record RTT sampling instant

1 files changed, 6 insertions, 0 deletions

diff --git a/src/state.rs b/src/state.rs
index 6021baa..9d567a8 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -473,6 +473,12 @@ pub(crate) struct Timing {
 }
 
 impl Timing {
+    /// How long a round-trip sample stays meaningful (`swarm::rtt`): a few keepalive
+    /// intervals, since nodes move.
+    pub(crate) fn rtt_fresh_for(&self) -> Duration {
+        self.keepalive * 5
+    }
+
     // Recommended values
     //  Environment                                 | Keepalive | Notes
     //  --------------------------------------------+-----------+------------------------------------------------------------