From fe9c4a0b5ba9c86c8b7913c1390962c73d32621c Mon Sep 17 00:00:00 2001
From: David Pedersen <david.pdrsn@gmail.com>
Date: Sun, 12 Mar 2023 15:43:22 +0100
Subject: [PATCH] Clone state a bit less (#1837)

---
 axum/CHANGELOG.md             |  2 ++
 axum/Cargo.toml               |  1 +
 axum/src/routing/mod.rs       | 55 +++++++++++++++--------------------
 axum/src/routing/tests/mod.rs | 54 +++++++++++++++++++++++++++++++++-
 4 files changed, 79 insertions(+), 33 deletions(-)

diff --git a/axum/CHANGELOG.md b/axum/CHANGELOG.md
index 7bb85253..64c6d7dc 100644
--- a/axum/CHANGELOG.md
+++ b/axum/CHANGELOG.md
@@ -8,8 +8,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 # Unreleased
 
 - **fixed:** Don't require `S: Debug` for `impl Debug for Router<S>` ([#1836])
+- **fixed:** Clone state a bit less when handling requests ([#1837])
 
 [#1836]: https://github.com/tokio-rs/axum/pull/1836
+[#1837]: https://github.com/tokio-rs/axum/pull/1837
 
 # 0.6.10 (03. March, 2023)
 
diff --git a/axum/Cargo.toml b/axum/Cargo.toml
index bf05310e..e9460852 100644
--- a/axum/Cargo.toml
+++ b/axum/Cargo.toml
@@ -107,6 +107,7 @@ futures = "0.3"
 quickcheck = "1.0"
 quickcheck_macros = "1.0"
 reqwest = { version = "0.11.14", default-features = false, features = ["json", "stream", "multipart"] }
+rustversion = "1.0.9"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 time = { version = "0.3", features = ["serde-human-readable"] }
diff --git a/axum/src/routing/mod.rs b/axum/src/routing/mod.rs
index 4f028389..7322401c 100644
--- a/axum/src/routing/mod.rs
+++ b/axum/src/routing/mod.rs
@@ -447,7 +447,29 @@ where
                     }
                 }
 
-                self.call_route(match_, req, state)
+                let id = *match_.value;
+
+                #[cfg(feature = "matched-path")]
+                crate::extract::matched_path::set_matched_path_for_request(
+                    id,
+                    &self.node.route_id_to_path,
+                    req.extensions_mut(),
+                );
+
+                url_params::insert_url_params(req.extensions_mut(), match_.params);
+
+                let endpont = self
+                    .routes
+                    .get_mut(&id)
+                    .expect("no route for id. This is a bug in axum. Please file an issue");
+
+                match endpont {
+                    Endpoint::MethodRouter(method_router) => {
+                        method_router.call_with_state(req, state)
+                    }
+                    Endpoint::Route(route) => route.call(req),
+                    Endpoint::NestedRouter(router) => router.clone().call_with_state(req, state),
+                }
             }
             Err(
                 MatchError::NotFound
@@ -469,37 +491,6 @@ where
         }
     }
 
-    #[inline]
-    fn call_route(
-        &self,
-        match_: matchit::Match<&RouteId>,
-        mut req: Request<B>,
-        state: S,
-    ) -> RouteFuture<B, Infallible> {
-        let id = *match_.value;
-
-        #[cfg(feature = "matched-path")]
-        crate::extract::matched_path::set_matched_path_for_request(
-            id,
-            &self.node.route_id_to_path,
-            req.extensions_mut(),
-        );
-
-        url_params::insert_url_params(req.extensions_mut(), match_.params);
-
-        let endpont = self
-            .routes
-            .get(&id)
-            .expect("no route for id. This is a bug in axum. Please file an issue")
-            .clone();
-
-        match endpont {
-            Endpoint::MethodRouter(mut method_router) => method_router.call_with_state(req, state),
-            Endpoint::Route(mut route) => route.call(req),
-            Endpoint::NestedRouter(router) => router.call_with_state(req, state),
-        }
-    }
-
     fn next_route_id(&mut self) -> RouteId {
         let next_id = self
             .prev_route_id
diff --git a/axum/src/routing/tests/mod.rs b/axum/src/routing/tests/mod.rs
index 33770e33..70fccaf0 100644
--- a/axum/src/routing/tests/mod.rs
+++ b/axum/src/routing/tests/mod.rs
@@ -15,7 +15,7 @@ use serde_json::json;
 use std::{
     convert::Infallible,
     future::{ready, Ready},
-    sync::atomic::{AtomicUsize, Ordering},
+    sync::atomic::{AtomicBool, AtomicUsize, Ordering},
     task::{Context, Poll},
     time::Duration,
 };
@@ -812,3 +812,55 @@ fn method_router_fallback_with_state() {
         .fallback(get(fallback).fallback(not_found))
         .with_state(state);
 }
+
+#[crate::test]
+async fn state_isnt_cloned_too_much() {
+    static SETUP_DONE: AtomicBool = AtomicBool::new(false);
+    static COUNT: AtomicUsize = AtomicUsize::new(0);
+
+    struct AppState;
+
+    impl Clone for AppState {
+        fn clone(&self) -> Self {
+            #[rustversion::since(1.65)]
+            #[track_caller]
+            fn count() {
+                if SETUP_DONE.load(Ordering::SeqCst) {
+                    let bt = std::backtrace::Backtrace::force_capture();
+                    let bt = bt
+                        .to_string()
+                        .lines()
+                        .filter(|line| line.contains("axum") || line.contains("./src"))
+                        .collect::<Vec<_>>()
+                        .join("\n");
+                    println!("AppState::Clone:\n===============\n{}\n", bt);
+                    COUNT.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            #[rustversion::not(since(1.65))]
+            fn count() {
+                if SETUP_DONE.load(Ordering::SeqCst) {
+                    COUNT.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            count();
+
+            Self
+        }
+    }
+
+    let app = Router::new()
+        .route("/", get(|_: State<AppState>| async {}))
+        .with_state(AppState);
+
+    let client = TestClient::new(app);
+
+    // ignore clones made during setup
+    SETUP_DONE.store(true, Ordering::SeqCst);
+
+    client.get("/").send().await;
+
+    assert_eq!(COUNT.load(Ordering::SeqCst), 4);
+}