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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.
import math
ADJUSTMENT_TYPES = (
EXACT_CAPACITY, CHANGE_IN_CAPACITY, PERCENT_CHANGE_IN_CAPACITY) = (
'exact_capacity', 'change_in_capacity', 'percent_change_in_capacity')
CFN_ADJUSTMENT_TYPES = (
CFN_EXACT_CAPACITY, CFN_CHANGE_IN_CAPACITY,
CFN_PERCENT_CHANGE_IN_CAPACITY) = ('ExactCapacity', 'ChangeInCapacity',
'PercentChangeInCapacity')
def calculate_new_capacity(current, adjustment, adjustment_type,
min_adjustment_step, minimum, maximum):
"""Calculates new capacity from the given adjustments.
Given the current capacity, calculates the new capacity which results
from applying the given adjustment of the given adjustment-type. The
new capacity will be kept within the maximum and minimum bounds.
"""
def _get_minimum_adjustment(adjustment, min_adjustment_step):
if min_adjustment_step and min_adjustment_step > abs(adjustment):
adjustment = (min_adjustment_step if adjustment > 0
else -min_adjustment_step)
return adjustment
if adjustment_type in (CHANGE_IN_CAPACITY, CFN_CHANGE_IN_CAPACITY):
new_capacity = current + adjustment
elif adjustment_type in (EXACT_CAPACITY, CFN_EXACT_CAPACITY):
new_capacity = adjustment
else:
# PercentChangeInCapacity
delta = current * adjustment / 100.0
if math.fabs(delta) < 1.0:
rounded = int(math.ceil(delta) if delta > 0.0
else math.floor(delta))
else:
rounded = int(math.floor(delta) if delta > 0.0
else math.ceil(delta))
adjustment = _get_minimum_adjustment(rounded, min_adjustment_step)
new_capacity = current + adjustment
if new_capacity > maximum:
return maximum
if new_capacity < minimum:
return minimum
return new_capacity
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