Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 195 insertions, 0 deletions

diff --git a/third_party/rust/neqo-transport/src/rtt.rs b/third_party/rust/neqo-transport/src/rtt.rs
new file mode 100644
index 0000000000..3d6d0e70f8
--- /dev/null
+++ b/third_party/rust/neqo-transport/src/rtt.rs
@@ -0,0 +1,195 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Tracking of sent packets and detecting their loss.
+
+#![deny(clippy::pedantic)]
+
+use std::cmp::{max, min};
+use std::time::{Duration, Instant};
+
+use neqo_common::{qlog::NeqoQlog, qtrace};
+
+use crate::ackrate::{AckRate, PeerAckDelay};
+use crate::packet::PacketBuilder;
+use crate::qlog::{self, QlogMetric};
+use crate::recovery::RecoveryToken;
+use crate::stats::FrameStats;
+use crate::tracking::PacketNumberSpace;
+
+/// The smallest time that the system timer (via `sleep()`, `nanosleep()`,
+/// `select()`, or similar) can reliably deliver; see `neqo_common::hrtime`.
+pub const GRANULARITY: Duration = Duration::from_millis(1);
+// Defined in -recovery 6.2 as 333ms but using lower value.
+pub(crate) const INITIAL_RTT: Duration = Duration::from_millis(100);
+
+#[derive(Debug)]
+#[allow(clippy::module_name_repetitions)]
+pub struct RttEstimate {
+    first_sample_time: Option<Instant>,
+    latest_rtt: Duration,
+    smoothed_rtt: Duration,
+    rttvar: Duration,
+    min_rtt: Duration,
+    ack_delay: PeerAckDelay,
+}
+
+impl RttEstimate {
+    fn init(&mut self, rtt: Duration) {
+        // Only allow this when there are no samples.
+        debug_assert!(self.first_sample_time.is_none());
+        self.latest_rtt = rtt;
+        self.min_rtt = rtt;
+        self.smoothed_rtt = rtt;
+        self.rttvar = rtt / 2;
+    }
+
+    pub fn set_initial(&mut self, rtt: Duration) {
+        qtrace!("initial RTT={:?}", rtt);
+        if rtt >= GRANULARITY {
+            // Ignore if the value is too small.
+            self.init(rtt);
+        }
+    }
+
+    /// For a new path, prime the RTT based on the state of another path.
+    pub fn prime_rtt(&mut self, other: &Self) {
+        self.set_initial(other.smoothed_rtt + other.rttvar);
+        self.ack_delay = other.ack_delay.clone();
+    }
+
+    pub fn set_ack_delay(&mut self, ack_delay: PeerAckDelay) {
+        self.ack_delay = ack_delay;
+    }
+
+    pub fn update_ack_delay(&mut self, cwnd: usize, mtu: usize) {
+        self.ack_delay.update(cwnd, mtu, self.smoothed_rtt);
+    }
+
+    pub fn update(
+        &mut self,
+        qlog: &mut NeqoQlog,
+        mut rtt_sample: Duration,
+        ack_delay: Duration,
+        confirmed: bool,
+        now: Instant,
+    ) {
+        // Limit ack delay by max_ack_delay if confirmed.
+        let mad = self.ack_delay.max();
+        let ack_delay = if confirmed && ack_delay > mad {
+            mad
+        } else {
+            ack_delay
+        };
+
+        // min_rtt ignores ack delay.
+        self.min_rtt = min(self.min_rtt, rtt_sample);
+        // Adjust for ack delay unless it goes below `min_rtt`.
+        if rtt_sample - self.min_rtt >= ack_delay {
+            rtt_sample -= ack_delay;
+        }
+
+        if self.first_sample_time.is_none() {
+            self.init(rtt_sample);
+            self.first_sample_time = Some(now);
+        } else {
+            // Calculate EWMA RTT (based on {{?RFC6298}}).
+            let rttvar_sample = if self.smoothed_rtt > rtt_sample {
+                self.smoothed_rtt - rtt_sample
+            } else {
+                rtt_sample - self.smoothed_rtt
+            };
+
+            self.latest_rtt = rtt_sample;
+            self.rttvar = (self.rttvar * 3 + rttvar_sample) / 4;
+            self.smoothed_rtt = (self.smoothed_rtt * 7 + rtt_sample) / 8;
+        }
+        qtrace!(
+            "RTT latest={:?} -> estimate={:?}~{:?}",
+            self.latest_rtt,
+            self.smoothed_rtt,
+            self.rttvar
+        );
+        qlog::metrics_updated(
+            qlog,
+            &[
+                QlogMetric::LatestRtt(self.latest_rtt),
+                QlogMetric::MinRtt(self.min_rtt),
+                QlogMetric::SmoothedRtt(self.smoothed_rtt),
+            ],
+        );
+    }
+
+    /// Get the estimated value.
+    pub fn estimate(&self) -> Duration {
+        self.smoothed_rtt
+    }
+
+    pub fn pto(&self, pn_space: PacketNumberSpace) -> Duration {
+        let mut t = self.estimate() + max(4 * self.rttvar, GRANULARITY);
+        if pn_space == PacketNumberSpace::ApplicationData {
+            t += self.ack_delay.max();
+        }
+        t
+    }
+
+    /// Calculate the loss delay based on the current estimate and the last
+    /// RTT measurement received.
+    pub fn loss_delay(&self) -> Duration {
+        // kTimeThreshold = 9/8
+        // loss_delay = kTimeThreshold * max(latest_rtt, smoothed_rtt)
+        // loss_delay = max(loss_delay, kGranularity)
+        let rtt = max(self.latest_rtt, self.smoothed_rtt);
+        max(rtt * 9 / 8, GRANULARITY)
+    }
+
+    pub fn first_sample_time(&self) -> Option<Instant> {
+        self.first_sample_time
+    }
+
+    #[cfg(test)]
+    pub fn latest(&self) -> Duration {
+        self.latest_rtt
+    }
+
+    pub fn rttvar(&self) -> Duration {
+        self.rttvar
+    }
+
+    pub fn minimum(&self) -> Duration {
+        self.min_rtt
+    }
+
+    pub fn write_frames(
+        &mut self,
+        builder: &mut PacketBuilder,
+        tokens: &mut Vec<RecoveryToken>,
+        stats: &mut FrameStats,
+    ) {
+        self.ack_delay.write_frames(builder, tokens, stats);
+    }
+
+    pub fn frame_lost(&mut self, lost: &AckRate) {
+        self.ack_delay.frame_lost(lost);
+    }
+
+    pub fn frame_acked(&mut self, acked: &AckRate) {
+        self.ack_delay.frame_acked(acked);
+    }
+}
+
+impl Default for RttEstimate {
+    fn default() -> Self {
+        Self {
+            first_sample_time: None,
+            latest_rtt: INITIAL_RTT,
+            smoothed_rtt: INITIAL_RTT,
+            rttvar: INITIAL_RTT / 2,
+            min_rtt: INITIAL_RTT,
+            ack_delay: PeerAckDelay::default(),
+        }
+    }
+}