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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
# 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_log import log as logging
from heat.common import exception
from heat.common.i18n import _
from heat.engine import resource
from oslo_utils import timeutils
import six
LOG = logging.getLogger(__name__)
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 _check_scaling_allowed(self):
metadata = self.metadata_get()
if metadata.get('scaling_in_progress'):"Can not perform scaling action: resource %s "
"is already in scaling.",
reason = _('due to scaling activity')
raise resource.NoActionRequired(,
# Negative values don't make sense, so they are clamped to zero
cooldown = max(0,[self.COOLDOWN])
except TypeError:
# If not specified, it will be None, same as cooldown == 0
cooldown = 0
if cooldown != 0:
if 'cooldown' not in metadata:
# Note: this is for supporting old version cooldown logic
if metadata:
last_adjust = next(six.iterkeys(metadata))
self._cooldown_check(cooldown, last_adjust)
last_adjust = next(six.iterkeys(metadata['cooldown']))
self._cooldown_check(cooldown, last_adjust)
except ValueError:
# occurs when metadata has only {scaling_in_progress: False}
# Assumes _finished_scaling is called
# after the scaling operation completes
metadata['scaling_in_progress'] = True
def _cooldown_check(self, cooldown, last_adjust):
if not timeutils.is_older_than(last_adjust, cooldown):"Can not perform scaling action: "
"resource %(name)s is in cooldown (%(cooldown)s).",
'cooldown': cooldown})
reason = _('due to cooldown, '
'cooldown %s') % cooldown
raise resource.NoActionRequired(, reason=reason)
def _finished_scaling(self, cooldown_reason, size_changed=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 size_changed:
now = timeutils.utcnow().isoformat()
metadata['cooldown'] = {now: cooldown_reason}
metadata['scaling_in_progress'] = False
except exception.NotFound:
def handle_metadata_reset(self):
metadata = self.metadata_get()
if 'scaling_in_progress' in metadata:
metadata['scaling_in_progress'] = False