概览
Motore 是一个使用了 GAT 和 TAIT 特性的中间件抽象层。
基于 Motore,我们编写了一些模块化并且可复用的,用来编写 client 和 server 的组件。
Motore 深受Tower
启发。
Motore 使用 GAT 和 TAIT 来减轻编写异步代码的精神负担,尤其是为了避免 Box
的开销而导致的负担,以减少使用者的焦虑。
Motore 最核心的抽象是 Service
trait:
pub trait Service<Cx, Request> {
/// Responses given by the service.
type Response;
/// Errors produced by the service.
type Error;
/// The future response value.
type Future<'cx>: Future<Output = Result<Self::Response, Self::Error>> + Send + 'cx
where
Cx: 'cx,
Self: 'cx;
/// Process the request and return the response asynchronously.
fn call<'cx, 's>(&'s mut self, cx: &'cx mut Cx, req: Request) -> Self::Future<'cx>
where
's: 'cx;
}
快速上手
通过将 GAT 和 TAIT 组合在一起,我们可以以非常简洁易读的方式编写异步代码:
pub struct Timeout<S> {
inner: S,
duration: Duration,
}
impl<Cx, Req, S> Service<Cx, Req> for Timeout<S>
where
Req: 'static + Send,
S: Service<Cx, Req> + 'static + Send,
Cx: 'static + Send,
S::Error: Send + Sync + Into<BoxError>,
{
type Response = S::Response;
type Error = BoxError;
type Future<'cx> = impl Future<Output = Result<S::Response, Self::Error>> + 'cx;
fn call<'cx, 's>(&'s mut self, cx: &'cx mut Cx, req: Req) -> Self::Future<'cx>
where
's: 'cx,
{
async move {
let sleep = tokio::time::sleep(self.duration);
tokio::select! {
r = self.inner.call(cx, req) => {
r.map_err(Into::into)
},
_ = sleep => Err(std::io::Error::new(std::io::ErrorKind::TimedOut, "service time out").into()),
}
}
}
}
我们还提供了#[motore::service]
宏以使编写 Service
更加像编写原生异步 Rust:
use motore::service;
pub struct S<I> {
inner: I,
}
#[service]
impl<Cx, Req, I> Service<Cx, Req> for S<I>
where
Req: Send + 'static,
I: Service<Cx, Req> + Send + 'static,
Cx: Send + 'static,
{
async fn call(&mut self, cx: &mut Cx, req: Req) -> Result<I::Response, I::Error> {
self.inner.call(cx, req).await
}
}
最后修改
July 3, 2023
: Update _index.md (f1d978d)