tower_util/boxed/
sync.rs

1use tower_service::Service;
2
3use std::fmt;
4use std::{
5    future::Future,
6    pin::Pin,
7    task::{Context, Poll},
8};
9
10/// A boxed `Service + Send` trait object.
11///
12/// `BoxService` turns a service into a trait object, allowing the response
13/// future type to be dynamic. This type requires both the service and the
14/// response future to be `Send`.
15///
16/// See module level documentation for more details.
17pub struct BoxService<T, U, E> {
18    inner: Box<dyn Service<T, Response = U, Error = E, Future = BoxFuture<U, E>> + Send>,
19}
20
21/// A boxed `Future + Send` trait object.
22///
23/// This type alias represents a boxed future that is `Send` and can be moved
24/// across threads.
25type BoxFuture<T, E> = Pin<Box<dyn Future<Output = Result<T, E>> + Send>>;
26
27#[derive(Debug)]
28struct Boxed<S> {
29    inner: S,
30}
31
32impl<T, U, E> BoxService<T, U, E> {
33    #[allow(missing_docs)]
34    pub fn new<S>(inner: S) -> Self
35    where
36        S: Service<T, Response = U, Error = E> + Send + 'static,
37        S::Future: Send + 'static,
38    {
39        let inner = Box::new(Boxed { inner });
40        BoxService { inner }
41    }
42}
43
44impl<T, U, E> Service<T> for BoxService<T, U, E> {
45    type Response = U;
46    type Error = E;
47    type Future = BoxFuture<U, E>;
48
49    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), E>> {
50        self.inner.poll_ready(cx)
51    }
52
53    fn call(&mut self, request: T) -> BoxFuture<U, E> {
54        self.inner.call(request)
55    }
56}
57
58impl<T, U, E> fmt::Debug for BoxService<T, U, E>
59where
60    T: fmt::Debug,
61    U: fmt::Debug,
62    E: fmt::Debug,
63{
64    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
65        fmt.debug_struct("BoxService").finish()
66    }
67}
68
69impl<S, Request> Service<Request> for Boxed<S>
70where
71    S: Service<Request> + 'static,
72    S::Future: Send + 'static,
73{
74    type Response = S::Response;
75    type Error = S::Error;
76    type Future = Pin<Box<dyn Future<Output = Result<S::Response, S::Error>> + Send>>;
77
78    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
79        self.inner.poll_ready(cx)
80    }
81
82    fn call(&mut self, request: Request) -> Self::Future {
83        Box::pin(self.inner.call(request))
84    }
85}
tower_util/boxed/sync.rs

tower_util/boxed/
sync.rs
