feat(server): add Server::serve_service

davidpdrsn · davidpdrsn · commit 4931c8b1ac7e · 2021-05-06T22:29:23.000+02:00
This adds `Server::serve_service` which is a convenience for doing ```rust Server::bind(&addr).serve(make_service_fn(|_| async move { Ok::<_, Infallible>(service_fn(handler)) })); ``` That now becomes ```rust Server::bind(&addr).serve_service(service_fn(handler)); ``` It basically copies [`tower::make::Shared`][] into Hyper so users don't need to add another dependency to do this. Fixes #2154 [`tower::make::Shared`]: https://docs.rs/tower/0.4.7/tower/make/struct.Shared.html
diff --git a/src/server/mod.rs b/src/server/mod.rs
@@ -34,13 +34,8 @@
 //!     // Construct our SocketAddr to listen on...
 //!     let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
 //!
-//!     // And a MakeService to handle each connection...
-//!     let make_service = make_service_fn(|_conn| async {
-//!         Ok::<_, Infallible>(service_fn(handle))
-//!     });
-//!
 //!     // Then bind and serve...
-//!     let server = Server::bind(&addr).serve(make_service);
+//!     let server = Server::bind(&addr).serve_service(service_fn(handle));
 //!
 //!     // And run forever...
 //!     if let Err(e) = server.await {
@@ -51,26 +46,30 @@
 //! # fn main() {}
 //! ```
 //!
-//! If you don't need the connection and your service implements `Clone` you can use
-//! [`tower::make::Shared`] instead of `make_service_fn` which is a bit simpler:
+//! If you need the incoming connection to handle the request you can use [`make_service_fn`] to
+//! create a [`Service`] on demand:
 //!
 //! ```no_run
-//! # use std::convert::Infallible;
-//! # use std::net::SocketAddr;
-//! # use hyper::{Body, Request, Response, Server};
-//! # use hyper::service::{make_service_fn, service_fn};
-//! # use tower::make::Shared;
-//! # async fn handle(_req: Request<Body>) -> Result<Response<Body>, Infallible> {
-//! #     Ok(Response::new(Body::from("Hello World")))
-//! # }
+//! use std::convert::Infallible;
+//! use std::net::SocketAddr;
+//! use hyper::{Body, Request, Response, Server};
+//! use hyper::service::{make_service_fn, service_fn};
+//! use hyper::server::conn::AddrStream;
+//!
+//! async fn handle(_req: Request<Body>) -> Result<Response<Body>, Infallible> {
+//!     Ok(Response::new(Body::from("Hello World")))
+//! }
+//!
 //! # #[cfg(feature = "runtime")]
 //! #[tokio::main]
 //! async fn main() {
 //!     // Construct our SocketAddr to listen on...
 //!     let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
 //!
-//!     // Shared is a MakeService that produces services by cloning an inner service...
-//!     let make_service = Shared::new(service_fn(handle));
+//!     // And a MakeService to handle each connection...
+//!     let make_service = make_service_fn(|conn: &AddrStream| async {
+//!         Ok::<_, Infallible>(service_fn(handle))
+//!     });
 //!
 //!     // Then bind and serve...
 //!     let server = Server::bind(&addr).serve(make_service);
@@ -84,7 +83,9 @@
 //! # fn main() {}
 //! ```
 //!
-//! [`tower::make::Shared`]: https://docs.rs/tower/latest/tower/make/struct.Shared.html
+//! [`make_service_fn`]: crate::service::make_service_fn
+//! [`Server::serve_service`]: crate::server::Server::serve_service
+//! [`Service`]: crate::service::Service
 
 pub mod accept;
 
diff --git a/src/server/server.rs b/src/server/server.rs
@@ -13,7 +13,7 @@ use super::accept::Accept;
 use crate::body::{Body, HttpBody};
 use crate::common::exec::{ConnStreamExec, Exec, NewSvcExec};
 use crate::common::{task, Future, Pin, Poll, Unpin};
-use crate::service::{HttpService, MakeServiceRef};
+use crate::service::{HttpService, MakeServiceRef, Shared, SharedFuture};
 // Renamed `Http` as `Http_` for now so that people upgrading don't see an
 // error that `hyper::server::Http` is private...
 use super::conn::{Http as Http_, NoopWatcher, SpawnAll};
@@ -418,22 +418,65 @@ impl<I, E> Builder<I, E> {
     /// }
     /// # }
     /// ```
-    pub fn serve<S, B>(self, new_service: S) -> Server<I, S, E>
+    pub fn serve<M, B>(self, new_service: M) -> Server<I, M, E>
     where
         I: Accept,
         I::Error: Into<Box<dyn StdError + Send + Sync>>,
         I::Conn: AsyncRead + AsyncWrite + Unpin + Send + 'static,
-        S: MakeServiceRef<I::Conn, Body, ResBody = B>,
-        S::Error: Into<Box<dyn StdError + Send + Sync>>,
+        M: MakeServiceRef<I::Conn, Body, ResBody = B>,
+        M::Error: Into<Box<dyn StdError + Send + Sync>>,
         B: HttpBody + 'static,
         B::Error: Into<Box<dyn StdError + Send + Sync>>,
-        E: NewSvcExec<I::Conn, S::Future, S::Service, E, NoopWatcher>,
-        E: ConnStreamExec<<S::Service as HttpService<Body>>::Future, B>,
+        E: NewSvcExec<I::Conn, M::Future, M::Service, E, NoopWatcher>,
+        E: ConnStreamExec<<M::Service as HttpService<Body>>::Future, B>,
     {
         let serve = self.protocol.serve(self.incoming, new_service);
         let spawn_all = serve.spawn_all();
         Server { spawn_all }
     }
+
+    /// Consume this `Builder`, creating a [`Server`](Server) that will run the given service.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[cfg(feature = "tcp")]
+    /// # async fn run() {
+    /// use hyper::{Body, Error, Response, Server};
+    /// use hyper::service::{make_service_fn, service_fn};
+    ///
+    /// // Construct our SocketAddr to listen on...
+    /// let addr = ([127, 0, 0, 1], 3000).into();
+    ///
+    /// // Our service used to respond to requests...
+    /// let service = service_fn(|_req| async {
+    ///     Ok::<_, Error>(Response::new(Body::from("Hello World")))
+    /// });
+    ///
+    /// // Then bind and serve...
+    /// let server = Server::bind(&addr).serve_service(service);
+    ///
+    /// // Run forever-ish...
+    /// if let Err(err) = server.await {
+    ///     eprintln!("server error: {}", err);
+    /// }
+    /// # }
+    /// ```
+    pub fn serve_service<S, B>(self, service: S) -> Server<I, Shared<S>, E>
+    where
+        S: HttpService<Body, ResBody = B> + Clone,
+        S::Error: Into<Box<dyn StdError + Send + Sync>>,
+        B: HttpBody + 'static,
+        B::Error: Into<Box<dyn StdError + Send + Sync>>,
+        I: Accept,
+        I::Error: Into<Box<dyn StdError + Send + Sync>>,
+        I::Conn: AsyncRead + AsyncWrite + Unpin + Send + 'static,
+        E: NewSvcExec<I::Conn, SharedFuture<S>, S, E, NoopWatcher>,
+        E: ConnStreamExec<S::Future, B>,
+    {
+        let make_service = Shared::new(service);
+        self.serve(make_service)
+    }
 }
 
 #[cfg(feature = "tcp")]
diff --git a/src/service/make.rs b/src/service/make.rs
@@ -1,11 +1,14 @@
+use std::convert::Infallible;
 use std::error::Error as StdError;
 use std::fmt;
 
 use tokio::io::{AsyncRead, AsyncWrite};
 
+use pin_project::pin_project;
+
 use super::{HttpService, Service};
 use crate::body::HttpBody;
-use crate::common::{task, Future, Poll};
+use crate::common::{task, Future, Pin, Poll};
 
 // The same "trait alias" as tower::MakeConnection, but inlined to reduce
 // dependencies.
@@ -174,6 +177,48 @@ impl<F> fmt::Debug for MakeServiceFn<F> {
     }
 }
 
+/// A `MakeService` that produces services by cloning an inner service.
+#[derive(Debug, Clone, Copy)]
+pub struct Shared<S> {
+    svc: S,
+}
+
+impl<S> Shared<S> {
+    pub(crate) fn new(svc: S) -> Self {
+        Self { svc }
+    }
+}
+
+impl<T, S> Service<T> for Shared<S>
+where
+    S: Clone,
+{
+    type Error = Infallible;
+    type Response = S;
+    type Future = SharedFuture<S>;
+
+    fn poll_ready(&mut self, _cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn call(&mut self, _target: T) -> Self::Future {
+        SharedFuture(futures_util::future::ok(self.svc.clone()))
+    }
+}
+
+/// Response future for [`Shared`].
+#[pin_project]
+#[derive(Debug)]
+pub struct SharedFuture<S>(#[pin] futures_util::future::Ready<Result<S, Infallible>>);
+
+impl<S> Future for SharedFuture<S> {
+    type Output = Result<S, Infallible>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        self.project().0.poll(cx)
+    }
+}
+
 mod sealed {
     pub trait Sealed<X> {}
 
diff --git a/src/service/mod.rs b/src/service/mod.rs
@@ -47,7 +47,7 @@ pub(super) use self::http::HttpService;
 #[cfg(all(any(feature = "http1", feature = "http2"), feature = "client"))]
 pub(super) use self::make::MakeConnection;
 #[cfg(all(any(feature = "http1", feature = "http2"), feature = "server"))]
-pub(super) use self::make::MakeServiceRef;
+pub(super) use self::make::{MakeServiceRef, Shared, SharedFuture};
 #[cfg(all(any(feature = "http1", feature = "http2"), feature = "client"))]
 pub(super) use self::oneshot::{oneshot, Oneshot};
 
