Struct BbrCongestionController

pub struct BbrCongestionController { /* private fields */ }

A congestion controller that implements “Bottleneck Bandwidth and Round-trip propagation time” version 2 (BBRv2) as specified in https://datatracker.ietf.org/doc/draft-cardwell-iccrg-bbr-congestion-control/.

Based in part on the Chromium BBRv2 implementation, see https://source.chromium.org/chromium/chromium/src/+/main:net/third_party/quiche/src/quic/core/congestion_control/bbr2_sender.cc and the Linux Kernel TCP BBRv2 implementation, see https://github.com/google/bbr/blob/v2alpha/net/ipv4/tcp_bbr2.c

Implementations

impl BbrCongestionController

pub fn new(max_datagram_size: u16, app_settings: ApplicationSettings) -> Self

Constructs a new BbrCongestionController max_datagram_size is the current max_datagram_size, and is expected to be 1200 when the congestion controller is created.

pub fn pacing_rate(&self) -> Bandwidth

Returns the current pacing rate

Trait Implementations

impl Clone for BbrCongestionController

fn clone(&self) -> BbrCongestionController

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl CongestionController for BbrCongestionController

type PacketInfo = PacketInfo

Additional metadata about a packet to track until a sent packet is either acknowledged or declared lost

fn congestion_window(&self) -> u32

Returns the size of the current congestion window in bytes

fn bytes_in_flight(&self) -> u32

Returns the current bytes in flight

fn is_congestion_limited(&self) -> bool

Returns true if the congestion window does not have sufficient space for a packet of max_datagram_size considering the current bytes in flight

fn requires_fast_retransmission(&self) -> bool

Returns true if the current state of the congestion controller requires a packet to be transmitted without respecting the available congestion window

fn on_packet_sent<Pub: Publisher>( &mut self, time_sent: Timestamp, sent_bytes: usize, app_limited: Option<bool>, rtt_estimator: &RttEstimator, publisher: &mut Pub, ) -> Self::PacketInfo

Invoked when a packet is sent

fn on_rtt_update<Pub: Publisher>( &mut self, _time_sent: Timestamp, _now: Timestamp, rtt_estimator: &RttEstimator, publisher: &mut Pub, )

Invoked each time the round trip time is updated, which is whenever the newest acknowledged packet in an ACK frame is newly acknowledged

fn on_ack<Pub: Publisher>( &mut self, newest_acked_time_sent: Timestamp, bytes_acknowledged: usize, newest_acked_packet_info: Self::PacketInfo, rtt_estimator: &RttEstimator, random_generator: &mut dyn Generator, ack_receive_time: Timestamp, publisher: &mut Pub, )

Invoked when an acknowledgement of one or more previously unacknowledged packets is received

fn on_packet_lost<Pub: Publisher>( &mut self, lost_bytes: u32, packet_info: Self::PacketInfo, _persistent_congestion: bool, new_loss_burst: bool, random_generator: &mut dyn Generator, timestamp: Timestamp, publisher: &mut Pub, )

Invoked when a packet is declared lost

fn on_explicit_congestion<Pub: Publisher>( &mut self, ce_count: u64, event_time: Timestamp, _publisher: &mut Pub, )

Invoked when the Explicit Congestion Notification counter increases.

fn on_mtu_update<Pub: Publisher>( &mut self, max_datagram_size: u16, _publisher: &mut Pub, )

Invoked when the path maximum transmission unit is updated.

fn on_packet_discarded<Pub: Publisher>( &mut self, bytes_sent: usize, _publisher: &mut Pub, )

Invoked for each packet discarded when a packet number space is discarded.

fn earliest_departure_time(&self) -> Option<Timestamp>

Returns the earliest time that a packet may be transmitted.

fn send_quantum(&self) -> Option<usize>

The maximum number of bytes for an aggregation of packets scheduled and transmitted together.

impl Debug for BbrCongestionController

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.