55 lines
1.9 KiB
Python
55 lines
1.9 KiB
Python
# 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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"""Bench of utility methods used by filters."""
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from nova.i18n import _LI
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from nova import objects
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from nova.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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def aggregate_values_from_db(context, host, key_name):
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"""Returns a set of values based on a metadata key for a specific host."""
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# TODO(sahid): DB query in filter is a performance hit, especially for
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# system with lots of hosts. Will need a general solution here to fix
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# all filters with aggregate DB call things.
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aggrlist = objects.AggregateList.get_by_host(
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context.elevated(), host, key=key_name)
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aggregate_vals = set(aggr.metadata[key_name] for aggr in aggrlist)
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return aggregate_vals
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def validate_num_values(vals, default=None, cast_to=int, based_on=min):
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"""Returns a corretly casted value based on a set of values.
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This method is useful to work with per-aggregate filters, It takes
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a set of values then return the 'based_on'{min/max} converted to
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'cast_to' of the set or the default value.
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Note: The cast implies a possible ValueError
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"""
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num_values = len(vals)
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if num_values == 0:
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return default
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if num_values > 1:
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LOG.info(_LI("%(num_values)d values found, "
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"of which the minimum value will be used."),
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{'num_values': num_values})
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return cast_to(based_on(vals))
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