fix(client): handle negative RTT and simplify sample generation

crates/irtt-client/src/client.rs

@@ -373,7 +373,6 @@ impl Client {
             session.completed.insert(wire_seq, pending.logical_seq);
 
             let mut events = Vec::new();
-            if let Some(rtt_sample) = rtt {
             if is_late {
                 events.push(ClientEvent::LateReply {
                     seq: wire_seq,
@@ -382,7 +381,7 @@ impl Client {
                     remote: self.remote,
                     sent_at: Some(pending.sent_at),
                     received_at: now,
-                        rtt: Some(rtt_sample),
+                    rtt: Some(rtt),
                     server_timing,
                     one_way,
                     received_stats,
@@ -395,14 +394,13 @@ impl Client {
                     remote: self.remote,
                     sent_at: pending.sent_at,
                     received_at: now,
-                        rtt: rtt_sample,
+                    rtt,
                     server_timing,
                     one_way,
                     received_stats,
                     packet_meta: PacketMeta::default(),
                 });
             }
-            }
             Ok(events)
         } else if session.completed.contains(wire_seq) {
             update_highest_received(session, wire_seq);
@@ -564,8 +562,11 @@ fn compute_rtt(
     sent_at: &ClientTimestamp,
     received_at: &ClientTimestamp,
     ts: &TimestampFields,
-) -> Option<RttSample> {
+) -> RttSample {
-    let raw = received_at.mono.checked_duration_since(sent_at.mono)?;
+    let raw = received_at
+        .mono
+        .checked_duration_since(sent_at.mono)
+        .unwrap_or(Duration::ZERO);
 
     let server_processing = compute_server_processing(ts);
 
@@ -573,11 +574,11 @@ fn compute_rtt(
 
     let effective = adjusted.unwrap_or(raw);
 
-    Some(RttSample {
+    RttSample {
         raw,
         adjusted,
         effective,
-    })
+    }
 }
 
 fn compute_server_processing(ts: &TimestampFields) -> Option<Duration> {
@@ -1718,8 +1719,7 @@ mod tests {
                 send_mono: Some(1_000_000_000),
                 ..Default::default()
             },
-        )
+        );
-        .unwrap();
         assert!(rtt.adjusted.is_none());
         assert_eq!(rtt.effective, rtt.raw);
     }