters
class BaseHostFilter(filters.BaseFilter):
"""Base class for host filters."""
# This is set to True if this filter should be run for rebuild.
# For example, with rebuild, we need to ask the scheduler if the
# existing host is still legit for a rebuild with the new image and
# other parameters. We care about running policy filters (i.e.
# ImagePropertiesFilter) but not things that check usage on the
# existing compute node, etc.
# This also means that filters marked with RUN_ON_REBUILD = True cannot
# filter on allocation candidates or need to handle the rebuild case
# specially.
RUN_ON_REBUILD = False
def _filter_one(self, obj, spec):
"""Return True if the object passes the filter, otherwise False."""
# Do this here so we don't get scheduler.filters.utils
from nova.scheduler import utils
if not self.RUN_ON_REBUILD and utils.request_is_rebuild(spec):
# If we don't filter, default to passing the host.
return True
else:
# We are either a rebuild filter, in which case we always run,
# or this request is not rebuild in which case all filters
# should run.
return self.host_passes(obj, spec)
def host_passes(self, host_state, filter_properties):
"""Return True if the HostState passes the filter, otherwise False.
Override this in a subclass.
"""
raise NotImplementedError()
class HostFilterHandler(filters.BaseFilterHandler):
def __init__(self):
super(HostFilterHandler, self).__init__(BaseHostFilter)
def all_filters():
"""Return a list of filter classes found in this directory.
This method is used as the default for available scheduler filters
and should return a list of all filter classes available.
"""
return HostFilterHandler().get_all_classes()
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