From d0305d57e56dedeb9fb4854d16fe9a11d503e2a2 Mon Sep 17 00:00:00 2001
From: Eliza Weisman <eliza@buoyant.io>
Date: Mon, 16 Aug 2021 12:43:34 -0700
Subject: [PATCH] tracing: change span naming to new console convention (#4042)

Currently, the per-task spans generated by Tokio's `tracing` feature
have the span name "task" and the target "tokio::task". This is because
the console subscriber identified tasks by looking specifically for the
"tokio::task" target.

In tokio-rs/console#41, it was proposed that the console change to a
more generic system for identifying the spans that correspond to tasks,
to allow recording tasks belonging to multiple runtime crates (e.g. an
application that uses Tokio for async tasks and Rayon for CPU-bound
tasks). PR tokio-rs/console#68 changed the console to track any spans
"runtime.spawn", regardless of target (so that the target can be used to
identify the runtime a task came from), with "tokio::task/task" tracked
for backwards-compatibility with the current release version of tokio.

This branch changes Tokio's span naming to the new convention. I also
rearranged a couple fields so that the task's kind field always comes
before the name and spawn location, since it's likely to be the
shortest, and renamed the `function` field on blocking tasks to `fn`,
for brevity's sake.

Signed-off-by: Eliza Weisman <eliza@buoyant.io>
---
 tokio/src/runtime/handle.rs | 12 ++++++------
 tokio/src/util/trace.rs     |  8 ++++----
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/tokio/src/runtime/handle.rs b/tokio/src/runtime/handle.rs
index ddc170a929d..46072f381d1 100644
--- a/tokio/src/runtime/handle.rs
+++ b/tokio/src/runtime/handle.rs
@@ -192,20 +192,20 @@ impl Handle {
             let location = std::panic::Location::caller();
             #[cfg(tokio_track_caller)]
             let span = tracing::trace_span!(
-                target: "tokio::task",
-                "task",
+                target: "tokio::task::blocking",
+                "runtime.spawn",
                 kind = %"blocking",
-                function = %std::any::type_name::<F>(),
                 task.name = %name.unwrap_or_default(),
+                "fn" = %std::any::type_name::<F>(),
                 spawn.location = %format_args!("{}:{}:{}", location.file(), location.line(), location.column()),
             );
             #[cfg(not(tokio_track_caller))]
             let span = tracing::trace_span!(
-                target: "tokio::task",
-                "task",
+                target: "tokio::task::blocking",
+                "runtime.spawn",
                 kind = %"blocking",
                 task.name = %name.unwrap_or_default(),
-                function = %std::any::type_name::<F>(),
+                "fn" = %std::any::type_name::<F>(),
             );
             fut.instrument(span)
         };
diff --git a/tokio/src/util/trace.rs b/tokio/src/util/trace.rs
index c51a5a72bce..61c155c5b03 100644
--- a/tokio/src/util/trace.rs
+++ b/tokio/src/util/trace.rs
@@ -11,17 +11,17 @@ cfg_trace! {
             #[cfg(tokio_track_caller)]
             let span = tracing::trace_span!(
                 target: "tokio::task",
-                "task",
+                "runtime.spawn",
                 %kind,
+                task.name = %name.unwrap_or_default(),
                 spawn.location = %format_args!("{}:{}:{}", location.file(), location.line(), location.column()),
-                task.name = %name.unwrap_or_default()
             );
             #[cfg(not(tokio_track_caller))]
             let span = tracing::trace_span!(
                 target: "tokio::task",
-                "task",
+                "runtime.spawn",
                 %kind,
-                task.name = %name.unwrap_or_default()
+                task.name = %name.unwrap_or_default(),
             );
             task.instrument(span)
         }