refactor h2 dispatcher to async/await.reduce duplicate code (#2211)

actix-http/src/h2/dispatcher.rs

@@ -1,20 +1,26 @@
-use std::task::{Context, Poll};
+use std::{
-use std::{cmp, future::Future, marker::PhantomData, net, pin::Pin, rc::Rc};
+    cmp,
+    future::Future,
+    marker::PhantomData,
+    net,
+    pin::Pin,
+    rc::Rc,
+    task::{Context, Poll},
+};
 
 use actix_codec::{AsyncRead, AsyncWrite};
 use actix_service::Service;
+use actix_utils::future::poll_fn;
 use bytes::{Bytes, BytesMut};
 use futures_core::ready;
-use h2::{
+use h2::server::{Connection, SendResponse};
-    server::{Connection, SendResponse},
-    SendStream,
-};
 use http::header::{HeaderValue, CONNECTION, CONTENT_LENGTH, DATE, TRANSFER_ENCODING};
 use log::{error, trace};
+use pin_project_lite::pin_project;
 
-use crate::body::{Body, BodySize, MessageBody};
+use crate::body::{BodySize, MessageBody};
 use crate::config::ServiceConfig;
-use crate::error::{DispatchError, Error};
+use crate::error::Error;
 use crate::message::ResponseHead;
 use crate::payload::Payload;
 use crate::request::Request;
@@ -24,14 +30,9 @@ use crate::OnConnectData;
 
 const CHUNK_SIZE: usize = 16_384;
 
+pin_project! {
     /// Dispatcher for HTTP/2 protocol.
-#[pin_project::pin_project]
+    pub struct Dispatcher<T, S, B, X, U> {
-pub struct Dispatcher<T, S, B, X, U>
-where
-    T: AsyncRead + AsyncWrite + Unpin,
-    S: Service<Request>,
-    B: MessageBody,
-{
         flow: Rc<HttpFlow<S, X, U>>,
         connection: Connection<T, Bytes>,
         on_connect_data: OnConnectData,
@@ -39,15 +40,9 @@ where
         peer_addr: Option<net::SocketAddr>,
         _phantom: PhantomData<B>,
     }
+}
 
-impl<T, S, B, X, U> Dispatcher<T, S, B, X, U>
+impl<T, S, B, X, U> Dispatcher<T, S, B, X, U> {
-where
-    T: AsyncRead + AsyncWrite + Unpin,
-    S: Service<Request>,
-    S::Error: Into<Error>,
-    S::Response: Into<Response<B>>,
-    B: MessageBody,
-{
     pub(crate) fn new(
         flow: Rc<HttpFlow<S, X, U>>,
         connection: Connection<T, Bytes>,
@@ -55,7 +50,7 @@ where
         config: ServiceConfig,
         peer_addr: Option<net::SocketAddr>,
     ) -> Self {
-        Dispatcher {
+        Self {
             flow,
             config,
             peer_addr,
@@ -71,26 +66,22 @@ where
     T: AsyncRead + AsyncWrite + Unpin,
 
     S: Service<Request>,
-    S::Error: Into<Error> + 'static,
+    S::Error: Into<Error>,
     S::Future: 'static,
-    S::Response: Into<Response<B>> + 'static,
+    S::Response: Into<Response<B>>,
 
-    B: MessageBody + 'static,
+    B: MessageBody,
     B::Error: Into<Error>,
 {
-    type Output = Result<(), DispatchError>;
+    type Output = Result<(), crate::error::DispatchError>;
 
     #[inline]
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         let this = self.get_mut();
 
-        loop {
+        while let Some((req, tx)) =
-            match ready!(Pin::new(&mut this.connection).poll_accept(cx)) {
+            ready!(Pin::new(&mut this.connection).poll_accept(cx)?)
-                None => return Poll::Ready(Ok(())),
+        {
-
-                Some(Err(err)) => return Poll::Ready(Err(err.into())),
-
-                Some(Ok((req, res))) => {
             let (parts, body) = req.into_parts();
             let pl = crate::h2::Payload::new(body);
             let pl = Payload::<crate::payload::PayloadStream>::H2(pl);
@@ -106,50 +97,113 @@ where
             // merge on_connect_ext data into request extensions
             this.on_connect_data.merge_into(&mut req);
 
-                    let svc = ServiceResponse {
+            let fut = this.flow.service.call(req);
-                        state: ServiceResponseState::ServiceCall(
+            let config = this.config.clone();
-                            this.flow.service.call(req),
+
-                            Some(res),
+            // multiplex request handling with spawn task
-                        ),
+            actix_rt::spawn(async move {
-                        config: this.config.clone(),
+                // resolve service call and send response.
-                        buffer: None,
+                let res = match fut.await {
-                        _phantom: PhantomData,
+                    Ok(res) => handle_response(res.into(), tx, config).await,
+                    Err(err) => {
+                        let res = Response::from_error(err.into());
+                        handle_response(res, tx, config).await
+                    }
                 };
 
-                    actix_rt::spawn(svc);
+                // log error.
+                if let Err(err) = res {
+                    match err {
+                        DispatchError::SendResponse(err) => {
+                            trace!("Error sending HTTP/2 response: {:?}", err)
+                        }
+                        DispatchError::SendData(err) => warn!("{:?}", err),
+                        DispatchError::ResponseBody(err) => {
+                            error!("Response payload stream error: {:?}", err)
                         }
                     }
                 }
+            });
+        }
+
+        Poll::Ready(Ok(()))
     }
 }
 
-#[pin_project::pin_project]
+enum DispatchError {
-struct ServiceResponse<F, I, E, B> {
+    SendResponse(h2::Error),
-    #[pin]
+    SendData(h2::Error),
-    state: ServiceResponseState<F, B>,
+    ResponseBody(Error),
+}
+
+async fn handle_response<B>(
+    res: Response<B>,
+    mut tx: SendResponse<Bytes>,
     config: ServiceConfig,
-    buffer: Option<Bytes>,
+) -> Result<(), DispatchError>
-    _phantom: PhantomData<(I, E)>,
-}
-
-#[pin_project::pin_project(project = ServiceResponseStateProj)]
-enum ServiceResponseState<F, B> {
-    ServiceCall(#[pin] F, Option<SendResponse<Bytes>>),
-    SendPayload(SendStream<Bytes>, #[pin] B),
-    SendErrorPayload(SendStream<Bytes>, #[pin] Body),
-}
-
-impl<F, I, E, B> ServiceResponse<F, I, E, B>
 where
-    F: Future<Output = Result<I, E>>,
-    E: Into<Error>,
-    I: Into<Response<B>>,
-
     B: MessageBody,
     B::Error: Into<Error>,
 {
+    let (res, body) = res.replace_body(());
+
+    // prepare response.
+    let mut size = body.size();
+    let res = prepare_response(config, res.head(), &mut size);
+    let eof = size.is_eof();
+
+    // send response head and return on eof.
+    let mut stream = tx
+        .send_response(res, eof)
+        .map_err(DispatchError::SendResponse)?;
+
+    if eof {
+        return Ok(());
+    }
+
+    // poll response body and send chunks to client.
+    actix_rt::pin!(body);
+
+    while let Some(res) = poll_fn(|cx| body.as_mut().poll_next(cx)).await {
+        let mut chunk = res.map_err(|err| DispatchError::ResponseBody(err.into()))?;
+
+        'send: loop {
+            // reserve enough space and wait for stream ready.
+            stream.reserve_capacity(cmp::min(chunk.len(), CHUNK_SIZE));
+
+            match poll_fn(|cx| stream.poll_capacity(cx)).await {
+                // No capacity left. drop body and return.
+                None => return Ok(()),
+                Some(res) => {
+                    // Split chuck to writeable size and send to client.
+                    let cap = res.map_err(DispatchError::SendData)?;
+
+                    let len = chunk.len();
+                    let bytes = chunk.split_to(cmp::min(cap, len));
+
+                    stream
+                        .send_data(bytes, false)
+                        .map_err(DispatchError::SendData)?;
+
+                    // Current chuck completely sent. break send loop and poll next one.
+                    if chunk.is_empty() {
+                        break 'send;
+                    }
+                }
+            }
+        }
+    }
+
+    // response body streaming finished. send end of stream and return.
+    stream
+        .send_data(Bytes::new(), true)
+        .map_err(DispatchError::SendData)?;
+
+    Ok(())
+}
+
 fn prepare_response(
-        &self,
+    config: ServiceConfig,
     head: &ResponseHead,
     size: &mut BodySize,
 ) -> http::Response<()> {
@@ -205,7 +259,7 @@ where
     // set date header
     if !has_date {
         let mut bytes = BytesMut::with_capacity(29);
-            self.config.set_date_header(&mut bytes);
+        config.set_date_header(&mut bytes);
         res.headers_mut().insert(
             DATE,
             // SAFETY: serialized date-times are known ASCII strings
@@ -215,187 +269,3 @@ where
 
     res
 }
-}
-
-impl<F, I, E, B> Future for ServiceResponse<F, I, E, B>
-where
-    F: Future<Output = Result<I, E>>,
-    E: Into<Error>,
-    I: Into<Response<B>>,
-
-    B: MessageBody,
-    B::Error: Into<Error>,
-{
-    type Output = ();
-
-    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        let mut this = self.as_mut().project();
-
-        match this.state.project() {
-            ServiceResponseStateProj::ServiceCall(call, send) => {
-                match ready!(call.poll(cx)) {
-                    Ok(res) => {
-                        let (res, body) = res.into().replace_body(());
-
-                        let mut send = send.take().unwrap();
-                        let mut size = body.size();
-                        let h2_res =
-                            self.as_mut().prepare_response(res.head(), &mut size);
-                        this = self.as_mut().project();
-
-                        let stream = match send.send_response(h2_res, size.is_eof()) {
-                            Err(e) => {
-                                trace!("Error sending HTTP/2 response: {:?}", e);
-                                return Poll::Ready(());
-                            }
-                            Ok(stream) => stream,
-                        };
-
-                        if size.is_eof() {
-                            Poll::Ready(())
-                        } else {
-                            this.state
-                                .set(ServiceResponseState::SendPayload(stream, body));
-                            self.poll(cx)
-                        }
-                    }
-
-                    Err(err) => {
-                        let res = Response::from_error(err.into());
-                        let (res, body) = res.replace_body(());
-
-                        let mut send = send.take().unwrap();
-                        let mut size = body.size();
-                        let h2_res =
-                            self.as_mut().prepare_response(res.head(), &mut size);
-                        this = self.as_mut().project();
-
-                        let stream = match send.send_response(h2_res, size.is_eof()) {
-                            Err(e) => {
-                                trace!("Error sending HTTP/2 response: {:?}", e);
-                                return Poll::Ready(());
-                            }
-                            Ok(stream) => stream,
-                        };
-
-                        if size.is_eof() {
-                            Poll::Ready(())
-                        } else {
-                            this.state.set(ServiceResponseState::SendErrorPayload(
-                                stream, body,
-                            ));
-                            self.poll(cx)
-                        }
-                    }
-                }
-            }
-
-            ServiceResponseStateProj::SendPayload(ref mut stream, ref mut body) => {
-                loop {
-                    match this.buffer {
-                        Some(ref mut buffer) => match ready!(stream.poll_capacity(cx)) {
-                            None => return Poll::Ready(()),
-
-                            Some(Ok(cap)) => {
-                                let len = buffer.len();
-                                let bytes = buffer.split_to(cmp::min(cap, len));
-
-                                if let Err(e) = stream.send_data(bytes, false) {
-                                    warn!("{:?}", e);
-                                    return Poll::Ready(());
-                                } else if !buffer.is_empty() {
-                                    let cap = cmp::min(buffer.len(), CHUNK_SIZE);
-                                    stream.reserve_capacity(cap);
-                                } else {
-                                    this.buffer.take();
-                                }
-                            }
-
-                            Some(Err(e)) => {
-                                warn!("{:?}", e);
-                                return Poll::Ready(());
-                            }
-                        },
-
-                        None => match ready!(body.as_mut().poll_next(cx)) {
-                            None => {
-                                if let Err(e) = stream.send_data(Bytes::new(), true) {
-                                    warn!("{:?}", e);
-                                }
-                                return Poll::Ready(());
-                            }
-
-                            Some(Ok(chunk)) => {
-                                stream
-                                    .reserve_capacity(cmp::min(chunk.len(), CHUNK_SIZE));
-                                *this.buffer = Some(chunk);
-                            }
-
-                            Some(Err(err)) => {
-                                error!(
-                                    "Response payload stream error: {:?}",
-                                    err.into()
-                                );
-
-                                return Poll::Ready(());
-                            }
-                        },
-                    }
-                }
-            }
-
-            ServiceResponseStateProj::SendErrorPayload(ref mut stream, ref mut body) => {
-                // TODO: de-dupe impl with SendPayload
-
-                loop {
-                    match this.buffer {
-                        Some(ref mut buffer) => match ready!(stream.poll_capacity(cx)) {
-                            None => return Poll::Ready(()),
-
-                            Some(Ok(cap)) => {
-                                let len = buffer.len();
-                                let bytes = buffer.split_to(cmp::min(cap, len));
-
-                                if let Err(e) = stream.send_data(bytes, false) {
-                                    warn!("{:?}", e);
-                                    return Poll::Ready(());
-                                } else if !buffer.is_empty() {
-                                    let cap = cmp::min(buffer.len(), CHUNK_SIZE);
-                                    stream.reserve_capacity(cap);
-                                } else {
-                                    this.buffer.take();
-                                }
-                            }
-
-                            Some(Err(e)) => {
-                                warn!("{:?}", e);
-                                return Poll::Ready(());
-                            }
-                        },
-
-                        None => match ready!(body.as_mut().poll_next(cx)) {
-                            None => {
-                                if let Err(e) = stream.send_data(Bytes::new(), true) {
-                                    warn!("{:?}", e);
-                                }
-                                return Poll::Ready(());
-                            }
-
-                            Some(Ok(chunk)) => {
-                                stream
-                                    .reserve_capacity(cmp::min(chunk.len(), CHUNK_SIZE));
-                                *this.buffer = Some(chunk);
-                            }
-
-                            Some(Err(err)) => {
-                                error!("Response payload stream error: {:?}", err);
-
-                                return Poll::Ready(());
-                            }
-                        },
-                    }
-                }
-            }
-        }
-    }
-}