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docs(service): add example of impl Service (#2209)

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Add `examples/service_struct_impl.rs`, which provides an up-to-date
example of implementing MakeService and Service on custom types.
The `Svc` struct has a Counter, which demonstrates how to instantiate
shared resources in the `MakeSvc` and pass the resource to the
services. Updates the `examples/README.md` and the doc in
`src/service/mod.rs`.

Closes #1691
This commit is contained in:
Thomas
2020-06-15 12:01:04 -07:00
committed by GitHub
parent 0d0d363547
commit 55ba000746
3 changed files with 81 additions and 2 deletions
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2
examples/README.md
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@@ -41,6 +41,8 @@ pretty_env_logger = "0.4"
* [`send_file`](send_file.rs) - A server that sends back content of files using tokio-util to read the files asynchronously. * [`send_file`](send_file.rs) - A server that sends back content of files using tokio-util to read the files asynchronously.
* [`service_struct_impl`](service_struct_impl.rs) - A struct that manually implements the `Service` trait and uses a shared counter across requests.
* [`single_threaded`](single_threaded.rs) - A server only running on 1 thread, so it can make use of `!Send` app state (like an `Rc` counter). * [`single_threaded`](single_threaded.rs) - A server only running on 1 thread, so it can make use of `!Send` app state (like an `Rc` counter).
* [`state`](state.rs) - A webserver showing basic state sharing among requests. A counter is shared, incremented for every request, and every response is sent the last count. * [`state`](state.rs) - A webserver showing basic state sharing among requests. A counter is shared, incremented for every request, and every response is sent the last count.

76
examples/service_struct_impl.rs Normal file
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@@ -0,0 +1,76 @@
use hyper::service::Service;
use hyper::{Body, Request, Response, Server};
use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll};
type Counter = i32;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
let addr = ([127, 0, 0, 1], 3000).into();
let server = Server::bind(&addr).serve(MakeSvc { counter: 81818 });
println!("Listening on http://{}", addr);
server.await?;
Ok(())
}
struct Svc {
counter: Counter,
}
impl Service<Request<Body>> for Svc {
type Response = Response<Body>;
type Error = hyper::Error;
type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;
fn poll_ready(&mut self, _: &mut Context) -> Poll<Result<(), Self::Error>> {
Poll::Ready(Ok(()))
}
fn call(&mut self, req: Request<Body>) -> Self::Future {
fn mk_response(s: String) -> Result<Response<Body>, hyper::Error> {
Ok(Response::builder().body(Body::from(s)).unwrap())
}
let res = match req.uri().path() {
"/" => mk_response(format!("home! counter = {:?}", self.counter)),
"/posts" => mk_response(format!("posts, of course! counter = {:?}", self.counter)),
"/authors" => mk_response(format!(
"authors extraordinare! counter = {:?}",
self.counter
)),
// Return the 404 Not Found for other routes, and don't increment counter.
_ => return Box::pin(async { mk_response("oh no! not found".into()) }),
};
if req.uri().path() != "/favicon.ico" {
self.counter += 1;
}
Box::pin(async { res })
}
}
struct MakeSvc {
counter: Counter,
}
impl<T> Service<T> for MakeSvc {
type Response = Svc;
type Error = hyper::Error;
type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;
fn poll_ready(&mut self, _: &mut Context) -> Poll<Result<(), Self::Error>> {
Poll::Ready(Ok(()))
}
fn call(&mut self, _: T) -> Self::Future {
let counter = self.counter.clone();
let fut = async move { Ok(Svc { counter }) };
Box::pin(fut)
}
}

5
src/service/mod.rs
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@@ -21,8 +21,9 @@
//! to a single connection. It defines how to respond to **all** requests that //! to a single connection. It defines how to respond to **all** requests that
//! connection will receive. //! connection will receive.
//! //!
//! While it's possible to implement `Service` for a type manually, the helper //! The helper [`service_fn`](service_fn) should be sufficient for most cases, but
//! [`service_fn`](service_fn) should be sufficient for most cases. //! if you need to implement `Service` for a type manually, you can follow the example
//! in `service_struct_impl.rs`.
//! //!
//! # MakeService //! # MakeService
//! //!