Connection state

[anton-dutov]

By example, some rpc service with persistent connections, typical work is

1. Connect
2. Auth
3. Quering...

At step two we created auth token and bound to socket (all socket's have bounded HashMap, where state saves), how to impl that via Service?

[carllerche]

The rule of thumb is that anything that is socket specific should not be at the Service layer (there are, of course, exceptions). It can be done at the transport layer, which is per socket: https://tokio.rs/docs/going-deeper-tokio/transports/.

That said, it can also be possible to do at the Service layer once NewService returns a future:

impl NewService for MyService {
    fn new_service(&self) -> Self::Future {
        let token = self.token.clone();
        self.proto.new_service()
            .and_then(|s| s.call(Auth(token))
            .and_then(|resp| {
                validate_resp(resp)?
                // return authenticated service
            })
    }
}

[anton-dutov]

So, where are save state between requests?

[carllerche]

If you want to save state between requests, you should use an Rc or Arc somewhere. The "somewhere" depends on the details of what you want the state to be shared across.