1 files changed, 57 insertions, 0 deletions
diff --git a/tokio/src/util/trace.rs b/tokio/src/util/trace.rs
new file mode 100644
index 00000000..d8c6120d
--- /dev/null
+++ b/tokio/src/util/trace.rs
@@ -0,0 +1,57 @@
+cfg_trace! {
+    cfg_rt_core! {
+        use std::future::Future;
+        use std::pin::Pin;
+        use std::task::{Context, Poll};
+        use pin_project_lite::pin_project;
+
+        use tracing::Span;
+
+        pin_project! {
+            /// A future that has been instrumented with a `tracing` span.
+            #[derive(Debug, Clone)]
+            pub(crate) struct Instrumented<T> {
+                #[pin]
+                inner: T,
+                span: Span,
+            }
+        }
+
+        impl<T: Future> Future for Instrumented<T> {
+            type Output = T::Output;
+
+            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+                let this = self.project();
+                let _enter = this.span.enter();
+                this.inner.poll(cx)
+            }
+        }
+
+        impl<T> Instrumented<T> {
+            pub(crate) fn new(inner: T, span: Span) -> Self {
+                Self { inner, span }
+            }
+        }
+
+        #[inline]
+        pub(crate) fn task<F>(task: F, kind: &'static str) -> Instrumented<F> {
+            let span = tracing::trace_span!(
+                target: "tokio::task",
+                "task",
+                %kind,
+                future = %std::any::type_name::<F>(),
+            );
+            Instrumented::new(task, span)
+        }
+    }
+}
+
+cfg_not_trace! {
+    cfg_rt_core! {
+        #[inline]
+        pub(crate) fn task<F>(task: F, _: &'static str) -> F {
+            // nop
+            task
+        }
+    }
+}