PeerState::Disconnected received before PeerState::Connected

[ndev-rs]

When a player joins a room, if the rest of the players quickly leave and rejoin to create a new session together, often the new player will see some or all of these disconnect and reconnects out of order.

    for (id, state) in socket.update_peers() {
        match state {
            PeerState::Connected => {
                info!("matchbox: peer connected: {:?}", id);
            }
            PeerState::Disconnected => {
                info!("matchbox: peer disconnected: {:?}", id);
            }
        }
    }

Output:

2023-10-27T18:33:02.740393Z  INFO *::network: matchbox: peer connected: PeerId(10e5cfbd-5f95-48df-a5b4-998951f56e88)
2023-10-27T18:33:02.740461Z  INFO *::network: matchbox: peer disconnected: PeerId(10e5cfbd-5f95-48df-a5b4-998951f56e88)
2023-10-27T18:33:02.740473Z  INFO *::network: matchbox: peer disconnected: PeerId(5004a446-0a23-4417-acd1-d6b18fee1455)
2023-10-27T18:33:03.007778Z  INFO *::network: matchbox: peer connected: PeerId(b3c558f9-50eb-4cb4-98f8-cb39713bf5bf)
2023-10-27T18:33:03.007956Z  INFO *::network: matchbox: peer connected: PeerId(78b5ff17-32a7-421c-955e-16a33f8cdfc4)
2023-10-27T18:33:03.820027Z  INFO *::network: matchbox: peer connected: PeerId(5004a446-0a23-4417-acd1-d6b18fee1455)

Full code

pub fn connect(
...
) {
    if socket.id().is_none() { return };
let now = SystemTime::now();
let mut msgs_to_send: Vec<(PeerId, Box<[u8]>)> = Vec::new();

// update peers
let peer_events = socket.update_peers();
let ids: HashSet<_> = socket.connected_peers().collect();
room_state.add_connected_peers(&ids);
room_state.remove_disconnected_peers(&ids);

// on connect
if room_state.room_time.is_none() {
    room_state.room_time = Some(now);
    room_state.add_local(&now);
} else if !peer_events.is_empty() {
    // update timeout window
    room_state.room_time = Some(now);
}

// broadcast join time to peers
for (id, state) in &peer_events {
    match state {
        PeerState::Connected => {
            info!("matchbox: peer connected: {:?}", id);
            let packet = encode(TIME, room_state.get_local().join_time);
            msgs_to_send.push((*id, packet));
        }
        PeerState::Disconnected => {
            info!("matchbox: peer disconnected: {:?}", id);
        }
    }
}

// recv msgs and update player state
recv_messages(&mut commands, &assets, &mut socket,
    &mut room_state, &mut level, &mut msgs_to_send,
);

// send msgs
for (id, packet) in msgs_to_send {
    socket.channel(1).send(packet, id);
}

// when all ready checks are recvd, start the game
if room_state.players.values().all(|player_state| player_state.ready) {
    let players: Vec<_> = room_state.players.iter()
        .map(|(key, _)| key.clone())
        .collect();

    create_ggrs_session(
        commands,
        players,
        socket,
        next_state
    );
}

}

bevy = { version = "0.11", features = ["dynamic_linking"] }
bevy_ggrs = { version = "0.13", features = ["wasm-bindgen"] }
bevy_matchbox = { version = "0.7", features=["ggrs"] }

Default matchbox_server, tested locally on native Linux.

[simbleau]

Ah, so the issue is that a disconnection can be reported before the connection, assuming the events happen close together

[johanhelsing]

I noticed yesterday that it's also possible to get only a Disconnected by itself if a peer tries to connect, but ice gathering fails.

[simbleau]

I noticed yesterday that it's also possible to get only a Disconnected by itself if a peer tries to connect, but ice gathering fails.

Are we tracking this in a separate issue?