lunatic::TcpListener accept() blocks ? about lunatic-rs

[pinkforest]

Cool. I was wondering why vanilla spawn_link! worked - thanks for the explanation. I will send a PR around documenting it and maybe example to do multiple listen's

[pinkforest]

.

[bkolobara]

Yes, TcpListener::accept() must block. The call to it will return a TcpStream, so it blocks until a TcpStream is available.

What you want is to concurrently listen on multiple ports in different processes, but you can't use AbstractProcesses for it. AbstractProcesses will handle incoming messages in the handle methods sequentially. This means if you have an infinite loop inside of the handle message, no other message will be handled because the handling of this one never finishes.

If you add a spawn_link! to your example:

impl ProcessRequest<HttpServerCommand> for HttpServer {
    type Response = u32;

    fn handle(state: &mut Self::State, _: HttpServerCommand) -> u32 {
        let _ = spawn_link!(|| {
            loop {
                if let Ok((tcp_stream, _peer)) = state.tcp_listener.accept() {
                    let http = Http::start(tcp_stream, Some("hmmm"));
                }
	    }
        });
    }
}

This means that every time the HttpServer receives a HttpServerCommand it will start a linked sub-process that concurrently listens to new incoming connections.

AbstractProcesses are meant for specific use-cases where you have a process that handles incoming messages in an elegant way. If you are dealing with networking, you are better of just using processes spawned from a function.

[pinkforest]

Done

• #26
• #27

[pinkforest]

I will also add more complete AbstractProcess & Supervisor example later