1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79

use tower_service::Service;

use std::fmt;
use std::{
    future::Future,
    pin::Pin,
    task::{Context, Poll},
};

/// A boxed `Service` trait object.
pub struct UnsyncBoxService<T, U, E> {
    inner: Box<dyn Service<T, Response = U, Error = E, Future = UnsyncBoxFuture<U, E>>>,
}

/// A boxed `Future` trait object.
///
/// This type alias represents a boxed future that is *not* `Send` and must
/// remain on the current thread.
type UnsyncBoxFuture<T, E> = Pin<Box<dyn Future<Output = Result<T, E>>>>;

#[derive(Debug)]
struct UnsyncBoxed<S> {
    inner: S,
}

impl<T, U, E> UnsyncBoxService<T, U, E> {
    #[allow(missing_docs)]
    pub fn new<S>(inner: S) -> Self
    where
        S: Service<T, Response = U, Error = E> + 'static,
        S::Future: 'static,
    {
        let inner = Box::new(UnsyncBoxed { inner });
        UnsyncBoxService { inner }
    }
}

impl<T, U, E> Service<T> for UnsyncBoxService<T, U, E> {
    type Response = U;
    type Error = E;
    type Future = UnsyncBoxFuture<U, E>;

    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), E>> {
        self.inner.poll_ready(cx)
    }

    fn call(&mut self, request: T) -> UnsyncBoxFuture<U, E> {
        self.inner.call(request)
    }
}

impl<T, U, E> fmt::Debug for UnsyncBoxService<T, U, E>
where
    T: fmt::Debug,
    U: fmt::Debug,
    E: fmt::Debug,
{
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt.debug_struct("UnsyncBoxService").finish()
    }
}

impl<S, Request> Service<Request> for UnsyncBoxed<S>
where
    S: Service<Request> + 'static,
    S::Future: 'static,
{
    type Response = S::Response;
    type Error = S::Error;
    type Future = Pin<Box<dyn Future<Output = Result<S::Response, S::Error>>>>;

    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
        self.inner.poll_ready(cx)
    }

    fn call(&mut self, request: Request) -> Self::Future {
        Box::pin(self.inner.call(request))
    }
}