From a128a672a165b413a6e31da7d0f75b77505d8d9d Mon Sep 17 00:00:00 2001
From: David Pedersen <david.pdrsn@gmail.com>
Date: Mon, 16 Aug 2021 09:19:37 +0200
Subject: [PATCH] Remove allocation when calling handler (#190)

`Handler::call` already returns a boxed future so we don't have to box
it again.
---
 src/handler/future.rs | 11 ++++++++---
 src/handler/mod.rs    | 12 ++++--------
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/handler/future.rs b/src/handler/future.rs
index 3c78cb42..d921494c 100644
--- a/src/handler/future.rs
+++ b/src/handler/future.rs
@@ -1,7 +1,8 @@
 //! Handler future types.
 
 use crate::body::{box_body, BoxBody};
-use futures_util::future::{BoxFuture, Either};
+use crate::util::{Either, EitherProj};
+use futures_util::{future::BoxFuture, ready};
 use http::{Method, Request, Response};
 use http_body::Empty;
 use pin_project_lite::pin_project;
@@ -21,7 +22,7 @@ pin_project! {
     {
         #[pin]
         pub(super) inner: Either<
-            BoxFuture<'static, Result<Response<BoxBody>, F::Error>>,
+            BoxFuture<'static, Response<BoxBody>>,
             Oneshot<F, Request<B>>,
         >,
         pub(super) req_method: Method,
@@ -36,7 +37,11 @@ where
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         let this = self.project();
-        let response = futures_util::ready!(this.inner.poll(cx))?;
+        let response = match this.inner.project() {
+            EitherProj::A { inner } => ready!(inner.poll(cx)),
+            EitherProj::B { inner } => ready!(inner.poll(cx))?,
+        };
+
         if this.req_method == &Method::HEAD {
             let response = response.map(|_| box_body(Empty::new()));
             Poll::Ready(Ok(response))
diff --git a/src/handler/mod.rs b/src/handler/mod.rs
index cda572da..b740453c 100644
--- a/src/handler/mod.rs
+++ b/src/handler/mod.rs
@@ -6,10 +6,10 @@ use crate::{
     response::IntoResponse,
     routing::{EmptyRouter, MethodFilter},
     service::{HandleError, HandleErrorFromRouter},
+    util::Either,
 };
 use async_trait::async_trait;
 use bytes::Bytes;
-use futures_util::future::Either;
 use http::{Request, Response};
 use std::{
     convert::Infallible,
@@ -601,15 +601,11 @@ where
         let req_method = req.method().clone();
 
         let fut = if self.method.matches(req.method()) {
-            let handler = self.handler.clone();
-            let fut = Box::pin(async move {
-                let res = Handler::call(handler, req).await;
-                Ok::<_, F::Error>(res)
-            }) as futures_util::future::BoxFuture<'static, _>;
-            Either::Left(fut)
+            let fut = Handler::call(self.handler.clone(), req);
+            Either::A { inner: fut }
         } else {
             let fut = self.fallback.clone().oneshot(req);
-            Either::Right(fut)
+            Either::B { inner: fut }
         };
 
         future::OnMethodFuture {