Fix up daemon retry logic. Also: named fields; better stop logic.

In particular:

1. The root facet is considered inert even if it has outbound
assertions. This is because the only outbound assertion it can have is
a half-link to a peer actor, which shouldn't prevent the actor from
terminating normally if the user-level "root" facet stops.

2. On stop_facet_and_continue, parent-facet continuations execute
inline rather than at commit time. This is so that a user-level "root"
facet can *replace* itself. Remains to be properly exercised/tested.

syndicate-macros/examples/box-and-client.rs

@@ -13,7 +13,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         let _ = t.prevent_inert_check();
 
         Actor::new().boot(syndicate::name!("box"), enclose!((ds) move |t| {
-            let current_value = t.field(0u64);
+            let current_value = t.named_field("current_value", 0u64);
 
             t.dataflow({
                 let mut state_assertion_handle = None;
@@ -41,7 +41,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
             t.dataflow(enclose!((current_value) move |t| {
                 if *t.get(&current_value) == 1000000 {
-                    t.stop();
+                    t.stop()?;
                 }
                 Ok(())
             }))?;
@@ -62,7 +62,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
                         *count = *count - 1;
                         if *count == 0 {
                             tracing::info!("box state retracted");
-                            t.stop();
+                            t.stop()?;
                         }
                         Ok(())
                     })))

syndicate-server/src/counter.rs

@@ -4,13 +4,13 @@ use syndicate::actor::*;
 
 pub fn adjust(t: &mut Activation, f: &Arc<Field<isize>>, delta: isize) {
     let f = f.clone();
-    tracing::trace!(v0 = ?t.get(&f), "adjust");
+    tracing::trace!(?f, v0 = ?t.get(&f), "adjust");
     *t.get_mut(&f) += delta;
-    tracing::trace!(v1 = ?t.get(&f), "adjust");
+    tracing::trace!(?f, v1 = ?t.get(&f), "adjust");
     t.on_stop(move |t| {
-        tracing::trace!(v0 = ?t.get(&f), "cleanup");
+        tracing::trace!(?f, v0 = ?t.get(&f), "cleanup");
         *t.get_mut(&f) -= delta;
-        tracing::trace!(v1 = ?t.get(&f), "cleanup");
+        tracing::trace!(?f, v1 = ?t.get(&f), "cleanup");
         Ok(())
     });
 }
@@ -18,9 +18,9 @@ pub fn adjust(t: &mut Activation, f: &Arc<Field<isize>>, delta: isize) {
 pub fn sync_and_adjust<M: 'static + Send>(t: &mut Activation, r: &Arc<Ref<M>>, f: &Arc<Field<isize>>, delta: isize) {
     let f = f.clone();
     let sync_handler = t.create(move |t: &mut Activation| {
-        tracing::trace!(v0 = ?t.get(&f), "sync");
+        tracing::trace!(?f, v0 = ?t.get(&f), "sync");
         *t.get_mut(&f) += delta;
-        tracing::trace!(v1 = ?t.get(&f), "sync");
+        tracing::trace!(?f, v1 = ?t.get(&f), "sync");
         Ok(())
     });
     t.sync(r, sync_handler)

syndicate-server/src/dependencies.rs

@@ -52,7 +52,7 @@ fn run(t: &mut Activation, ds: Arc<Cap>, service_name: AnyValue) -> ActorResult
         });
     }
 
-    let obstacle_count = t.field(1isize);
+    let obstacle_count = t.named_field("obstacle_count", 1isize);
     t.dataflow(enclose!((obstacle_count) move |t| {
         tracing::trace!(obstacle_count = ?t.get(&obstacle_count));
         Ok(())

syndicate-server/src/services/config_watcher.rs

@@ -202,8 +202,7 @@ fn run(t: &mut Activation, ds: Arc<Cap>, spec: internal_services::ConfigWatcher)
 
         let _ = facet.activate(Account::new(syndicate::name!("termination")), |t| {
             tracing::trace!("linked thread terminating associated facet");
-            t.stop();
-            Ok(())
+            t.stop()
         });
 
         tracing::trace!("linked thread done");

syndicate-server/src/services/daemon.rs

@@ -64,73 +64,84 @@ impl CommandLine {
 
 struct DaemonProcessInstance {
     name: tracing::Span,
-    facet: FacetRef,
     cmd: process::Command,
     announce_presumed_readiness: bool,
     unready_configs: Arc<Field<isize>>,
+    completed_processes: Arc<Field<isize>>,
     restart_policy: RestartPolicy,
 }
 
 impl DaemonProcessInstance {
-    async fn handle_exit(self, error_message: Option<String>) -> Result<LinkedTaskTermination, Error> {
-        let delay_ms = if let None = error_message { 200 } else { 1000 };
-        let sleep_after_exit = || tokio::time::sleep(std::time::Duration::from_millis(delay_ms));
-        Ok(match self.restart_policy {
-            RestartPolicy::Always => {
-                sleep_after_exit().await;
-                self.start()?;
-                LinkedTaskTermination::Normal
+    fn handle_exit(self, t: &mut Activation, error_message: Option<String>) -> ActorResult {
+        let delay =
+            std::time::Duration::from_millis(if let None = error_message { 200 } else { 1000 });
+        t.stop_facet_and_continue(t.facet.facet_id, Some(move |t: &mut Activation| {
+            enum NextStep {
+                SleepAndRestart,
+                SignalSuccessfulCompletion,
             }
-            RestartPolicy::OnError =>
-                match error_message {
-                    None => LinkedTaskTermination::KeepFacet,
-                    Some(_) => {
-                        sleep_after_exit().await;
-                        self.start()?;
-                        LinkedTaskTermination::Normal
-                    }
-                },
-            RestartPolicy::All =>
-                match error_message {
-                    None => LinkedTaskTermination::KeepFacet,
-                    Some(s) => Err(s.as_str())?,
-                },
-        })
+            use NextStep::*;
+
+            let next_step = match self.restart_policy {
+                RestartPolicy::Always => SleepAndRestart,
+                RestartPolicy::OnError =>
+                    match error_message {
+                        None => SignalSuccessfulCompletion,
+                        Some(_) => SleepAndRestart,
+                    },
+                RestartPolicy::All =>
+                    match error_message {
+                        None => SignalSuccessfulCompletion,
+                        Some(s) => Err(s.as_str())?,
+                    },
+            };
+
+            match next_step {
+                SleepAndRestart => t.after(delay, |t| self.start(t)),
+                SignalSuccessfulCompletion => {
+                    t.facet(|t| {
+                        let _ = t.prevent_inert_check();
+                        counter::adjust(t, &self.completed_processes, 1);
+                        counter::adjust(t, &self.unready_configs, -1);
+                        Ok(())
+                    })?;
+                    ()
+                }
+            }
+            Ok(())
+        }))
     }
 
-    fn start(mut self) -> ActorResult {
-        tracing::trace!("DaemonProcessInstance start (outer)");
-        self.facet.clone().activate(
-            Account::new(syndicate::name!(parent: self.name.clone(), "instance")), |t| {
-                tracing::trace!("DaemonProcessInstance start (inner)");
-                t.facet(|t| {
-                    tracing::trace!(cmd = ?self.cmd, "starting");
-                    let mut child = match self.cmd.spawn() {
-                        Ok(child) => child,
-                        Err(e) => {
-                            tracing::info!(spawn_err = ?e);
-                            t.linked_task(syndicate::name!(parent: self.name.clone(), "fail"),
-                                          self.handle_exit(Some(format!("{}", e))));
-                            return Ok(());
-                        }
-                    };
-                    tracing::info!(pid = ?child.id(), cmd = ?self.cmd, "started");
+    fn start(mut self, t: &mut Activation) -> ActorResult {
+        t.facet(|t| {
+            tracing::trace!(cmd = ?self.cmd, "starting");
+            let mut child = match self.cmd.spawn() {
+                Ok(child) => child,
+                Err(e) => {
+                    tracing::info!(spawn_err = ?e);
+                    return self.handle_exit(t, Some(format!("{}", e)));
+                }
+            };
+            tracing::info!(pid = ?child.id(), cmd = ?self.cmd, "started");
 
-                    if self.announce_presumed_readiness {
-                        counter::adjust(t, &self.unready_configs, -1);
-                    }
+            if self.announce_presumed_readiness {
+                counter::adjust(t, &self.unready_configs, -1);
+            }
 
-                    t.linked_task(syndicate::name!(parent: self.name.clone(), "wait"), async move {
-                        tracing::trace!("waiting for process exit");
-                        let status = child.wait().await?;
-                        tracing::info!(?status);
-                        self.handle_exit(
-                            if status.success() { None } else { Some(format!("{}", status)) }).await
-                    });
-                    Ok(())
+            let facet = t.facet.clone();
+            t.linked_task(syndicate::name!(parent: self.name.clone(), "wait"), async move {
+                tracing::trace!("waiting for process exit");
+                let status = child.wait().await?;
+                tracing::info!(?status);
+                facet.activate(Account::new(syndicate::name!("instance-terminated")), |t| {
+                    let m = if status.success() { None } else { Some(format!("{}", status)) };
+                    self.handle_exit(t, m)
                 })?;
-                Ok(())
-            })
+                Ok(LinkedTaskTermination::Normal)
+            });
+            Ok(())
+        })?;
+        Ok(())
     }
 }
 
@@ -142,7 +153,10 @@ fn run(
 ) -> ActorResult {
     let spec = language().unparse(&service);
 
-    let unready_configs = t.field(1isize);
+    let total_configs = t.named_field("total_configs", 0isize);
+    let unready_configs = t.named_field("unready_configs", 1isize);
+    let completed_processes = t.named_field("completed_processes", 0isize);
+
     t.dataflow({
         let mut handle = None;
         let ready = lifecycle::ready(&spec);
@@ -154,11 +168,21 @@ fn run(
         })
     })?;
 
-    enclose!((unready_configs) during!(t, config_ds, language(), <daemon #(service.id.0) $config>, {
-        let unready_configs = unready_configs.clone();
-        |t: &mut Activation| {
-            tracing::debug!(?config, "new unready config");
+    t.dataflow(enclose!((completed_processes, total_configs) move |t| {
+        let total = *t.get(&total_configs);
+        let completed = *t.get(&completed_processes);
+        tracing::debug!(total_configs = ?total, completed_processes = ?completed);
+        if total > 0 && total == completed {
+            t.stop()?;
+        }
+        Ok(())
+    }))?;
+
+    enclose!((unready_configs, completed_processes) during!(t, config_ds, language(), <daemon #(service.id.0) $config>, {
+        enclose!((unready_configs, completed_processes) |t: &mut Activation| {
+            tracing::debug!(?config, "new config");
             counter::adjust(t, &unready_configs, 1);
+            counter::adjust(t, &total_configs, 1);
 
             match language().parse::<DaemonSpec>(&config) {
                 Ok(config) => {
@@ -238,15 +262,18 @@ fn run(
                         cmd.stderr(std::process::Stdio::inherit());
                         cmd.kill_on_drop(true);
 
-                        (DaemonProcessInstance {
+                        let process_instance = DaemonProcessInstance {
                             name: tracing::Span::current(),
-                            facet,
                             cmd,
                             announce_presumed_readiness,
                             unready_configs,
+                            completed_processes,
                             restart_policy,
-                        }).start()?;
+                        };
 
+                        facet.activate(Account::new(syndicate::name!("instance-startup")), |t| {
+                            process_instance.start(t)
+                        })?;
                         Ok(LinkedTaskTermination::KeepFacet)
                     });
                     Ok(())
@@ -256,7 +283,7 @@ fn run(
                     return Ok(());
                 }
             }
-        }
+        })
     }));
 
     tracing::debug!("syncing to ds");

syndicate/benches/bench_dataspace.rs

@@ -33,8 +33,7 @@ struct ShutdownEntity;
 
 impl Entity<AnyValue> for ShutdownEntity {
     fn message(&mut self, t: &mut Activation, _m: AnyValue) -> ActorResult {
-        t.stop();
-        Ok(())
+        t.stop()
     }
 }
 
@@ -94,12 +93,7 @@ pub fn bench_pub(c: &mut Criterion) {
                         let ds = Cap::new(&t.create(Dataspace::new()));
 
                         let shutdown = entity(())
-                            .on_asserted(|_, _, _| {
-                                Ok(Some(Box::new(|_, t| {
-                                    t.stop();
-                                    Ok(())
-                                })))
-                            })
+                            .on_asserted(|_, _, _| Ok(Some(Box::new(|_, t| t.stop()))))
                             .create_cap(t);
 
                         ds.assert(t, language(), &Observe {

syndicate/benches/ring.rs

@@ -59,7 +59,7 @@ pub fn bench_ring(c: &mut Criterion) {
                 }
 
                 impl Counter {
-                    fn step(&mut self, t: &mut Activation) {
+                    fn step(&mut self, t: &mut Activation) -> ActorResult {
                         if self.remaining_to_send > 0 {
                             self.remaining_to_send -= 1;
                             MESSAGES_SENT.fetch_add(1, Ordering::Relaxed);
@@ -68,20 +68,21 @@ pub fn bench_ring(c: &mut Criterion) {
                             tracing::info!(iters = self.iters,
                                            actors_created = ACTORS_CREATED.load(Ordering::SeqCst),
                                            messages_sent = MESSAGES_SENT.load(Ordering::SeqCst));
-                            t.stop();
+                            t.stop()?;
                             self.tx.send(self.start.elapsed() / ACTOR_COUNT).unwrap()
                         }
+                        Ok(())
                     }
                 }
 
                 impl Entity<()> for Counter {
                     fn message(&mut self, t: &mut Activation, _message: ()) -> ActorResult {
-                        Ok(self.step(t))
+                        self.step(t)
                     }
                 }
 
                 impl Spawner {
-                    fn step(&mut self, t: &mut Activation, next: Arc<Ref<()>>) {
+                    fn step(&mut self, t: &mut Activation, next: Arc<Ref<()>>) -> ActorResult {
                         if self.i < ACTOR_COUNT {
                             let i = self.i;
                             self.i += 1;
@@ -103,15 +104,16 @@ pub fn bench_ring(c: &mut Criterion) {
                                 iters: self.iters,
                                 next,
                             };
-                            c_state.step(t);
+                            c_state.step(t)?;
                             self.c.become_entity(c_state);
                         }
+                        Ok(())
                     }
                 }
 
                 impl Entity<Arc<Ref<()>>> for Spawner {
                     fn message(&mut self, t: &mut Activation, f: Arc<Ref<()>>) -> ActorResult {
-                        Ok(self.step(t, f))
+                        self.step(t, f)
                     }
                 }
 
@@ -125,7 +127,7 @@ pub fn bench_ring(c: &mut Criterion) {
                         i: 1,
                         c: t.create_inert(),
                     };
-                    s.step(t, Arc::clone(&s.c));
+                    s.step(t, Arc::clone(&s.c))?;
                     Arc::clone(&s.self_ref).become_entity(s);
                     Ok(())
                 }).await.unwrap().unwrap();

syndicate/src/actor.rs

@@ -355,8 +355,8 @@ pub struct RunningActor {
 /// values. Use [`Activation::dataflow`] to create a reactive block within a facet that will be
 /// (re-)executed whenever some dependent field changes value.
 ///
-#[derive(Debug)]
 pub struct Field<T: Any + Send> {
+    pub name: String,
     pub field_id: FieldId,
     tx: UnboundedSender<SystemMessage>,
     phantom: PhantomData<T>,
@@ -925,7 +925,7 @@ impl<'activation> Activation<'activation> {
                                 f.linked_tasks.remove(&task_id);
                             }
                             if let LinkedTaskTermination::Normal = result {
-                                t.stop();
+                                t.stop()?;
                             }
                             Ok(())
                         });
@@ -938,18 +938,28 @@ impl<'activation> Activation<'activation> {
 
     /// Executes the given action after the given duration has elapsed (so long as the active
     /// facet still exists at that time).
-    pub fn after(&mut self, duration: time::Duration, a: Action) {
+    pub fn after<F: 'static + Send + FnOnce(&mut Activation) -> ActorResult>(
+        &mut self,
+        duration: time::Duration,
+        a: F,
+    ) {
         self.at(time::Instant::now() + duration, a)
     }
 
     /// Executes the given action at the given instant (so long as the active facet still
     /// exists at that time).
-    pub fn at<I: Into<tokio::time::Instant>>(&mut self, instant: I, a: Action) {
+    pub fn at<I: Into<tokio::time::Instant>, F: 'static + Send + FnOnce(&mut Activation) -> ActorResult>(
+        &mut self,
+        instant: I,
+        a: F,
+    ) {
         let account = Arc::clone(self.account());
         let instant = instant.into();
         let facet = self.facet.clone();
-        self.linked_task(crate::name!("Activation::at"), async move {
+        let span = tracing::Span::current().clone();
+        self.linked_task(crate::name!(parent: None, "Activation::at"), async move {
             tokio::time::sleep_until(instant.into()).await;
+            let _entry = span.enter();
             facet.activate(account, a)?;
             Ok(LinkedTaskTermination::KeepFacet)
         });
@@ -1006,7 +1016,9 @@ impl<'activation> Activation<'activation> {
         let f = Facet::new(Some(self.facet.facet_id));
         let facet_id = f.facet_id;
         self.state.facet_nodes.insert(facet_id, f);
-        tracing::trace!(?facet_id, facet_count = ?self.state.facet_nodes.len());
+        tracing::debug!(parent_id = ?self.facet.facet_id,
+                        ?facet_id,
+                        actor_facet_count = ?self.state.facet_nodes.len());
         self.state.facet_children.entry(self.facet.facet_id).or_default().insert(facet_id);
         self.with_facet(true /* TODO: tiny optimisation: "false" would be safe here */, facet_id, move |t| {
             boot(t)?;
@@ -1039,28 +1051,43 @@ impl<'activation> Activation<'activation> {
     }
 
     /// Arranges for the [`Facet`] named by `facet_id` to be stopped cleanly when `self`
-    /// commits. If `continuation` is supplied, the facet to be stopped hasn't been stopped at
-    /// the time of the `stop_facet` call, none of the shutdown handlers yields an error, and
-    /// the facet's parent facet is alive, executes `continuation` in the parent facet's
-    /// context.
-    pub fn stop_facet(&mut self, facet_id: FacetId, continuation: Option<Action>) {
+    /// commits.
+    ///
+    /// Then,
+    ///  - if `continuation` is supplied, and
+    ///  - the facet to be stopped hasn't been stopped at the time of the `stop_facet_and_continue` call, and
+    ///  - none of the shutdown handlers yields an error, and
+    ///  - the facet's parent facet is alive,
+    /// executes `continuation` (immediately) in the *parent* facet's context.
+    ///
+    pub fn stop_facet_and_continue<F: 'static + Send + FnOnce(&mut Activation) -> ActorResult>(
+        &mut self,
+        facet_id: FacetId,
+        continuation: Option<F>,
+    ) -> ActorResult {
         let maybe_parent_id = self.active_facet().and_then(|f| f.parent_facet_id);
-        self.enqueue_for_myself_at_commit(Box::new(move |t| {
-            t._terminate_facet(facet_id, true)?;
-            if let Some(k) = continuation {
-                if let Some(parent_id) = maybe_parent_id {
-                    t.with_facet(true, parent_id, k)?;
-                }
+        self.enqueue_for_myself_at_commit(Box::new(move |t| t._terminate_facet(facet_id, true)));
+        if let Some(k) = continuation {
+            if let Some(parent_id) = maybe_parent_id {
+                self.with_facet(true, parent_id, k)?;
             }
-            Ok(())
-        }));
+        }
+        Ok(())
+    }
+
+    /// Arranges for the [`Facet`] named by `facet_id` to be stopped cleanly when `self`
+    /// commits.
+    ///
+    /// Equivalent to `self.stop_facet_and_continue(facet_id, None)`.
+    pub fn stop_facet(&mut self, facet_id: FacetId) -> ActorResult {
+        self.stop_facet_and_continue::<Action>(facet_id, None)
     }
 
     /// Arranges for the active facet to be stopped cleanly when `self` commits.
     ///
-    /// Equivalent to `self.stop_facet(self.facet.facet_id, None)`.
-    pub fn stop(&mut self) {
-        self.stop_facet(self.facet.facet_id, None)
+    /// Equivalent to `self.stop_facet(self.facet.facet_id)`.
+    pub fn stop(&mut self) -> ActorResult {
+        self.stop_facet(self.facet.facet_id)
     }
 
     fn stop_if_inert(&mut self) {
@@ -1069,7 +1096,7 @@ impl<'activation> Activation<'activation> {
             tracing::trace!("Checking inertness of facet {} from facet {}", facet_id, t.facet.facet_id);
             if t.state.facet_exists_and_is_inert(facet_id) {
                 tracing::trace!(" - facet {} is inert, stopping it", facet_id);
-                t.stop_facet(facet_id, None);
+                t.stop_facet(facet_id)?;
             } else {
                 tracing::trace!(" - facet {} is not inert", facet_id);
             }
@@ -1079,7 +1106,8 @@ impl<'activation> Activation<'activation> {
 
     fn _terminate_facet(&mut self, facet_id: FacetId, alive: bool) -> ActorResult {
         if let Some(mut f) = self.state.facet_nodes.remove(&facet_id) {
-            tracing::debug!("{} termination of {:?}",
+            tracing::debug!(actor_facet_count = ?self.state.facet_nodes.len(),
+                            "{} termination of {:?}",
                             if alive { "living" } else { "post-exit" },
                             facet_id);
             if let Some(p) = f.parent_facet_id {
@@ -1101,9 +1129,13 @@ impl<'activation> Activation<'activation> {
                     // cleanup-actions are performed before parent-facet cleanup-actions.
                     if let Some(p) = parent_facet_id {
                         if t.state.facet_exists_and_is_inert(p) {
+                            tracing::trace!("terminating parent {:?} of facet {:?}", p, facet_id);
                             t._terminate_facet(p, true)?;
+                        } else {
+                            tracing::trace!("not terminating parent {:?} of facet {:?}", p, facet_id);
                         }
                     } else {
+                        tracing::trace!("terminating actor of root facet {:?}", facet_id);
                         t.state.shutdown();
                     }
                 } else {
@@ -1116,25 +1148,31 @@ impl<'activation> Activation<'activation> {
         }
     }
 
-    /// Create a new dataflow variable (field) within the active [`Actor`].
-    pub fn field<T: Any + Send>(&mut self, initial_value: T) -> Arc<Field<T>> {
+    /// Create a new named dataflow variable (field) within the active [`Actor`].
+    pub fn named_field<T: Any + Send>(&mut self, name: &str, initial_value: T) -> Arc<Field<T>> {
         let field_id = FieldId::new(NEXT_FIELD_ID.fetch_add(BUMP_AMOUNT.into(), Ordering::Relaxed))
             .expect("Internal error: Attempt to allocate FieldId of zero. Too many FieldIds allocated. Restart the process.");
         self.state.fields.insert(field_id, Box::new(initial_value));
         Arc::new(Field {
+            name: name.to_owned(),
             field_id,
             tx: self.state.tx.clone(),
             phantom: PhantomData,
         })
     }
 
+    /// Create a new anonymous dataflow variable (field) within the active [`Actor`].
+    pub fn field<T: Any + Send>(&mut self, initial_value: T) -> Arc<Field<T>> {
+        self.named_field("", initial_value)
+    }
+
     /// Retrieve a reference to the current value of a dataflow variable (field); if execution
     /// is currently within a [dataflow block][Activation::dataflow], marks the block as
     /// *depending upon* the field.
     ///
     pub fn get<T: Any + Send>(&mut self, field: &Field<T>) -> &T {
-        tracing::trace!(field = ?field.field_id, block = ?self.active_block, "get");
         if let Some(block) = self.active_block {
+            tracing::trace!(?field, ?block, action = "get", "observed");
             self.state.dataflow.record_observation(block, field.field_id);
         }
         let any = self.state.fields.get(&field.field_id)
@@ -1149,12 +1187,13 @@ impl<'activation> Activation<'activation> {
     /// reevaluation of dependent blocks.
     ///
     pub fn get_mut<T: Any + Send>(&mut self, field: &Field<T>) -> &mut T {
-        tracing::trace!(field = ?field.field_id, block = ?self.active_block, "get_mut");
         {
             // Overapproximation.
             if let Some(block) = self.active_block {
+                tracing::trace!(?field, ?block, action = "get_mut", "observed");
                 self.state.dataflow.record_observation(block, field.field_id);
             }
+            tracing::trace!(?field, active_block = ?self.active_block, action = "get_mut", "damaged");
             self.state.dataflow.record_damage(field.field_id);
         }
         let any = self.state.fields.get_mut(&field.field_id)
@@ -1166,7 +1205,7 @@ impl<'activation> Activation<'activation> {
     /// the new value is [`eq`][std::cmp::PartialEq::eq] to the value being overwritten.
     ///
     pub fn set<T: Any + Send>(&mut self, field: &Field<T>, value: T) {
-        tracing::trace!(field = ?field.field_id, block = ?self.active_block, "set");
+        tracing::trace!(?field, active_block = ?self.active_block, action = "set", "damaged");
         // Overapproximation in many cases, since the new value may not produce an
         // observable difference (may be equal to the current value).
         self.state.dataflow.record_damage(field.field_id);
@@ -1213,7 +1252,9 @@ impl<'activation> Activation<'activation> {
                 }
             }
         }
-        tracing::trace!(passes = ?pass_number, "repair_dataflow complete");
+        if pass_number > 0 {
+            tracing::trace!(passes = ?pass_number, "repair_dataflow complete");
+        }
         Ok(pass_number > 0)
     }
 
@@ -1421,7 +1462,7 @@ impl Actor {
         let (tx, rx) = unbounded_channel();
         let actor_id = next_actor_id();
         let root = Facet::new(None);
-        // tracing::trace!(id = actor_id, "Actor::new");
+        tracing::trace!(?actor_id, root_facet_id = ?root.facet_id, "Actor::new");
         let mut st = RunningActor {
             actor_id,
             tx,
@@ -1656,11 +1697,17 @@ impl RunningActor {
     fn facet_exists_and_is_inert(&mut self, facet_id: FacetId) -> bool {
         let no_kids = self.facet_children.get(&facet_id).map(|cs| cs.is_empty()).unwrap_or(true);
         if let Some(f) = self.get_facet(facet_id) {
-            no_kids &&
-                f.outbound_handles.is_empty() &&
-                f.linked_tasks.is_empty() &&
-                f.inert_check_preventers.load(Ordering::Relaxed) == 0
+            // The only outbound handle the root facet of an actor may have is a link
+            // assertion, from [Activation::link]. This is not to be considered a "real"
+            // assertion for purposes of keeping the facet alive!
+            let no_outbound_handles = f.outbound_handles.is_empty();
+            let is_root_facet = f.parent_facet_id.is_none();
+            let no_linked_tasks = f.linked_tasks.is_empty();
+            let no_inert_check_preventers = f.inert_check_preventers.load(Ordering::Relaxed) == 0;
+            tracing::trace!(?facet_id, ?no_kids, ?no_outbound_handles, ?is_root_facet, ?no_linked_tasks, ?no_inert_check_preventers);
+            no_kids && (no_outbound_handles || is_root_facet) && no_linked_tasks && no_inert_check_preventers
         } else {
+            tracing::trace!(?facet_id, exists = ?false);
             false
         }
     }
@@ -1684,6 +1731,12 @@ impl RunningActor {
     }
 }
 
+impl<T: Any + Send> std::fmt::Debug for Field<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
+        write!(f, "#<Field {:?} {}>", self.name, self.field_id)
+    }
+}
+
 impl<T: Any + Send> Eq for Field<T> {}
 impl<T: Any + Send> PartialEq for Field<T> {
     fn eq(&self, other: &Field<T>) -> bool {
@@ -1943,8 +1996,7 @@ where
 
 impl<M> Entity<M> for StopOnRetract {
     fn retract(&mut self, t: &mut Activation, _h: Handle) -> ActorResult {
-        t.stop();
-        Ok(())
+        t.stop()
     }
 }
 

syndicate/src/during.rs

@@ -118,10 +118,7 @@ where
                 let _ = t.prevent_inert_check();
                 assertion_handler(state, t, a)
             })?;
-            Ok(Some(Box::new(move |_state, t| {
-                t.stop_facet(facet_id, None);
-                Ok(())
-            })))
+            Ok(Some(Box::new(move |_state, t| t.stop_facet(facet_id))))
         }))
     }
 

syndicate/src/supervise.rs

@@ -109,11 +109,11 @@ impl Entity<Protocol> for Supervisor
                 } else {
                     self.config.pause_time
                 };
-                t.after(wait_time, Box::new(move |t| {
+                t.after(wait_time, move |t| {
                     tracing::trace!("Sending retry trigger");
                     t.message(&self_ref, Protocol::Retry);
                     Ok(())
-                }));
+                });
             },
         }
         Ok(())
@@ -151,7 +151,7 @@ impl Supervisor {
         let _entry = name.enter();
         tracing::trace!(?config);
         let self_ref = t.create_inert();
-        let state_field = t.field(State::Started);
+        let state_field = t.named_field("supervisee_state", State::Started);
         let mut supervisor = Supervisor {
             self_ref: Arc::clone(&self_ref),
             name: name.clone(),