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#
# 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.
from oslo_utils import timeutils
import six
class CooldownMixin(object):
"""Utility class to encapsulate Cooldown related logic.
This class is shared between AutoScalingGroup and ScalingPolicy.
This logic includes both cooldown timestamp comparing and scaling in
progress checking.
"""
def _is_scaling_allowed(self):
metadata = self.metadata_get()
if metadata.get('scaling_in_progress'):
return False
try:
# Negative values don't make sense, so they are clamped to zero
cooldown = max(0, self.properties[self.COOLDOWN])
except TypeError:
# If not specified, it will be None, same as cooldown == 0
cooldown = 0
if 'cooldown' not in metadata:
# Note: this is for supporting old version cooldown checking
if metadata and cooldown != 0:
last_adjust = next(six.iterkeys(metadata))
if not timeutils.is_older_than(last_adjust, cooldown):
return False
elif cooldown != 0:
last_adjust = next(six.iterkeys(metadata['cooldown']))
if not timeutils.is_older_than(last_adjust, cooldown):
return False
# Assumes _finished_scaling is called
# after the scaling operation completes
metadata['scaling_in_progress'] = True
self.metadata_set(metadata)
return True
def _finished_scaling(self, cooldown_reason,
changed_size=True):
# If we wanted to implement the AutoScaling API like AWS does,
# we could maintain event history here, but since we only need
# the latest event for cooldown, just store that for now
metadata = self.metadata_get()
if changed_size:
now = timeutils.utcnow().isoformat()
metadata['cooldown'] = {now: cooldown_reason}
metadata['scaling_in_progress'] = False
self.metadata_set(metadata)
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