Rust hyper HTTP(S) server to read/write arbitrary amount of bytes

Question

I'm looking to build a basic HTTP(S) server using rust hyper, with the purpose of throughput measurement. Essentially it has two functions

on GET request, send an infinite (or arbitrary large) stream of bytes.
on POST, discard all incoming bytes, then send a short acknowledgement.

I have this working for HTTP using std::net, but would like to add it to hyper to be able to measure HTTP and HTTPS. Being fairly new to rust, I am wondering how to add it to the hyper HTTPS example server - that is, how I can get the response builder to expose a stream (io::stream?) I can write a static buffer of random bytes to, without building the entire response body in memory.

Essentially, I would like to go

    loop {
        match stream.write(rand_bytes) {
            Ok(_) => {},
            Err(_) => break,
        }
    }

here

async fn echo(req: Request<Body>) -> Result<Response<Body>, hyper::Error> {
    let mut response = Response::new(Body::empty());
    match (req.method(), req.uri().path()) {
        // Help route.
        (&Method::GET, "/") => {
            *response.body_mut() = Body::from("I want to be a stream.\n");
        }
...

I see that I could wrap a futures stream using wrap_stream, so maybe my question is how to define a stream iterator that I can use in wrap_stream which returns the same bytes over and over again.

You can have an infinitely repeating iterator with [`std::iter::repeat`](https://doc.rust-lang.org/stable/std/iter/fn.repeat.html) and turn an iterator into a stream with [`futures::stream::iter`](https://docs.rs/futures/latest/futures/stream/fn.iter.html). I haven't tried, but that should work with `wrap_stream`? — Caesar, Feb 14 '22 at 12:56
Thank you. This worked: `let infstream: futures::stream::Iter>> = stream::iter(std::iter::repeat(Ok(rand_string)));` and `*response.body_mut() = Body::wrap_stream(infstream);` I'll just leave the question open for a little longer while I confirm the memory requirements. — relet, Feb 14 '22 at 13:30

score 0 · Answer 1 · answered Feb 19 '22 at 10:00

Thanks to the comment from Caesar above, the following snippet worked for me:

let infstream: futures::stream::Iter<std::iter::Repeat<Result<String, String>>> = stream::iter(std::iter::repeat(Ok(rand_string))); 
*response.body_mut() = Body::wrap_stream(infstream);

This does not implement any termination criteria, but it could easily be modified to return a fixed number of bytes.

Rust hyper HTTP(S) server to read/write arbitrary amount of bytes

1 Answers1