101 lines
2.8 KiB
C++
101 lines
2.8 KiB
C++
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#include "limeric.hpp"
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#include <vanetza/common/runtime.hpp>
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#include <cassert>
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#include <cmath>
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#include <numeric>
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namespace vanetza
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{
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namespace dcc
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{
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static const Limeric::Parameters limericDefaultParams;
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Limeric::Limeric(Runtime& rt) : Limeric(rt, limericDefaultParams)
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{
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}
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Limeric::Limeric(Runtime& rt, const Parameters& params) :
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on_duty_cycle_change(m_duty_cycle_change), m_runtime(rt), m_params(params),
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m_duty_cycle(mean(params.delta_max, params.delta_min)), m_cbr(2)
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{
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assert(m_cbr.empty());
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schedule();
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}
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Limeric::~Limeric()
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{
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m_runtime.cancel(this);
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}
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ChannelLoad Limeric::average_cbr() const
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{
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if (m_cbr.full()) {
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return 0.5 * mean(m_cbr.begin(), m_cbr.end()) + 0.5 * m_channel_load;
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} else {
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return m_channel_load;
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}
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}
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void Limeric::update_cbr(ChannelLoad cbr)
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{
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const bool full = m_cbr.full();
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m_cbr.push_back(cbr);
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if (!full) {
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m_channel_load = mean(m_cbr.begin(), m_cbr.end());
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}
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}
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UnitInterval Limeric::calculate_duty_cycle() const
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{
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const double cbr_delta = m_params.cbr_target.value() - m_channel_load.value();
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double delta_offset = 0.0;
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if (cbr_delta > 0.0) {
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delta_offset = std::min(m_params.beta.value() * cbr_delta, m_params.g_plus_max);
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} else {
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delta_offset = std::max(m_params.beta.value() * cbr_delta, m_params.g_minus_max);
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}
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UnitInterval delta = m_params.alpha.complement() * m_duty_cycle + delta_offset;
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delta = std::min(std::max(delta, m_params.delta_min), m_params.delta_max);
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if (m_dual_alpha) {
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if (m_duty_cycle - delta > m_dual_alpha->threshold) {
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delta = m_dual_alpha->alternate_alpha.complement() * m_duty_cycle + delta_offset;
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delta = std::min(std::max(delta, m_params.delta_min), m_params.delta_max);
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}
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}
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return delta;
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}
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void Limeric::calculate(Clock::time_point tp)
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{
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m_channel_load = average_cbr();
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m_duty_cycle = calculate_duty_cycle(); // uses m_channel_load
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m_duty_cycle_change(this, tp);
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schedule();
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}
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void Limeric::schedule()
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{
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// schedule for next possible modulo 2 * cbr_interval (usually 200ms) time point
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const Clock::duration scheduling_interval = 2 * m_params.cbr_interval;
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Clock::time_point tp = m_runtime.now() + scheduling_interval;
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const Clock::duration scheduling_bias = tp.time_since_epoch() % scheduling_interval;
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if (scheduling_bias > m_params.cbr_interval) {
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tp += scheduling_interval - scheduling_bias;
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} else if (scheduling_bias > Clock::duration::zero()) {
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tp -= scheduling_bias;
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}
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m_runtime.schedule(tp, [this](Clock::time_point tp) {
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this->calculate(tp);
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});
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}
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void Limeric::configure_dual_alpha(const boost::optional<DualAlphaParameters>& params)
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{
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m_dual_alpha = params;
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}
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} // namespace dcc
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} // namespace vanetza
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