Add rpc2

crates/rpc2/src/peer.rs

@@ -0,0 +1,933 @@
+use super::{
+    proto::{self, AnyTypedEnvelope, EnvelopedMessage, MessageStream, PeerId, RequestMessage},
+    Connection,
+};
+use anyhow::{anyhow, Context, Result};
+use collections::HashMap;
+use futures::{
+    channel::{mpsc, oneshot},
+    stream::BoxStream,
+    FutureExt, SinkExt, StreamExt, TryFutureExt,
+};
+use parking_lot::{Mutex, RwLock};
+use serde::{ser::SerializeStruct, Serialize};
+use std::{fmt, sync::atomic::Ordering::SeqCst};
+use std::{
+    future::Future,
+    marker::PhantomData,
+    sync::{
+        atomic::{self, AtomicU32},
+        Arc,
+    },
+    time::Duration,
+};
+use tracing::instrument;
+
+#[derive(Clone, Copy, Default, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Serialize)]
+pub struct ConnectionId {
+    pub owner_id: u32,
+    pub id: u32,
+}
+
+impl Into<PeerId> for ConnectionId {
+    fn into(self) -> PeerId {
+        PeerId {
+            owner_id: self.owner_id,
+            id: self.id,
+        }
+    }
+}
+
+impl From<PeerId> for ConnectionId {
+    fn from(peer_id: PeerId) -> Self {
+        Self {
+            owner_id: peer_id.owner_id,
+            id: peer_id.id,
+        }
+    }
+}
+
+impl fmt::Display for ConnectionId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}/{}", self.owner_id, self.id)
+    }
+}
+
+pub struct Receipt<T> {
+    pub sender_id: ConnectionId,
+    pub message_id: u32,
+    payload_type: PhantomData<T>,
+}
+
+impl<T> Clone for Receipt<T> {
+    fn clone(&self) -> Self {
+        Self {
+            sender_id: self.sender_id,
+            message_id: self.message_id,
+            payload_type: PhantomData,
+        }
+    }
+}
+
+impl<T> Copy for Receipt<T> {}
+
+#[derive(Clone, Debug)]
+pub struct TypedEnvelope<T> {
+    pub sender_id: ConnectionId,
+    pub original_sender_id: Option<PeerId>,
+    pub message_id: u32,
+    pub payload: T,
+}
+
+impl<T> TypedEnvelope<T> {
+    pub fn original_sender_id(&self) -> Result<PeerId> {
+        self.original_sender_id
+            .ok_or_else(|| anyhow!("missing original_sender_id"))
+    }
+}
+
+impl<T: RequestMessage> TypedEnvelope<T> {
+    pub fn receipt(&self) -> Receipt<T> {
+        Receipt {
+            sender_id: self.sender_id,
+            message_id: self.message_id,
+            payload_type: PhantomData,
+        }
+    }
+}
+
+pub struct Peer {
+    epoch: AtomicU32,
+    pub connections: RwLock<HashMap<ConnectionId, ConnectionState>>,
+    next_connection_id: AtomicU32,
+}
+
+#[derive(Clone, Serialize)]
+pub struct ConnectionState {
+    #[serde(skip)]
+    outgoing_tx: mpsc::UnboundedSender<proto::Message>,
+    next_message_id: Arc<AtomicU32>,
+    #[allow(clippy::type_complexity)]
+    #[serde(skip)]
+    response_channels:
+        Arc<Mutex<Option<HashMap<u32, oneshot::Sender<(proto::Envelope, oneshot::Sender<()>)>>>>>,
+}
+
+const KEEPALIVE_INTERVAL: Duration = Duration::from_secs(1);
+const WRITE_TIMEOUT: Duration = Duration::from_secs(2);
+pub const RECEIVE_TIMEOUT: Duration = Duration::from_secs(10);
+
+impl Peer {
+    pub fn new(epoch: u32) -> Arc<Self> {
+        Arc::new(Self {
+            epoch: AtomicU32::new(epoch),
+            connections: Default::default(),
+            next_connection_id: Default::default(),
+        })
+    }
+
+    pub fn epoch(&self) -> u32 {
+        self.epoch.load(SeqCst)
+    }
+
+    #[instrument(skip_all)]
+    pub fn add_connection<F, Fut, Out>(
+        self: &Arc<Self>,
+        connection: Connection,
+        create_timer: F,
+    ) -> (
+        ConnectionId,
+        impl Future<Output = anyhow::Result<()>> + Send,
+        BoxStream<'static, Box<dyn AnyTypedEnvelope>>,
+    )
+    where
+        F: Send + Fn(Duration) -> Fut,
+        Fut: Send + Future<Output = Out>,
+        Out: Send,
+    {
+        // For outgoing messages, use an unbounded channel so that application code
+        // can always send messages without yielding. For incoming messages, use a
+        // bounded channel so that other peers will receive backpressure if they send
+        // messages faster than this peer can process them.
+        #[cfg(any(test, feature = "test-support"))]
+        const INCOMING_BUFFER_SIZE: usize = 1;
+        #[cfg(not(any(test, feature = "test-support")))]
+        const INCOMING_BUFFER_SIZE: usize = 64;
+        let (mut incoming_tx, incoming_rx) = mpsc::channel(INCOMING_BUFFER_SIZE);
+        let (outgoing_tx, mut outgoing_rx) = mpsc::unbounded();
+
+        let connection_id = ConnectionId {
+            owner_id: self.epoch.load(SeqCst),
+            id: self.next_connection_id.fetch_add(1, SeqCst),
+        };
+        let connection_state = ConnectionState {
+            outgoing_tx,
+            next_message_id: Default::default(),
+            response_channels: Arc::new(Mutex::new(Some(Default::default()))),
+        };
+        let mut writer = MessageStream::new(connection.tx);
+        let mut reader = MessageStream::new(connection.rx);
+
+        let this = self.clone();
+        let response_channels = connection_state.response_channels.clone();
+        let handle_io = async move {
+            tracing::trace!(%connection_id, "handle io future: start");
+
+            let _end_connection = util::defer(|| {
+                response_channels.lock().take();
+                this.connections.write().remove(&connection_id);
+                tracing::trace!(%connection_id, "handle io future: end");
+            });
+
+            // Send messages on this frequency so the connection isn't closed.
+            let keepalive_timer = create_timer(KEEPALIVE_INTERVAL).fuse();
+            futures::pin_mut!(keepalive_timer);
+
+            // Disconnect if we don't receive messages at least this frequently.
+            let receive_timeout = create_timer(RECEIVE_TIMEOUT).fuse();
+            futures::pin_mut!(receive_timeout);
+
+            loop {
+                tracing::trace!(%connection_id, "outer loop iteration start");
+                let read_message = reader.read().fuse();
+                futures::pin_mut!(read_message);
+
+                loop {
+                    tracing::trace!(%connection_id, "inner loop iteration start");
+                    futures::select_biased! {
+                        outgoing = outgoing_rx.next().fuse() => match outgoing {
+                            Some(outgoing) => {
+                                tracing::trace!(%connection_id, "outgoing rpc message: writing");
+                                futures::select_biased! {
+                                    result = writer.write(outgoing).fuse() => {
+                                        tracing::trace!(%connection_id, "outgoing rpc message: done writing");
+                                        result.context("failed to write RPC message")?;
+                                        tracing::trace!(%connection_id, "keepalive interval: resetting after sending message");
+                                        keepalive_timer.set(create_timer(KEEPALIVE_INTERVAL).fuse());
+                                    }
+                                    _ = create_timer(WRITE_TIMEOUT).fuse() => {
+                                        tracing::trace!(%connection_id, "outgoing rpc message: writing timed out");
+                                        Err(anyhow!("timed out writing message"))?;
+                                    }
+                                }
+                            }
+                            None => {
+                                tracing::trace!(%connection_id, "outgoing rpc message: channel closed");
+                                return Ok(())
+                            },
+                        },
+                        _ = keepalive_timer => {
+                            tracing::trace!(%connection_id, "keepalive interval: pinging");
+                            futures::select_biased! {
+                                result = writer.write(proto::Message::Ping).fuse() => {
+                                    tracing::trace!(%connection_id, "keepalive interval: done pinging");
+                                    result.context("failed to send keepalive")?;
+                                    tracing::trace!(%connection_id, "keepalive interval: resetting after pinging");
+                                    keepalive_timer.set(create_timer(KEEPALIVE_INTERVAL).fuse());
+                                }
+                                _ = create_timer(WRITE_TIMEOUT).fuse() => {
+                                    tracing::trace!(%connection_id, "keepalive interval: pinging timed out");
+                                    Err(anyhow!("timed out sending keepalive"))?;
+                                }
+                            }
+                        }
+                        incoming = read_message => {
+                            let incoming = incoming.context("error reading rpc message from socket")?;
+                            tracing::trace!(%connection_id, "incoming rpc message: received");
+                            tracing::trace!(%connection_id, "receive timeout: resetting");
+                            receive_timeout.set(create_timer(RECEIVE_TIMEOUT).fuse());
+                            if let proto::Message::Envelope(incoming) = incoming {
+                                tracing::trace!(%connection_id, "incoming rpc message: processing");
+                                futures::select_biased! {
+                                    result = incoming_tx.send(incoming).fuse() => match result {
+                                        Ok(_) => {
+                                            tracing::trace!(%connection_id, "incoming rpc message: processed");
+                                        }
+                                        Err(_) => {
+                                            tracing::trace!(%connection_id, "incoming rpc message: channel closed");
+                                            return Ok(())
+                                        }
+                                    },
+                                    _ = create_timer(WRITE_TIMEOUT).fuse() => {
+                                        tracing::trace!(%connection_id, "incoming rpc message: processing timed out");
+                                        Err(anyhow!("timed out processing incoming message"))?
+                                    }
+                                }
+                            }
+                            break;
+                        },
+                        _ = receive_timeout => {
+                            tracing::trace!(%connection_id, "receive timeout: delay between messages too long");
+                            Err(anyhow!("delay between messages too long"))?
+                        }
+                    }
+                }
+            }
+        };
+
+        let response_channels = connection_state.response_channels.clone();
+        self.connections
+            .write()
+            .insert(connection_id, connection_state);
+
+        let incoming_rx = incoming_rx.filter_map(move |incoming| {
+            let response_channels = response_channels.clone();
+            async move {
+                let message_id = incoming.id;
+                tracing::trace!(?incoming, "incoming message future: start");
+                let _end = util::defer(move || {
+                    tracing::trace!(%connection_id, message_id, "incoming message future: end");
+                });
+
+                if let Some(responding_to) = incoming.responding_to {
+                    tracing::trace!(
+                        %connection_id,
+                        message_id,
+                        responding_to,
+                        "incoming response: received"
+                    );
+                    let channel = response_channels.lock().as_mut()?.remove(&responding_to);
+                    if let Some(tx) = channel {
+                        let requester_resumed = oneshot::channel();
+                        if let Err(error) = tx.send((incoming, requester_resumed.0)) {
+                            tracing::trace!(
+                                %connection_id,
+                                message_id,
+                                responding_to = responding_to,
+                                ?error,
+                                "incoming response: request future dropped",
+                            );
+                        }
+
+                        tracing::trace!(
+                            %connection_id,
+                            message_id,
+                            responding_to,
+                            "incoming response: waiting to resume requester"
+                        );
+                        let _ = requester_resumed.1.await;
+                        tracing::trace!(
+                            %connection_id,
+                            message_id,
+                            responding_to,
+                            "incoming response: requester resumed"
+                        );
+                    } else {
+                        tracing::warn!(
+                            %connection_id,
+                            message_id,
+                            responding_to,
+                            "incoming response: unknown request"
+                        );
+                    }
+
+                    None
+                } else {
+                    tracing::trace!(%connection_id, message_id, "incoming message: received");
+                    proto::build_typed_envelope(connection_id, incoming).or_else(|| {
+                        tracing::error!(
+                            %connection_id,
+                            message_id,
+                            "unable to construct a typed envelope"
+                        );
+                        None
+                    })
+                }
+            }
+        });
+        (connection_id, handle_io, incoming_rx.boxed())
+    }
+
+    #[cfg(any(test, feature = "test-support"))]
+    pub fn add_test_connection(
+        self: &Arc<Self>,
+        connection: Connection,
+        executor: Arc<gpui::executor::Background>,
+    ) -> (
+        ConnectionId,
+        impl Future<Output = anyhow::Result<()>> + Send,
+        BoxStream<'static, Box<dyn AnyTypedEnvelope>>,
+    ) {
+        let executor = executor.clone();
+        self.add_connection(connection, move |duration| executor.timer(duration))
+    }
+
+    pub fn disconnect(&self, connection_id: ConnectionId) {
+        self.connections.write().remove(&connection_id);
+    }
+
+    pub fn reset(&self, epoch: u32) {
+        self.teardown();
+        self.next_connection_id.store(0, SeqCst);
+        self.epoch.store(epoch, SeqCst);
+    }
+
+    pub fn teardown(&self) {
+        self.connections.write().clear();
+    }
+
+    pub fn request<T: RequestMessage>(
+        &self,
+        receiver_id: ConnectionId,
+        request: T,
+    ) -> impl Future<Output = Result<T::Response>> {
+        self.request_internal(None, receiver_id, request)
+            .map_ok(|envelope| envelope.payload)
+    }
+
+    pub fn request_envelope<T: RequestMessage>(
+        &self,
+        receiver_id: ConnectionId,
+        request: T,
+    ) -> impl Future<Output = Result<TypedEnvelope<T::Response>>> {
+        self.request_internal(None, receiver_id, request)
+    }
+
+    pub fn forward_request<T: RequestMessage>(
+        &self,
+        sender_id: ConnectionId,
+        receiver_id: ConnectionId,
+        request: T,
+    ) -> impl Future<Output = Result<T::Response>> {
+        self.request_internal(Some(sender_id), receiver_id, request)
+            .map_ok(|envelope| envelope.payload)
+    }
+
+    pub fn request_internal<T: RequestMessage>(
+        &self,
+        original_sender_id: Option<ConnectionId>,
+        receiver_id: ConnectionId,
+        request: T,
+    ) -> impl Future<Output = Result<TypedEnvelope<T::Response>>> {
+        let (tx, rx) = oneshot::channel();
+        let send = self.connection_state(receiver_id).and_then(|connection| {
+            let message_id = connection.next_message_id.fetch_add(1, SeqCst);
+            connection
+                .response_channels
+                .lock()
+                .as_mut()
+                .ok_or_else(|| anyhow!("connection was closed"))?
+                .insert(message_id, tx);
+            connection
+                .outgoing_tx
+                .unbounded_send(proto::Message::Envelope(request.into_envelope(
+                    message_id,
+                    None,
+                    original_sender_id.map(Into::into),
+                )))
+                .map_err(|_| anyhow!("connection was closed"))?;
+            Ok(())
+        });
+        async move {
+            send?;
+            let (response, _barrier) = rx.await.map_err(|_| anyhow!("connection was closed"))?;
+
+            if let Some(proto::envelope::Payload::Error(error)) = &response.payload {
+                Err(anyhow!(
+                    "RPC request {} failed - {}",
+                    T::NAME,
+                    error.message
+                ))
+            } else {
+                Ok(TypedEnvelope {
+                    message_id: response.id,
+                    sender_id: receiver_id,
+                    original_sender_id: response.original_sender_id,
+                    payload: T::Response::from_envelope(response)
+                        .ok_or_else(|| anyhow!("received response of the wrong type"))?,
+                })
+            }
+        }
+    }
+
+    pub fn send<T: EnvelopedMessage>(&self, receiver_id: ConnectionId, message: T) -> Result<()> {
+        let connection = self.connection_state(receiver_id)?;
+        let message_id = connection
+            .next_message_id
+            .fetch_add(1, atomic::Ordering::SeqCst);
+        connection
+            .outgoing_tx
+            .unbounded_send(proto::Message::Envelope(
+                message.into_envelope(message_id, None, None),
+            ))?;
+        Ok(())
+    }
+
+    pub fn forward_send<T: EnvelopedMessage>(
+        &self,
+        sender_id: ConnectionId,
+        receiver_id: ConnectionId,
+        message: T,
+    ) -> Result<()> {
+        let connection = self.connection_state(receiver_id)?;
+        let message_id = connection
+            .next_message_id
+            .fetch_add(1, atomic::Ordering::SeqCst);
+        connection
+            .outgoing_tx
+            .unbounded_send(proto::Message::Envelope(message.into_envelope(
+                message_id,
+                None,
+                Some(sender_id.into()),
+            )))?;
+        Ok(())
+    }
+
+    pub fn respond<T: RequestMessage>(
+        &self,
+        receipt: Receipt<T>,
+        response: T::Response,
+    ) -> Result<()> {
+        let connection = self.connection_state(receipt.sender_id)?;
+        let message_id = connection
+            .next_message_id
+            .fetch_add(1, atomic::Ordering::SeqCst);
+        connection
+            .outgoing_tx
+            .unbounded_send(proto::Message::Envelope(response.into_envelope(
+                message_id,
+                Some(receipt.message_id),
+                None,
+            )))?;
+        Ok(())
+    }
+
+    pub fn respond_with_error<T: RequestMessage>(
+        &self,
+        receipt: Receipt<T>,
+        response: proto::Error,
+    ) -> Result<()> {
+        let connection = self.connection_state(receipt.sender_id)?;
+        let message_id = connection
+            .next_message_id
+            .fetch_add(1, atomic::Ordering::SeqCst);
+        connection
+            .outgoing_tx
+            .unbounded_send(proto::Message::Envelope(response.into_envelope(
+                message_id,
+                Some(receipt.message_id),
+                None,
+            )))?;
+        Ok(())
+    }
+
+    pub fn respond_with_unhandled_message(
+        &self,
+        envelope: Box<dyn AnyTypedEnvelope>,
+    ) -> Result<()> {
+        let connection = self.connection_state(envelope.sender_id())?;
+        let response = proto::Error {
+            message: format!("message {} was not handled", envelope.payload_type_name()),
+        };
+        let message_id = connection
+            .next_message_id
+            .fetch_add(1, atomic::Ordering::SeqCst);
+        connection
+            .outgoing_tx
+            .unbounded_send(proto::Message::Envelope(response.into_envelope(
+                message_id,
+                Some(envelope.message_id()),
+                None,
+            )))?;
+        Ok(())
+    }
+
+    fn connection_state(&self, connection_id: ConnectionId) -> Result<ConnectionState> {
+        let connections = self.connections.read();
+        let connection = connections
+            .get(&connection_id)
+            .ok_or_else(|| anyhow!("no such connection: {}", connection_id))?;
+        Ok(connection.clone())
+    }
+}
+
+impl Serialize for Peer {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        let mut state = serializer.serialize_struct("Peer", 2)?;
+        state.serialize_field("connections", &*self.connections.read())?;
+        state.end()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::TypedEnvelope;
+    use async_tungstenite::tungstenite::Message as WebSocketMessage;
+    use gpui::TestAppContext;
+
+    #[ctor::ctor]
+    fn init_logger() {
+        if std::env::var("RUST_LOG").is_ok() {
+            env_logger::init();
+        }
+    }
+
+    #[gpui::test(iterations = 50)]
+    async fn test_request_response(cx: &mut TestAppContext) {
+        let executor = cx.foreground();
+
+        // create 2 clients connected to 1 server
+        let server = Peer::new(0);
+        let client1 = Peer::new(0);
+        let client2 = Peer::new(0);
+
+        let (client1_to_server_conn, server_to_client_1_conn, _kill) =
+            Connection::in_memory(cx.background());
+        let (client1_conn_id, io_task1, client1_incoming) =
+            client1.add_test_connection(client1_to_server_conn, cx.background());
+        let (_, io_task2, server_incoming1) =
+            server.add_test_connection(server_to_client_1_conn, cx.background());
+
+        let (client2_to_server_conn, server_to_client_2_conn, _kill) =
+            Connection::in_memory(cx.background());
+        let (client2_conn_id, io_task3, client2_incoming) =
+            client2.add_test_connection(client2_to_server_conn, cx.background());
+        let (_, io_task4, server_incoming2) =
+            server.add_test_connection(server_to_client_2_conn, cx.background());
+
+        executor.spawn(io_task1).detach();
+        executor.spawn(io_task2).detach();
+        executor.spawn(io_task3).detach();
+        executor.spawn(io_task4).detach();
+        executor
+            .spawn(handle_messages(server_incoming1, server.clone()))
+            .detach();
+        executor
+            .spawn(handle_messages(client1_incoming, client1.clone()))
+            .detach();
+        executor
+            .spawn(handle_messages(server_incoming2, server.clone()))
+            .detach();
+        executor
+            .spawn(handle_messages(client2_incoming, client2.clone()))
+            .detach();
+
+        assert_eq!(
+            client1
+                .request(client1_conn_id, proto::Ping {},)
+                .await
+                .unwrap(),
+            proto::Ack {}
+        );
+
+        assert_eq!(
+            client2
+                .request(client2_conn_id, proto::Ping {},)
+                .await
+                .unwrap(),
+            proto::Ack {}
+        );
+
+        assert_eq!(
+            client1
+                .request(client1_conn_id, proto::Test { id: 1 },)
+                .await
+                .unwrap(),
+            proto::Test { id: 1 }
+        );
+
+        assert_eq!(
+            client2
+                .request(client2_conn_id, proto::Test { id: 2 })
+                .await
+                .unwrap(),
+            proto::Test { id: 2 }
+        );
+
+        client1.disconnect(client1_conn_id);
+        client2.disconnect(client1_conn_id);
+
+        async fn handle_messages(
+            mut messages: BoxStream<'static, Box<dyn AnyTypedEnvelope>>,
+            peer: Arc<Peer>,
+        ) -> Result<()> {
+            while let Some(envelope) = messages.next().await {
+                let envelope = envelope.into_any();
+                if let Some(envelope) = envelope.downcast_ref::<TypedEnvelope<proto::Ping>>() {
+                    let receipt = envelope.receipt();
+                    peer.respond(receipt, proto::Ack {})?
+                } else if let Some(envelope) = envelope.downcast_ref::<TypedEnvelope<proto::Test>>()
+                {
+                    peer.respond(envelope.receipt(), envelope.payload.clone())?
+                } else {
+                    panic!("unknown message type");
+                }
+            }
+
+            Ok(())
+        }
+    }
+
+    #[gpui::test(iterations = 50)]
+    async fn test_order_of_response_and_incoming(cx: &mut TestAppContext) {
+        let executor = cx.foreground();
+        let server = Peer::new(0);
+        let client = Peer::new(0);
+
+        let (client_to_server_conn, server_to_client_conn, _kill) =
+            Connection::in_memory(cx.background());
+        let (client_to_server_conn_id, io_task1, mut client_incoming) =
+            client.add_test_connection(client_to_server_conn, cx.background());
+        let (server_to_client_conn_id, io_task2, mut server_incoming) =
+            server.add_test_connection(server_to_client_conn, cx.background());
+
+        executor.spawn(io_task1).detach();
+        executor.spawn(io_task2).detach();
+
+        executor
+            .spawn(async move {
+                let request = server_incoming
+                    .next()
+                    .await
+                    .unwrap()
+                    .into_any()
+                    .downcast::<TypedEnvelope<proto::Ping>>()
+                    .unwrap();
+
+                server
+                    .send(
+                        server_to_client_conn_id,
+                        proto::Error {
+                            message: "message 1".to_string(),
+                        },
+                    )
+                    .unwrap();
+                server
+                    .send(
+                        server_to_client_conn_id,
+                        proto::Error {
+                            message: "message 2".to_string(),
+                        },
+                    )
+                    .unwrap();
+                server.respond(request.receipt(), proto::Ack {}).unwrap();
+
+                // Prevent the connection from being dropped
+                server_incoming.next().await;
+            })
+            .detach();
+
+        let events = Arc::new(Mutex::new(Vec::new()));
+
+        let response = client.request(client_to_server_conn_id, proto::Ping {});
+        let response_task = executor.spawn({
+            let events = events.clone();
+            async move {
+                response.await.unwrap();
+                events.lock().push("response".to_string());
+            }
+        });
+
+        executor
+            .spawn({
+                let events = events.clone();
+                async move {
+                    let incoming1 = client_incoming
+                        .next()
+                        .await
+                        .unwrap()
+                        .into_any()
+                        .downcast::<TypedEnvelope<proto::Error>>()
+                        .unwrap();
+                    events.lock().push(incoming1.payload.message);
+                    let incoming2 = client_incoming
+                        .next()
+                        .await
+                        .unwrap()
+                        .into_any()
+                        .downcast::<TypedEnvelope<proto::Error>>()
+                        .unwrap();
+                    events.lock().push(incoming2.payload.message);
+
+                    // Prevent the connection from being dropped
+                    client_incoming.next().await;
+                }
+            })
+            .detach();
+
+        response_task.await;
+        assert_eq!(
+            &*events.lock(),
+            &[
+                "message 1".to_string(),
+                "message 2".to_string(),
+                "response".to_string()
+            ]
+        );
+    }
+
+    #[gpui::test(iterations = 50)]
+    async fn test_dropping_request_before_completion(cx: &mut TestAppContext) {
+        let executor = cx.foreground();
+        let server = Peer::new(0);
+        let client = Peer::new(0);
+
+        let (client_to_server_conn, server_to_client_conn, _kill) =
+            Connection::in_memory(cx.background());
+        let (client_to_server_conn_id, io_task1, mut client_incoming) =
+            client.add_test_connection(client_to_server_conn, cx.background());
+        let (server_to_client_conn_id, io_task2, mut server_incoming) =
+            server.add_test_connection(server_to_client_conn, cx.background());
+
+        executor.spawn(io_task1).detach();
+        executor.spawn(io_task2).detach();
+
+        executor
+            .spawn(async move {
+                let request1 = server_incoming
+                    .next()
+                    .await
+                    .unwrap()
+                    .into_any()
+                    .downcast::<TypedEnvelope<proto::Ping>>()
+                    .unwrap();
+                let request2 = server_incoming
+                    .next()
+                    .await
+                    .unwrap()
+                    .into_any()
+                    .downcast::<TypedEnvelope<proto::Ping>>()
+                    .unwrap();
+
+                server
+                    .send(
+                        server_to_client_conn_id,
+                        proto::Error {
+                            message: "message 1".to_string(),
+                        },
+                    )
+                    .unwrap();
+                server
+                    .send(
+                        server_to_client_conn_id,
+                        proto::Error {
+                            message: "message 2".to_string(),
+                        },
+                    )
+                    .unwrap();
+                server.respond(request1.receipt(), proto::Ack {}).unwrap();
+                server.respond(request2.receipt(), proto::Ack {}).unwrap();
+
+                // Prevent the connection from being dropped
+                server_incoming.next().await;
+            })
+            .detach();
+
+        let events = Arc::new(Mutex::new(Vec::new()));
+
+        let request1 = client.request(client_to_server_conn_id, proto::Ping {});
+        let request1_task = executor.spawn(request1);
+        let request2 = client.request(client_to_server_conn_id, proto::Ping {});
+        let request2_task = executor.spawn({
+            let events = events.clone();
+            async move {
+                request2.await.unwrap();
+                events.lock().push("response 2".to_string());
+            }
+        });
+
+        executor
+            .spawn({
+                let events = events.clone();
+                async move {
+                    let incoming1 = client_incoming
+                        .next()
+                        .await
+                        .unwrap()
+                        .into_any()
+                        .downcast::<TypedEnvelope<proto::Error>>()
+                        .unwrap();
+                    events.lock().push(incoming1.payload.message);
+                    let incoming2 = client_incoming
+                        .next()
+                        .await
+                        .unwrap()
+                        .into_any()
+                        .downcast::<TypedEnvelope<proto::Error>>()
+                        .unwrap();
+                    events.lock().push(incoming2.payload.message);
+
+                    // Prevent the connection from being dropped
+                    client_incoming.next().await;
+                }
+            })
+            .detach();
+
+        // Allow the request to make some progress before dropping it.
+        cx.background().simulate_random_delay().await;
+        drop(request1_task);
+
+        request2_task.await;
+        assert_eq!(
+            &*events.lock(),
+            &[
+                "message 1".to_string(),
+                "message 2".to_string(),
+                "response 2".to_string()
+            ]
+        );
+    }
+
+    #[gpui::test(iterations = 50)]
+    async fn test_disconnect(cx: &mut TestAppContext) {
+        let executor = cx.foreground();
+
+        let (client_conn, mut server_conn, _kill) = Connection::in_memory(cx.background());
+
+        let client = Peer::new(0);
+        let (connection_id, io_handler, mut incoming) =
+            client.add_test_connection(client_conn, cx.background());
+
+        let (io_ended_tx, io_ended_rx) = oneshot::channel();
+        executor
+            .spawn(async move {
+                io_handler.await.ok();
+                io_ended_tx.send(()).unwrap();
+            })
+            .detach();
+
+        let (messages_ended_tx, messages_ended_rx) = oneshot::channel();
+        executor
+            .spawn(async move {
+                incoming.next().await;
+                messages_ended_tx.send(()).unwrap();
+            })
+            .detach();
+
+        client.disconnect(connection_id);
+
+        let _ = io_ended_rx.await;
+        let _ = messages_ended_rx.await;
+        assert!(server_conn
+            .send(WebSocketMessage::Binary(vec![]))
+            .await
+            .is_err());
+    }
+
+    #[gpui::test(iterations = 50)]
+    async fn test_io_error(cx: &mut TestAppContext) {
+        let executor = cx.foreground();
+        let (client_conn, mut server_conn, _kill) = Connection::in_memory(cx.background());
+
+        let client = Peer::new(0);
+        let (connection_id, io_handler, mut incoming) =
+            client.add_test_connection(client_conn, cx.background());
+        executor.spawn(io_handler).detach();
+        executor
+            .spawn(async move { incoming.next().await })
+            .detach();
+
+        let response = executor.spawn(client.request(connection_id, proto::Ping {}));
+        let _request = server_conn.rx.next().await.unwrap().unwrap();
+
+        drop(server_conn);
+        assert_eq!(
+            response.await.unwrap_err().to_string(),
+            "connection was closed"
+        );
+    }
+}