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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use crate::recovery::RecoveryToken;
use std::cmp::{max, min};
use std::time::{Duration, Instant};
#[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 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);
}
pub fn expiry(&self, now: Instant, pto: Duration, keep_alive: bool) -> Instant {
let start = match self.state {
IdleTimeoutState::Init => now,
IdleTimeoutState::PacketReceived(t) | IdleTimeoutState::AckElicitingPacketSent(t) => t,
};
let delay = if keep_alive && !self.keep_alive_outstanding {
// 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.
max(self.timeout / 2, pto)
} else {
max(self.timeout, pto * 3)
};
start + delay
}
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, false)
}
pub fn send_keep_alive(
&mut self,
now: Instant,
pto: Duration,
tokens: &mut Vec<RecoveryToken>,
) -> bool {
if !self.keep_alive_outstanding && now >= self.expiry(now, pto, true) {
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;
}
}
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