Remove Send bound from ClientHandler trait.

proto/src/server/testing/server.rs

@@ -15,7 +15,7 @@ use crate::core::{FrameReader, FrameWriter, Worker};
 use crate::server::{LoginResponse, ServerRequest, ServerResponse};
 
 /// A handler for a single client connected to the server.
-pub trait ClientHandler: Send {
+pub trait ClientHandler {
   /// Runs this handler against the given incoming stream of requests.
   fn run(
     self,
@@ -44,7 +44,7 @@ pub trait RequestHandler {
 
 /// Blanket implementation of `ClientHandler` for `RequestHandler` types.
 /// Simply handles each incoming request in turn and sends responses back.
-impl<H: RequestHandler + Send> ClientHandler for H {
+impl<H: RequestHandler> ClientHandler for H {
   fn run(
     mut self,
     mut request_rx: mpsc::Receiver<ServerRequest>,
@@ -71,7 +71,7 @@ struct LoginHandler<H> {
   inner: H,
 }
 
-impl<H: ClientHandler + 'static> LoginHandler<H> {
+impl<H: ClientHandler + Send + 'static> LoginHandler<H> {
   fn ipv4_address(&self) -> Ipv4Addr {
     match self.peer_address.ip() {
       IpAddr::V4(ipv4_addr) => ipv4_addr,
@@ -135,7 +135,7 @@ struct GracefulHandler<H> {
   shutdown_rx: watch::Receiver<()>,
 }
 
-impl<H: ClientHandler + 'static> GracefulHandler<H> {
+impl<H: ClientHandler + Send + 'static> GracefulHandler<H> {
   async fn run(mut self) -> anyhow::Result<()> {
     tokio::select!(
       result = self.handler.run() => {
@@ -163,7 +163,7 @@ struct SenderHandler<H> {
   result_tx: mpsc::Sender<anyhow::Result<()>>,
 }
 
-impl<H: ClientHandler + 'static> SenderHandler<H> {
+impl<H: ClientHandler + Send + 'static> SenderHandler<H> {
   async fn run(self) {
     let result = self.handler.run().await;
     let _ = self.result_tx.send(result).await;
@@ -176,7 +176,11 @@ pub struct ServerBuilder<F> {
   factory: F,
 }
 
-impl<F: ClientHandlerFactory> ServerBuilder<F> {
+impl<F> ServerBuilder<F>
+where
+  F: ClientHandlerFactory,
+  <F as ClientHandlerFactory>::Handler: Send,
+{
   /// `handler` will be used to handle incoming connections.
   pub fn new(factory: F) -> Self {
     ServerBuilder { factory }
@@ -258,7 +262,11 @@ impl ServerHandle {
   }
 }
 
-impl<F: ClientHandlerFactory> Server<F> {
+impl<F> Server<F>
+where
+  F: ClientHandlerFactory,
+  <F as ClientHandlerFactory>::Handler: Send,
+{
   /// Returns the address to which this server is bound.
   /// This is always localhost and a random port chosen by the OS.
   pub fn address(&self) -> io::Result<SocketAddr> {