fix(managed): correct pacing and drain cleanup

crates/irtt-client/src/async_client.rs

@@ -663,6 +663,13 @@ impl AsyncClient {
         self.schedule.as_ref()?.next_send_deadline()
     }
 
+    pub(crate) fn probe_interval(&self) -> Option<Duration> {
+        if !self.machine.is_open() {
+            return None;
+        }
+        self.schedule.as_ref().map(ProbeSchedule::interval)
+    }
+
     /// Return the configured local probe timeout.
     pub fn probe_timeout(&self) -> Duration {
         self.machine.probe_timeout()

crates/irtt-client/src/client/schedule.rs

@@ -50,6 +50,11 @@ impl ProbeSchedule {
         self.next_send_at
     }
 
+    #[cfg(feature = "tokio")]
+    pub(crate) fn interval(&self) -> Duration {
+        self.interval
+    }
+
     pub(crate) fn permit_probe_at(&mut self, now: Instant) -> bool {
         if self.next_send_at.is_none() {
             return false;

crates/irtt-client/src/managed/task.rs

@@ -35,6 +35,7 @@ use super::{
 };
 
 const TARGET_WORK_BUDGET: usize = 128;
+const POST_DEADLINE_RECEIVE_BUDGET: usize = TARGET_WORK_BUDGET;
 
 /// Entry point for constructing a unified Tokio managed task.
 #[derive(Debug, Default)]
@@ -144,6 +145,8 @@ type ConnectFuture =
 type WakeFuture = Pin<Box<dyn Future<Output = Option<watch::Receiver<()>>> + Send + 'static>>;
 #[cfg(test)]
 type EventObservations = Arc<std::sync::Mutex<Vec<(ManagedEvent, Arc<ManagedStatus>)>>>;
+#[cfg(test)]
+type StaggerObservations = Arc<std::sync::Mutex<Vec<(usize, Duration)>>>;
 
 fn arm_wake(mut receiver: watch::Receiver<()>) -> WakeFuture {
     Box::pin(async move {
@@ -170,11 +173,14 @@ enum TargetState {
         client: AsyncClient,
         deadline: Instant,
         primary_end: ManagedTargetEndReason,
+        cleanup_failure: Option<ManagedTargetFailure>,
+        post_deadline_receives_remaining: usize,
     },
     Closing {
         client: AsyncClient,
         deadline: Instant,
         primary_end: ManagedTargetEndReason,
+        cleanup_failure: Option<ManagedTargetFailure>,
     },
     Terminal,
 }
@@ -317,6 +323,18 @@ pub struct ManagedClientTask {
     _next_generation: u64,
     #[cfg(test)]
     event_observations: Option<EventObservations>,
+    #[cfg(test)]
+    stagger_observations: Option<StaggerObservations>,
+    #[cfg(test)]
+    drain_test_hook: DrainTestHook,
+}
+
+#[cfg(test)]
+#[derive(Default)]
+struct DrainTestHook {
+    defer_work_until_deadline: bool,
+    fail_receive: bool,
+    fail_close: bool,
 }
 
 impl ManagedClientTask {
@@ -616,7 +634,28 @@ impl ManagedClientTask {
                 mut client,
                 deadline,
                 primary_end,
+                mut cleanup_failure,
+                mut post_deadline_receives_remaining,
             } => {
+                #[cfg(test)]
+                let defer_work = self.drain_test_hook.defer_work_until_deadline && now < deadline;
+                #[cfg(not(test))]
+                let defer_work = false;
+                if defer_work {
+                    self.targets[index].state = TargetState::Draining {
+                        client,
+                        deadline,
+                        primary_end,
+                        cleanup_failure,
+                        post_deadline_receives_remaining,
+                    };
+                    return false;
+                }
+
+                #[cfg(test)]
+                let injected_receive_failure = self.take_drain_receive_failure();
+                #[cfg(not(test))]
+                let injected_receive_failure = None;
                 let received = match client.poll_recv(cx) {
                     Poll::Pending => false,
                     Poll::Ready(Ok(events)) => {
@@ -625,13 +664,22 @@ impl ManagedClientTask {
                     }
                     Poll::Ready(Err(error)) => {
                         self.targets[index].counters.packets_sent = client.packets_sent();
-                        self.fail_target(index, ManagedTargetFailurePhase::Receiving, error);
-                        return false;
+                        cleanup_failure.get_or_insert_with(|| {
+                            classify_client_error(ManagedTargetFailurePhase::Receiving, &error)
+                        });
+                        return self.begin_close(index, client, primary_end, cleanup_failure, now);
                     }
                 };
+                if let Some(error) = injected_receive_failure {
+                    self.targets[index].counters.packets_sent = client.packets_sent();
+                    cleanup_failure.get_or_insert_with(|| {
+                        classify_client_error(ManagedTargetFailurePhase::Receiving, &error)
+                    });
+                    return self.begin_close(index, client, primary_end, cleanup_failure, now);
+                }
                 if client.is_peer_closed() {
                     self.targets[index].counters.packets_sent = client.packets_sent();
-                    self.finish_target(index, ManagedTargetEndReason::PeerClosed, None);
+                    self.finish_target(index, primary_end, cleanup_failure);
                     return false;
                 }
                 if client
@@ -642,27 +690,40 @@ impl ManagedClientTask {
                         Ok(events) => self.publish_client_events(index, events),
                         Err(error) => {
                             self.targets[index].counters.packets_sent = client.packets_sent();
-                            self.fail_target(index, ManagedTargetFailurePhase::Timing, error);
-                            return false;
+                            cleanup_failure.get_or_insert_with(|| {
+                                classify_client_error(ManagedTargetFailurePhase::Timing, &error)
+                            });
+                            return self.begin_close(
+                                index,
+                                client,
+                                primary_end,
+                                cleanup_failure,
+                                now,
+                            );
                         }
                     }
                 }
                 if now >= deadline {
-                    let close_deadline = now.checked_add(self.config.final_drain).unwrap_or(now);
-                    self.install_target_state(
-                        index,
-                        TargetState::Closing {
+                    if received && post_deadline_receives_remaining > 1 {
+                        post_deadline_receives_remaining -= 1;
+                        self.targets[index].state = TargetState::Draining {
                             client,
-                            deadline: close_deadline,
+                            deadline,
                             primary_end,
-                        },
-                    );
+                            cleanup_failure,
+                            post_deadline_receives_remaining,
+                        };
                         true
+                    } else {
+                        self.begin_close(index, client, primary_end, cleanup_failure, now)
+                    }
                 } else {
                     self.targets[index].state = TargetState::Draining {
                         client,
                         deadline,
                         primary_end,
+                        cleanup_failure,
+                        post_deadline_receives_remaining,
                     };
                     received
                 }
@@ -671,17 +732,23 @@ impl ManagedClientTask {
                 mut client,
                 deadline,
                 primary_end,
+                cleanup_failure,
             } => match client.poll_close(cx) {
                 Poll::Pending => {
                     if now >= deadline {
                         self.targets[index].counters.packets_sent = client.packets_sent();
-                        self.finish_target(index, primary_end, Some(close_timeout_failure()));
+                        self.finish_target(
+                            index,
+                            primary_end,
+                            cleanup_failure.or_else(|| Some(close_timeout_failure())),
+                        );
                         false
                     } else {
                         self.targets[index].state = TargetState::Closing {
                             client,
                             deadline,
                             primary_end,
+                            cleanup_failure,
                         };
                         false
                     }
@@ -689,13 +756,23 @@ impl ManagedClientTask {
                 Poll::Ready(Ok(events)) => {
                     self.targets[index].counters.packets_sent = client.packets_sent();
                     self.publish_client_events(index, events);
-                    self.finish_target(index, primary_end, None);
+                    #[cfg(test)]
+                    let injected_close_failure = self.take_drain_close_failure().map(|error| {
+                        classify_client_error(ManagedTargetFailurePhase::Closing, &error)
+                    });
+                    #[cfg(not(test))]
+                    let injected_close_failure = None;
+                    self.finish_target(
+                        index,
+                        primary_end,
+                        cleanup_failure.or(injected_close_failure),
+                    );
                     false
                 }
                 Poll::Ready(Err(error)) => {
                     self.targets[index].counters.packets_sent = client.packets_sent();
                     let cleanup = classify_client_error(ManagedTargetFailurePhase::Closing, &error);
-                    self.finish_target(index, primary_end, Some(cleanup));
+                    self.finish_target(index, primary_end, cleanup_failure.or(Some(cleanup)));
                     false
                 }
             },
@@ -734,11 +811,54 @@ impl ManagedClientTask {
                 client,
                 deadline,
                 primary_end,
+                cleanup_failure: None,
+                post_deadline_receives_remaining: POST_DEADLINE_RECEIVE_BUDGET,
             },
         );
         true
     }
 
+    fn begin_close(
+        &mut self,
+        index: usize,
+        client: AsyncClient,
+        primary_end: ManagedTargetEndReason,
+        cleanup_failure: Option<ManagedTargetFailure>,
+        now: Instant,
+    ) -> bool {
+        let deadline = now.checked_add(self.config.final_drain).unwrap_or(now);
+        self.install_target_state(
+            index,
+            TargetState::Closing {
+                client,
+                deadline,
+                primary_end,
+                cleanup_failure,
+            },
+        );
+        true
+    }
+
+    #[cfg(test)]
+    fn take_drain_receive_failure(&mut self) -> Option<ClientError> {
+        if !mem::take(&mut self.drain_test_hook.fail_receive) {
+            return None;
+        }
+        Some(ClientError::Socket(std::io::Error::other(
+            "injected drain receive failure",
+        )))
+    }
+
+    #[cfg(test)]
+    fn take_drain_close_failure(&mut self) -> Option<ClientError> {
+        if !mem::take(&mut self.drain_test_hook.fail_close) {
+            return None;
+        }
+        Some(ClientError::Socket(std::io::Error::other(
+            "injected drain close failure",
+        )))
+    }
+
     fn active_count(&self) -> usize {
         self.targets
             .iter()
@@ -746,6 +866,22 @@ impl ManagedClientTask {
             .count()
     }
 
+    fn active_stagger_spacing(&self) -> Option<(usize, Duration)> {
+        let mut active = 0;
+        let mut minimum: Option<Duration> = None;
+        for target in &self.targets {
+            let TargetState::Active { client } = &target.state else {
+                continue;
+            };
+            active += 1;
+            let interval = client
+                .probe_interval()
+                .expect("active managed targets have a committed probe schedule");
+            minimum = minimum.into_iter().chain(Some(interval)).min();
+        }
+        minimum.map(|interval| (active, stagger_spacing(interval, active)))
+    }
+
     fn poll_one_send(&mut self, index: usize, cx: &mut Context<'_>, now: Instant) -> SendResult {
         let state = mem::replace(&mut self.targets[index].state, TargetState::Terminal);
         let TargetState::Active { mut client } = state else {
@@ -802,8 +938,7 @@ impl ManagedClientTask {
     }
 
     fn poll_staggered_send(&mut self, cx: &mut Context<'_>, now: Instant) -> bool {
-        let active = self.active_count();
-        if active == 0 || self.send_gate.is_some_and(|gate| gate > now) {
+        if self.active_count() == 0 || self.send_gate.is_some_and(|gate| gate > now) {
             return false;
         }
         if self.stagger_remaining == 0 {
@@ -817,14 +952,20 @@ impl ManagedClientTask {
             if !matches!(self.targets[index].state, TargetState::Active { .. }) {
                 continue;
             }
+            let stagger_spacing = self.active_stagger_spacing();
             let result = self.poll_one_send(index, cx, now);
             if result == SendResult::NotAttempted {
                 continue;
             }
             self.stagger_remaining = 0;
             if result.accepted() {
-                self.send_gate = Instant::now()
-                    .checked_add(stagger_spacing(self.config.client.interval, active));
+                if let Some((_active, spacing)) = stagger_spacing {
+                    #[cfg(test)]
+                    if let Some(observations) = &self.stagger_observations {
+                        observations.lock().unwrap().push((_active, spacing));
+                    }
+                    self.send_gate = Instant::now().checked_add(spacing);
+                }
             }
             return matches!(result, SendResult::Ready { .. } | SendResult::Failed { .. });
         }
@@ -894,9 +1035,17 @@ impl ManagedClientTask {
                 TargetState::Draining {
                     client, deadline, ..
                 } => {
+                    #[cfg(test)]
+                    let defer_work = self.drain_test_hook.defer_work_until_deadline;
+                    #[cfg(not(test))]
+                    let defer_work = false;
                     non_send_deadline = non_send_deadline
                         .into_iter()
-                        .chain(client.next_probe_timeout_deadline())
+                        .chain(
+                            (!defer_work)
+                                .then(|| client.next_probe_timeout_deadline())
+                                .flatten(),
+                        )
                         .chain(Some(*deadline))
                         .min();
                 }
@@ -1193,6 +1342,10 @@ fn build_task(
         _next_generation: next_generation,
         #[cfg(test)]
         event_observations: None,
+        #[cfg(test)]
+        stagger_observations: None,
+        #[cfg(test)]
+        drain_test_hook: DrainTestHook::default(),
     };
     let handle = ManagedClientHandle {
         stop,

crates/irtt-client/src/managed/tests.rs

@@ -15,7 +15,7 @@ use irtt_proto::{
 use tokio::runtime::{Builder, Runtime};
 
 use super::*;
-use crate::{socket::resolution_call_counts, ClientAuthConfig, RunMode};
+use crate::{socket::resolution_call_counts, ClientAuthConfig, NegotiationPolicy, RunMode};
 
 const TOKEN: u64 = 0x1234_5678_90ab_cdef;
 
@@ -25,6 +25,7 @@ enum ServerBehavior {
     NoTest,
     PeerClose,
     DelayedEcho(Duration),
+    DeferredBurst(usize),
 }
 
 #[derive(Clone, Debug)]
@@ -55,6 +56,14 @@ impl TestServer {
 }
 
 fn start_server(behavior: ServerBehavior, key: Option<Vec<u8>>) -> TestServer {
+    start_server_negotiating(behavior, key, None)
+}
+
+fn start_server_negotiating(
+    behavior: ServerBehavior,
+    key: Option<Vec<u8>>,
+    interval: Option<Duration>,
+) -> TestServer {
     let socket = UdpSocket::bind("127.0.0.1:0").unwrap();
     socket
         .set_read_timeout(Some(Duration::from_secs(3)))
@@ -72,6 +81,10 @@ fn start_server(behavior: ServerBehavior, key: Option<Vec<u8>>) -> TestServer {
             at: Instant::now(),
         });
         let request = decode_open_request(&buffer[..open_len], key.as_deref()).unwrap();
+        let mut negotiated = request.params.clone();
+        if let Some(interval) = interval {
+            negotiated.interval_ns = i64::try_from(interval.as_nanos()).unwrap();
+        }
         let no_test = matches!(behavior, ServerBehavior::NoTest);
         let open_reply = encode_open_reply(
             &OpenReply {
@@ -79,7 +92,7 @@ fn start_server(behavior: ServerBehavior, key: Option<Vec<u8>>) -> TestServer {
                     | flags::FLAG_REPLY
                     | if no_test { flags::FLAG_CLOSE } else { 0 },
                 token: if no_test { 0 } else { TOKEN },
-                params: request.params.clone(),
+                params: negotiated.clone(),
             },
             key.as_deref(),
         )
@@ -89,12 +102,13 @@ fn start_server(behavior: ServerBehavior, key: Option<Vec<u8>>) -> TestServer {
             return;
         }
 
+        let mut deferred_burst_sent = false;
         loop {
             let Ok((len, packet_peer)) = socket.recv_from(&mut buffer) else {
                 return;
             };
             let packet = &buffer[..len];
-            if let Ok(probe) = decode_echo_request(packet, &request.params, key.as_deref()) {
+            if let Ok(probe) = decode_echo_request(packet, &negotiated, key.as_deref()) {
                 thread_records.lock().unwrap().push(PacketRecord {
                     kind: PacketKind::Probe,
                     at: Instant::now(),
@@ -105,6 +119,35 @@ fn start_server(behavior: ServerBehavior, key: Option<Vec<u8>>) -> TestServer {
                 if let ServerBehavior::DelayedEcho(delay) = behavior {
                     thread::sleep(delay);
                 }
+                if let ServerBehavior::DeferredBurst(count) = behavior {
+                    if deferred_burst_sent {
+                        continue;
+                    }
+                    deferred_burst_sent = true;
+                    thread::sleep(Duration::from_millis(30));
+                    for reply_index in 0..count {
+                        let reply = encode_echo_reply(
+                            &EchoReply {
+                                flags: flags::FLAG_REPLY,
+                                token: TOKEN,
+                                sequence: if reply_index < 2 {
+                                    probe.sequence
+                                } else {
+                                    u32::MAX
+                                },
+                                recv_count: None,
+                                recv_window: None,
+                                timestamps: TimestampFields::default(),
+                                payload: Vec::new(),
+                            },
+                            &negotiated,
+                            key.as_deref(),
+                        )
+                        .unwrap();
+                        socket.send_to(&reply, packet_peer).unwrap();
+                    }
+                    continue;
+                }
                 let peer_close = matches!(behavior, ServerBehavior::PeerClose);
                 let reply = encode_echo_reply(
                     &EchoReply {
@@ -116,7 +159,7 @@ fn start_server(behavior: ServerBehavior, key: Option<Vec<u8>>) -> TestServer {
                         timestamps: TimestampFields::default(),
                         payload: Vec::new(),
                     },
-                    &request.params,
+                    &negotiated,
                     key.as_deref(),
                 )
                 .unwrap();
@@ -223,6 +266,75 @@ fn assert_rotated_without_catchup(sends: &[(TargetInstance, u32, Instant, Instan
     }
 }
 
+fn run_negotiated_stagger_case(
+    requested: Duration,
+    negotiated: &[Duration],
+) -> (Vec<(usize, Duration)>, Vec<u64>) {
+    let servers = negotiated
+        .iter()
+        .map(|interval| start_server_negotiating(ServerBehavior::Echo, None, Some(*interval)))
+        .collect::<Vec<_>>();
+    let mut managed = config(ManagedPacing::Staggered);
+    managed.client.duration = Some(Duration::from_millis(190));
+    managed.client.interval = requested;
+    managed.client.negotiation_policy = NegotiationPolicy::Loose;
+    let targets = servers
+        .iter()
+        .enumerate()
+        .map(|(index, server)| target(&format!("target-{index}"), server.addr))
+        .collect();
+    let (mut task, _) = ManagedClient::task(managed, targets).unwrap();
+    let observations = Arc::new(Mutex::new(Vec::new()));
+    task.stagger_observations = Some(Arc::clone(&observations));
+    let outcome = runtime().block_on(task);
+    let packets_sent = (0..servers.len())
+        .map(|index| {
+            outcome
+                .recent_target_outcomes
+                .iter()
+                .find(|target| target.target.id.as_ref() == format!("target-{index}"))
+                .unwrap()
+                .packets_sent
+        })
+        .collect();
+    for server in servers {
+        server.finish();
+    }
+    let spacings = observations.lock().unwrap().clone();
+    (spacings, packets_sent)
+}
+
+fn run_deferred_drain_burst(packet_count: usize) -> ManagedOutcome {
+    let server = start_server(ServerBehavior::DeferredBurst(packet_count), None);
+    let mut managed = config(ManagedPacing::Staggered);
+    managed.completion = ManagedCompletionPolicy::ExplicitStop;
+    managed.client.duration = None;
+    managed.client.interval = Duration::from_millis(100);
+    managed.client.probe_timeout = Duration::from_millis(60);
+    managed.final_drain = Duration::from_millis(20);
+    let (mut task, handle) =
+        ManagedClient::task(managed, vec![target("one", server.addr)]).unwrap();
+    task.drain_test_hook.defer_work_until_deadline = true;
+    let seen = Arc::clone(&server.probe_seen);
+    let stopper = thread::spawn(move || {
+        let (flag, ready) = &*seen;
+        let guard = flag.lock().unwrap();
+        let (guard, timeout) = ready
+            .wait_timeout_while(guard, Duration::from_secs(2), |seen| !*seen)
+            .unwrap();
+        assert!(*guard && !timeout.timed_out());
+        drop(handle.stop());
+    });
+    let outcome = runtime().block_on(async {
+        tokio::time::timeout(Duration::from_secs(2), task)
+            .await
+            .unwrap()
+    });
+    stopper.join().unwrap();
+    server.finish();
+    outcome
+}
+
 #[test]
 fn construction_is_runtime_and_io_free() {
     let before = resolution_call_counts();
@@ -446,6 +558,45 @@ fn staggered_pacing_fairness() {
     second.finish();
 }
 
+#[test]
+fn staggered_pacing_uses_all_active_negotiated_intervals() {
+    let requested = Duration::from_millis(120);
+
+    let (single, single_packets) =
+        run_negotiated_stagger_case(requested, &[Duration::from_millis(40)]);
+    assert!(single
+        .iter()
+        .all(|entry| *entry == (1, Duration::from_millis(40))));
+    assert!(single_packets[0] >= 4);
+
+    let (different, different_packets) = run_negotiated_stagger_case(
+        requested,
+        &[Duration::from_millis(30), Duration::from_millis(90)],
+    );
+    let while_both_active = different
+        .iter()
+        .filter(|(active, _)| *active == 2)
+        .collect::<Vec<_>>();
+    assert!(!while_both_active.is_empty());
+    assert!(while_both_active
+        .iter()
+        .all(|(_, spacing)| *spacing == Duration::from_millis(15)));
+    assert!(different_packets[0] > different_packets[1]);
+
+    let (equal, _) = run_negotiated_stagger_case(
+        requested,
+        &[Duration::from_millis(60), Duration::from_millis(60)],
+    );
+    let while_both_active = equal
+        .iter()
+        .filter(|(active, _)| *active == 2)
+        .collect::<Vec<_>>();
+    assert!(!while_both_active.is_empty());
+    assert!(while_both_active
+        .iter()
+        .all(|(_, spacing)| *spacing == Duration::from_millis(30)));
+}
+
 #[test]
 fn committed_probe_graceful_drain() {
     let server = start_server(ServerBehavior::DelayedEcho(Duration::from_millis(25)), None);
@@ -480,6 +631,94 @@ fn committed_probe_graceful_drain() {
     assert_eq!(probes(&records).len(), 1);
 }
 
+#[test]
+fn drain_failures_preserve_primary_outcome_and_first_cleanup_failure() {
+    let completed_server = start_server(ServerBehavior::Echo, None);
+    let (mut completed_task, _) = ManagedClient::task(
+        config(ManagedPacing::Staggered),
+        vec![target("completed", completed_server.addr)],
+    )
+    .unwrap();
+    completed_task.drain_test_hook.fail_receive = true;
+    completed_task.drain_test_hook.fail_close = true;
+    let completed = runtime().block_on(completed_task);
+    let completed_target = &completed.recent_target_outcomes[0];
+    assert!(matches!(
+        completed_target.end_reason,
+        ManagedTargetEndReason::TestComplete
+    ));
+    assert_eq!(completed.failed_target_outcomes, 0);
+    assert!(matches!(
+        completed_target.cleanup_failure,
+        Some(ManagedTargetFailure {
+            phase: ManagedTargetFailurePhase::Receiving,
+            kind: ManagedTargetFailureKind::Socket,
+            ..
+        })
+    ));
+    completed_server.finish();
+
+    let stopped_server = start_server(ServerBehavior::Echo, None);
+    let mut managed = config(ManagedPacing::Staggered);
+    managed.completion = ManagedCompletionPolicy::ExplicitStop;
+    managed.client.duration = None;
+    let (mut stopped_task, handle) =
+        ManagedClient::task(managed, vec![target("stopped", stopped_server.addr)]).unwrap();
+    stopped_task.drain_test_hook.fail_receive = true;
+    let seen = Arc::clone(&stopped_server.probe_seen);
+    let stopper = thread::spawn(move || {
+        let (flag, ready) = &*seen;
+        let guard = flag.lock().unwrap();
+        let (guard, timeout) = ready
+            .wait_timeout_while(guard, Duration::from_secs(2), |seen| !*seen)
+            .unwrap();
+        assert!(*guard && !timeout.timed_out());
+        drop(handle.stop());
+    });
+    let stopped = runtime().block_on(stopped_task);
+    stopper.join().unwrap();
+    let stopped_target = &stopped.recent_target_outcomes[0];
+    assert!(matches!(
+        stopped_target.end_reason,
+        ManagedTargetEndReason::Stopped
+    ));
+    assert_eq!(stopped.failed_target_outcomes, 0);
+    assert!(matches!(
+        stopped_target.cleanup_failure,
+        Some(ManagedTargetFailure {
+            phase: ManagedTargetFailurePhase::Receiving,
+            kind: ManagedTargetFailureKind::Socket,
+            ..
+        })
+    ));
+    stopped_server.finish();
+}
+
+#[test]
+fn post_deadline_receive_sweep_drains_queued_packets_and_is_bounded() {
+    let drained = run_deferred_drain_burst(3);
+    let drained_target = &drained.recent_target_outcomes[0];
+    assert!(matches!(
+        drained_target.end_reason,
+        ManagedTargetEndReason::Stopped
+    ));
+    assert_eq!(drained_target.replies_received, 1);
+    assert_eq!(drained_target.duplicates, 1);
+    assert_eq!(drained_target.late, 1);
+
+    let bounded = run_deferred_drain_burst(POST_DEADLINE_RECEIVE_BUDGET + 64);
+    let bounded_target = &bounded.recent_target_outcomes[0];
+    assert!(matches!(
+        bounded_target.end_reason,
+        ManagedTargetEndReason::Stopped
+    ));
+    assert_eq!(
+        bounded_target.replies_received + bounded_target.duplicates + bounded_target.late,
+        u64::try_from(POST_DEADLINE_RECEIVE_BUDGET).unwrap()
+    );
+    assert_eq!(bounded.failed_target_outcomes, 0);
+}
+
 #[test]
 fn event_loss_independence() {
     let server = start_server(ServerBehavior::Echo, None);