tor_proto/congestion/
fixed.rs

1//! Implementation of the Fixed Window congestion control algorithm.
2//!
3//! This is used by the circuit reactor in order to decide when to send data and SENDMEs.
4//!
5//! The vanilla flow control system of fixed window SENDMEs in the spec.
6
7use crate::Result;
8
9use super::{
10    CongestionControlAlgorithm, CongestionSignals, CongestionWindow, State,
11    params::{Algorithm, FixedWindowParams},
12    rtt::{ClockStall, RoundtripTimeEstimator},
13    sendme::{self, WindowParams},
14};
15
16/// Fixed window algorithm which is essentially the SENDME v0 with fixed receive and send window
17/// size.
18#[derive(Clone, Debug)]
19pub(crate) struct FixedWindow {
20    /// Window used to say how many cells we can receive.
21    recvwindow: sendme::CircRecvWindow,
22    /// Window used to say how many cells we can send.
23    sendwindow: sendme::CircSendWindow,
24    /// The params from the consensus.
25    params: FixedWindowParams,
26}
27
28impl FixedWindow {
29    /// Create a new `FixedWindow` form a given initial sendwindow size.
30    ///
31    /// Note: the initial recvwindow size is given by [`sendme::CircParams::start`].
32    pub(crate) fn new(params: FixedWindowParams) -> Self {
33        let initial_window = params.circ_window_start();
34        Self {
35            recvwindow: sendme::CircRecvWindow::new(sendme::CircParams::start()),
36            sendwindow: sendme::CircSendWindow::new(initial_window),
37            params,
38        }
39    }
40}
41
42impl CongestionControlAlgorithm for FixedWindow {
43    fn uses_stream_sendme(&self) -> bool {
44        true
45    }
46
47    fn uses_xon_xoff(&self) -> bool {
48        false
49    }
50
51    fn is_next_cell_sendme(&self) -> bool {
52        self.sendwindow.should_record_tag()
53    }
54
55    fn can_send(&self) -> bool {
56        self.sendwindow.window() > 0
57    }
58
59    fn cwnd(&self) -> Option<CongestionWindow> {
60        None
61    }
62
63    fn sendme_received(
64        &mut self,
65        _state: &mut State,
66        _rtt: &mut RoundtripTimeEstimator,
67        _signals: CongestionSignals,
68        _clock_stall: ClockStall,
69    ) -> Result<()> {
70        self.sendwindow.put()
71    }
72
73    fn sendme_sent(&mut self) -> Result<()> {
74        self.recvwindow.put();
75        Ok(())
76    }
77
78    fn data_received(&mut self) -> Result<bool> {
79        self.recvwindow.take()
80    }
81
82    fn data_sent(&mut self) -> Result<()> {
83        self.sendwindow.take()
84    }
85
86    #[cfg(feature = "conflux")]
87    fn inflight(&self) -> Option<u32> {
88        None
89    }
90
91    #[cfg(test)]
92    fn send_window(&self) -> u32 {
93        u32::from(self.sendwindow.window())
94    }
95
96    fn algorithm(&self) -> Algorithm {
97        Algorithm::FixedWindow(self.params)
98    }
99}
tor_proto/congestion/fixed.rs

tor_proto/congestion/
fixed.rs
