feat(client): provide tower::Service support for clients (#1915)

src/client/service.rs

@@ -0,0 +1,85 @@
+//! Utilities used to interact with the Tower ecosystem.
+//!
+//! This module provides exports of `Service`, `MakeService` and `Connect` which
+//! all provide hook-ins into the Tower ecosystem.
+
+use super::conn::{SendRequest, Builder};
+use std::marker::PhantomData;
+use crate::{common::{Poll, task, Pin}, body::Payload};
+use std::future::Future;
+use std::error::Error as StdError;
+use tower_make::MakeConnection;
+
+pub use tower_service::Service;
+pub use tower_make::MakeService;
+
+/// Creates a connection via `SendRequest`.
+///
+/// This accepts a `hyper::client::conn::Builder` and provides
+/// a `MakeService` implementation to create connections from some
+/// target `T`.
+#[derive(Debug)]
+pub struct Connect<C, B, T> {
+    inner: C,
+    builder: Builder,
+    _pd: PhantomData<fn(T, B)>
+}
+
+impl<C, B, T> Connect<C, B, T> {
+    /// Create a new `Connect` with some inner connector `C` and a connection
+    /// builder.
+    pub fn new(inner: C, builder: Builder) -> Self {
+        Self {
+            inner,
+            builder,
+            _pd: PhantomData
+        }
+    }
+}
+
+impl<C, B, T> Service<T> for Connect<C, B, T>
+where
+    C: MakeConnection<T>,
+    C::Connection: Unpin + Send + 'static,
+    C::Future: Send + 'static,
+    C::Error: Into<Box<dyn StdError + Send + Sync>> + Send,
+    B: Payload + Unpin + 'static,
+    B::Data: Unpin,
+{
+    type Response = SendRequest<B>;
+    type Error = crate::Error;
+    type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send + 'static>>;
+
+    fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.inner.poll_ready(cx).map_err(|e| crate::Error::new(crate::error::Kind::Connect).with(e.into()))
+    }
+
+    fn call(&mut self, req: T) -> Self::Future {
+        let builder = self.builder.clone();
+        let io = self.inner.make_connection(req);
+
+        let fut = async move {
+            match io.await {
+                Ok(io) => {
+                    match builder.handshake(io).await {
+                        Ok((sr, conn)) => {
+                            builder.exec.execute(async move {
+                                if let Err(e) = conn.await {
+                                    debug!("connection error: {:?}", e);
+                                }
+                            })?;
+                            Ok(sr)
+                        },
+                        Err(e) => Err(e)
+                    }
+                },
+                Err(e) => {
+                    let err = crate::Error::new(crate::error::Kind::Connect).with(e.into());
+                    Err(err)
+                }
+            }
+        };
+
+        Box::pin(fut)
+    }
+}