Add strong/weak pointer counts to Shared (#2346)

Co-authored-by: Harry Barber <harry.barber@disneystreaming.com>

Author: hlbarber

futures-util/src/future/future/shared.rs

@@ -126,6 +126,32 @@ where
  }
  None
  }
+
+ /// Gets the number of strong pointers to this allocation.
+ ///
+ /// Returns [`None`] if it has already been polled to completion.
+ ///
+ /// # Safety
+ ///
+ /// This method by itself is safe, but using it correctly requires extra care. Another thread
+ /// can change the strong count at any time, including potentially between calling this method
+ /// and acting on the result.
+ pub fn strong_count(&self) -> Option<usize> {
+ self.inner.as_ref().map(|arc| Arc::strong_count(arc))
+ }
+
+ /// Gets the number of weak pointers to this allocation.
+ ///
+ /// Returns [`None`] if it has already been polled to completion.
+ ///
+ /// # Safety
+ ///
+ /// This method by itself is safe, but using it correctly requires extra care. Another thread
+ /// can change the weak count at any time, including potentially between calling this method
+ /// and acting on the result.
+ pub fn weak_count(&self) -> Option<usize> {
+ self.inner.as_ref().map(|arc| Arc::weak_count(arc))
+ }
 }
 
 impl<Fut> Inner<Fut>