quinn_proto/
congestion.rs

1//! Logic for controlling the rate at which data is sent
2
3use crate::Instant;
4use crate::connection::RttEstimator;
5use std::any::Any;
6use std::sync::Arc;
7
8mod bbr;
9mod cubic;
10mod new_reno;
11
12pub use bbr::{Bbr, BbrConfig};
13pub use cubic::{Cubic, CubicConfig};
14pub use new_reno::{NewReno, NewRenoConfig};
15
16/// Common interface for different congestion controllers
17pub trait Controller: Send + Sync {
18    /// One or more packets were just sent
19    #[allow(unused_variables)]
20    fn on_sent(&mut self, now: Instant, bytes: u64, last_packet_number: u64) {}
21
22    /// Packet deliveries were confirmed
23    ///
24    /// `app_limited` indicates whether the connection was blocked on outgoing
25    /// application data prior to receiving these acknowledgements.
26    #[allow(unused_variables)]
27    fn on_ack(
28        &mut self,
29        now: Instant,
30        sent: Instant,
31        bytes: u64,
32        app_limited: bool,
33        rtt: &RttEstimator,
34    ) {
35    }
36
37    /// Packets are acked in batches, all with the same `now` argument. This indicates one of those batches has completed.
38    #[allow(unused_variables)]
39    fn on_end_acks(
40        &mut self,
41        now: Instant,
42        in_flight: u64,
43        app_limited: bool,
44        largest_packet_num_acked: Option<u64>,
45    ) {
46    }
47
48    /// Packets were deemed lost or marked congested
49    ///
50    /// `in_persistent_congestion` indicates whether all packets sent within the persistent
51    /// congestion threshold period ending when the most recent packet in this batch was sent were
52    /// lost.
53    /// `lost_bytes` indicates how many bytes were lost. This value will be 0 for ECN triggers.
54    fn on_congestion_event(
55        &mut self,
56        now: Instant,
57        sent: Instant,
58        is_persistent_congestion: bool,
59        lost_bytes: u64,
60    );
61
62    /// The known MTU for the current network path has been updated
63    fn on_mtu_update(&mut self, new_mtu: u16);
64
65    /// Number of ack-eliciting bytes that may be in flight
66    fn window(&self) -> u64;
67
68    /// Retrieve implementation-specific metrics used to populate `qlog` traces when they are enabled
69    fn metrics(&self) -> ControllerMetrics {
70        ControllerMetrics {
71            congestion_window: self.window(),
72            ssthresh: None,
73            pacing_rate: None,
74        }
75    }
76
77    /// Duplicate the controller's state
78    fn clone_box(&self) -> Box<dyn Controller>;
79
80    /// Initial congestion window
81    fn initial_window(&self) -> u64;
82
83    /// Returns Self for use in down-casting to extract implementation details
84    fn into_any(self: Box<Self>) -> Box<dyn Any>;
85}
86
87/// Common congestion controller metrics
88#[derive(Default)]
89#[non_exhaustive]
90pub struct ControllerMetrics {
91    /// Congestion window (bytes)
92    pub congestion_window: u64,
93    /// Slow start threshold (bytes)
94    pub ssthresh: Option<u64>,
95    /// Pacing rate (bits/s)
96    pub pacing_rate: Option<u64>,
97}
98
99/// Constructs controllers on demand
100pub trait ControllerFactory {
101    /// Construct a fresh `Controller`
102    fn build(self: Arc<Self>, now: Instant, current_mtu: u16) -> Box<dyn Controller>;
103}
104
105const BASE_DATAGRAM_SIZE: u64 = 1200;
quinn_proto/congestion.rs

quinn_proto/
congestion.rs
