feat: Expose recover error service (#2159)

tonic/src/service/mod.rs

@@ -13,3 +13,6 @@ pub use self::layered::{LayerExt, Layered};
 pub use self::router::{Routes, RoutesBuilder};
 #[cfg(feature = "router")]
 pub use axum::{body::Body as AxumBody, Router as AxumRouter};
+
+pub mod recover_error;
+pub use self::recover_error::{RecoverError, RecoverErrorLayer};

tonic/src/transport/server/service/recover_error.rs → tonic/src/service/recover_error.rs

@@ -1,24 +1,50 @@
+//! Middleware which recovers from error.
+
 use std::{
+    fmt,
     future::Future,
     pin::Pin,
     task::{ready, Context, Poll},
 };
 
 use http::Response;
 use pin_project::pin_project;
+use tower_layer::Layer;
 use tower_service::Service;
 
 use crate::Status;
 
+/// Layer which applies the [`RecoverError`] middleware.
+#[derive(Debug, Default, Clone)]
+pub struct RecoverErrorLayer {
+    _priv: (),
+}
+
+impl RecoverErrorLayer {
+    /// Create a new `RecoverErrorLayer`.
+    pub fn new() -> Self {
+        Self { _priv: () }
+    }
+}
+
+impl<S> Layer<S> for RecoverErrorLayer {
+    type Service = RecoverError<S>;
+
+    fn layer(&self, inner: S) -> Self::Service {
+        RecoverError::new(inner)
+    }
+}
+
 /// Middleware that attempts to recover from service errors by turning them into a response built
 /// from the `Status`.
 #[derive(Debug, Clone)]
-pub(crate) struct RecoverError<S> {
+pub struct RecoverError<S> {
     inner: S,
 }
 
 impl<S> RecoverError<S> {
-    pub(crate) fn new(inner: S) -> Self {
+    /// Create a new `RecoverError` middleware.
+    pub fn new(inner: S) -> Self {
         Self { inner }
     }
 }
@@ -43,12 +69,19 @@ where
     }
 }
 
+/// Response future for [`RecoverError`].
 #[pin_project]
-pub(crate) struct ResponseFuture<F> {
+pub struct ResponseFuture<F> {
     #[pin]
     inner: F,
 }
 
+impl<F> fmt::Debug for ResponseFuture<F> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("ResponseFuture").finish()
+    }
+}
+
 impl<F, E, ResBody> Future for ResponseFuture<F>
 where
     F: Future<Output = Result<Response<ResBody>, E>>,
@@ -74,12 +107,19 @@ where
     }
 }
 
+/// Response body for [`RecoverError`].
 #[pin_project]
-pub(crate) struct ResponseBody<B> {
+pub struct ResponseBody<B> {
     #[pin]
     inner: Option<B>,
 }
 
+impl<B> fmt::Debug for ResponseBody<B> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("ResponseBody").finish()
+    }
+}
+
 impl<B> ResponseBody<B> {
     fn full(inner: B) -> Self {
         Self { inner: Some(inner) }

tonic/src/transport/server/mod.rs

@@ -41,9 +41,10 @@ pub use incoming::TcpIncoming;
 #[cfg(feature = "_tls-any")]
 use crate::transport::Error;
 
-use self::service::{ConnectInfoLayer, RecoverError, ServerIo};
+use self::service::{ConnectInfoLayer, ServerIo};
 use super::service::GrpcTimeout;
 use crate::body::Body;
+use crate::service::RecoverErrorLayer;
 use bytes::Bytes;
 use http::{Request, Response};
 use http_body_util::BodyExt;
@@ -1087,7 +1088,7 @@ where
         let trace_interceptor = self.trace_interceptor.clone();
 
         let svc = ServiceBuilder::new()
-            .layer_fn(RecoverError::new)
+            .layer(RecoverErrorLayer::new())
             .option_layer(concurrency_limit.map(ConcurrencyLimitLayer::new))
             .layer_fn(|s| GrpcTimeout::new(s, timeout))
             .service(svc);

tonic/src/transport/server/service/mod.rs

@@ -1,9 +1,6 @@
 mod io;
 pub(crate) use self::io::{ConnectInfoLayer, ServerIo};
 
-mod recover_error;
-pub(crate) use self::recover_error::RecoverError;
-
 #[cfg(feature = "_tls-any")]
 mod tls;
 #[cfg(feature = "_tls-any")]