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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// Congestion control
#![allow(clippy::module_name_repetitions)]
use std::{
fmt::{self, Display},
time::{Duration, Instant},
};
use neqo_common::{qdebug, qlog::NeqoQlog};
use crate::{
cc::{ClassicCongestionControl, CongestionControl, CongestionControlAlgorithm, Cubic, NewReno},
pace::Pacer,
pmtud::Pmtud,
recovery::SentPacket,
rtt::RttEstimate,
Stats,
};
/// The number of packets we allow to burst from the pacer.
pub const PACING_BURST_SIZE: usize = 2;
#[derive(Debug)]
pub struct PacketSender {
cc: Box<dyn CongestionControl>,
pacer: Pacer,
}
impl Display for PacketSender {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{} {}", self.cc, self.pacer)
}
}
impl PacketSender {
#[must_use]
pub fn new(
alg: CongestionControlAlgorithm,
pacing_enabled: bool,
pmtud: Pmtud,
now: Instant,
) -> Self {
let mtu = pmtud.plpmtu();
Self {
cc: match alg {
CongestionControlAlgorithm::NewReno => {
Box::new(ClassicCongestionControl::new(NewReno::default(), pmtud))
}
CongestionControlAlgorithm::Cubic => {
Box::new(ClassicCongestionControl::new(Cubic::default(), pmtud))
}
},
pacer: Pacer::new(pacing_enabled, now, mtu * PACING_BURST_SIZE, mtu),
}
}
pub fn set_qlog(&mut self, qlog: NeqoQlog) {
self.cc.set_qlog(qlog);
}
pub fn pmtud(&self) -> &Pmtud {
self.cc.pmtud()
}
pub fn pmtud_mut(&mut self) -> &mut Pmtud {
self.cc.pmtud_mut()
}
#[must_use]
pub fn cwnd(&self) -> usize {
self.cc.cwnd()
}
#[must_use]
pub fn cwnd_avail(&self) -> usize {
self.cc.cwnd_avail()
}
#[cfg(test)]
#[must_use]
pub fn cwnd_min(&self) -> usize {
self.cc.cwnd_min()
}
fn maybe_update_pacer_mtu(&mut self) {
let current_mtu = self.pmtud().plpmtu();
if current_mtu != self.pacer.mtu() {
qdebug!(
"PLPMTU changed from {} to {}, updating pacer",
self.pacer.mtu(),
current_mtu
);
self.pacer.set_mtu(current_mtu);
}
}
pub fn on_packets_acked(
&mut self,
acked_pkts: &[SentPacket],
rtt_est: &RttEstimate,
now: Instant,
stats: &mut Stats,
) {
self.cc.on_packets_acked(acked_pkts, rtt_est, now);
self.pmtud_mut().on_packets_acked(acked_pkts, stats);
self.maybe_update_pacer_mtu();
}
/// Called when packets are lost. Returns true if the congestion window was reduced.
pub fn on_packets_lost(
&mut self,
first_rtt_sample_time: Option<Instant>,
prev_largest_acked_sent: Option<Instant>,
pto: Duration,
lost_packets: &[SentPacket],
stats: &mut Stats,
now: Instant,
) -> bool {
let ret = self.cc.on_packets_lost(
first_rtt_sample_time,
prev_largest_acked_sent,
pto,
lost_packets,
now,
);
// Call below may change the size of MTU probes, so it needs to happen after the CC
// reaction above, which needs to ignore probes based on their size.
self.pmtud_mut().on_packets_lost(lost_packets, stats, now);
self.maybe_update_pacer_mtu();
ret
}
/// Called when ECN CE mark received. Returns true if the congestion window was reduced.
pub fn on_ecn_ce_received(&mut self, largest_acked_pkt: &SentPacket, now: Instant) -> bool {
self.cc.on_ecn_ce_received(largest_acked_pkt, now)
}
pub fn discard(&mut self, pkt: &SentPacket, now: Instant) {
self.cc.discard(pkt, now);
}
/// When we migrate, the congestion controller for the previously active path drops
/// all bytes in flight.
pub fn discard_in_flight(&mut self, now: Instant) {
self.cc.discard_in_flight(now);
}
pub fn on_packet_sent(&mut self, pkt: &SentPacket, rtt: Duration, now: Instant) {
self.pacer
.spend(pkt.time_sent(), rtt, self.cc.cwnd(), pkt.len());
self.cc.on_packet_sent(pkt, now);
}
#[must_use]
pub fn next_paced(&self, rtt: Duration) -> Option<Instant> {
// Only pace if there are bytes in flight.
if self.cc.bytes_in_flight() > 0 {
Some(self.pacer.next(rtt, self.cc.cwnd()))
} else {
None
}
}
#[must_use]
pub fn recovery_packet(&self) -> bool {
self.cc.recovery_packet()
}
}