add debug information for signal subscriptions

packages/signals/src/signal.rs

@@ -202,6 +202,7 @@ impl<T, S: Storage<SignalData<T>>> Readable for Signal<T, S> {
         let inner = self.inner.try_read()?;
 
         if let Some(reactive_context) = ReactiveContext::current() {
+            tracing::trace!("Subscribing to the reactive context {}", reactive_context);
             inner.subscribers.lock().unwrap().insert(reactive_context);
         }
 
@@ -244,7 +245,11 @@ impl<T: 'static, S: Storage<SignalData<T>>> Writable for Signal<T, S> {
             let borrow = S::map_mut(inner, |v| &mut v.value);
             Write {
                 write: borrow,
-                drop_signal: Box::new(SignalSubscriberDrop { signal: *self }),
+                drop_signal: Box::new(SignalSubscriberDrop {
+                    signal: *self,
+                    #[cfg(debug_assertions)]
+                    origin: std::panic::Location::caller(),
+                }),
             }
         })
     }
@@ -344,10 +349,17 @@ impl<T: ?Sized, S: AnyStorage> DerefMut for Write<T, S> {
 
 struct SignalSubscriberDrop<T: 'static, S: Storage<SignalData<T>>> {
     signal: Signal<T, S>,
+    #[cfg(debug_assertions)]
+    origin: &'static std::panic::Location<'static>,
 }
 
 impl<T: 'static, S: Storage<SignalData<T>>> Drop for SignalSubscriberDrop<T, S> {
     fn drop(&mut self) {
+        #[cfg(debug_assertions)]
+        tracing::trace!(
+            "Write on signal at {:?} finished, updating subscribers",
+            self.origin
+        );
         self.signal.update_subscribers();
     }
 }