feat(body): update Body trait to use Frames

The `Body` trait was adjusted to be forwards compatible with adding new
frame types. That resulted in changing from `poll_data` and `poll_trailers`
to a single `poll_frame` function. More can be learned from the proposal
in #2840.

BREAKING CHANGE: The polling functions of the `Body` trait have been
  redesigned.

  The free functions `hyper::body::to_bytes` and `aggregate` have been
  removed. Similar functionality is on
  `http_body_util::BodyExt::collect`.

examples/client.rs

@@ -3,8 +3,8 @@
 use std::env;
 
 use bytes::Bytes;
-use http_body_util::Empty;
-use hyper::{body::Body as _, Request};
+use http_body_util::{BodyExt, Empty};
+use hyper::Request;
 use tokio::io::{self, AsyncWriteExt as _};
 use tokio::net::TcpStream;
 
@@ -62,9 +62,11 @@ async fn fetch_url(url: hyper::Uri) -> Result<()> {
 
     // Stream the body, writing each chunk to stdout as we get it
     // (instead of buffering and printing at the end).
-    while let Some(next) = res.data().await {
-        let chunk = next?;
-        io::stdout().write_all(&chunk).await?;
+    while let Some(next) = res.frame().await {
+        let frame = next?;
+        if let Some(chunk) = frame.data_ref() {
+            io::stdout().write_all(&chunk).await?;
+        }
     }
 
     println!("\n\nDone!");

examples/client_json.rs

@@ -2,7 +2,7 @@
 #![warn(rust_2018_idioms)]
 
 use bytes::Bytes;
-use http_body_util::Empty;
+use http_body_util::{BodyExt, Empty};
 use hyper::{body::Buf, Request};
 use serde::Deserialize;
 use tokio::net::TcpStream;
@@ -48,7 +48,7 @@ async fn fetch_json(url: hyper::Uri) -> Result<Vec<User>> {
     let res = sender.send_request(req).await?;
 
     // asynchronously aggregate the chunks of the body
-    let body = hyper::body::aggregate(res).await?;
+    let body = res.collect().await?.aggregate();
 
     // try to parse as json with serde_json
     let users = serde_json::from_reader(body.reader())?;

examples/echo.rs

@@ -50,7 +50,7 @@ async fn echo(req: Request<Recv>) -> Result<Response<BoxBody<Bytes, hyper::Error
                 return Ok(resp);
             }
 
-            let whole_body = hyper::body::to_bytes(req.into_body()).await?;
+            let whole_body = req.collect().await?.to_bytes();
 
             let reversed_body = whole_body.iter().rev().cloned().collect::<Vec<u8>>();
             Ok(Response::new(full(reversed_body)))

examples/params.rs

@@ -25,7 +25,7 @@ async fn param_example(
         (&Method::GET, "/") | (&Method::GET, "/post") => Ok(Response::new(full(INDEX))),
         (&Method::POST, "/post") => {
             // Concatenate the body...
-            let b = hyper::body::to_bytes(req).await?;
+            let b = req.collect().await?.to_bytes();
             // Parse the request body. form_urlencoded::parse
             // always succeeds, but in general parsing may
             // fail (for example, an invalid post of json), so

examples/single_threaded.rs

@@ -6,8 +6,7 @@ use std::net::SocketAddr;
 use std::rc::Rc;
 use tokio::net::TcpListener;
 
-use hyper::body::{Body as HttpBody, Bytes};
-use hyper::header::{HeaderMap, HeaderValue};
+use hyper::body::{Body as HttpBody, Bytes, Frame};
 use hyper::service::service_fn;
 use hyper::{Error, Response};
 use std::marker::PhantomData;
@@ -33,18 +32,11 @@ impl HttpBody for Body {
     type Data = Bytes;
     type Error = Error;
 
-    fn poll_data(
+    fn poll_frame(
         self: Pin<&mut Self>,
         _: &mut Context<'_>,
-    ) -> Poll<Option<Result<Self::Data, Self::Error>>> {
-        Poll::Ready(self.get_mut().data.take().map(Ok))
-    }
-
-    fn poll_trailers(
-        self: Pin<&mut Self>,
-        _: &mut Context<'_>,
-    ) -> Poll<Result<Option<HeaderMap<HeaderValue>>, Self::Error>> {
-        Poll::Ready(Ok(None))
+    ) -> Poll<Option<Result<Frame<Self::Data>, Self::Error>>> {
+        Poll::Ready(self.get_mut().data.take().map(|d| Ok(Frame::data(d))))
     }
 }
 

examples/web_api.rs

@@ -48,7 +48,7 @@ async fn client_request_response() -> Result<Response<BoxBody>> {
 
 async fn api_post_response(req: Request<Recv>) -> Result<Response<BoxBody>> {
     // Aggregate the body...
-    let whole_body = hyper::body::aggregate(req).await?;
+    let whole_body = req.collect().await?.aggregate();
     // Decode as JSON...
     let mut data: serde_json::Value = serde_json::from_reader(whole_body.reader())?;
     // Change the JSON...

src/body/body.rs

@@ -3,9 +3,9 @@ use std::fmt;
 use bytes::Bytes;
 use futures_channel::mpsc;
 use futures_channel::oneshot;
-use futures_core::Stream; // for mpsc::Receiver
+use futures_core::{FusedStream, Stream}; // for mpsc::Receiver
 use http::HeaderMap;
-use http_body::{Body, SizeHint};
+use http_body::{Body, Frame, SizeHint};
 
 use super::DecodedLength;
 use crate::common::Future;
@@ -39,8 +39,9 @@ enum Kind {
     },
     #[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
     H2 {
-        ping: ping::Recorder,
         content_length: DecodedLength,
+        data_done: bool,
+        ping: ping::Recorder,
         recv: h2::RecvStream,
     },
     #[cfg(feature = "ffi")]
@@ -131,6 +132,7 @@ impl Recv {
             content_length = DecodedLength::ZERO;
         }
         let body = Recv::new(Kind::H2 {
+            data_done: false,
             ping,
             content_length,
             recv,
@@ -153,86 +155,78 @@ impl Recv {
             _ => unreachable!(),
         }
     }
+}
+
+impl Body for Recv {
+    type Data = Bytes;
+    type Error = crate::Error;
 
-    fn poll_inner(&mut self, cx: &mut task::Context<'_>) -> Poll<Option<crate::Result<Bytes>>> {
+    fn poll_frame(
+        mut self: Pin<&mut Self>,
+        cx: &mut task::Context<'_>,
+    ) -> Poll<Option<Result<Frame<Self::Data>, Self::Error>>> {
         match self.kind {
             Kind::Empty => Poll::Ready(None),
             Kind::Chan {
                 content_length: ref mut len,
                 ref mut data_rx,
                 ref mut want_tx,
-                ..
+                ref mut trailers_rx,
             } => {
                 want_tx.send(WANT_READY);
 
-                match ready!(Pin::new(data_rx).poll_next(cx)?) {
-                    Some(chunk) => {
-                        len.sub_if(chunk.len() as u64);
-                        Poll::Ready(Some(Ok(chunk)))
+                if !data_rx.is_terminated() {
+                    match ready!(Pin::new(data_rx).poll_next(cx)?) {
+                        Some(chunk) => {
+                            len.sub_if(chunk.len() as u64);
+                            return Poll::Ready(Some(Ok(Frame::data(chunk))));
+                        }
+                        // fall through to trailers
+                        None => (),
                     }
-                    None => Poll::Ready(None),
+                }
+
+                // check trailers after data is terminated
+                match ready!(Pin::new(trailers_rx).poll(cx)) {
+                    Ok(t) => Poll::Ready(Some(Ok(Frame::trailers(t)))),
+                    Err(_) => Poll::Ready(None),
                 }
             }
             #[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
             Kind::H2 {
+                ref mut data_done,
                 ref ping,
                 recv: ref mut h2,
                 content_length: ref mut len,
-            } => match ready!(h2.poll_data(cx)) {
-                Some(Ok(bytes)) => {
-                    let _ = h2.flow_control().release_capacity(bytes.len());
-                    len.sub_if(bytes.len() as u64);
-                    ping.record_data(bytes.len());
-                    Poll::Ready(Some(Ok(bytes)))
+            } => {
+                if !*data_done {
+                    match ready!(h2.poll_data(cx)) {
+                        Some(Ok(bytes)) => {
+                            let _ = h2.flow_control().release_capacity(bytes.len());
+                            len.sub_if(bytes.len() as u64);
+                            ping.record_data(bytes.len());
+                            return Poll::Ready(Some(Ok(Frame::data(bytes))));
+                        }
+                        Some(Err(e)) => return Poll::Ready(Some(Err(crate::Error::new_body(e)))),
+                        None => {
+                            *data_done = true;
+                            // fall through to trailers
+                        }
+                    }
                 }
-                Some(Err(e)) => Poll::Ready(Some(Err(crate::Error::new_body(e)))),
-                None => Poll::Ready(None),
-            },
-
-            #[cfg(feature = "ffi")]
-            Kind::Ffi(ref mut body) => body.poll_data(cx),
-        }
-    }
-}
 
-impl Body for Recv {
-    type Data = Bytes;
-    type Error = crate::Error;
-
-    fn poll_data(
-        mut self: Pin<&mut Self>,
-        cx: &mut task::Context<'_>,
-    ) -> Poll<Option<Result<Self::Data, Self::Error>>> {
-        self.poll_inner(cx)
-    }
-
-    fn poll_trailers(
-        #[cfg_attr(not(feature = "http2"), allow(unused_mut))] mut self: Pin<&mut Self>,
-        #[cfg_attr(not(feature = "http2"), allow(unused))] cx: &mut task::Context<'_>,
-    ) -> Poll<Result<Option<HeaderMap>, Self::Error>> {
-        match self.kind {
-            Kind::Empty => Poll::Ready(Ok(None)),
-            #[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
-            Kind::H2 {
-                recv: ref mut h2,
-                ref ping,
-                ..
-            } => match ready!(h2.poll_trailers(cx)) {
-                Ok(t) => {
-                    ping.record_non_data();
-                    Poll::Ready(Ok(t))
+                // after data, check trailers
+                match ready!(h2.poll_trailers(cx)) {
+                    Ok(t) => {
+                        ping.record_non_data();
+                        Poll::Ready(Ok(t.map(Frame::trailers)).transpose())
+                    }
+                    Err(e) => Poll::Ready(Some(Err(crate::Error::new_h2(e)))),
                 }
-                Err(e) => Poll::Ready(Err(crate::Error::new_h2(e))),
-            },
-            Kind::Chan {
-                ref mut trailers_rx,
-                ..
-            } => match ready!(Pin::new(trailers_rx).poll(cx)) {
-                Ok(t) => Poll::Ready(Ok(Some(t))),
-                Err(_) => Poll::Ready(Ok(None)),
-            },
+            }
+
             #[cfg(feature = "ffi")]
-            Kind::Ffi(ref mut body) => body.poll_trailers(cx),
+            Kind::Ffi(ref mut body) => body.poll_data(cx),
         }
     }
 
@@ -388,14 +382,15 @@ mod tests {
     use std::task::Poll;
 
     use super::{Body, DecodedLength, Recv, Sender, SizeHint};
+    use http_body_util::BodyExt;
 
     #[test]
     fn test_size_of() {
         // These are mostly to help catch *accidentally* increasing
         // the size by too much.
 
         let body_size = mem::size_of::<Recv>();
-        let body_expected_size = mem::size_of::<u64>() * 6;
+        let body_expected_size = mem::size_of::<u64>() * 5;
         assert!(
             body_size <= body_expected_size,
             "Body size = {} <= {}",
@@ -444,7 +439,7 @@ mod tests {
 
         tx.abort();
 
-        let err = rx.data().await.unwrap().unwrap_err();
+        let err = rx.frame().await.unwrap().unwrap_err();
         assert!(err.is_body_write_aborted(), "{:?}", err);
     }
 
@@ -457,10 +452,16 @@ mod tests {
         // buffer is full, but can still send abort
         tx.abort();
 
-        let chunk1 = rx.data().await.expect("item 1").expect("chunk 1");
+        let chunk1 = rx
+            .frame()
+            .await
+            .expect("item 1")
+            .expect("chunk 1")
+            .into_data()
+            .unwrap();
         assert_eq!(chunk1, "chunk 1");
 
-        let err = rx.data().await.unwrap().unwrap_err();
+        let err = rx.frame().await.unwrap().unwrap_err();
         assert!(err.is_body_write_aborted(), "{:?}", err);
     }
 
@@ -481,7 +482,7 @@ mod tests {
     async fn channel_empty() {
         let (_, mut rx) = Recv::channel();
 
-        assert!(rx.data().await.is_none());
+        assert!(rx.frame().await.is_none());
     }
 
     #[test]
@@ -498,7 +499,7 @@ mod tests {
         let (mut tx, mut rx) = Recv::new_channel(DecodedLength::CHUNKED, /*wanter = */ true);
 
         let mut tx_ready = tokio_test::task::spawn(tx.ready());
-        let mut rx_data = tokio_test::task::spawn(rx.data());
+        let mut rx_data = tokio_test::task::spawn(rx.frame());
 
         assert!(
             tx_ready.poll().is_pending(),

src/body/mod.rs

@@ -17,19 +17,16 @@
 
 pub use bytes::{Buf, Bytes};
 pub use http_body::Body;
+pub use http_body::Frame;
 pub use http_body::SizeHint;
 
-pub use self::aggregate::aggregate;
 pub use self::body::Recv;
 #[cfg(feature = "http1")]
 pub(crate) use self::body::Sender;
 pub(crate) use self::length::DecodedLength;
-pub use self::to_bytes::to_bytes;
 
-mod aggregate;
 mod body;
 mod length;
-mod to_bytes;
 
 fn _assert_send_sync() {
     fn _assert_send<T: Send>() {}