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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.
use std::{
cmp::{max, min},
time::{Duration, Instant},
};
use neqo_common::qtrace;
use crate::recovery::RecoveryToken;
#[derive(Debug, Clone)]
/// There's a little bit of different behavior for resetting idle timeout. See
/// -transport 10.2 ("Idle Timeout").
enum IdleTimeoutState {
Init,
PacketReceived(Instant),
AckElicitingPacketSent(Instant),
}
#[derive(Debug, Clone)]
/// There's a little bit of different behavior for resetting idle timeout. See
/// -transport 10.2 ("Idle Timeout").
pub struct IdleTimeout {
timeout: Duration,
state: IdleTimeoutState,
keep_alive_outstanding: bool,
}
impl IdleTimeout {
pub const fn new(timeout: Duration) -> Self {
Self {
timeout,
state: IdleTimeoutState::Init,
keep_alive_outstanding: false,
}
}
}
impl IdleTimeout {
pub fn set_peer_timeout(&mut self, peer_timeout: Duration) {
self.timeout = min(self.timeout, peer_timeout);
}
const fn start(&self, now: Instant) -> Instant {
match self.state {
IdleTimeoutState::Init => now,
IdleTimeoutState::PacketReceived(t) | IdleTimeoutState::AckElicitingPacketSent(t) => t,
}
}
pub fn expiry(&self, now: Instant, pto: Duration) -> Instant {
let delay = max(self.timeout, pto * 3);
let t = self.start(now) + delay;
qtrace!("IdleTimeout::expiry@{now:?} pto={pto:?} => {t:?}");
t
}
pub fn on_packet_sent(&mut self, now: Instant) {
// Only reset idle timeout if we've received a packet since the last
// time we reset the timeout here.
match self.state {
IdleTimeoutState::AckElicitingPacketSent(_) => {}
IdleTimeoutState::Init | IdleTimeoutState::PacketReceived(_) => {
self.state = IdleTimeoutState::AckElicitingPacketSent(now);
}
}
}
pub fn on_packet_received(&mut self, now: Instant) {
// Only update if this doesn't rewind the idle timeout.
// We sometimes process packets after caching them, which uses
// the time the packet was received. That could be in the past.
let update = match self.state {
IdleTimeoutState::Init => true,
IdleTimeoutState::AckElicitingPacketSent(t) | IdleTimeoutState::PacketReceived(t) => {
t <= now
}
};
if update {
self.state = IdleTimeoutState::PacketReceived(now);
}
}
pub fn expired(&self, now: Instant, pto: Duration) -> bool {
now >= self.expiry(now, pto)
}
fn keep_alive_timeout(&self, now: Instant, pto: Duration) -> Instant {
// For a keep-alive timer, wait for half the timeout interval, but be sure
// not to wait too little or we will send many unnecessary probes.
self.start(now) + max(self.timeout / 2, pto)
}
pub fn next_keep_alive(&self, now: Instant, pto: Duration) -> Option<Instant> {
if self.keep_alive_outstanding {
return None;
}
let timeout = self.keep_alive_timeout(now, pto);
// Timer is in the past, i.e. we should have sent a keep alive,
// but we were unable to, e.g. due to CC.
if timeout <= now {
return None;
}
Some(timeout)
}
pub fn send_keep_alive(
&mut self,
now: Instant,
pto: Duration,
tokens: &mut Vec<RecoveryToken>,
) -> bool {
if !self.keep_alive_outstanding && now >= self.keep_alive_timeout(now, pto) {
self.keep_alive_outstanding = true;
tokens.push(RecoveryToken::KeepAlive);
true
} else {
false
}
}
pub fn lost_keep_alive(&mut self) {
self.keep_alive_outstanding = false;
}
pub fn ack_keep_alive(&mut self) {
self.keep_alive_outstanding = false;
}
}