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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 super::rng::RandomDuration;
use super::{Node, Rng};
use neqo_common::Datagram;
use neqo_transport::Output;
use std::collections::BTreeMap;
use std::fmt::{self, Debug};
use std::iter;
use std::ops::Range;
use std::time::{Duration, Instant};
///
pub struct RandomDrop {
threshold: u64,
max: u64,
rng: Rng,
}
impl RandomDuration {
/// Make a new random `Duration` generator. This asserts 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>, rng: Rng) -> Self {
let max = u64::try_from((bounds.end - bounds.start).as_nanos()).unwrap();
Self {
start: bounds.start,
max,
rng,
}
}
fn next(&mut self) -> Duration {
let r = if self.max == 0 {
Duration::new(0, 0)
} else {
self.rng.borrow_mut().random_from(0..self.max)
}
self.start + Duration::from_nanos(r)
}
}
enum DelayState {
New(Range<Duration>),
Ready(RandomDuration),
}
pub struct Delay {
state: DelayState,
queue: BTreeMap<Instant, Datagram>,
}
impl Delay
{
pub fn new(bounds: Range<Duration>) -> Self
{
Self {
State: DelayState::New(bounds),
queue: BTreeMap::default(),
}
}
fn insert(&mut self, d: Datagram, now: Instant) {
let mut t = if let State::Ready(r) = self.state {
now + self.source.next()
} else {
unreachable!();
}
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) {
if let DelayState::New(bounds) = self.state {
self.state = RandomDuration::new(bounds);
} else {
unreachable!();
}
}
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).nth(0) {
Output::Datagram(self.queue.remove(&k).unwrap())
} else if let Some(&t) = self.queue.keys().nth(0) {
Output::Callback(t - now)
} else {
Output::None
}
}
}
impl<T> Debug for Delay<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("delay")
}
}
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