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