mirror of
https://github.com/zerotier/ZeroTierOne.git
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125 lines
3.5 KiB
C++
125 lines
3.5 KiB
C++
/*
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* ZeroTier One - Global Peer to Peer Ethernet
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* Copyright (C) 2012-2013 ZeroTier Networks LLC
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* --
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*
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* ZeroTier may be used and distributed under the terms of the GPLv3, which
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* are available at: http://www.gnu.org/licenses/gpl-3.0.html
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*
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* If you would like to embed ZeroTier into a commercial application or
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* redistribute it in a modified binary form, please contact ZeroTier Networks
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* LLC. Start here: http://www.zerotier.com/
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*/
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#ifndef _ZT_BWACCOUNT_HPP
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#define _ZT_BWACCOUNT_HPP
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#include <stdint.h>
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#include <math.h>
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#include <algorithm>
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#include <utility>
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#include "Constants.hpp"
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#include "Utils.hpp"
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namespace ZeroTier {
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/**
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* Bandwidth account used for rate limiting multicast groups
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*
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* This is used to apply a bank account model to multicast groups. Each
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* multicast packet counts against a balance, which accrues at a given
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* rate in bytes per second. Debt is possible. These parameters are
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* configurable.
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*
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* A bank account model permits bursting behavior, which correctly models
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* how OSes and apps typically use multicast. It's common for things to
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* spew lots of multicast messages at once, wait a while, then do it
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* again. A consistent bandwidth limit model doesn't fit.
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*/
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class BandwidthAccount
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{
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public:
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/**
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* Create an uninitialized account
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*
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* init() must be called before this is used.
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*/
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BandwidthAccount() throw() {}
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/**
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* Create and initialize
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*
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* @param preload Initial balance to place in account
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* @param minb Minimum allowed balance (or maximum debt) (<= 0)
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* @param maxb Maximum allowed balance (> 0)
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* @param acc Rate of accrual in bytes per second
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*/
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BandwidthAccount(int32_t preload,int32_t minb,int32_t maxb,int32_t acc)
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throw()
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{
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init(preload,minb,maxb,acc);
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}
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/**
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* Initialize or re-initialize account
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*
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* @param preload Initial balance to place in account
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* @param minb Minimum allowed balance (or maximum debt) (<= 0)
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* @param maxb Maximum allowed balance (> 0)
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* @param acc Rate of accrual in bytes per second
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*/
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inline void init(int32_t preload,int32_t minb,int32_t maxb,int32_t acc)
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throw()
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{
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_lastTime = Utils::nowf();
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_balance = preload;
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_minBalance = minb;
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_maxBalance = maxb;
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_accrual = acc;
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}
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/**
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* Update balance by accruing and then deducting
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*
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* @param deduct Amount to deduct, or 0.0 to just update
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* @return New balance with deduction applied, and whether or not deduction fit
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*/
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inline std::pair<int32_t,bool> update(int32_t deduct)
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throw()
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{
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double lt = _lastTime;
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double now = Utils::nowf();
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_lastTime = now;
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int32_t newbal = (int32_t)round((double)_balance + ((double)_accrual * (now - lt))) - deduct;
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bool fits = (newbal > 0);
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return std::pair<int32_t,bool>((_balance = std::max(_minBalance,std::min(_maxBalance,newbal))),fits);
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}
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private:
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double _lastTime;
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int32_t _balance;
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int32_t _minBalance;
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int32_t _maxBalance;
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int32_t _accrual;
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};
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} // namespace ZeroTier
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#endif
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