mirror of
https://github.com/zerotier/ZeroTierOne.git
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133 lines
3.3 KiB
C++
133 lines
3.3 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_RATELIMITER_HPP
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#define _ZT_RATELIMITER_HPP
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#include <math.h>
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#include "Constants.hpp"
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#include "Utils.hpp"
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#ifdef __WINDOWS__
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#define fmin(a,b) (((a) <= (b)) ? (a) : (b))
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#define fmax(a,b) (((a) >= (b)) ? (a) : (b))
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#endif
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namespace ZeroTier {
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/**
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* Data transfer accounting used for 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 RateLimiter
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{
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public:
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/**
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* Rate and min/max to apply on rate limiter update
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*/
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struct Rate
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{
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/**
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* Rate of balance accrual in bytes per second
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*/
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double bytesPerSecond;
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/**
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* Maximum balance that can ever be accrued (should be > 0.0)
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*/
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double maxBalance;
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/**
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* Minimum balance, or maximum allowable "debt" (should be <= 0.0)
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*/
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double minBalance;
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};
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/**
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* Create an uninitialized rate limiter
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*
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* init() must be called before this is used.
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*/
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RateLimiter() throw() {}
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/**
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* Create an initialize rate limiter
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*
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* @param preload Initial balance to place in account
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*/
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RateLimiter(double preload)
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throw()
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{
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init(preload);
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}
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/**
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* Initialize or re-initialize rate limiter
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*
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* @param preload Initial balance to place in account
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*/
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inline void init(double preload)
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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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}
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/**
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* Update balance based on current clock and supplied rate
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*
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* @param lim Current limits in effect
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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
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*/
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inline double update(const Rate &r,double deduct)
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throw()
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{
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double lt = _lastTime;
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double now = _lastTime = Utils::nowf();
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return (_balance = fmax(r.minBalance,fmin(r.maxBalance,(_balance + (r.bytesPerSecond * (now - lt))) - deduct)));
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}
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private:
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double _lastTime;
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double _balance;
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};
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} // namespace ZeroTier
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#endif
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