Invert rsync architecture (#467)

Summary:
Pull Request resolved: #467

This inverts the rsync setup, so that the rsync daemon runs on the "client", and the
rsync clients run on the actors.  This helps in a couple ways:
- We don't leave a rsync daemon running on the actors.
- We avoid spawning lots of sub-processes for each rsync client on the "client"
- The rsync client supports reporting file changes, which subsequent changes
   can use to facilitate things like targeted module reloading (based on the actual
   things that were changed).

Differential Revision: D77952087

Author: andrewjcg

hyperactor_mesh/src/code_sync/rsync.rs

@@ -19,12 +19,16 @@ use anyhow::bail;
 use anyhow::ensure;
 use async_trait::async_trait;
 use futures::StreamExt;
+use futures::TryFutureExt;
 use futures::TryStreamExt;
 use futures::stream;
 use futures::try_join;
 use hyperactor::Actor;
+use hyperactor::Bind;
 use hyperactor::Handler;
 use hyperactor::Named;
+use hyperactor::OncePortRef;
+use hyperactor::Unbind;
 use hyperactor::clock::Clock;
 use hyperactor::clock::RealClock;
 use nix::sys::signal;
@@ -56,8 +60,8 @@ pub async fn do_rsync(addr: &SocketAddr, workspace: &Path) -> Result<()> {
         .arg("--delay-updates")
         .arg("--exclude=.rsync-tmp.*")
         .arg(format!("--partial-dir=.rsync-tmp.{}", addr.port()))
-        .arg(format!("{}/", workspace.display()))
         .arg(format!("rsync://{}/workspace", addr))
+        .arg(format!("{}/", workspace.display()))
         .stderr(Stdio::piped())
         .output()
         .await?;
@@ -89,8 +93,8 @@ impl RsyncDaemon {
     path = {workspace}
     use chroot = no
     list = no
-    read only = false
-    write only = true
+    read only = true
+    write only = false
     uid = {uid}
     hosts allow = localhost
 "#,
@@ -158,43 +162,58 @@ impl RsyncDaemon {
     }
 }
 
+#[derive(Debug, Named, Serialize, Deserialize, Bind, Unbind)]
+pub struct RsyncMessage {
+    /// The connect message to create a duplex bytestream with the client.
+    pub connect: Connect,
+    /// A port to send back any errors from the rsync.
+    pub result: OncePortRef<Result<(), String>>,
+}
+
 #[derive(Debug, Named, Serialize, Deserialize)]
 pub struct RsyncParams {
     pub workspace: WorkspaceLocation,
 }
 
 #[derive(Debug)]
-#[hyperactor::export(
-    spawn = true,
-    handlers = [Connect { cast = true }],
-)]
+#[hyperactor::export(spawn = true, handlers = [RsyncMessage { cast = true }])]
 pub struct RsyncActor {
-    daemon: RsyncDaemon,
+    workspace: WorkspaceLocation,
+    //daemon: RsyncDaemon,
 }
 
 #[async_trait]
 impl Actor for RsyncActor {
     type Params = RsyncParams;
 
     async fn new(RsyncParams { workspace }: Self::Params) -> Result<Self> {
-        let workspace = workspace.resolve()?;
-        let daemon = RsyncDaemon::spawn(TcpListener::bind(("::1", 0)).await?, &workspace).await?;
-        Ok(Self { daemon })
+        Ok(Self { workspace })
     }
 }
 
 #[async_trait]
-impl Handler<Connect> for RsyncActor {
+impl Handler<RsyncMessage> for RsyncActor {
     async fn handle(
         &mut self,
         cx: &hyperactor::Context<Self>,
-        message: Connect,
+        RsyncMessage { connect, result }: RsyncMessage,
     ) -> Result<(), anyhow::Error> {
-        let (mut local, mut stream) = try_join!(
-            async { Ok(TcpStream::connect(self.daemon.addr()).await?) },
-            accept(cx, cx.self_id().clone(), message),
-        )?;
-        tokio::io::copy_bidirectional(&mut local, &mut stream).await?;
+        let res = async {
+            let workspace = self.workspace.resolve()?;
+            let (listener, mut stream) = try_join!(
+                TcpListener::bind(("::1", 0)).err_into(),
+                accept(cx, cx.self_id().clone(), connect),
+            )?;
+            let addr = listener.local_addr()?;
+            try_join!(do_rsync(&addr, &workspace), async move {
+                let (mut local, _) = listener.accept().await?;
+                tokio::io::copy_bidirectional(&mut stream, &mut local).await?;
+                anyhow::Ok(())
+            },)?;
+            anyhow::Ok(())
+        }
+        .await;
+        result.send(cx, res.map_err(|e| format!("{:#?}", e)))?;
         Ok(())
     }
 }
@@ -203,45 +222,63 @@ pub async fn rsync_mesh<M>(actor_mesh: &M, workspace: PathBuf) -> Result<()>
 where
     M: ActorMesh<Actor = RsyncActor>,
 {
+    // Spawn a rsync daemon to acceopt incoming connections from actors.
+    let daemon = RsyncDaemon::spawn(TcpListener::bind(("::1", 0)).await?, &workspace).await?;
+    let daemon_addr = daemon.addr();
+
     // We avoid casting here as we need point-to-point connections to each individual actor.
     stream::iter(actor_mesh.iter_actor_refs())
+        .map(anyhow::Ok)
         // Connect to all actors in the mesh.
-        .map(|actor| async move {
+        .try_for_each_concurrent(None, |actor| async move {
             let mailbox = actor_mesh.proc_mesh().client();
             let (connect, completer) = Connect::allocate(mailbox.actor_id().clone(), mailbox);
-            actor.send(mailbox, connect)?;
-            completer.complete().await
-        })
-        // Max the connections run in parallel.
-        .buffer_unordered(usize::MAX)
-        // Initiate the rsync, in parallel.
-        .try_for_each_concurrent(None, |mut local| async {
-            let workspace = workspace.clone();
-            let listener = TcpListener::bind(("::1", 0)).await?;
-            let addr = listener.local_addr()?;
-            try_join!(
-                async move { do_rsync(&addr, &workspace).await },
-                async move {
-                    let (mut stream, _) = listener.accept().await?;
-                    tokio::io::copy_bidirectional(&mut stream, &mut local).await?;
-                    anyhow::Ok(())
+            let (tx, rx) = mailbox.open_once_port::<Result<(), String>>();
+            actor.send(
+                mailbox,
+                RsyncMessage {
+                    connect,
+                    result: tx.bind(),
                 },
             )?;
+            let (mut local, mut stream) = try_join!(
+                TcpStream::connect(daemon_addr.clone()).err_into(),
+                completer.complete(),
+            )?;
+            // Pipe the remote rsync client to the local rsync server, but don't propagate failures yet.
+            let copy_res = tokio::io::copy_bidirectional(&mut local, &mut stream).await;
+            // Now wait for the final result to be sent back.  We wrap in a timeout, as we should get this
+            // back pretty quickly after the copy above is done.
+            let () = RealClock
+                .timeout(Duration::from_secs(1), rx.recv())
+                .await??
+                .map_err(anyhow::Error::msg)
+                .with_context(|| format!("actor: {}", actor.actor_id()))?;
+            // Finally, propagate any copy errors, in case there were some but not result error.
+            let _ = copy_res?;
             anyhow::Ok(())
         })
         .await?;
+
+    daemon.shutdown().await?;
+
     Ok(())
 }
 
 #[cfg(test)]
 mod tests {
     use anyhow::Result;
     use anyhow::anyhow;
+    use ndslice::shape;
     use tempfile::TempDir;
     use tokio::fs;
     use tokio::net::TcpListener;
 
     use super::*;
+    use crate::alloc::AllocSpec;
+    use crate::alloc::Allocator;
+    use crate::alloc::local::LocalAllocator;
+    use crate::proc_mesh::ProcMesh;
 
     #[tokio::test]
     async fn test_simple() -> Result<()> {
@@ -259,4 +296,46 @@ mod tests {
 
         Ok(())
     }
+
+    #[tokio::test]
+    async fn test_rsync_actor_and_mesh() -> Result<()> {
+        // Create source workspace with test files
+        let source_workspace = TempDir::new()?;
+        fs::write(source_workspace.path().join("test1.txt"), "content1").await?;
+        fs::write(source_workspace.path().join("test2.txt"), "content2").await?;
+        fs::create_dir(source_workspace.path().join("subdir")).await?;
+        fs::write(source_workspace.path().join("subdir/test3.txt"), "content3").await?;
+
+        // Create target workspace for the actors
+        let target_workspace = TempDir::new()?;
+
+        // Set up actor mesh with 2 RsyncActors
+        let alloc = LocalAllocator
+            .allocate(AllocSpec {
+                shape: shape! { replica = 1 },
+                constraints: Default::default(),
+            })
+            .await?;
+
+        let proc_mesh = ProcMesh::allocate(alloc).await?;
+
+        // Create RsyncParams - all actors will use the same target workspace for this test
+        let params = RsyncParams {
+            workspace: WorkspaceLocation::Constant(target_workspace.path().to_path_buf()),
+        };
+
+        // Spawn actor mesh with RsyncActors
+        let actor_mesh = proc_mesh.spawn::<RsyncActor>("rsync_test", &params).await?;
+
+        // Test rsync_mesh function - this coordinates rsync operations across the mesh
+        rsync_mesh(&actor_mesh, source_workspace.path().to_path_buf()).await?;
+
+        // Verify we copied correctly.
+        assert!(
+            !dir_diff::is_different(&source_workspace, &target_workspace)
+                .map_err(|e| anyhow!("{:?}", e))?
+        );
+
+        Ok(())
+    }
 }