Serve concurrent terminal sessions with exact teardown

crates/lazaret-host-coordinator/src/control.rs

@@ -838,6 +838,16 @@ pub struct PublishedControlFace {
     interactive_executor: Arc<dyn InteractiveSessionExecutor>,
 }
 
+pub(crate) struct AcceptedControlConnection {
+    socket: std::os::unix::net::UnixStream,
+}
+
+impl AcceptedControlConnection {
+    pub(crate) fn cancellation_handle(&self) -> std::io::Result<std::os::unix::net::UnixStream> {
+        self.socket.try_clone()
+    }
+}
+
 pub trait NonInteractiveSessionExecutor: Send + Sync {
     /// # Errors
     /// Returns a runtime, stream, or exact-session execution failure.
@@ -1514,6 +1524,25 @@ impl PublishedControlFace {
     /// failure.
     pub fn serve_next_coordinated<Admit, Disconnect>(
         &self,
+        admit: Admit,
+        disconnect: Disconnect,
+    ) -> Result<(), ControlError>
+    where
+        Admit: FnMut(ControlSessionAdmission) -> Result<(), ControlError>,
+        Disconnect: FnMut(SessionId) -> Result<(), ControlError>,
+    {
+        let connection = self.accept_connection()?;
+        self.serve_connection_coordinated(connection, admit, disconnect)
+    }
+
+    pub(crate) fn accept_connection(&self) -> Result<AcceptedControlConnection, ControlError> {
+        let (socket, _) = self.listener.accept()?;
+        Ok(AcceptedControlConnection { socket })
+    }
+
+    pub(crate) fn serve_connection_coordinated<Admit, Disconnect>(
+        &self,
+        connection: AcceptedControlConnection,
         mut admit: Admit,
         mut disconnect: Disconnect,
     ) -> Result<(), ControlError>
@@ -1521,7 +1550,7 @@ impl PublishedControlFace {
         Admit: FnMut(ControlSessionAdmission) -> Result<(), ControlError>,
         Disconnect: FnMut(SessionId) -> Result<(), ControlError>,
     {
-        let (socket, _) = self.listener.accept()?;
+        let socket = connection.socket;
         let peer = socket_peercred(&socket).map_err(io::Error::from)?;
         require_peer_uid(peer.uid.as_raw(), self.uid)?;
         self.validate_publication()?;