Rate Limiting in hyper 1.0

[dbgilley]

Hello,

I'm trying to upgrade a server from version 0.14.20 to version 1.2.0, and I'm running into some issues. The server uses tower middleware, and I'm having problems updating it. I've read the server middleware page of the Hyper docs, but that pattern (creating the middleware stack within the handler loop) doesn't look viable for middlewares which need to maintain state.

I've also tried creating the middlware stack outside of the loop and cloning it on each iteration (example below), but I'm stymied by the fact that tower::limit::RateLimit doesn't implement Clone.

let listener = TcpListener::bind(addr).await?;

let svc = tower::ServiceBuilder::new()
    .concurrency_limit(10) // Implements Clone: uses an Arc<Semaphore> internally
    .rate_limit(5, Duration::from_secs(1)) // Does not implement Clone
    .service_fn(|req: Type| /* do some work that takes a long time */);
let svc = hyper_util::service::TowerToHyperService(svc);

loop {
    let stream = listener.accept().await.map(|(stream, _)| TokioIo::new(stream))?;
    tokio::spawn({
        let svc = svc.clone(); // Error: Clone is not implemented
        async {
             let _ = hyper::server::conn::http2::Builder::new(TokioExecutor::new())
                .serve_connection(stream, svc.clone())
                .await;
        }
    });
}

What is the recommended path forward here? Is there a way to make tower::limit::RateLimit work with hyper 1.0, or is the recommendation to simply not use it and either switch over to some kind of other rate limiter or write our own rate limiter that is Cloneable?