[hyperactor] make all variants of spawn sync

Pull Request resolved: #1968

Building on the previous diff, separating out remote from local instantiation, this diff implements synchronous spawns throughout. This means we can always spawn an actor in a nonblocking way, regardless of context.

Spawns should also become infallible, instead relying on supervision to handle errors.
ghstack-source-id: 325032813

Differential Revision: [D87608082](https://our.internmc.facebook.com/intern/diff/D87608082/)

**NOTE FOR REVIEWERS**: This PR has internal Meta-specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D87608082/)!

Author: mariusae

hyperactor/example/stream.rs

@@ -83,10 +83,8 @@ impl Handler<u64> for CountClient {
 async fn main() {
     let proc = Proc::local();
 
-    let counter_actor: ActorHandle<CounterActor> = proc
-        .spawn("counter", CounterActor::default())
-        .await
-        .unwrap();
+    let counter_actor: ActorHandle<CounterActor> =
+        proc.spawn("counter", CounterActor::default()).unwrap();
 
     for i in 0..10 {
         // Spawn new "countees". Every time each subscribes, the counter broadcasts
@@ -96,7 +94,6 @@ async fn main() {
                 &format!("countee_{}", i),
                 CountClient::new(counter_actor.port().bind()),
             )
-            .await
             .unwrap();
         #[allow(clippy::disallowed_methods)]
         tokio::time::sleep(Duration::from_millis(100)).await;

hyperactor/src/actor.rs

@@ -98,8 +98,8 @@ pub trait Actor: Sized + Send + Debug + 'static {
 
     /// Spawn a child actor, given a spawning capability (usually given by [`Instance`]).
     /// The spawned actor will be supervised by the parent (spawning) actor.
-    async fn spawn(self, cx: &impl context::Actor) -> anyhow::Result<ActorHandle<Self>> {
-        cx.instance().spawn(self).await
+    fn spawn(self, cx: &impl context::Actor) -> anyhow::Result<ActorHandle<Self>> {
+        cx.instance().spawn(self)
     }
 
     /// Spawns this actor in a detached state, handling its messages
@@ -108,8 +108,8 @@ pub trait Actor: Sized + Send + Debug + 'static {
     ///
     /// Actors spawned through `spawn_detached` are not attached to a supervision
     /// hierarchy, and not managed by a [`Proc`].
-    async fn spawn_detached(self) -> Result<ActorHandle<Self>, anyhow::Error> {
-        Proc::local().spawn("anon", self).await
+    fn spawn_detached(self) -> Result<ActorHandle<Self>, anyhow::Error> {
+        Proc::local().spawn("anon", self)
     }
 
     /// This method is used by the runtime to spawn the actor server. It can be
@@ -260,7 +260,7 @@ pub trait RemoteSpawn: Actor + Referable + Binds<Self> {
         Box::pin(async move {
             let params = bincode::deserialize(&serialized_params)?;
             let actor = Self::new(params).await?;
-            let handle = proc.spawn(&name, actor).await?;
+            let handle = proc.spawn(&name, actor)?;
             // We return only the ActorId, not a typed ActorRef.
             // Callers that hold this ID can interact with the actor
             // only via the serialized/opaque messaging path, which
@@ -792,7 +792,7 @@ mod tests {
         let client = proc.attach("client").unwrap();
         let (tx, mut rx) = client.open_port();
         let actor = EchoActor(tx.bind());
-        let handle = proc.spawn::<EchoActor>("echo", actor).await.unwrap();
+        let handle = proc.spawn::<EchoActor>("echo", actor).unwrap();
         handle.send(123u64).unwrap();
         handle.drain_and_stop().unwrap();
         handle.await;
@@ -808,14 +808,8 @@ mod tests {
 
         let ping_actor = PingPongActor::new(Some(undeliverable_msg_tx.bind()), None, None);
         let pong_actor = PingPongActor::new(Some(undeliverable_msg_tx.bind()), None, None);
-        let ping_handle = proc
-            .spawn::<PingPongActor>("ping", ping_actor)
-            .await
-            .unwrap();
-        let pong_handle = proc
-            .spawn::<PingPongActor>("pong", pong_actor)
-            .await
-            .unwrap();
+        let ping_handle = proc.spawn::<PingPongActor>("ping", ping_actor).unwrap();
+        let pong_handle = proc.spawn::<PingPongActor>("pong", pong_actor).unwrap();
 
         let (local_port, local_receiver) = client.open_once_port();
 
@@ -842,14 +836,8 @@ mod tests {
             PingPongActor::new(Some(undeliverable_msg_tx.bind()), Some(error_ttl), None);
         let pong_actor =
             PingPongActor::new(Some(undeliverable_msg_tx.bind()), Some(error_ttl), None);
-        let ping_handle = proc
-            .spawn::<PingPongActor>("ping", ping_actor)
-            .await
-            .unwrap();
-        let pong_handle = proc
-            .spawn::<PingPongActor>("pong", pong_actor)
-            .await
-            .unwrap();
+        let ping_handle = proc.spawn::<PingPongActor>("ping", ping_actor).unwrap();
+        let pong_handle = proc.spawn::<PingPongActor>("pong", pong_actor).unwrap();
 
         let (local_port, local_receiver) = client.open_once_port();
 
@@ -895,7 +883,7 @@ mod tests {
     async fn test_init() {
         let proc = Proc::local();
         let actor = InitActor(false);
-        let handle = proc.spawn::<InitActor>("init", actor).await.unwrap();
+        let handle = proc.spawn::<InitActor>("init", actor).unwrap();
         let client = proc.attach("client").unwrap();
 
         let (port, receiver) = client.open_once_port();
@@ -954,7 +942,7 @@ mod tests {
             let proc = Proc::local();
             let values: MultiValues = Arc::new(Mutex::new((0, "".to_string())));
             let actor = MultiActor(values.clone());
-            let handle = proc.spawn::<MultiActor>("myactor", actor).await.unwrap();
+            let handle = proc.spawn::<MultiActor>("myactor", actor).unwrap();
             let (client, client_handle) = proc.instance("client").unwrap();
             Self {
                 proc,
@@ -1072,7 +1060,7 @@ mod tests {
         // Just test that we can round-trip the handle through a downcast.
 
         let proc = Proc::local();
-        let handle = proc.spawn("nothing", NothingActor).await.unwrap();
+        let handle = proc.spawn("nothing", NothingActor).unwrap();
         let cell = handle.cell();
 
         // Invalid actor doesn't succeed.

hyperactor/src/host.rs

@@ -1220,7 +1220,7 @@ mod tests {
     #[tokio::test]
     async fn test_basic() {
         let proc_manager =
-            LocalProcManager::new(|proc: Proc| async move { proc.spawn::<()>("agent", ()).await });
+            LocalProcManager::new(|proc: Proc| async move { proc.spawn::<()>("agent", ()) });
         let procs = Arc::clone(&proc_manager.procs);
         let (mut host, _handle) =
             Host::serve(proc_manager, ChannelAddr::any(ChannelTransport::Local))

hyperactor/src/mailbox.rs

@@ -3125,7 +3125,7 @@ mod tests {
         let mut proc = Proc::new(proc_id.clone(), proc_forwarder);
         ProcSupervisionCoordinator::set(&proc).await.unwrap();
 
-        let foo = proc.spawn("foo", Foo).await.unwrap();
+        let foo = proc.spawn("foo", Foo).unwrap();
         let return_handle = foo.port::<Undeliverable<MessageEnvelope>>();
         let message = MessageEnvelope::new(
             foo.actor_id().clone(),