yamux 0.14.0

Multiplexer over reliable, ordered connections
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151

// Copyright (c) 2023 Protocol Labs.
//
// Licensed under the Apache License, Version 2.0 or MIT license, at your option.
//
// A copy of the Apache License, Version 2.0 is included in the software as
// LICENSE-APACHE and a copy of the MIT license is included in the software
// as LICENSE-MIT. You may also obtain a copy of the Apache License, Version 2.0
// at https://www.apache.org/licenses/LICENSE-2.0 and a copy of the MIT license
// at https://opensource.org/licenses/MIT.

//! Connection round-trip time measurement

use std::sync::{
    atomic::{AtomicU32, Ordering},
    Arc,
};

use parking_lot::Mutex;
use web_time::{Duration, Instant};

use crate::connection::Action;
use crate::frame::{header::Ping, Frame};

const PING_INTERVAL: Duration = Duration::from_secs(10);

#[derive(Clone, Debug)]
pub(crate) struct Rtt {
    inner: Arc<Mutex<RttInner>>,
    /// Next ping identifier, used for matching pongs.
    next_id: Arc<AtomicU32>,
}

impl Rtt {
    pub(crate) fn new() -> Self {
        Self {
            inner: Arc::new(Mutex::new(RttInner {
                rtt: None,
                state: RttState::Waiting {
                    next: Instant::now(),
                },
            })),
            next_id: Arc::new(AtomicU32::new(0)),
        }
    }

    pub(crate) fn next_ping(&mut self) -> Option<Frame<Ping>> {
        let state = &mut self.inner.lock().state;

        match state {
            RttState::AwaitingPong { .. } => return None,
            RttState::Waiting { next } => {
                if *next > Instant::now() {
                    return None;
                }
            }
        }

        let id = self.next_id.fetch_add(1, Ordering::Relaxed);
        *state = RttState::AwaitingPong {
            sent_at: Instant::now(),
            id,
        };
        log::debug!("sending ping {id}");
        Some(Frame::ping(id))
    }

    pub(crate) fn handle_pong(&mut self, received_id: u32) -> Action {
        let inner = &mut self.inner.lock();

        let (sent_at, expected_id) = match inner.state {
            RttState::Waiting { .. } => {
                log::error!("received unexpected pong {received_id}");
                return Action::Terminate(Frame::protocol_error());
            }
            RttState::AwaitingPong { sent_at, id } => (sent_at, id),
        };

        if received_id != expected_id {
            log::error!("received pong with {received_id} but expected {expected_id}");
            return Action::Terminate(Frame::protocol_error());
        }

        let rtt = sent_at.elapsed();
        inner.rtt = Some(rtt);
        log::debug!("received pong {received_id}, estimated round-trip-time {rtt:?}");

        inner.state = RttState::Waiting {
            next: Instant::now() + PING_INTERVAL,
        };

        Action::None
    }

    pub(crate) fn get(&self) -> Option<Duration> {
        self.inner.lock().rtt
    }
}

#[cfg(test)]
impl quickcheck::Arbitrary for Rtt {
    fn arbitrary(g: &mut quickcheck::Gen) -> Self {
        Self {
            inner: Arc::new(Mutex::new(RttInner::arbitrary(g))),
            next_id: Arc::new(AtomicU32::new(0)),
        }
    }
}

#[derive(Debug)]
#[cfg_attr(test, derive(Clone))]
struct RttInner {
    state: RttState,
    rtt: Option<Duration>,
}

#[cfg(test)]
impl quickcheck::Arbitrary for RttInner {
    fn arbitrary(g: &mut quickcheck::Gen) -> Self {
        Self {
            state: RttState::arbitrary(g),
            rtt: if bool::arbitrary(g) {
                Some(Duration::arbitrary(g))
            } else {
                None
            },
        }
    }
}

#[derive(Debug)]
#[cfg_attr(test, derive(Clone))]
enum RttState {
    AwaitingPong { sent_at: Instant, id: u32 },
    Waiting { next: Instant },
}

#[cfg(test)]
impl quickcheck::Arbitrary for RttState {
    fn arbitrary(g: &mut quickcheck::Gen) -> Self {
        if bool::arbitrary(g) {
            RttState::AwaitingPong {
                sent_at: Instant::now(),
                id: u32::arbitrary(g),
            }
        } else {
            RttState::Waiting {
                next: Instant::now(),
            }
        }
    }
}