From 6ebd0575e44fe022e1bc3cf3d184044bcc4dc7a5 Mon Sep 17 00:00:00 2001
From: Sean McArthur <sean@seanmonstar.com>
Date: Thu, 9 Sep 2021 08:58:21 -0700
Subject: [PATCH] runtime: add tracing span for block_on futures (#4094)

---
 tokio/src/runtime/handle.rs | 4 ++++
 tokio/src/runtime/mod.rs    | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/tokio/src/runtime/handle.rs b/tokio/src/runtime/handle.rs
index 1ae83cb25..bad6a0087 100644
--- a/tokio/src/runtime/handle.rs
+++ b/tokio/src/runtime/handle.rs
@@ -296,7 +296,11 @@ impl Handle {
     /// [`tokio::fs`]: crate::fs
     /// [`tokio::net`]: crate::net
     /// [`tokio::time`]: crate::time
+    #[cfg_attr(tokio_track_caller, track_caller)]
     pub fn block_on<F: Future>(&self, future: F) -> F::Output {
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let future = crate::util::trace::task(future, "block_on", None);
+
         // Enter the **runtime** context. This configures spawning, the current I/O driver, ...
         let _rt_enter = self.enter();
 
diff --git a/tokio/src/runtime/mod.rs b/tokio/src/runtime/mod.rs
index c01c6c8d8..ec7d0c09a 100644
--- a/tokio/src/runtime/mod.rs
+++ b/tokio/src/runtime/mod.rs
@@ -450,7 +450,11 @@ cfg_rt! {
         /// ```
         ///
         /// [handle]: fn@Handle::block_on
+        #[cfg_attr(tokio_track_caller, track_caller)]
         pub fn block_on<F: Future>(&self, future: F) -> F::Output {
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            let future = crate::util::trace::task(future, "block_on", None);
+
             let _enter = self.enter();
 
             match &self.kind {