tower/util/
boxed_clone_sync.rs

1use super::ServiceExt;
2use futures_util::future::BoxFuture;
3use std::{
4    fmt,
5    task::{Context, Poll},
6};
7use tower_layer::{layer_fn, LayerFn};
8use tower_service::Service;
9
10/// A [`Clone`] + [`Send`] + [`Sync`] boxed [`Service`].
11///
12/// [`BoxCloneSyncService`] turns a service into a trait object, allowing the
13/// response future type to be dynamic, and allowing the service to be cloned and shared.
14///
15/// This is similar to [`BoxCloneService`](super::BoxCloneService) except the resulting
16/// service implements [`Sync`].
17/// ```
18pub struct BoxCloneSyncService<T, U, E>(
19    Box<
20        dyn CloneService<T, Response = U, Error = E, Future = BoxFuture<'static, Result<U, E>>>
21            + Send
22            + Sync,
23    >,
24);
25
26impl<T, U, E> BoxCloneSyncService<T, U, E> {
27    /// Create a new `BoxCloneSyncService`.
28    pub fn new<S>(inner: S) -> Self
29    where
30        S: Service<T, Response = U, Error = E> + Clone + Send + Sync + 'static,
31        S::Future: Send + 'static,
32    {
33        let inner = inner.map_future(|f| Box::pin(f) as _);
34        BoxCloneSyncService(Box::new(inner))
35    }
36
37    /// Returns a [`Layer`] for wrapping a [`Service`] in a [`BoxCloneSyncService`]
38    /// middleware.
39    ///
40    /// [`Layer`]: crate::Layer
41    pub fn layer<S>() -> LayerFn<fn(S) -> Self>
42    where
43        S: Service<T, Response = U, Error = E> + Clone + Send + Sync + 'static,
44        S::Future: Send + 'static,
45    {
46        layer_fn(Self::new)
47    }
48}
49
50impl<T, U, E> Service<T> for BoxCloneSyncService<T, U, E> {
51    type Response = U;
52    type Error = E;
53    type Future = BoxFuture<'static, Result<U, E>>;
54
55    #[inline]
56    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), E>> {
57        self.0.poll_ready(cx)
58    }
59
60    #[inline]
61    fn call(&mut self, request: T) -> Self::Future {
62        self.0.call(request)
63    }
64}
65
66impl<T, U, E> Clone for BoxCloneSyncService<T, U, E> {
67    fn clone(&self) -> Self {
68        Self(self.0.clone_box())
69    }
70}
71
72trait CloneService<R>: Service<R> {
73    fn clone_box(
74        &self,
75    ) -> Box<
76        dyn CloneService<R, Response = Self::Response, Error = Self::Error, Future = Self::Future>
77            + Send
78            + Sync,
79    >;
80}
81
82impl<R, T> CloneService<R> for T
83where
84    T: Service<R> + Send + Sync + Clone + 'static,
85{
86    fn clone_box(
87        &self,
88    ) -> Box<
89        dyn CloneService<R, Response = T::Response, Error = T::Error, Future = T::Future>
90            + Send
91            + Sync,
92    > {
93        Box::new(self.clone())
94    }
95}
96
97impl<T, U, E> fmt::Debug for BoxCloneSyncService<T, U, E> {
98    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
99        fmt.debug_struct("BoxCloneSyncService").finish()
100    }
101}
tower/util/boxed_clone_sync.rs

tower/util/
boxed_clone_sync.rs
