hyper/service/
service.rs

1use std::future::Future;
2
3/// An asynchronous function from a `Request` to a `Response`.
4///
5/// The `Service` trait is a simplified interface making it easy to write
6/// network applications in a modular and reusable way, decoupled from the
7/// underlying protocol.
8///
9/// # Functional
10///
11/// A `Service` is a function of a `Request`. It immediately returns a
12/// `Future` representing the eventual completion of processing the
13/// request. The actual request processing may happen at any time in the
14/// future, on any thread or executor. The processing may depend on calling
15/// other services. At some point in the future, the processing will complete,
16/// and the `Future` will resolve to a response or error.
17///
18/// At a high level, the `Service::call` function represents an RPC request. The
19/// `Service` value can be a server or a client.
20pub trait Service<Request> {
21    /// Responses given by the service.
22    type Response;
23
24    /// Errors produced by the service.
25    type Error;
26
27    /// The future response value.
28    type Future: Future<Output = Result<Self::Response, Self::Error>>;
29
30    /// Process the request and return the response asynchronously.
31    /// `call` takes `&self` instead of `mut &self` because:
32    /// - It prepares the way for async fn,
33    ///   since then the future only borrows `&self`, and thus a Service can concurrently handle
34    ///   multiple outstanding requests at once.
35    /// - It's clearer that Services can likely be cloned
36    /// - To share state across clones, you generally need `Arc<Mutex<_>>`
37    ///   That means you're not really using the `&mut self` and could do with a `&self`.
38    /// The discussion on this is here: <https://github.com/hyperium/hyper/issues/3040>
39    fn call(&self, req: Request) -> Self::Future;
40}
41
42impl<Request, S: Service<Request> + ?Sized> Service<Request> for &'_ S {
43    type Response = S::Response;
44    type Error = S::Error;
45    type Future = S::Future;
46
47    #[inline]
48    fn call(&self, req: Request) -> Self::Future {
49        (**self).call(req)
50    }
51}
52
53impl<Request, S: Service<Request> + ?Sized> Service<Request> for &'_ mut S {
54    type Response = S::Response;
55    type Error = S::Error;
56    type Future = S::Future;
57
58    #[inline]
59    fn call(&self, req: Request) -> Self::Future {
60        (**self).call(req)
61    }
62}
63
64impl<Request, S: Service<Request> + ?Sized> Service<Request> for Box<S> {
65    type Response = S::Response;
66    type Error = S::Error;
67    type Future = S::Future;
68
69    #[inline]
70    fn call(&self, req: Request) -> Self::Future {
71        (**self).call(req)
72    }
73}
74
75impl<Request, S: Service<Request> + ?Sized> Service<Request> for std::rc::Rc<S> {
76    type Response = S::Response;
77    type Error = S::Error;
78    type Future = S::Future;
79
80    #[inline]
81    fn call(&self, req: Request) -> Self::Future {
82        (**self).call(req)
83    }
84}
85
86impl<Request, S: Service<Request> + ?Sized> Service<Request> for std::sync::Arc<S> {
87    type Response = S::Response;
88    type Error = S::Error;
89    type Future = S::Future;
90
91    #[inline]
92    fn call(&self, req: Request) -> Self::Future {
93        (**self).call(req)
94    }
95}
hyper/service/service.rs

hyper/service/
service.rs
