# -*- coding: utf-8 -*- # Copyright 2020 PrivateStorage.io, LLC # # 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. """ Calculate the price, in ZKAPs, for storing files. The underlying storage system operates only on individual shares. Thus, it *does not* use this file-oriented calculator. However, for end-users, file-oriented pricing is often more helpful. This calculator builds on the share-oriented price calculation to present file-oriented price information. It accounts for erasure encoding data expansion. It does not account for the real state of the storage system (e.g., if some data is *already* stored then storing it "again" is essentially free but this will not be reflected by this calculator). """ import attr from .storage_common import required_passes, share_size_for_data @attr.s class PriceCalculator(object): """ :ivar int _shares_needed: The number of shares which are required to reconstruct the original data. :ivar int _shares_total: The total number of shares which will be produced in the erasure encoding process. :ivar int _pass_value: The bytes component of the bytes×time value of a single pass. """ _shares_needed = attr.ib() _shares_total = attr.ib() _pass_value = attr.ib() def calculate(self, sizes): """ Calculate the price to store data of the given sizes for one lease period. :param [int] sizes: The sizes of the individual data items in bytes. :return int: The number of ZKAPs required. """ share_sizes = (share_size_for_data(self._shares_needed, size) for size in sizes) all_required_passes = ( required_passes(self._pass_value, [share_size] * self._shares_total) for share_size in share_sizes ) price = sum(all_required_passes, 0) return price