1 files changed, 20 insertions, 0 deletions
diff --git a/src/sync/rwlock/owned_write_guard_mapped.rs b/src/sync/rwlock/owned_write_guard_mapped.rs
index d88ee01..55a24d9 100644
--- a/src/sync/rwlock/owned_write_guard_mapped.rs
+++ b/src/sync/rwlock/owned_write_guard_mapped.rs
@@ -15,6 +15,8 @@ use std::sync::Arc;
 /// [mapping]: method@crate::sync::OwnedRwLockWriteGuard::map
 /// [`OwnedRwLockWriteGuard`]: struct@crate::sync::OwnedRwLockWriteGuard
 pub struct OwnedRwLockMappedWriteGuard<T: ?Sized, U: ?Sized = T> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(super) resource_span: tracing::Span,
     pub(super) permits_acquired: u32,
     // ManuallyDrop allows us to destructure into this field without running the destructor.
     pub(super) lock: ManuallyDrop<Arc<RwLock<T>>>,
@@ -63,13 +65,18 @@ impl<T: ?Sized, U: ?Sized> OwnedRwLockMappedWriteGuard<T, U> {
         let data = f(&mut *this) as *mut V;
         let lock = unsafe { ManuallyDrop::take(&mut this.lock) };
         let permits_acquired = this.permits_acquired;
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = this.resource_span.clone();
         // NB: Forget to avoid drop impl from being called.
         mem::forget(this);
+
         OwnedRwLockMappedWriteGuard {
             permits_acquired,
             lock: ManuallyDrop::new(lock),
             data,
             _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span,
         }
     }
 
@@ -120,13 +127,18 @@ impl<T: ?Sized, U: ?Sized> OwnedRwLockMappedWriteGuard<T, U> {
         };
         let lock = unsafe { ManuallyDrop::take(&mut this.lock) };
         let permits_acquired = this.permits_acquired;
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = this.resource_span.clone();
         // NB: Forget to avoid drop impl from being called.
         mem::forget(this);
+
         Ok(OwnedRwLockMappedWriteGuard {
             permits_acquired,
             lock: ManuallyDrop::new(lock),
             data,
             _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span,
         })
     }
 }
@@ -166,6 +178,14 @@ where
 impl<T: ?Sized, U: ?Sized> Drop for OwnedRwLockMappedWriteGuard<T, U> {
     fn drop(&mut self) {
         self.lock.s.release(self.permits_acquired as usize);
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
         unsafe { ManuallyDrop::drop(&mut self.lock) };
     }
 }