From 83abf67d20e3294ae9e8be3bc99e92b89f2c9844 Mon Sep 17 00:00:00 2001 From: Ruslan Nigmatullin Date: Wed, 15 Apr 2026 11:52:53 -0700 Subject: [PATCH] app-server: track remote-control seq IDs per stream (#17902) ## Summary - Track outbound remote-control sequence IDs independently for each client stream. - Retain unacked outbound messages per stream using FIFO buffers. - Require stream-scoped acks and update tests for contiguous per-stream sequencing. ## Why The remote-control peer uses outbound sequence gaps to detect lost messages and re-initialize. A single global outbound sequence counter can create apparent gaps on an individual stream when another stream receives an interleaved message. ## Validation - `just fmt` - `cargo test -p codex-app-server remote_control` - `just fix -p codex-app-server` - `git diff --check` --- .../src/transport/remote_control/protocol.rs | 7 +- .../src/transport/remote_control/tests.rs | 36 ++- .../src/transport/remote_control/websocket.rs | 271 ++++++++++++------ 3 files changed, 216 insertions(+), 98 deletions(-) diff --git a/codex-rs/app-server/src/transport/remote_control/protocol.rs b/codex-rs/app-server/src/transport/remote_control/protocol.rs index 857855f2a..dcb79e5c3 100644 --- a/codex-rs/app-server/src/transport/remote_control/protocol.rs +++ b/codex-rs/app-server/src/transport/remote_control/protocol.rs @@ -48,9 +48,8 @@ pub enum ClientEvent { message: JSONRPCMessage, }, /// Backend-generated acknowledgement for all server envelopes addressed to - /// `client_id` whose envelope `seq_id` is less than or equal to this ack's - /// `seq_id`. This cursor is client-scoped, not stream-scoped, so receivers - /// must not use `stream_id` to partition acks. + /// `client_id` and `stream_id` whose envelope `seq_id` is less than or equal + /// to this ack's `seq_id`. This cursor is stream-scoped. Ack, Ping, ClientClosed, @@ -65,7 +64,7 @@ pub(crate) struct ClientEnvelope { pub(crate) client_id: ClientId, #[serde(rename = "stream_id", skip_serializing_if = "Option::is_none")] pub(crate) stream_id: Option, - /// For `Ack`, this is the backend-generated per-client cursor over + /// For `Ack`, this is the backend-generated per-stream cursor over /// `ServerEnvelope.seq_id`. #[serde(rename = "seq_id", skip_serializing_if = "Option::is_none")] pub(crate) seq_id: Option, diff --git a/codex-rs/app-server/src/transport/remote_control/tests.rs b/codex-rs/app-server/src/transport/remote_control/tests.rs index 6dd6978fa..2dd687a3d 100644 --- a/codex-rs/app-server/src/transport/remote_control/tests.rs +++ b/codex-rs/app-server/src/transport/remote_control/tests.rs @@ -5,6 +5,7 @@ use super::enroll::update_persisted_remote_control_enrollment; use super::protocol::ClientEnvelope; use super::protocol::ClientEvent; use super::protocol::ClientId; +use super::protocol::StreamId; use super::protocol::normalize_remote_control_url; use super::websocket::REMOTE_CONTROL_PROTOCOL_VERSION; use super::*; @@ -163,7 +164,7 @@ async fn remote_control_transport_manages_virtual_clients_and_routes_messages() json!({ "type": "pong", "client_id": "client-1", - "seq_id": 0, + "seq_id": 1, "status": "unknown", }) ); @@ -369,7 +370,7 @@ async fn remote_control_transport_manages_virtual_clients_and_routes_messages() json!({ "type": "pong", "client_id": "client-1", - "seq_id": 3, + "seq_id": 1, "status": "unknown", }) ); @@ -618,12 +619,13 @@ async fn remote_control_transport_clears_outgoing_buffer_when_backend_acks() { )) .await .expect("remote writer should accept outgoing message"); + let (server_event, stream_id) = read_server_event_with_stream_id(&mut first_websocket).await; assert_eq!( - read_server_event(&mut first_websocket).await, + server_event, json!({ "type": "server_message", "client_id": "client-1", - "seq_id": 0, + "seq_id": 1, "message": { "method": "configWarning", "params": { @@ -639,8 +641,8 @@ async fn remote_control_transport_clears_outgoing_buffer_when_backend_acks() { ClientEnvelope { event: ClientEvent::Ack, client_id: client_id.clone(), - stream_id: None, - seq_id: Some(0), + stream_id: Some(stream_id), + seq_id: Some(1), cursor: None, }, ) @@ -854,7 +856,7 @@ async fn remote_control_http_mode_enrolls_before_connecting() { json!({ "type": "server_message", "client_id": backend_client_id.0.clone(), - "seq_id": 0, + "seq_id": 1, "message": { "id": 11, "result": { @@ -882,7 +884,7 @@ async fn remote_control_http_mode_enrolls_before_connecting() { json!({ "type": "server_message", "client_id": backend_client_id.0.clone(), - "seq_id": 1, + "seq_id": 2, "message": { "method": "configWarning", "params": { @@ -1356,6 +1358,12 @@ async fn send_client_event( } async fn read_server_event(websocket: &mut WebSocketStream) -> serde_json::Value { + read_server_event_with_stream_id(websocket).await.0 +} + +async fn read_server_event_with_stream_id( + websocket: &mut WebSocketStream, +) -> (serde_json::Value, StreamId) { loop { let frame = timeout(Duration::from_secs(5), websocket.next()) .await @@ -1366,13 +1374,15 @@ async fn read_server_event(websocket: &mut WebSocketStream) -> serde_ tungstenite::Message::Text(text) => { let mut event: serde_json::Value = serde_json::from_str(text.as_ref()).expect("server event should deserialize"); - if let Some(stream_id) = event + let stream_id = event .as_object_mut() .and_then(|event| event.remove("stream_id")) - { - assert!(stream_id.is_string(), "stream_id should be a string"); - } - return event; + .expect("stream_id should be present"); + let stream_id = stream_id + .as_str() + .expect("stream_id should be a string") + .to_string(); + return (event, StreamId(stream_id)); } tungstenite::Message::Ping(payload) => { websocket diff --git a/codex-rs/app-server/src/transport/remote_control/websocket.rs b/codex-rs/app-server/src/transport/remote_control/websocket.rs index d168ec0e1..82e5f35b3 100644 --- a/codex-rs/app-server/src/transport/remote_control/websocket.rs +++ b/codex-rs/app-server/src/transport/remote_control/websocket.rs @@ -14,6 +14,7 @@ use super::protocol::ClientEvent; use super::protocol::ClientId; use super::protocol::RemoteControlTarget; use super::protocol::ServerEnvelope; +use super::protocol::StreamId; use axum::http::HeaderValue; use base64::Engine; use codex_core::util::backoff; @@ -25,8 +26,8 @@ use futures::SinkExt; use futures::StreamExt; use futures::stream::SplitSink; use futures::stream::SplitStream; -use std::collections::BTreeMap; use std::collections::HashMap; +use std::collections::VecDeque; use std::io; use std::io::ErrorKind; use std::sync::Arc; @@ -57,10 +58,7 @@ const REMOTE_CONTROL_ACCOUNT_ID_RETRY_INTERVAL: std::time::Duration = std::time::Duration::from_secs(1); struct BoundedOutboundBuffer { - // Remote-control acks are generated by the backend at client scope, so - // retransmit retention is keyed by client_id only. stream_id stays on each - // envelope for routing, but it is not part of the ack cursor. - buffer_by_client: HashMap>, + buffer_by_stream: HashMap<(ClientId, StreamId), VecDeque>, used_tx: watch::Sender, } @@ -68,46 +66,50 @@ impl BoundedOutboundBuffer { fn new() -> (Self, watch::Receiver) { let (used_tx, used_rx) = watch::channel(0); let buffer = Self { - buffer_by_client: HashMap::new(), + buffer_by_stream: HashMap::new(), used_tx, }; (buffer, used_rx) } fn insert(&mut self, server_envelope: &ServerEnvelope) { - self.buffer_by_client - .entry(server_envelope.client_id.clone()) + self.buffer_by_stream + .entry(( + server_envelope.client_id.clone(), + server_envelope.stream_id.clone(), + )) .or_default() - .insert(server_envelope.seq_id, server_envelope.clone()); + .push_back(server_envelope.clone()); self.used_tx.send_modify(|used| *used += 1); } - fn ack(&mut self, client_id: &ClientId, acked_seq_id: u64) { - let Some(buffer) = self.buffer_by_client.get_mut(client_id) else { + fn ack(&mut self, client_id: &ClientId, stream_id: &StreamId, acked_seq_id: u64) { + let key = (client_id.clone(), stream_id.clone()); + let Some(buffer) = self.buffer_by_stream.get_mut(&key) else { return; }; - while let Some(seq_id) = buffer.first_key_value().map(|(seq_id, _)| seq_id) - && *seq_id <= acked_seq_id + while let Some(server_envelope) = buffer.front() + && server_envelope.seq_id <= acked_seq_id { - buffer.pop_first(); + buffer.pop_front(); self.used_tx.send_modify(|used| *used -= 1); } if buffer.is_empty() { - self.buffer_by_client.remove(client_id); + self.buffer_by_stream.remove(&key); } } fn server_envelopes(&self) -> impl Iterator { - self.buffer_by_client + self.buffer_by_stream .values() - .flat_map(|buffer| buffer.values()) + .flat_map(|buffer| buffer.iter()) } } struct WebsocketState { outbound_buffer: BoundedOutboundBuffer, subscribe_cursor: Option, - next_seq_id: u64, + next_seq_id_by_stream: HashMap<(ClientId, StreamId), u64>, } pub(crate) struct RemoteControlWebsocket { @@ -162,7 +164,7 @@ impl RemoteControlWebsocket { state: Arc::new(Mutex::new(WebsocketState { outbound_buffer, subscribe_cursor: None, - next_seq_id: 0, + next_seq_id_by_stream: HashMap::new(), })), server_event_rx: Arc::new(Mutex::new(server_event_rx)), used_rx, @@ -445,10 +447,16 @@ impl RemoteControlWebsocket { } } }; - let (server_envelope, write_complete_tx) = { + let (payload, write_complete_tx) = { let mut state = state.lock().await; - let seq_id = state.next_seq_id; - state.next_seq_id = state.next_seq_id.saturating_add(1); + let seq_key = ( + queued_server_envelope.client_id.clone(), + queued_server_envelope.stream_id.clone(), + ); + let seq_id = *state + .next_seq_id_by_stream + .entry(seq_key.clone()) + .or_insert(1); let server_envelope = ServerEnvelope { event: queued_server_envelope.event, @@ -456,17 +464,19 @@ impl RemoteControlWebsocket { seq_id, stream_id: queued_server_envelope.stream_id, }; + let payload = match serde_json::to_string(&server_envelope) { + Ok(payload) => payload, + Err(err) => { + error!("failed to serialize remote-control server event: {err}"); + continue; + } + }; + state + .next_seq_id_by_stream + .insert(seq_key, seq_id.saturating_add(1)); state.outbound_buffer.insert(&server_envelope); - (server_envelope, queued_server_envelope.write_complete_tx) - }; - - let payload = match serde_json::to_string(&server_envelope) { - Ok(payload) => payload, - Err(err) => { - error!("failed to serialize remote-control server event: {err}"); - continue; - } + (payload, queued_server_envelope.write_complete_tx) }; tokio::select! { @@ -590,10 +600,13 @@ impl RemoteControlWebsocket { } if let ClientEvent::Ack = &client_envelope.event && let Some(acked_seq_id) = client_envelope.seq_id + && let Some(stream_id) = client_envelope.stream_id.as_ref() { - websocket_state - .outbound_buffer - .ack(&client_envelope.client_id, acked_seq_id); + websocket_state.outbound_buffer.ack( + &client_envelope.client_id, + stream_id, + acked_seq_id, + ); } drop(websocket_state); @@ -1220,7 +1233,7 @@ mod tests { let state = Arc::new(Mutex::new(WebsocketState { outbound_buffer, subscribe_cursor: None, - next_seq_id: 0, + next_seq_id_by_stream: HashMap::new(), })); let (_server_event_tx, server_event_rx) = mpsc::channel(super::super::CHANNEL_CAPACITY); let server_event_rx = Arc::new(Mutex::new(server_event_rx)); @@ -1248,6 +1261,83 @@ mod tests { .expect("writer should stop cleanly"); } + #[tokio::test] + async fn run_server_writer_inner_assigns_contiguous_seq_ids_per_stream() { + let (client_stream, mut server_stream) = connected_websocket_pair().await; + let (websocket_writer, _websocket_reader) = client_stream.split(); + let (outbound_buffer, used_rx) = BoundedOutboundBuffer::new(); + let state = Arc::new(Mutex::new(WebsocketState { + outbound_buffer, + subscribe_cursor: None, + next_seq_id_by_stream: HashMap::new(), + })); + let (server_event_tx, server_event_rx) = mpsc::channel(super::super::CHANNEL_CAPACITY); + let server_event_rx = Arc::new(Mutex::new(server_event_rx)); + let shutdown_token = CancellationToken::new(); + let writer_task = tokio::spawn(RemoteControlWebsocket::run_server_writer_inner( + state, + server_event_rx, + used_rx, + websocket_writer, + Duration::from_secs(60), + shutdown_token.clone(), + )); + + let client_id = ClientId("client-1".to_string()); + let first_stream = StreamId("stream-1".to_string()); + let second_stream = StreamId("stream-2".to_string()); + for stream_id in [&first_stream, &second_stream, &first_stream] { + server_event_tx + .send(super::super::QueuedServerEnvelope { + event: ServerEvent::Pong { + status: crate::transport::remote_control::protocol::PongStatus::Active, + }, + client_id: client_id.clone(), + stream_id: stream_id.clone(), + write_complete_tx: None, + }) + .await + .expect("server event should queue"); + } + + assert_eq!( + read_server_text_event(&mut server_stream).await, + serde_json::json!({ + "type": "pong", + "client_id": "client-1", + "stream_id": "stream-1", + "seq_id": 1, + "status": "active", + }) + ); + assert_eq!( + read_server_text_event(&mut server_stream).await, + serde_json::json!({ + "type": "pong", + "client_id": "client-1", + "stream_id": "stream-2", + "seq_id": 1, + "status": "active", + }) + ); + assert_eq!( + read_server_text_event(&mut server_stream).await, + serde_json::json!({ + "type": "pong", + "client_id": "client-1", + "stream_id": "stream-1", + "seq_id": 2, + "status": "active", + }) + ); + + shutdown_token.cancel(); + writer_task + .await + .expect("writer task should join") + .expect("writer should stop cleanly"); + } + #[tokio::test] async fn run_websocket_reader_inner_times_out_without_pong_frames() { let (client_stream, _server_stream) = connected_websocket_pair().await; @@ -1256,7 +1346,7 @@ mod tests { let state = Arc::new(Mutex::new(WebsocketState { outbound_buffer, subscribe_cursor: None, - next_seq_id: 0, + next_seq_id_by_stream: HashMap::new(), })); let (server_event_tx, _server_event_rx) = mpsc::channel(super::super::CHANNEL_CAPACITY); let (transport_event_tx, _transport_event_rx) = @@ -1287,70 +1377,32 @@ mod tests { } #[test] - fn outbound_buffer_acks_by_client_id_across_stream_ids() { + fn outbound_buffer_acks_by_stream_id() { let (mut outbound_buffer, used_rx) = BoundedOutboundBuffer::new(); let client_1 = ClientId("client-1".to_string()); let client_2 = ClientId("client-2".to_string()); + let stream_1 = StreamId("stream-1".to_string()); outbound_buffer.insert(&server_envelope( &client_1, "stream-1", - /*seq_id*/ 0, + /*seq_id*/ 1, "first-client-old-stream", )); outbound_buffer.insert(&server_envelope( &client_2, "stream-1", - /*seq_id*/ 1, + /*seq_id*/ 2, "second-client", )); outbound_buffer.insert(&server_envelope( &client_1, "stream-2", - /*seq_id*/ 2, + /*seq_id*/ 3, "first-client-new-stream", )); - outbound_buffer.ack(&client_1, /*acked_seq_id*/ 2); - - let mut retained = outbound_buffer - .server_envelopes() - .map(|server_envelope| { - ( - server_envelope.client_id.0.as_str(), - server_envelope.stream_id.0.as_str(), - server_envelope.seq_id, - ) - }) - .collect::>(); - retained.sort_unstable(); - assert_eq!(retained, vec![("client-2", "stream-1", 1)]); - assert_eq!(*used_rx.borrow(), 1); - } - - #[test] - fn outbound_buffer_retains_unacked_messages_until_ack_advances() { - let (mut outbound_buffer, used_rx) = BoundedOutboundBuffer::new(); - let client_1 = ClientId("client-1".to_string()); - let client_2 = ClientId("client-2".to_string()); - - outbound_buffer.insert(&server_envelope( - &client_1, - "stream-1", - /*seq_id*/ 0, - "first-old", - )); - outbound_buffer.insert(&server_envelope( - &client_1, - "stream-2", - /*seq_id*/ 1, - "first-new", - )); - outbound_buffer.insert(&server_envelope( - &client_2, "stream-1", /*seq_id*/ 2, "second", - )); - - outbound_buffer.ack(&client_1, /*acked_seq_id*/ 0); + outbound_buffer.ack(&client_1, &stream_1, /*acked_seq_id*/ 3); let mut retained = outbound_buffer .server_envelopes() @@ -1365,7 +1417,50 @@ mod tests { retained.sort_unstable(); assert_eq!( retained, - vec![("client-1", "stream-2", 1), ("client-2", "stream-1", 2)] + vec![("client-1", "stream-2", 3), ("client-2", "stream-1", 2)] + ); + assert_eq!(*used_rx.borrow(), 2); + } + + #[test] + fn outbound_buffer_retains_unacked_messages_until_ack_advances() { + let (mut outbound_buffer, used_rx) = BoundedOutboundBuffer::new(); + let client_1 = ClientId("client-1".to_string()); + let client_2 = ClientId("client-2".to_string()); + let stream_1 = StreamId("stream-1".to_string()); + + outbound_buffer.insert(&server_envelope( + &client_1, + "stream-1", + /*seq_id*/ 1, + "first-old", + )); + outbound_buffer.insert(&server_envelope( + &client_1, + "stream-2", + /*seq_id*/ 2, + "first-new", + )); + outbound_buffer.insert(&server_envelope( + &client_2, "stream-1", /*seq_id*/ 3, "second", + )); + + outbound_buffer.ack(&client_1, &stream_1, /*acked_seq_id*/ 1); + + let mut retained = outbound_buffer + .server_envelopes() + .map(|server_envelope| { + ( + server_envelope.client_id.0.as_str(), + server_envelope.stream_id.0.as_str(), + server_envelope.seq_id, + ) + }) + .collect::>(); + retained.sort_unstable(); + assert_eq!( + retained, + vec![("client-1", "stream-2", 2), ("client-2", "stream-1", 3)] ); assert_eq!(*used_rx.borrow(), 2); } @@ -1450,6 +1545,20 @@ mod tests { (client_stream, server_stream) } + async fn read_server_text_event( + server_stream: &mut WebSocketStream, + ) -> serde_json::Value { + let message = timeout(Duration::from_secs(5), server_stream.next()) + .await + .expect("server event should arrive in time") + .expect("server websocket should stay open") + .expect("server event should read"); + let tungstenite::Message::Text(text) = message else { + panic!("expected text event, got {message:?}"); + }; + serde_json::from_str(text.as_ref()).expect("server event should deserialize") + } + async fn respond_with_status_and_headers( mut stream: TcpStream, status: &str,