fix(tonic): Remove Sync requirement for streams (#804)

Cargo.toml

@@ -1,29 +1,24 @@
 [workspace]
 members = [
-    "tonic",
-    "tonic-build",
-    "tonic-health",
-    "tonic-types",
-    "tonic-reflection",
-    "tonic-web",
-
-    # Non-published crates
-    "examples",
-    "interop",
-
-    # Tests
-    "tests/included_service",
-    "tests/same_name",
-    "tests/service_named_service",
-    "tests/wellknown",
-    "tests/wellknown-compiled",
-    "tests/extern_path/uuid",
-    "tests/ambiguous_methods",
-    "tests/extern_path/my_application",
-    "tests/integration_tests",
-    "tests/stream_conflict",
-    "tests/root-crate-path",
-    "tests/compression",
-    "tonic-web/tests/integration"
+  "tonic",
+  "tonic-build",
+  "tonic-health",
+  "tonic-types",
+  "tonic-reflection",
+  "tonic-web", # Non-published crates
+  "examples",
+  "interop", # Tests
+  "tests/included_service",
+  "tests/same_name",
+  "tests/service_named_service",
+  "tests/wellknown",
+  "tests/wellknown-compiled",
+  "tests/extern_path/uuid",
+  "tests/ambiguous_methods",
+  "tests/extern_path/my_application",
+  "tests/integration_tests",
+  "tests/stream_conflict",
+  "tests/root-crate-path",
+  "tests/compression",
+  "tonic-web/tests/integration",
 ]
-

examples/routeguide-tutorial.md

@@ -300,7 +300,7 @@ impl RouteGuide for RouteGuideService {
         unimplemented!()
     }
 
-    type RouteChatStream = Pin<Box<dyn Stream<Item = Result<RouteNote, Status>> + Send + Sync + 'static>>;
+    type RouteChatStream = Pin<Box<dyn Stream<Item = Result<RouteNote, Status>> + Send  + 'static>>;
 
     async fn route_chat(
         &self,
@@ -493,7 +493,7 @@ use std::collections::HashMap;
 
 ```rust
 type RouteChatStream =
-    Pin<Box<dyn Stream<Item = Result<RouteNote, Status>> + Send + Sync + 'static>>;
+    Pin<Box<dyn Stream<Item = Result<RouteNote, Status>> + Send  + 'static>>;
 
 
 async fn route_chat(

examples/src/authentication/server.rs

@@ -8,7 +8,7 @@ use std::pin::Pin;
 use tonic::{metadata::MetadataValue, transport::Server, Request, Response, Status, Streaming};
 
 type EchoResult<T> = Result<Response<T>, Status>;
-type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send + Sync>>;
+type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send>>;
 
 #[derive(Default)]
 pub struct EchoServer;

examples/src/dynamic_load_balance/server.rs

@@ -11,7 +11,7 @@ use tonic::{transport::Server, Request, Response, Status, Streaming};
 use pb::{EchoRequest, EchoResponse};
 
 type EchoResult<T> = Result<Response<T>, Status>;
-type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send + Sync>>;
+type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send>>;
 
 #[derive(Debug)]
 pub struct EchoServer {

examples/src/hyper_warp_multiplex/server.rs

@@ -35,7 +35,7 @@ use echo::{
     EchoRequest, EchoResponse,
 };
 
-type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send + Sync>>;
+type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send>>;
 
 #[derive(Default)]
 pub struct MyGreeter {}

examples/src/load_balance/server.rs

@@ -11,7 +11,7 @@ use tonic::{transport::Server, Request, Response, Status, Streaming};
 use pb::{EchoRequest, EchoResponse};
 
 type EchoResult<T> = Result<Response<T>, Status>;
-type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send + Sync>>;
+type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send>>;
 
 #[derive(Debug)]
 pub struct EchoServer {

examples/src/multiplex/server.rs

@@ -20,7 +20,7 @@ use echo::{
     EchoRequest, EchoResponse,
 };
 
-type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send + Sync>>;
+type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send>>;
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {

examples/src/routeguide/server.rs

@@ -102,8 +102,7 @@ impl RouteGuide for RouteGuideService {
         Ok(Response::new(summary))
     }
 
-    type RouteChatStream =
-        Pin<Box<dyn Stream<Item = Result<RouteNote, Status>> + Send + Sync + 'static>>;
+    type RouteChatStream = Pin<Box<dyn Stream<Item = Result<RouteNote, Status>> + Send + 'static>>;
 
     async fn route_chat(
         &self,

examples/src/streaming/server.rs

@@ -12,7 +12,7 @@ use tonic::{transport::Server, Request, Response, Status, Streaming};
 use pb::{EchoRequest, EchoResponse};
 
 type EchoResult<T> = Result<Response<T>, Status>;
-type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send + Sync>>;
+type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send>>;
 
 #[derive(Debug)]
 pub struct EchoServer {}

examples/src/tls/server.rs

@@ -14,7 +14,7 @@ use tonic::{
 };
 
 type EchoResult<T> = Result<Response<T>, Status>;
-type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send + Sync>>;
+type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send>>;
 
 #[derive(Default)]
 pub struct EchoServer;

examples/src/tls_client_auth/server.rs

@@ -9,7 +9,7 @@ use tonic::transport::{Certificate, Identity, Server, ServerTlsConfig};
 use tonic::{Request, Response, Status};
 
 type EchoResult<T> = Result<Response<T>, Status>;
-type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send + Sync>>;
+type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send>>;
 
 #[derive(Default)]
 pub struct EchoServer;

interop/src/server.rs

@@ -18,9 +18,8 @@ pub struct TestService;
 
 type Result<T> = std::result::Result<Response<T>, Status>;
 type Streaming<T> = Request<tonic::Streaming<T>>;
-type Stream<T> = Pin<
-    Box<dyn futures_core::Stream<Item = std::result::Result<T, Status>> + Send + Sync + 'static>,
->;
+type Stream<T> =
+    Pin<Box<dyn futures_core::Stream<Item = std::result::Result<T, Status>> + Send + 'static>>;
 type BoxFuture<T, E> = Pin<Box<dyn Future<Output = std::result::Result<T, E>> + Send + 'static>>;
 
 #[tonic::async_trait]

tests/compression/src/lib.rs

@@ -69,7 +69,7 @@ impl test_server::Test for Svc {
     }
 
     type CompressOutputServerStreamStream =
-        Pin<Box<dyn Stream<Item = Result<SomeData, Status>> + Send + Sync + 'static>>;
+        Pin<Box<dyn Stream<Item = Result<SomeData, Status>> + Send + 'static>>;
 
     async fn compress_output_server_stream(
         &self,
@@ -110,7 +110,7 @@ impl test_server::Test for Svc {
     }
 
     type CompressInputOutputBidirectionalStreamStream =
-        Pin<Box<dyn Stream<Item = Result<SomeData, Status>> + Send + Sync + 'static>>;
+        Pin<Box<dyn Stream<Item = Result<SomeData, Status>> + Send + 'static>>;
 
     async fn compress_input_output_bidirectional_stream(
         &self,

tests/integration_tests/Cargo.toml

@@ -12,14 +12,15 @@ version = "0.1.0"
 bytes = "1.0"
 futures-util = "0.3"
 prost = "0.9"
+tokio = {version = "1.0", features = ["macros", "rt-multi-thread", "net"]}
 tonic = {path = "../../tonic"}
 
 [dev-dependencies]
+async-stream = "0.3"
 futures = "0.3"
 http = "0.2"
 http-body = "0.4"
 hyper = "0.14"
-tokio = {version = "1.0", features = ["macros", "rt-multi-thread", "net"]}
 tokio-stream = {version = "0.1.5", features = ["net"]}
 tower = {version = "0.4", features = []}
 tower-service = "0.3"

tests/integration_tests/src/lib.rs

@@ -2,3 +2,54 @@ pub mod pb {
     tonic::include_proto!("test");
     tonic::include_proto!("stream");
 }
+
+pub mod mock {
+    use std::{
+        pin::Pin,
+        task::{Context, Poll},
+    };
+
+    use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
+    use tonic::transport::server::Connected;
+
+    #[derive(Debug)]
+    pub struct MockStream(pub tokio::io::DuplexStream);
+
+    impl Connected for MockStream {
+        type ConnectInfo = ();
+
+        /// Create type holding information about the connection.
+        fn connect_info(&self) -> Self::ConnectInfo {}
+    }
+
+    impl AsyncRead for MockStream {
+        fn poll_read(
+            mut self: Pin<&mut Self>,
+            cx: &mut Context<'_>,
+            buf: &mut ReadBuf<'_>,
+        ) -> Poll<std::io::Result<()>> {
+            Pin::new(&mut self.0).poll_read(cx, buf)
+        }
+    }
+
+    impl AsyncWrite for MockStream {
+        fn poll_write(
+            mut self: Pin<&mut Self>,
+            cx: &mut Context<'_>,
+            buf: &[u8],
+        ) -> Poll<std::io::Result<usize>> {
+            Pin::new(&mut self.0).poll_write(cx, buf)
+        }
+
+        fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
+            Pin::new(&mut self.0).poll_flush(cx)
+        }
+
+        fn poll_shutdown(
+            mut self: Pin<&mut Self>,
+            cx: &mut Context<'_>,
+        ) -> Poll<std::io::Result<()>> {
+            Pin::new(&mut self.0).poll_shutdown(cx)
+        }
+    }
+}

tests/integration_tests/tests/status.rs

@@ -1,6 +1,7 @@
 use bytes::Bytes;
 use futures_util::FutureExt;
 use http::Uri;
+use integration_tests::mock::MockStream;
 use integration_tests::pb::{
     test_client, test_server, test_stream_client, test_stream_server, Input, InputStream, Output,
     OutputStream,
@@ -125,9 +126,8 @@ async fn status_with_metadata() {
     jh.await.unwrap();
 }
 
-type Stream<T> = std::pin::Pin<
-    Box<dyn futures::Stream<Item = std::result::Result<T, Status>> + Send + Sync + 'static>,
->;
+type Stream<T> =
+    std::pin::Pin<Box<dyn futures::Stream<Item = std::result::Result<T, Status>> + Send + 'static>>;
 
 #[tokio::test]
 async fn status_from_server_stream() {
@@ -184,7 +184,7 @@ async fn status_from_server_stream_with_source() {
     let channel = Endpoint::try_from("http://[::]:50051")
         .unwrap()
         .connect_with_connector_lazy(tower::service_fn(move |_: Uri| async move {
-            Err::<mock::MockStream, _>(std::io::Error::new(std::io::ErrorKind::Other, "WTF"))
+            Err::<MockStream, _>(std::io::Error::new(std::io::ErrorKind::Other, "WTF"))
         }))
         .unwrap();
 
@@ -201,54 +201,3 @@ fn trace_init() {
         .with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
         .try_init();
 }
-
-mod mock {
-    use std::{
-        pin::Pin,
-        task::{Context, Poll},
-    };
-
-    use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
-    use tonic::transport::server::Connected;
-
-    #[derive(Debug)]
-    pub struct MockStream(pub tokio::io::DuplexStream);
-
-    impl Connected for MockStream {
-        type ConnectInfo = ();
-
-        /// Create type holding information about the connection.
-        fn connect_info(&self) -> Self::ConnectInfo {}
-    }
-
-    impl AsyncRead for MockStream {
-        fn poll_read(
-            mut self: Pin<&mut Self>,
-            cx: &mut Context<'_>,
-            buf: &mut ReadBuf<'_>,
-        ) -> Poll<std::io::Result<()>> {
-            Pin::new(&mut self.0).poll_read(cx, buf)
-        }
-    }
-
-    impl AsyncWrite for MockStream {
-        fn poll_write(
-            mut self: Pin<&mut Self>,
-            cx: &mut Context<'_>,
-            buf: &[u8],
-        ) -> Poll<std::io::Result<usize>> {
-            Pin::new(&mut self.0).poll_write(cx, buf)
-        }
-
-        fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
-            Pin::new(&mut self.0).poll_flush(cx)
-        }
-
-        fn poll_shutdown(
-            mut self: Pin<&mut Self>,
-            cx: &mut Context<'_>,
-        ) -> Poll<std::io::Result<()>> {
-            Pin::new(&mut self.0).poll_shutdown(cx)
-        }
-    }
-}

tests/integration_tests/tests/streams.rs

@@ -0,0 +1,47 @@
+use futures::FutureExt;
+use integration_tests::pb::{test_stream_server, InputStream, OutputStream};
+use tonic::{transport::Server, Request, Response, Status};
+
+type Stream<T> =
+    std::pin::Pin<Box<dyn futures::Stream<Item = std::result::Result<T, Status>> + Send + 'static>>;
+
+#[tokio::test]
+async fn status_from_server_stream_with_source() {
+    struct Svc;
+
+    #[tonic::async_trait]
+    impl test_stream_server::TestStream for Svc {
+        type StreamCallStream = Stream<OutputStream>;
+
+        async fn stream_call(
+            &self,
+            _: Request<InputStream>,
+        ) -> Result<Response<Self::StreamCallStream>, Status> {
+            let s = Unsync(0 as *mut ());
+
+            Ok(Response::new(Box::pin(s) as Self::StreamCallStream))
+        }
+    }
+
+    let svc = test_stream_server::TestStreamServer::new(Svc);
+
+    Server::builder()
+        .add_service(svc)
+        .serve("127.0.0.1:1339".parse().unwrap())
+        .now_or_never();
+}
+
+struct Unsync(*mut ());
+
+unsafe impl Send for Unsync {}
+
+impl futures::Stream for Unsync {
+    type Item = Result<OutputStream, Status>;
+
+    fn poll_next(
+        self: std::pin::Pin<&mut Self>,
+        _cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Option<Self::Item>> {
+        unimplemented!()
+    }
+}

tonic-build/src/client.rs

@@ -57,7 +57,7 @@ pub fn generate<T: Service>(
             impl<T> #service_ident<T>
             where
                 T: tonic::client::GrpcService<tonic::body::BoxBody>,
-                T::ResponseBody: Body + Send + Sync + 'static,
+                T::ResponseBody: Body + Send  + 'static,
                 T::Error: Into<StdError>,
                 <T::ResponseBody as Body>::Error: Into<StdError> + Send,
             {
@@ -203,8 +203,8 @@ fn generate_server_streaming<T: Method>(
                         tonic::Status::new(tonic::Code::Unknown, format!("Service was not ready: {}", e.into()))
             })?;
             let codec = #codec_name::default();
-           let path = http::uri::PathAndQuery::from_static(#path);
-           self.inner.server_streaming(request.into_request(), path, codec).await
+            let path = http::uri::PathAndQuery::from_static(#path);
+            self.inner.server_streaming(request.into_request(), path, codec).await
         }
     }
 }
@@ -255,8 +255,8 @@ fn generate_streaming<T: Method>(
                         tonic::Status::new(tonic::Code::Unknown, format!("Service was not ready: {}", e.into()))
             })?;
             let codec = #codec_name::default();
-           let path = http::uri::PathAndQuery::from_static(#path);
-           self.inner.streaming(request.into_streaming_request(), path, codec).await
+            let path = http::uri::PathAndQuery::from_static(#path);
+            self.inner.streaming(request.into_streaming_request(), path, codec).await
         }
     }
 }

tonic-build/src/server.rs

@@ -115,7 +115,7 @@ pub fn generate<T: Service>(
             impl<T, B> tonic::codegen::Service<http::Request<B>> for #server_service<T>
                 where
                     T: #server_trait,
-                    B: Body + Send + Sync + 'static,
+                    B: Body + Send + 'static,
                     B::Error: Into<StdError> + Send + 'static,
             {
                 type Response = http::Response<tonic::body::BoxBody>;
@@ -232,7 +232,7 @@ fn generate_trait_methods<T: Service>(
 
                 quote! {
                     #stream_doc
-                    type #stream: futures_core::Stream<Item = Result<#res_message, tonic::Status>> + Send + Sync + 'static;
+                    type #stream: futures_core::Stream<Item = Result<#res_message, tonic::Status>> + Send + 'static;
 
                     #method_doc
                     async fn #name(&self, request: tonic::Request<#req_message>)
@@ -248,7 +248,7 @@ fn generate_trait_methods<T: Service>(
 
                 quote! {
                     #stream_doc
-                    type #stream: futures_core::Stream<Item = Result<#res_message, tonic::Status>> + Send + Sync + 'static;
+                    type #stream: futures_core::Stream<Item = Result<#res_message, tonic::Status>> + Send + 'static;
 
                     #method_doc
                     async fn #name(&self, request: tonic::Request<tonic::Streaming<#req_message>>)

tonic-health/src/server.rs

@@ -133,7 +133,7 @@ impl Health for HealthService {
     }
 
     type WatchStream =
-        Pin<Box<dyn Stream<Item = Result<HealthCheckResponse, Status>> + Send + Sync + 'static>>;
+        Pin<Box<dyn Stream<Item = Result<HealthCheckResponse, Status>> + Send + 'static>>;
 
     async fn watch(
         &self,

tonic-web/tests/integration/src/lib.rs

@@ -9,7 +9,7 @@ pub mod pb {
     tonic::include_proto!("test");
 }
 
-type BoxStream<T> = Pin<Box<dyn Stream<Item = Result<T, Status>> + Send + Sync + 'static>>;
+type BoxStream<T> = Pin<Box<dyn Stream<Item = Result<T, Status>> + Send + 'static>>;
 
 pub struct Svc;
 

tonic/Cargo.toml

@@ -55,7 +55,7 @@ http = "0.2"
 tracing = "0.1"
 
 async-stream = "0.3"
-http-body = "0.4.2"
+http-body = "0.4.4"
 percent-encoding = "2.1"
 pin-project = "1.0"
 tokio-util = {version = "0.6", features = ["codec"]}
@@ -71,7 +71,7 @@ async-trait = {version = "0.1.13", optional = true}
 
 # transport
 h2 = {version = "0.3", optional = true}
-hyper = {version = "0.14.2", features = ["full"], optional = true}
+hyper = {version = "0.14.4", features = ["full"], optional = true}
 hyper-timeout = {version = "0.4", optional = true}
 tokio = {version = "1.0.1", features = ["net"], optional = true}
 tokio-stream = "0.1"

tonic/src/body.rs

@@ -3,11 +3,13 @@
 use http_body::Body;
 
 /// A type erased HTTP body used for tonic services.
-pub type BoxBody = http_body::combinators::BoxBody<bytes::Bytes, crate::Status>;
+pub type BoxBody = http_body::combinators::UnsyncBoxBody<bytes::Bytes, crate::Status>;
 
 // this also exists in `crate::codegen` but we need it here since `codegen` has
 // `#[cfg(feature = "codegen")]`.
 /// Create an empty `BoxBody`
 pub fn empty_body() -> BoxBody {
-    http_body::Empty::new().map_err(|err| match err {}).boxed()
+    http_body::Empty::new()
+        .map_err(|err| match err {})
+        .boxed_unsync()
 }

tonic/src/client/grpc.rs

@@ -150,7 +150,7 @@ impl<T> Grpc<T> {
     ) -> Result<Response<M2>, Status>
     where
         T: GrpcService<BoxBody>,
-        T::ResponseBody: Body + Send + Sync + 'static,
+        T::ResponseBody: Body + Send + 'static,
         <T::ResponseBody as Body>::Error: Into<crate::Error>,
         C: Codec<Encode = M1, Decode = M2>,
         M1: Send + Sync + 'static,
@@ -169,9 +169,9 @@ impl<T> Grpc<T> {
     ) -> Result<Response<M2>, Status>
     where
         T: GrpcService<BoxBody>,
-        T::ResponseBody: Body + Send + Sync + 'static,
+        T::ResponseBody: Body + Send + 'static,
         <T::ResponseBody as Body>::Error: Into<crate::Error>,
-        S: Stream<Item = M1> + Send + Sync + 'static,
+        S: Stream<Item = M1> + Send + 'static,
         C: Codec<Encode = M1, Decode = M2>,
         M1: Send + Sync + 'static,
         M2: Send + Sync + 'static,
@@ -206,7 +206,7 @@ impl<T> Grpc<T> {
     ) -> Result<Response<Streaming<M2>>, Status>
     where
         T: GrpcService<BoxBody>,
-        T::ResponseBody: Body + Send + Sync + 'static,
+        T::ResponseBody: Body + Send + 'static,
         <T::ResponseBody as Body>::Error: Into<crate::Error>,
         C: Codec<Encode = M1, Decode = M2>,
         M1: Send + Sync + 'static,
@@ -225,9 +225,9 @@ impl<T> Grpc<T> {
     ) -> Result<Response<Streaming<M2>>, Status>
     where
         T: GrpcService<BoxBody>,
-        T::ResponseBody: Body + Send + Sync + 'static,
+        T::ResponseBody: Body + Send + 'static,
         <T::ResponseBody as Body>::Error: Into<crate::Error>,
-        S: Stream<Item = M1> + Send + Sync + 'static,
+        S: Stream<Item = M1> + Send + 'static,
         C: Codec<Encode = M1, Decode = M2>,
         M1: Send + Sync + 'static,
         M2: Send + Sync + 'static,

tonic/src/codec/decode.rs

@@ -21,7 +21,7 @@ const BUFFER_SIZE: usize = 8 * 1024;
 /// This will wrap some inner [`Body`] and [`Decoder`] and provide an interface
 /// to fetch the message stream and trailing metadata
 pub struct Streaming<T> {
-    decoder: Box<dyn Decoder<Item = T, Error = Status> + Send + Sync + 'static>,
+    decoder: Box<dyn Decoder<Item = T, Error = Status> + Send + 'static>,
     body: BoxBody,
     state: State,
     direction: Direction,
@@ -56,9 +56,9 @@ impl<T> Streaming<T> {
         #[cfg(feature = "compression")] encoding: Option<CompressionEncoding>,
     ) -> Self
     where
-        B: Body + Send + Sync + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error>,
-        D: Decoder<Item = T, Error = Status> + Send + Sync + 'static,
+        D: Decoder<Item = T, Error = Status> + Send + 'static,
     {
         Self::new(
             decoder,
@@ -71,9 +71,9 @@ impl<T> Streaming<T> {
 
     pub(crate) fn new_empty<B, D>(decoder: D, body: B) -> Self
     where
-        B: Body + Send + Sync + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error>,
-        D: Decoder<Item = T, Error = Status> + Send + Sync + 'static,
+        D: Decoder<Item = T, Error = Status> + Send + 'static,
     {
         Self::new(
             decoder,
@@ -91,9 +91,9 @@ impl<T> Streaming<T> {
         #[cfg(feature = "compression")] encoding: Option<CompressionEncoding>,
     ) -> Self
     where
-        B: Body + Send + Sync + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error>,
-        D: Decoder<Item = T, Error = Status> + Send + Sync + 'static,
+        D: Decoder<Item = T, Error = Status> + Send + 'static,
     {
         Self::new(
             decoder,
@@ -111,16 +111,16 @@ impl<T> Streaming<T> {
         #[cfg(feature = "compression")] encoding: Option<CompressionEncoding>,
     ) -> Self
     where
-        B: Body + Send + Sync + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error>,
-        D: Decoder<Item = T, Error = Status> + Send + Sync + 'static,
+        D: Decoder<Item = T, Error = Status> + Send + 'static,
     {
         Self {
             decoder: Box::new(decoder),
             body: body
                 .map_data(|mut buf| buf.copy_to_bytes(buf.remaining()))
                 .map_err(|err| Status::map_error(err.into()))
-                .boxed(),
+                .boxed_unsync(),
             state: State::ReadHeader,
             direction,
             buf: BytesMut::with_capacity(BUFFER_SIZE),
@@ -140,7 +140,7 @@ impl<T> Streaming<T> {
     /// # use std::fmt::Debug;
     /// # async fn next_message_ex<T, D>(mut request: Streaming<T>) -> Result<(), Status>
     /// # where T: Debug,
-    /// # D: Decoder<Item = T, Error = Status> + Send + Sync + 'static,
+    /// # D: Decoder<Item = T, Error = Status> + Send  + 'static,
     /// # {
     /// if let Some(next_message) = request.message().await? {
     ///     println!("{:?}", next_message);
@@ -378,4 +378,4 @@ impl<T> fmt::Debug for Streaming<T> {
 }
 
 #[cfg(test)]
-static_assertions::assert_impl_all!(Streaming<()>: Send, Sync);
+static_assertions::assert_impl_all!(Streaming<()>: Send);

tonic/src/codec/encode.rs

@@ -22,9 +22,8 @@ pub(crate) fn encode_server<T, U>(
     #[cfg(feature = "compression")] compression_override: SingleMessageCompressionOverride,
 ) -> EncodeBody<impl Stream<Item = Result<Bytes, Status>>>
 where
-    T: Encoder<Error = Status> + Send + Sync + 'static,
-    T::Item: Send + Sync,
-    U: Stream<Item = Result<T::Item, Status>> + Send + Sync + 'static,
+    T: Encoder<Error = Status>,
+    U: Stream<Item = Result<T::Item, Status>>,
 {
     let stream = encode(
         encoder,
@@ -45,9 +44,8 @@ pub(crate) fn encode_client<T, U>(
     #[cfg(feature = "compression")] compression_encoding: Option<CompressionEncoding>,
 ) -> EncodeBody<impl Stream<Item = Result<Bytes, Status>>>
 where
-    T: Encoder<Error = Status> + Send + Sync + 'static,
-    T::Item: Send + Sync,
-    U: Stream<Item = T::Item> + Send + Sync + 'static,
+    T: Encoder<Error = Status>,
+    U: Stream<Item = T::Item>,
 {
     let stream = encode(
         encoder,
@@ -157,7 +155,7 @@ pub(crate) struct EncodeBody<S> {
 
 impl<S> EncodeBody<S>
 where
-    S: Stream<Item = Result<Bytes, Status>> + Send + Sync + 'static,
+    S: Stream<Item = Result<Bytes, Status>>,
 {
     pub(crate) fn new_client(inner: S) -> Self {
         Self {

tonic/src/codec/mod.rs

@@ -40,9 +40,9 @@ pub trait Codec: Default {
     type Decode: Send + 'static;
 
     /// The encoder that can encode a message.
-    type Encoder: Encoder<Item = Self::Encode, Error = Status> + Send + Sync + 'static;
+    type Encoder: Encoder<Item = Self::Encode, Error = Status> + Send + 'static;
     /// The encoder that can decode a message.
-    type Decoder: Decoder<Item = Self::Decode, Error = Status> + Send + Sync + 'static;
+    type Decoder: Decoder<Item = Self::Decode, Error = Status> + Send + 'static;
 
     /// Fetch the encoder.
     fn encoder(&mut self) -> Self::Encoder;

tonic/src/codegen.rs

@@ -35,5 +35,7 @@ impl std::fmt::Display for Never {
 impl std::error::Error for Never {}
 
 pub fn empty_body() -> crate::body::BoxBody {
-    http_body::Empty::new().map_err(|err| match err {}).boxed()
+    http_body::Empty::new()
+        .map_err(|err| match err {})
+        .boxed_unsync()
 }

tonic/src/request.rs

@@ -86,7 +86,7 @@ pub trait IntoRequest<T>: sealed::Sealed {
 /// ```
 pub trait IntoStreamingRequest: sealed::Sealed {
     /// The RPC request stream type
-    type Stream: Stream<Item = Self::Message> + Send + Sync + 'static;
+    type Stream: Stream<Item = Self::Message> + Send + 'static;
 
     /// The RPC request type
     type Message;
@@ -357,7 +357,7 @@ impl<T> IntoRequest<T> for Request<T> {
 
 impl<T> IntoStreamingRequest for T
 where
-    T: Stream + Send + Sync + 'static,
+    T: Stream + Send + 'static,
 {
     type Stream = T;
     type Message = T::Item;
@@ -369,7 +369,7 @@ where
 
 impl<T> IntoStreamingRequest for Request<T>
 where
-    T: Stream + Send + Sync + 'static,
+    T: Stream + Send + 'static,
 {
     type Stream = T;
     type Message = T::Item;

tonic/src/server/grpc.rs

@@ -44,7 +44,6 @@ pub struct Grpc<T> {
 impl<T> Grpc<T>
 where
     T: Codec,
-    T::Encode: Sync,
 {
     /// Creates a new gRPC server with the provided [`Codec`].
     pub fn new(codec: T) -> Self {
@@ -173,7 +172,7 @@ where
     ) -> http::Response<BoxBody>
     where
         S: UnaryService<T::Decode, Response = T::Encode>,
-        B: Body + Send + Sync + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error> + Send,
     {
         #[cfg(feature = "compression")]
@@ -221,8 +220,8 @@ where
     ) -> http::Response<BoxBody>
     where
         S: ServerStreamingService<T::Decode, Response = T::Encode>,
-        S::ResponseStream: Send + Sync + 'static,
-        B: Body + Send + Sync + 'static,
+        S::ResponseStream: Send + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error> + Send,
     {
         #[cfg(feature = "compression")]
@@ -265,7 +264,7 @@ where
     ) -> http::Response<BoxBody>
     where
         S: ClientStreamingService<T::Decode, Response = T::Encode>,
-        B: Body + Send + Sync + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error> + Send + 'static,
     {
         #[cfg(feature = "compression")]
@@ -301,8 +300,8 @@ where
     ) -> http::Response<BoxBody>
     where
         S: StreamingService<T::Decode, Response = T::Encode> + Send,
-        S::ResponseStream: Send + Sync + 'static,
-        B: Body + Send + Sync + 'static,
+        S::ResponseStream: Send + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error> + Send,
     {
         #[cfg(feature = "compression")]
@@ -329,7 +328,7 @@ where
         request: http::Request<B>,
     ) -> Result<Request<T::Decode>, Status>
     where
-        B: Body + Send + Sync + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error> + Send,
     {
         #[cfg(feature = "compression")]
@@ -365,7 +364,7 @@ where
         request: http::Request<B>,
     ) -> Result<Request<Streaming<T::Decode>>, Status>
     where
-        B: Body + Send + Sync + 'static,
+        B: Body + Send + 'static,
         B::Error: Into<crate::Error> + Send,
     {
         #[cfg(feature = "compression")]
@@ -388,7 +387,7 @@ where
         #[cfg(feature = "compression")] compression_override: SingleMessageCompressionOverride,
     ) -> http::Response<BoxBody>
     where
-        B: TryStream<Ok = T::Encode, Error = Status> + Send + Sync + 'static,
+        B: TryStream<Ok = T::Encode, Error = Status> + Send + 'static,
     {
         let response = match response {
             Ok(r) => r,

tonic/src/transport/server/mod.rs

@@ -54,7 +54,7 @@ use tower::{
     Service, ServiceBuilder,
 };
 
-type BoxHttpBody = http_body::combinators::BoxBody<Bytes, crate::Error>;
+type BoxHttpBody = http_body::combinators::UnsyncBoxBody<Bytes, crate::Error>;
 type BoxService = tower::util::BoxService<Request<Body>, Response<BoxHttpBody>, crate::Error>;
 type TraceInterceptor = Arc<dyn Fn(&http::Request<()>) -> tracing::Span + Send + Sync + 'static>;
 
@@ -465,7 +465,7 @@ impl<L> Server<L> {
         IO::ConnectInfo: Clone + Send + Sync + 'static,
         IE: Into<crate::Error>,
         F: Future<Output = ()>,
-        ResBody: http_body::Body<Data = Bytes> + Send + Sync + 'static,
+        ResBody: http_body::Body<Data = Bytes> + Send + 'static,
         ResBody::Error: Into<crate::Error>,
     {
         let trace_interceptor = self.trace_interceptor.clone();
@@ -627,7 +627,7 @@ where
             Send + 'static,
         <<L as Layer<Routes<A, B, Request<Body>>>>::Service as Service<Request<Body>>>::Error:
             Into<crate::Error> + Send,
-        ResBody: http_body::Body<Data = Bytes> + Send + Sync + 'static,
+        ResBody: http_body::Body<Data = Bytes> + Send + 'static,
         ResBody::Error: Into<crate::Error>,
     {
         let incoming = TcpIncoming::new(addr, self.server.tcp_nodelay, self.server.tcp_keepalive)
@@ -659,7 +659,7 @@ where
             Send + 'static,
         <<L as Layer<Routes<A, B, Request<Body>>>>::Service as Service<Request<Body>>>::Error:
             Into<crate::Error> + Send,
-        ResBody: http_body::Body<Data = Bytes> + Send + Sync + 'static,
+        ResBody: http_body::Body<Data = Bytes> + Send + 'static,
         ResBody::Error: Into<crate::Error>,
     {
         let incoming = TcpIncoming::new(addr, self.server.tcp_nodelay, self.server.tcp_keepalive)
@@ -688,7 +688,7 @@ where
             Send + 'static,
         <<L as Layer<Routes<A, B, Request<Body>>>>::Service as Service<Request<Body>>>::Error:
             Into<crate::Error> + Send,
-        ResBody: http_body::Body<Data = Bytes> + Send + Sync + 'static,
+        ResBody: http_body::Body<Data = Bytes> + Send + 'static,
         ResBody::Error: Into<crate::Error>,
     {
         self.server
@@ -723,7 +723,7 @@ where
             Send + 'static,
         <<L as Layer<Routes<A, B, Request<Body>>>>::Service as Service<Request<Body>>>::Error:
             Into<crate::Error> + Send,
-        ResBody: http_body::Body<Data = Bytes> + Send + Sync + 'static,
+        ResBody: http_body::Body<Data = Bytes> + Send + 'static,
         ResBody::Error: Into<crate::Error>,
     {
         self.server
@@ -740,7 +740,7 @@ where
             Send + 'static,
         <<L as Layer<Routes<A, B, Request<Body>>>>::Service as Service<Request<Body>>>::Error:
             Into<crate::Error> + Send,
-        ResBody: http_body::Body<Data = Bytes> + Send + Sync + 'static,
+        ResBody: http_body::Body<Data = Bytes> + Send + 'static,
         ResBody::Error: Into<crate::Error>,
     {
         let inner = self.server.layer.layer(self.routes);
@@ -763,7 +763,7 @@ impl<S, ResBody> Service<Request<Body>> for Svc<S>
 where
     S: Service<Request<Body>, Response = Response<ResBody>>,
     S::Error: Into<crate::Error>,
-    ResBody: http_body::Body<Data = Bytes> + Send + Sync + 'static,
+    ResBody: http_body::Body<Data = Bytes> + Send + 'static,
     ResBody::Error: Into<crate::Error>,
 {
     type Response = Response<BoxHttpBody>;
@@ -807,7 +807,7 @@ impl<F, E, ResBody> Future for SvcFuture<F>
 where
     F: Future<Output = Result<Response<ResBody>, E>>,
     E: Into<crate::Error>,
-    ResBody: http_body::Body<Data = Bytes> + Send + Sync + 'static,
+    ResBody: http_body::Body<Data = Bytes> + Send + 'static,
     ResBody::Error: Into<crate::Error>,
 {
     type Output = Result<Response<BoxHttpBody>, crate::Error>;
@@ -817,7 +817,7 @@ where
         let _guard = this.span.enter();
 
         let response: Response<ResBody> = ready!(this.inner.poll(cx)).map_err(Into::into)?;
-        let response = response.map(|body| body.map_err(Into::into).boxed());
+        let response = response.map(|body| body.map_err(Into::into).boxed_unsync());
         Poll::Ready(Ok(response))
     }
 }
@@ -842,7 +842,7 @@ where
     S: Service<Request<Body>, Response = Response<ResBody>> + Clone + Send + 'static,
     S::Future: Send + 'static,
     S::Error: Into<crate::Error> + Send,
-    ResBody: http_body::Body<Data = Bytes> + Send + Sync + 'static,
+    ResBody: http_body::Body<Data = Bytes> + Send + 'static,
     ResBody::Error: Into<crate::Error>,
 {
     type Response = BoxService;