introduce a callback into execute_query_implementation

src/memoized.rs

@@ -202,9 +202,12 @@ where
 
         // Query was not previously executed, or value is potentially
         // stale, or value is absent. Let's execute!
-        let (mut stamped_value, inputs) = db
-            .salsa_runtime()
-            .execute_query_implementation::<Q>(db, descriptor, key);
+        let (mut stamped_value, inputs) =
+            db.salsa_runtime()
+                .execute_query_implementation(db, descriptor, || {
+                    debug!("{:?}({:?}): executing query", Q::default(), key);
+                    Q::execute(db, key.clone())
+                });
 
         // We assume that query is side-effect free -- that is, does
         // not mutate the "inputs" to the query system. Sanity check

src/runtime.rs

@@ -88,16 +88,13 @@ where
         result
     }
 
-    crate fn execute_query_implementation<Q>(
+    crate fn execute_query_implementation<V>(
         &self,
         db: &DB,
         descriptor: &DB::QueryDescriptor,
-        key: &Q::Key,
-    ) -> (StampedValue<Q::Value>, QueryDescriptorSet<DB>)
-    where
-        Q: QueryFunction<DB>,
-    {
-        debug!("{:?}({:?}): executing query", Q::default(), key);
+        execute: impl FnOnce() -> V,
+    ) -> (StampedValue<V>, QueryDescriptorSet<DB>) {
+        debug!("{:?}: execute_query_implementation invoked", descriptor);
 
         // Push the active query onto the stack.
         let push_len = {
@@ -109,7 +106,7 @@ where
         };
 
         // Execute user's code, accumulating inputs etc.
-        let value = Q::execute(db, key.clone());
+        let value = execute();
 
         // Extract accumulated inputs.
         let ActiveQuery {

src/volatile.rs

@@ -64,7 +64,10 @@ where
             _inputs,
         ) = db
             .salsa_runtime()
-            .execute_query_implementation::<Q>(db, descriptor, key);
+            .execute_query_implementation(db, descriptor, || {
+                debug!("{:?}({:?}): executing query", Q::default(), key);
+                Q::execute(db, key.clone())
+            });
 
         let was_in_progress = self.in_progress.lock().remove(key);
         assert!(was_in_progress);