CP-51209: db_notification: enable/disable and begin/end hooks for bpf…

…trace

Signed-off-by: Marcus Granado <[email protected]>

ocaml/database/db_cache_types.ml

@@ -366,7 +366,11 @@ module Database = struct
   let unregister_callback name x =
     {x with callbacks= List.filter (fun (x, _) -> x <> name) x.callbacks}
 
+  let [@inline never][@specialize never] notify_begin () = ()
+  let [@inline never][@specialize never] notify_end () = ()
+
   let notify e db =
+    notify_begin ();
     List.iter
       (fun (name, f) ->
         try f e db
@@ -376,6 +380,7 @@ module Database = struct
           ()
       )
       db.callbacks
+    ;notify_end ()
 
   let reindex x =
     let g = x.manifest.Manifest.generation_count in