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//! Implementation of the Fixed Window congestion control algorithm.
//!
//! This is used by the circuit reactor in order to decide when to send data and SENDMEs.
//! The vanilla flow control system of fixed window SENDMEs in the spec.
use crate::Result;
use super::{
params::{Algorithm, FixedWindowParams},
rtt::RoundtripTimeEstimator,
sendme::{self, WindowParams},
CongestionControlAlgorithm, CongestionSignals, CongestionWindow, State,
};
/// Fixed window algorithm which is essentially the SENDME v0 with fixed receive and send window
/// size.
#[derive(Clone, Debug)]
pub(crate) struct FixedWindow {
/// Window used to say how many cells we can receive.
recvwindow: sendme::CircRecvWindow,
/// Window used to say how many cells we can send.
sendwindow: sendme::CircSendWindow,
/// The params from the consensus.
params: FixedWindowParams,
}
impl FixedWindow {
/// Create a new `FixedWindow` form a given initial sendwindow size.
///
/// Note: the initial recvwindow size is given by [`sendme::CircParams::start`].
pub(crate) fn new(params: FixedWindowParams) -> Self {
let initial_window = params.circ_window_start();
Self {
recvwindow: sendme::CircRecvWindow::new(sendme::CircParams::start()),
sendwindow: sendme::CircSendWindow::new(initial_window),
params,
impl CongestionControlAlgorithm for FixedWindow {
fn uses_stream_sendme(&self) -> bool {
true
fn is_next_cell_sendme(&self) -> bool {
self.sendwindow.should_record_tag()
fn can_send(&self) -> bool {
self.sendwindow.window() > 0
fn cwnd(&self) -> Option<&CongestionWindow> {
None
fn sendme_received(
&mut self,
_state: &mut State,
_rtt: &mut RoundtripTimeEstimator,
_signals: CongestionSignals,
) -> Result<()> {
self.sendwindow.put()
fn sendme_sent(&mut self) -> Result<()> {
self.recvwindow.put();
Ok(())
fn data_received(&mut self) -> Result<bool> {
self.recvwindow.take()
fn data_sent(&mut self) -> Result<()> {
self.sendwindow.take()
#[cfg(feature = "conflux")]
fn inflight(&self) -> Option<u32> {
#[cfg(test)]
fn send_window(&self) -> u32 {
u32::from(self.sendwindow.window())
fn algorithm(&self) -> Algorithm {
Algorithm::FixedWindow(self.params)