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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.
#![allow(clippy::module_name_repetitions)]
use std::{
collections::BTreeMap,
convert::TryFrom,
fmt::{self, Debug},
ops::Range,
time::{Duration, Instant},
};
use neqo_common::Datagram;
use neqo_transport::Output;
use super::{Node, Rng};
/// An iterator that shares a `Random` instance and produces uniformly
/// random `Duration`s within a specified range.
pub struct RandomDelay {
start: Duration,
max: u64,
rng: Option<Rng>,
}
impl RandomDelay {
/// Make a new random `Duration` generator. This panics if the range provided
/// is inverted (i.e., `bounds.start > bounds.end`), or spans 2^64
/// or more nanoseconds.
/// A zero-length range means that random values won't be taken from the Rng
pub fn new(bounds: Range<Duration>) -> Self {
let max = u64::try_from((bounds.end - bounds.start).as_nanos()).unwrap();
Self {
start: bounds.start,
max,
rng: None,
}
}
pub fn set_rng(&mut self, rng: Rng) {
self.rng = Some(rng);
}
pub fn next(&mut self) -> Duration {
let mut rng = self.rng.as_ref().unwrap().borrow_mut();
let r = rng.random_from(0..self.max);
self.start + Duration::from_nanos(r)
}
}
pub struct Delay {
random: RandomDelay,
queue: BTreeMap<Instant, Datagram>,
}
impl Delay {
pub fn new(bounds: Range<Duration>) -> Self {
Self {
random: RandomDelay::new(bounds),
queue: BTreeMap::default(),
}
}
fn insert(&mut self, d: Datagram, now: Instant) {
let mut t = now + self.random.next();
while self.queue.contains_key(&t) {
// This is a little inefficient, but it avoids drops on collisions,
// which are super-common for a fixed delay.
t += Duration::from_nanos(1);
}
self.queue.insert(t, d);
}
}
impl Node for Delay {
fn init(&mut self, rng: Rng, _now: Instant) {
self.random.set_rng(rng);
}
fn process(&mut self, d: Option<Datagram>, now: Instant) -> Output {
if let Some(dgram) = d {
self.insert(dgram, now);
}
if let Some((&k, _)) = self.queue.range(..=now).next() {
Output::Datagram(self.queue.remove(&k).unwrap())
} else if let Some(&t) = self.queue.keys().next() {
Output::Callback(t - now)
} else {
Output::None
}
}
}
impl Debug for Delay {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("delay")
}
}
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