Place new functionality behind a new 'tracing' feature

Author: alpeb

Cargo.toml

@@ -55,6 +55,7 @@ full = [
     "http1",
     "http2",
     "tokio",
+    "tracing",
 ]
 
 client = ["hyper/client", "dep:tracing", "dep:futures-channel", "dep:tower-service"]
@@ -69,7 +70,9 @@ service = ["dep:tower-service"]
 http1 = ["hyper/http1"]
 http2 = ["hyper/http2"]
 
-tokio = ["dep:tokio", "tokio/net", "tokio/rt", "tokio/time", "dep:tracing"]
+tokio = ["dep:tokio", "tokio/net", "tokio/rt", "tokio/time"]
+
+tracing = ["dep:tracing"]
 
 # internal features used in CI
 __internal_happy_eyeballs_tests = []

src/rt/tokio.rs

@@ -9,6 +9,8 @@ use std::{
 
 use hyper::rt::{Executor, Sleep, Timer};
 use pin_project_lite::pin_project;
+
+#[cfg(feature = "tracing")]
 use tracing::instrument::Instrument;
 
 /// Future executor that utilises `tokio` threads.
@@ -50,7 +52,11 @@ where
     Fut::Output: Send + 'static,
 {
     fn execute(&self, fut: Fut) {
+        #[cfg(feature = "tracing")]
         tokio::spawn(fut.in_current_span());
+
+        #[cfg(not(feature = "tracing"))]
+        tokio::spawn(fut);
     }
 }