Files
hyper/src/service/service.rs
2019-08-21 11:58:02 -07:00

128 lines
3.6 KiB
Rust

use std::error::Error as StdError;
use std::fmt;
use std::marker::PhantomData;
use crate::body::Payload;
use crate::common::{Future, Poll, task};
use crate::{Request, Response};
/// An asynchronous function from `Request` to `Response`.
pub trait Service<ReqBody>: sealed::Sealed<ReqBody> {
/// The `Payload` body of the `http::Response`.
type ResBody: Payload;
/// The error type that can occur within this `Service`.
///
/// Note: Returning an `Error` to a hyper server will cause the connection
/// to be abruptly aborted. In most cases, it is better to return a `Response`
/// with a 4xx or 5xx status code.
type Error: Into<Box<dyn StdError + Send + Sync>>;
/// The `Future` returned by this `Service`.
type Future: Future<Output=Result<Response<Self::ResBody>, Self::Error>>;
/// Returns `Ready` when the service is able to process requests.
///
/// The implementation of this method is allowed to return a `Ready` even if
/// the service is not ready to process. In this case, the future returned
/// from `call` will resolve to an error.
fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>>;
/// Calls this `Service` with a request, returning a `Future` of the response.
fn call(&mut self, req: Request<ReqBody>) -> Self::Future;
}
impl<T, B1, B2> Service<B1> for T
where
T: tower_service::Service<Request<B1>, Response = Response<B2>>,
B2: Payload,
T::Error: Into<Box<dyn StdError + Send + Sync>>,
{
type ResBody = B2;
type Error = T::Error;
type Future = T::Future;
fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
tower_service::Service::poll_ready(self, cx)
}
fn call(&mut self, req: Request<B1>) -> Self::Future {
tower_service::Service::call(self, req)
}
}
impl<T, B1, B2> sealed::Sealed<B1> for T
where
T: tower_service::Service<Request<B1>, Response = Response<B2>>,
B2: Payload,
{}
mod sealed {
pub trait Sealed<T> {}
}
/// Create a `Service` from a function.
///
/// # Example
///
/// ```rust
/// use hyper::{Body, Request, Response, Version};
/// use hyper::service::service_fn;
///
/// let service = service_fn(|req: Request<Body>| async move{
/// if req.version() == Version::HTTP_11 {
/// Ok(Response::new(Body::from("Hello World")))
/// } else {
/// // Note: it's usually better to return a Response
/// // with an appropriate StatusCode instead of an Err.
/// Err("not HTTP/1.1, abort connection")
/// }
/// });
/// ```
pub fn service_fn<F, R, S>(f: F) -> ServiceFn<F, R>
where
F: FnMut(Request<R>) -> S,
S: Future,
{
ServiceFn {
f,
_req: PhantomData,
}
}
// Not exported from crate as this will likely be replaced with `impl Service`.
pub struct ServiceFn<F, R> {
f: F,
_req: PhantomData<fn(R)>,
}
impl<F, ReqBody, Ret, ResBody, E> tower_service::Service<crate::Request<ReqBody>> for ServiceFn<F, ReqBody>
where
F: FnMut(Request<ReqBody>) -> Ret,
ReqBody: Payload,
Ret: Future<Output=Result<Response<ResBody>, E>>,
E: Into<Box<dyn StdError + Send + Sync>>,
ResBody: Payload,
{
type Response = crate::Response<ResBody>;
type Error = E;
type Future = Ret;
fn poll_ready(&mut self, _cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
Poll::Ready(Ok(()))
}
fn call(&mut self, req: Request<ReqBody>) -> Self::Future {
(self.f)(req)
}
}
impl<F, R> fmt::Debug for ServiceFn<F, R> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("impl Service")
.finish()
}
}