Hands-On Microservices with Rust

Counter

The handler that prints the total quantity of requests also has quite simple implementation, but in this case, we get access to a shared state:

fn counter(req: HttpRequest<State>) -> String {    format!("{}", req.state().0.borrow())}

We use the state method of HttpRequest to get a reference to a State instance. Since the counter value is stored in RefCell, we use the borrow method to get the value from a cell. We implemented all handlers, and now we have to add some middleware that will count every request to the microservice.