+ simcall_run_answered([&result, &code] { simgrid::xbt::fulfill_promise(result, std::forward<F>(code)); }, observer);
+ return result.get();
+}
+
+/** Use a setter on the `item` object. That's a simcall only if running in parallel or with MC activated.
+ *
+ * Simulation without MC and without parallelism (contexts/nthreads=1) will not pay the price of a simcall for an
+ * harmless setter. When running in parallel, you want your write access to be done in a mutual exclusion way, while the
+ * getters can still occur out of order.
+ *
+ * When running in MC, you want to make this access visible to the checker. Actually in this case, it's not visible from
+ * the checker (and thus still use a fast track) if the setter is called from the actor that created the object.
+ */
+template <class F> typename std::result_of_t<F()> simcall_object_access(ObjectAccessSimcallItem* item, F&& code)
+{
+ // If we are in the maestro, we take the fast path and execute the code directly
+ if (simgrid::s4u::Actor::is_maestro())
+ return std::forward<F>(code)();
+
+ // If called from another thread, do a real simcall. It will be short-cut on need
+ using R = typename std::result_of_t<F()>;
+ simgrid::xbt::Result<R> result;
+ simcall_run_object_access([&result, &code] { simgrid::xbt::fulfill_promise(result, std::forward<F>(code)); }, item);
+