Running Rocket inside LocalSet does not work.

[lolhol]

Having this main:

#[post("/request", format = "json", data = "<req>")]
async fn handle_request(
    state: &State<Mutex<RequestFunction>>,
    req: Json<Request>,
) -> String {
    println!("Got Request with value: {:?}", req.0);
    state.lock().unwrap()(req.0)
}

#[tokio::main]
async fn main() {
  let local = LocalSet::new();

  local
        .run_until(async {
            let structure = Arc::new(RwLock::new(Structure::new()));
            
            let request_function = {
                let structure = Arc::clone(&structure);
                Mutex::new(Box::new(move |req: requester::request::Request| {
                    let class_name = req.name_class.clone();
                    let token = req.token.clone();

                    structure
                        .write()
                        .unwrap()
                        .add_request(req, class_name, token); // add request function spawns local.
                }) as RequestFunction)
            };

            rocket::custom(config)
                .manage(request_function)
                .mount("/", routes![handle_request])
                .launch()
                .await
                .unwrap();       
        }).await;
}

and inside Structure struct:

    pub fn add_request(
        &mut self,
        req: Request,
        name: String,
        token: String,
    ) {
      ...
      let req =
            spawn_local(timeout(
                Duration::from_millis(max_time as u64),
                Self::send_request(inst.clone(), req, borrowed_mut.request_time.clone()),
            ));
     ...
    }

When the "handle_request" function is called when a http req comes, rust panics with:

`spawn_local` called from outside of a `task::LocalSet`

pointing to the line (in "add_request" function) that does "spawn_local".

Essentially I am trying to run rocket inside of a LocalSet. I am pretty new to tokio and spawning in general so I am not sure exactly what is going on.

[the10thWiz]

After re-reading your comment - local set doesn't work in nested tasks. You need to create and await the local set in the request handler.

Original:
Rocket is Send, so you should just spawn it with Tokio. spawn_local is worse for performance, so you should only use it if you need to.