feat(proto): replace BBR with BBRv3 + breaking Controller API changes

Pulls in upstream quinn PR quinn-rs/quinn#2481

Squashes the four upstream commits and adapts them to noq's multipath
divergence

Closes 603

Upstream commits
- f8b25b24b - granular packet events for congestion controllers
- 52f04ed9b - Pacer queries Controller for pacing rate / send quantum
- c022e308a - BBRv3 implementation + MaxFilter
- ce60e5b5c - remove old BBR implementation

Breaking changes to `Controller` trait:
- `on_ack` gains `pn: u64`
- `on_congestion_event` gains `largest_lost: u64`
- New optional `on_packet_sent`, `on_packet_lost`, `on_ack_frequency_update`
- New `metrics()` -> `ControllerMetrics { congestion_window, ssthresh,
  pacing_rate, send_quantum }`, used by the pacer

Pacer changes:
- `Pacer::delay()` now also takes `capacity: Option<u64>` and
  `pacing_rate: Option<u64>` from the controller; CC-supplied values
  take precedence over the window-derived defaults but are still capped
  by noq's `max_bytes_per_second`.

Co-authored-by: Tipuch <fiorini751@proton.me>

Author: dignifiedquire

noq-proto/Cargo.toml

@@ -64,6 +64,7 @@ identity-hash = { workspace = true }
 lru-slab = { workspace = true }
 qlog = { workspace = true, optional = true }
 rand = { workspace = true }
+rand_pcg = "0.10"
 ring = { workspace = true, optional = true }
 rustc-hash = { workspace = true }
 rustls = { workspace = true, optional = true }
@@ -86,7 +87,6 @@ web-time = { workspace = true }
 assert_matches = { workspace = true }
 hex-literal = { workspace = true  }
 proptest = { workspace = true }
-rand_pcg = "0.10"
 rcgen = { workspace = true }
 test-strategy = { workspace = true }
 testresult = "0.4.1"

noq-proto/src/congestion.rs

@@ -1,15 +1,15 @@
 //! Logic for controlling the rate at which data is sent
 
-use crate::Instant;
 use crate::connection::RttEstimator;
+use crate::{Duration, Instant};
 use std::any::Any;
 use std::sync::Arc;
 
-mod bbr;
+mod bbr3;
 mod cubic;
 mod new_reno;
 
-pub use bbr::{Bbr, BbrConfig};
+pub use bbr3::{Bbr3, Bbr3Config};
 pub use cubic::{Cubic, CubicConfig};
 pub use new_reno::{NewReno, NewRenoConfig};
 
@@ -19,6 +19,10 @@ pub trait Controller: Send + Sync + std::fmt::Debug {
     #[allow(unused_variables)]
     fn on_sent(&mut self, now: Instant, bytes: u64, last_packet_number: u64) {}
 
+    /// One packet was just sent
+    #[allow(unused_variables)]
+    fn on_packet_sent(&mut self, now: Instant, bytes: u16, packet_number: u64) {}
+
     /// Packet deliveries were confirmed
     ///
     /// `app_limited` indicates whether the connection was blocked on outgoing
@@ -29,6 +33,7 @@ pub trait Controller: Send + Sync + std::fmt::Debug {
         now: Instant,
         sent: Instant,
         bytes: u64,
+        pn: u64,
         app_limited: bool,
         rtt: &RttEstimator,
     ) {
@@ -51,15 +56,22 @@ pub trait Controller: Send + Sync + std::fmt::Debug {
     /// congestion threshold period ending when the most recent packet in this batch was sent were
     /// lost.
     /// `lost_bytes` indicates how many bytes were lost. This value will be 0 for ECN triggers.
+    /// `largest_lost` indicates the packet number of the packet with the highest packet number
+    /// in the congestion event.
     fn on_congestion_event(
         &mut self,
         now: Instant,
         sent: Instant,
         is_persistent_congestion: bool,
         is_ecn: bool,
         lost_bytes: u64,
+        largest_lost: u64,
     );
 
+    /// One packet was just lost
+    #[allow(unused_variables)]
+    fn on_packet_lost(&mut self, lost_bytes: u16, packet_number: u64, now: Instant) {}
+
     /// Packets were incorrectly deemed lost
     ///
     /// This function is called when all packets that were deemed lost (for instance because
@@ -69,15 +81,35 @@ pub trait Controller: Send + Sync + std::fmt::Debug {
     /// The known MTU for the current network path has been updated
     fn on_mtu_update(&mut self, new_mtu: u16);
 
+    /// The peer's ACK-frequency parameters have changed
+    ///
+    /// `ack_eliciting_threshold` is the number of ack-eliciting packets the peer may receive
+    /// before being required to send an immediate ACK (per the QUIC ACK frequency extension).
+    /// `requested_max_ack_delay` is the maximum delay we asked the peer to wait before sending
+    /// an ACK when the threshold hasn't been reached.
+    ///
+    /// Controllers can use this to refine estimates that depend on peer ACK behavior (e.g.
+    /// BBR's offload budget).
+    #[allow(unused_variables)]
+    fn on_ack_frequency_update(
+        &mut self,
+        ack_eliciting_threshold: u64,
+        requested_max_ack_delay: Duration,
+    ) {
+    }
+
     /// Number of ack-eliciting bytes that may be in flight
     fn window(&self) -> u64;
 
     /// Retrieve implementation-specific metrics used to populate `qlog` traces when they are enabled
+    /// This is also used to alter the pacing of the connection with
+    /// `pacing_rate` and `send_quantum`
     fn metrics(&self) -> ControllerMetrics {
         ControllerMetrics {
             congestion_window: self.window(),
             ssthresh: None,
             pacing_rate: None,
+            send_quantum: None,
         }
     }
 
@@ -91,16 +123,20 @@ pub trait Controller: Send + Sync + std::fmt::Debug {
     fn into_any(self: Box<Self>) -> Box<dyn Any>;
 }
 
-/// Common congestion controller metrics
-#[derive(Default, Debug)]
+/// Common congestion controller metrics used both for logging purposes
+/// but also to alter the pacing of the connection with
+/// `pacing_rate` and `send_quantum`
+#[derive(Default)]
 #[non_exhaustive]
 pub struct ControllerMetrics {
     /// Congestion window (bytes)
     pub congestion_window: u64,
     /// Slow start threshold (bytes)
     pub ssthresh: Option<u64>,
-    /// Pacing rate (bits/s)
+    /// Pacing rate (bytes/s)
     pub pacing_rate: Option<u64>,
+    /// Send Quantum (bytes) used to control the size of packet bursts
+    pub send_quantum: Option<u64>,
 }
 
 /// Constructs controllers on demand