Make client able to use non-Send executor

Cargo.toml

@@ -33,6 +33,7 @@ h2 = { version = "0.3.9", optional = true }
 itoa = "1"
 tracing = { version = "0.1", default-features = false, features = ["std"] }
 pin-project-lite = "0.2.4"
+pin-project = "1.0.12"
 tokio = { version = "1", features = ["sync"] }
 want = "0.3"
 
@@ -112,6 +113,11 @@ name = "client"
 path = "examples/client.rs"
 required-features = ["full"]
 
+[[example]]
+name = "client_single_thread"
+path = "examples/client_http2_single_threaded.rs"
+required-features = ["full"]
+
 [[example]]
 name = "client_json"
 path = "examples/client_json.rs"

examples/client_http2_single_threaded.rs

@@ -0,0 +1,132 @@
+#![deny(warnings)]
+#![warn(rust_2018_idioms)]
+use std::env;
+use std::marker::PhantomData;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+use bytes::Bytes;
+use http_body_util::BodyExt;
+use hyper::body::{Body as HttpBody, Frame};
+use hyper::Error;
+use hyper::Request;
+use tokio::io::{self, AsyncWriteExt as _};
+use tokio::net::TcpStream;
+
+struct Body {
+    // Our Body type is !Send and !Sync:
+    _marker: PhantomData<*const ()>,
+    data: Option<Bytes>,
+}
+
+impl From<String> for Body {
+    fn from(a: String) -> Self {
+        Body {
+            _marker: PhantomData,
+            data: Some(a.into()),
+        }
+    }
+}
+
+impl HttpBody for Body {
+    type Data = Bytes;
+    type Error = Error;
+
+    fn poll_frame(
+        self: Pin<&mut Self>,
+        _: &mut Context<'_>,
+    ) -> Poll<Option<Result<Frame<Self::Data>, Self::Error>>> {
+        Poll::Ready(self.get_mut().data.take().map(|d| Ok(Frame::data(d))))
+    }
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    pretty_env_logger::init();
+
+    // Configure a runtime that runs everything on the current thread
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .expect("build runtime");
+
+    // Combine it with a `LocalSet,  which means it can spawn !Send futures...
+    let local = tokio::task::LocalSet::new();
+    local.block_on(&rt, init())
+}
+
+async fn init() -> Result<(), Box<dyn std::error::Error>> {
+    // Some simple CLI args requirements...
+    let url = match env::args().nth(1) {
+        Some(url) => url,
+        None => {
+            println!("Usage: client <url>");
+            return Ok(());
+        }
+    };
+
+    // HTTPS requires picking a TLS implementation, so give a better
+    // warning if the user tries to request an 'https' URL.
+    let url = url.parse::<hyper::Uri>().unwrap();
+    if url.scheme_str() != Some("http") {
+        println!("This example only works with 'http' URLs.");
+        return Ok(());
+    }
+
+    fetch_url(url).await
+}
+
+async fn fetch_url(url: hyper::Uri) -> Result<(), Box<dyn std::error::Error>> {
+    let host = url.host().expect("uri has no host");
+    let port = url.port_u16().unwrap_or(80);
+    let addr = format!("{}:{}", host, port);
+    let stream = TcpStream::connect(addr).await?;
+
+    let (mut sender, conn) = hyper::client::conn::http2::handshake(LocalExec, stream).await?;
+    tokio::task::spawn_local(async move {
+        if let Err(err) = conn.await {
+            println!("Connection failed: {:?}", err);
+        }
+    });
+
+    let authority = url.authority().unwrap().clone();
+
+    let req = Request::builder()
+        .uri(url)
+        .header(hyper::header::HOST, authority.as_str())
+        .body(Body::from("test".to_string()))?;
+
+    let mut res = sender.send_request(req).await?;
+
+    println!("Response: {}", res.status());
+    println!("Headers: {:#?}\n", res.headers());
+
+    // 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.frame().await {
+        let frame = next?;
+        if let Some(chunk) = frame.data_ref() {
+            io::stdout().write_all(&chunk).await?;
+        }
+    }
+
+    println!("\n\nDone!");
+
+    Ok(())
+}
+
+// NOTE: This part is only needed for HTTP/2. HTTP/1 doesn't need an executor.
+//
+// Since the Server needs to spawn some background tasks, we needed
+// to configure an Executor that can spawn !Send futures...
+#[derive(Clone, Copy, Debug)]
+struct LocalExec;
+
+impl<F> hyper::rt::Executor<F> for LocalExec
+where
+    F: std::future::Future + 'static, // not requiring `Send`
+{
+    fn execute(&self, fut: F) {
+        // This will spawn into the currently running `LocalSet`.
+        tokio::task::spawn_local(fut);
+    }
+}

src/client/conn/http2.rs

@@ -11,6 +11,7 @@ use tokio::io::{AsyncRead, AsyncWrite};
 
 use super::super::dispatch;
 use crate::body::{Body, Incoming as IncomingBody};
+use crate::common::exec::ExecutorClient;
 use crate::common::time::Time;
 use crate::common::{
     exec::{BoxSendFuture, Exec},
@@ -26,7 +27,9 @@ pub struct SendRequest<B> {
 
 impl<B> Clone for SendRequest<B> {
     fn clone(&self) -> SendRequest<B> {
-        SendRequest { dispatch: self.dispatch.clone() }
+        SendRequest {
+            dispatch: self.dispatch.clone(),
+        }
     }
 }
 
@@ -35,20 +38,25 @@ impl<B> Clone for SendRequest<B> {
 /// In most cases, this should just be spawned into an executor, so that it
 /// can process incoming and outgoing messages, notice hangups, and the like.
 #[must_use = "futures do nothing unless polled"]
-pub struct Connection<T, B>
+pub struct Connection<T, B, E>
 where
-    T: AsyncRead + AsyncWrite + Send + 'static,
+    T: AsyncRead + AsyncWrite + Send + 'static + Unpin,
     B: Body + 'static,
+    E: ExecutorClient<B, T> + Unpin,
+    <B as http_body::Body>::Error: std::error::Error + Send + Sync + 'static,
 {
-    inner: (PhantomData<T>, proto::h2::ClientTask<B>),
+    inner: (PhantomData<T>, proto::h2::ClientTask<B, E, T>),
 }
 
 /// A builder to configure an HTTP connection.
 ///
 /// After setting options, the builder is used to create a handshake future.
 #[derive(Clone, Debug)]
-pub struct Builder {
-    pub(super) exec: Exec,
+pub struct Builder<Ex>
+where
+    Ex: Executor<BoxSendFuture> + Send + Sync + 'static + Clone,
+{
+    pub(super) exec: Ex,
     pub(super) timer: Time,
     h2_builder: proto::h2::client::Config,
 }
@@ -60,13 +68,15 @@ pub struct Builder {
 pub async fn handshake<E, T, B>(
     exec: E,
     io: T,
-) -> crate::Result<(SendRequest<B>, Connection<T, B>)>
+) -> crate::Result<(SendRequest<B>, Connection<T, B, E>)>
 where
     E: Executor<BoxSendFuture> + Send + Sync + 'static,
     T: AsyncRead + AsyncWrite + Unpin + Send + 'static,
     B: Body + 'static,
     B::Data: Send,
     B::Error: Into<Box<dyn StdError + Send + Sync>>,
+    E: ExecutorClient<B, T> + Unpin + Clone,
+    <B as http_body::Body>::Error: std::error::Error + Send + Sync + 'static,
 {
     Builder::new(exec).handshake(io).await
 }
@@ -189,12 +199,14 @@ impl<B> fmt::Debug for SendRequest<B> {
 
 // ===== impl Connection
 
-impl<T, B> Connection<T, B>
+impl<T, B, E> Connection<T, B, E>
 where
     T: AsyncRead + AsyncWrite + Unpin + Send + 'static,
     B: Body + Unpin + Send + 'static,
     B::Data: Send,
     B::Error: Into<Box<dyn StdError + Send + Sync>>,
+    E: ExecutorClient<B, T> + Unpin,
+    <B as http_body::Body>::Error: std::error::Error + Send + Sync + 'static,
 {
     /// Returns whether the [extended CONNECT protocol][1] is enabled or not.
     ///
@@ -210,22 +222,27 @@ where
     }
 }
 
-impl<T, B> fmt::Debug for Connection<T, B>
+impl<T, B, E> fmt::Debug for Connection<T, B, E>
 where
-    T: AsyncRead + AsyncWrite + fmt::Debug + Send + 'static,
+    T: AsyncRead + AsyncWrite + fmt::Debug + Send + 'static+ Unpin,
     B: Body + 'static,
+    E: ExecutorClient<B, T> + Unpin,
+    <B as http_body::Body>::Error: std::error::Error + Send + Sync + 'static,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("Connection").finish()
     }
 }
 
-impl<T, B> Future for Connection<T, B>
+impl<T, B, E> Future for Connection<T, B, E>
 where
     T: AsyncRead + AsyncWrite + Unpin + Send + 'static,
-    B: Body + Send + 'static,
+    B: Body + 'static + Unpin,
     B::Data: Send,
+    E: Unpin,
     B::Error: Into<Box<dyn StdError + Send + Sync>>,
+    E: ExecutorClient<B, T> + 'static + Send + Sync + Unpin,
+    <B as http_body::Body>::Error: std::error::Error + Send + Sync + 'static,
 {
     type Output = crate::Result<()>;
 
@@ -240,22 +257,22 @@ where
 
 // ===== impl Builder
 
-impl Builder {
+impl<Ex> Builder<Ex>
+where
+    Ex: Executor<BoxSendFuture> + Send + Sync + 'static + Clone,
+{
     /// Creates a new connection builder.
     #[inline]
-    pub fn new<E>(exec: E) -> Builder 
-    where
-        E: Executor<BoxSendFuture> + Send + Sync + 'static,
-    {
+    pub fn new(exec: Ex) -> Builder<Ex> {
         Builder {
-            exec: Exec::new(exec),
+            exec,
             timer: Time::Empty,
             h2_builder: Default::default(),
         }
     }
 
     /// Provide a timer to execute background HTTP2 tasks.
-    pub fn timer<M>(&mut self, timer: M) -> &mut Builder
+    pub fn timer<M>(&mut self, timer: M) -> &mut Builder<Ex>
     where
         M: Timer + Send + Sync + 'static,
     {
@@ -284,10 +301,7 @@ impl Builder {
     /// Passing `None` will do nothing.
     ///
     /// If not set, hyper will use a default.
-    pub fn initial_connection_window_size(
-        &mut self,
-        sz: impl Into<Option<u32>>,
-    ) -> &mut Self {
+    pub fn initial_connection_window_size(&mut self, sz: impl Into<Option<u32>>) -> &mut Self {
         if let Some(sz) = sz.into() {
             self.h2_builder.adaptive_window = false;
             self.h2_builder.initial_conn_window_size = sz;
@@ -329,10 +343,7 @@ impl Builder {
     /// Pass `None` to disable HTTP2 keep-alive.
     ///
     /// Default is currently disabled.
-    pub fn keep_alive_interval(
-        &mut self,
-        interval: impl Into<Option<Duration>>,
-    ) -> &mut Self {
+    pub fn keep_alive_interval(&mut self, interval: impl Into<Option<Duration>>) -> &mut Self {
         self.h2_builder.keep_alive_interval = interval.into();
         self
     }
@@ -395,12 +406,14 @@ impl Builder {
     pub fn handshake<T, B>(
         &self,
         io: T,
-    ) -> impl Future<Output = crate::Result<(SendRequest<B>, Connection<T, B>)>>
+    ) -> impl Future<Output = crate::Result<(SendRequest<B>, Connection<T, B, Ex>)>> + '_
     where
         T: AsyncRead + AsyncWrite + Unpin + Send + 'static,
         B: Body + 'static,
         B::Data: Send,
         B::Error: Into<Box<dyn StdError + Send + Sync>>,
+        Ex: ExecutorClient<B, T> + Unpin,
+        <B as http_body::Body>::Error: std::error::Error + Send + Sync + 'static,
     {
         let opts = self.clone();