Close track FFI handles automatically when a FfiRoom is closed. (#539)

* trying to dispose associated stream handles when a room is closed

* update Cargo.lock

* remove debug log

* store empty handle for existing ffi clients

* impl FfiHandle for ()

* add nanpa changeset

.nanpa/free-stream-handles-when-room-is-closed.kdl

@@ -0,0 +1 @@
+patch type="fixed" package="livekit-ffi" "Automatically close audio/video stream handles when the associated room is closed"

livekit-ffi/src/server/mod.rs

@@ -70,6 +70,7 @@ impl FfiHandle for Arc<Mutex<resampler::SoxResampler>> {}
 impl FfiHandle for AudioFrame<'static> {}
 impl FfiHandle for BoxVideoBuffer {}
 impl FfiHandle for Box<[u8]> {}
+impl FfiHandle for () {}
 
 pub struct FfiServer {
     /// Store all Ffi handles inside an HashMap, if this isn't efficient enough
@@ -133,7 +134,7 @@ impl FfiServer {
         log::info!("initializing ffi server v{}", env!("CARGO_PKG_VERSION")); // TODO: Move this log
     }
 
-    pub async fn dispose(&self) {
+    pub async fn dispose(&'static self) {
         self.logger.set_capture_logs(false);
         log::info!("disposing ffi server");
 
@@ -146,7 +147,7 @@ impl FfiServer {
         }
 
         for room in rooms {
-            room.close().await;
+            room.close(self).await;
         }
 
         // Drop all handles

livekit-ffi/src/server/requests.rs

@@ -67,7 +67,7 @@ fn on_disconnect(
         let ffi_room =
             server.retrieve_handle::<room::FfiRoom>(disconnect.room_handle).unwrap().clone();
 
-        ffi_room.close().await;
+        ffi_room.close(server).await;
 
         let _ =
             server.send_event(proto::ffi_event::Message::Disconnect(proto::DisconnectCallback {

livekit-ffi/src/server/room.rs

@@ -266,7 +266,15 @@ impl FfiRoom {
     }
 
     /// Close the room and stop the tasks
-    pub async fn close(&self) {
+    pub async fn close(&self, server: &'static FfiServer) {
+        // drop associated track handles
+        for (_, &handle) in self.inner.track_handle_lookup.lock().iter() {
+            if server.drop_handle(handle) {
+                // Store an empty handle for the FFI client that assumes a handle exists for this id.
+                server.store_handle(handle, ());
+            }
+        }
+
         let _ = self.inner.room.close().await;
 
         let handle = self.handle.lock().await.take();