81 lines
2.4 KiB
C++
81 lines
2.4 KiB
C++
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
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/**
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* Copyright (c) 2014-2017, Regents of the University of California,
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* Arizona Board of Regents,
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* Colorado State University,
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* University Pierre & Marie Curie, Sorbonne University,
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* Washington University in St. Louis,
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* Beijing Institute of Technology,
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* The University of Memphis
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*
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* This file is part of NFD (Named Data Networking Forwarding Daemon).
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* See AUTHORS.md for complete list of NFD authors and contributors.
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*
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* NFD is free software: you can redistribute it and/or modify it under the terms
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* of the GNU General Public License as published by the Free Software Foundation,
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* either version 3 of the License, or (at your option) any later version.
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*
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* NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the 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 along with
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* NFD, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
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**/
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#include "rtt-estimator.hpp"
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namespace nfd {
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RttEstimator::RttEstimator(uint16_t maxMultiplier, Duration minRto, double gain)
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: m_maxMultiplier(maxMultiplier)
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, m_minRto(minRto.count())
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, m_rtt(RttEstimator::getInitialRtt().count())
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, m_gain(gain)
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, m_variance(0)
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, m_multiplier(1)
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, m_nSamples(0)
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{
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}
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void
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RttEstimator::addMeasurement(Duration measure)
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{
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double m = static_cast<double>(measure.count());
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if (m_nSamples > 0) {
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double err = m - m_rtt;
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double gErr = err * m_gain;
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m_rtt += gErr;
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double difference = std::abs(err) - m_variance;
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m_variance += difference * m_gain;
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}
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else {
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m_rtt = m;
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m_variance = m;
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}
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++m_nSamples;
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m_multiplier = 1;
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}
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void
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RttEstimator::incrementMultiplier()
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{
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m_multiplier = std::min(static_cast<uint16_t>(m_multiplier + 1), m_maxMultiplier);
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}
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void
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RttEstimator::doubleMultiplier()
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{
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m_multiplier = std::min(static_cast<uint16_t>(m_multiplier * 2), m_maxMultiplier);
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}
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RttEstimator::Duration
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RttEstimator::computeRto() const
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{
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double rto = std::max(m_minRto, m_rtt + 4 * m_variance);
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rto *= m_multiplier;
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return Duration(static_cast<Duration::rep>(rto));
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}
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} // namespace nfd
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