simplify salsa_event and make it dyn-safe

src/derived/slot.rs

@@ -188,7 +188,7 @@ where
             if let Some(value) = memo.validate_memoized_value(db, revision_now) {
                 info!("{:?}: validated old memoized value", self,);
 
-                db.salsa_event(|| Event {
+                db.salsa_event(Event {
                     runtime_id: runtime.id(),
                     kind: EventKind::DidValidateMemoizedValue {
                         database_key: self.database_key_index,
@@ -342,8 +342,8 @@ where
                         // Release our lock on `self.state`, so other thread can complete.
                         std::mem::drop(state);
 
-                        db.salsa_event(|| Event {
-                            runtime_id: db.salsa_runtime().id(),
+                        db.salsa_event(Event {
+                            runtime_id: runtime.id(),
                             kind: EventKind::WillBlockOn {
                                 other_runtime_id: other_id,
                                 database_key: self.database_key_index,

src/lib.rs

@@ -115,7 +115,7 @@ pub trait Database: plumbing::DatabaseStorageTypes + plumbing::DatabaseOps {
     /// This function is invoked at key points in the salsa
     /// runtime. It permits the database to be customized and to
     /// inject logging or other custom behavior.
-    fn salsa_event(&self, event_fn: impl Fn() -> Event) {
+    fn salsa_event(&self, event_fn: Event) {
         #![allow(unused_variables)]
     }
 

src/runtime.rs

@@ -313,10 +313,10 @@ impl Runtime {
             database_key_index
         );
 
-        db.salsa_event(|| Event {
-            runtime_id: db.salsa_runtime().id(),
+        db.salsa_event(Event {
+            runtime_id: self.id(),
             kind: EventKind::WillExecute {
-                database_key: database_key_index.clone(),
+                database_key: database_key_index,
             },
         });
 

tests/on_demand_inputs.rs

@@ -43,9 +43,9 @@ struct Database {
 }
 
 impl salsa::Database for Database {
-    fn salsa_event(&self, event_fn: impl Fn() -> salsa::Event) {
+    fn salsa_event(&self, event: salsa::Event) {
         if let Some(cb) = &self.on_event {
-            cb(event_fn())
+            cb(event)
         }
     }
 }

tests/parallel/setup.rs

@@ -192,8 +192,7 @@ pub(crate) struct ParDatabaseImpl {
 }
 
 impl Database for ParDatabaseImpl {
-    fn salsa_event(&self, event_fn: impl Fn() -> salsa::Event) {
-        let event = event_fn();
+    fn salsa_event(&self, event: salsa::Event) {
         match event.kind {
             salsa::EventKind::WillBlockOn { .. } => {
                 self.signal(self.knobs().signal_on_will_block.get());