From 12d3eaa53c3578ecb9dfa20e5270dc9d5db58659 Mon Sep 17 00:00:00 2001
From: Shayne Fletcher <shaynefletcher@meta.com>
Date: Wed, 3 Dec 2025 15:46:50 -0800
Subject: [PATCH] : host: simplify map to set (#2044)

Summary:

this is a small simplification: the spawned procs' `ChannelAddr`s already live in `router: DialMailboxRouter`, so keeping a `HashMap<String, ChannelAddr>` in `procs` was redundant. switching `procs` to a `HashSet<String>` makes it clear that its only responsibility is guarding against duplicate proc names; routing remains the router's job.

Differential Revision: D88300708
---
 hyperactor/src/host.rs | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/hyperactor/src/host.rs b/hyperactor/src/host.rs
index 5c15089fb..53ca07e4f 100644
--- a/hyperactor/src/host.rs
+++ b/hyperactor/src/host.rs
@@ -41,6 +41,7 @@
 //! ```
 
 use std::collections::HashMap;
+use std::collections::HashSet;
 use std::fmt;
 use std::marker::PhantomData;
 use std::str::FromStr;
@@ -121,7 +122,7 @@ pub enum HostError {
 /// routing, as described in this module's documentation.
 #[derive(Debug)]
 pub struct Host<M> {
-    procs: HashMap<String, ChannelAddr>,
+    procs: HashSet<String>,
     frontend_addr: ChannelAddr,
     backend_addr: ChannelAddr,
     router: DialMailboxRouter,
@@ -159,7 +160,7 @@ impl<M: ProcManager> Host<M> {
         );
 
         let host = Host {
-            procs: HashMap::new(),
+            procs: HashSet::new(),
             frontend_addr,
             backend_addr,
             router,
@@ -203,7 +204,7 @@ impl<M: ProcManager> Host<M> {
         name: String,
         config: M::Config,
     ) -> Result<(ProcId, ActorRef<ManagerAgent<M>>), HostError> {
-        if self.procs.contains_key(&name) {
+        if self.procs.contains(&name) {
             return Err(HostError::ProcExists(name));
         }
 
@@ -250,7 +251,7 @@ impl<M: ProcManager> Host<M> {
         })?;
 
         self.router.bind(proc_id.clone().into(), addr.clone());
-        self.procs.insert(name, addr);
+        self.procs.insert(name);
 
         Ok((proc_id, agent_ref))
     }
@@ -1190,7 +1191,6 @@ pub mod testing {
     use crate::Context;
     use crate::Handler;
     use crate::OncePortRef;
-    use crate::RemoteSpawn;
 
     /// Just a simple actor, available in both the bootstrap binary as well as
     /// hyperactor tests.
@@ -1555,7 +1555,7 @@ mod tests {
 
         let (pid, agent) = host.spawn("ok".into(), ()).await.expect("must succeed");
         assert_eq!(agent.actor_id().proc_id(), &pid);
-        assert!(host.procs.contains_key("ok"));
+        assert!(host.procs.contains("ok"));
     }
 
     #[tokio::test]