Struct CongestionControl

pub(crate) struct CongestionControl {
    state: State,
    sendme_validator: SendmeValidator<SendmeTag>,
    rtt: RoundtripTimeEstimator,
    algorithm: Box<dyn CongestionControlAlgorithm>,
}

Congestion control state of a hop on a circuit.

This controls the entire logic of congestion control and circuit level SENDMEs.

Fields

state: State

Which congestion control state are we in?

sendme_validator: SendmeValidator<SendmeTag>

This is the SENDME validator as in it keeps track of the circuit tag found within an authenticated SENDME cell. It can store the tags and validate a tag against our queue of expected values.

rtt: RoundtripTimeEstimator

The RTT estimator for the circuit we are attached on.

algorithm: Box<dyn CongestionControlAlgorithm>

The congestion control algorithm.

Implementations

impl CongestionControl

pub(crate) fn new(params: &CongestionControlParams) -> Self

Construct a new CongestionControl

pub(crate) fn uses_stream_sendme(&self) -> bool

Return true iff the underlying algorithm uses stream level SENDMEs. At the moment, only FixedWindow uses it. It has been eliminated with Vegas.

pub(crate) fn can_send(&self) -> bool

Return true iff a DATA cell is allowed to be sent based on the congestion control state.

pub(crate) fn note_sendme_received( &mut self, tag: SendmeTag, signals: CongestionSignals, ) -> Result<()>

Called when a SENDME cell is received.

An error is returned if there is a protocol violation with regards to congestion control.

pub(crate) fn note_sendme_sent(&mut self) -> Result<()>

Called when a SENDME cell is sent.

pub(crate) fn note_data_received(&mut self) -> Result<bool>

Called when a DATA cell is received.

Returns true iff a SENDME should be sent false otherwise. An error is returned if there is a protocol violation with regards to flow or congestion control.

pub(crate) fn note_data_sent<U>(&mut self, tag: &U) -> Result<()>

where U: Clone + Into<SendmeTag>,

Called when a DATA cell is sent.

An error is returned if there is a protocol violation with regards to flow or congestion control.

pub(crate) fn inflight(&self) -> Option<u32>

Available on crate feature conflux only.

Return the number of in-flight cells (sent but awaiting SENDME ack).

Optional, because not all algorithms track this.

pub(crate) fn cwnd(&self) -> Option<&CongestionWindow>

Available on crate feature conflux only.

Return the congestion window object.

Optional, because not all algorithms track this.

pub(crate) fn rtt(&self) -> &RoundtripTimeEstimator

Available on crate feature conflux only.

Return a reference to the RTT estimator.

Used for conflux, for choosing the best circuit to send on.