X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/a707ad979be7c88d7581f403661c67598d320d55..fcf33975379cd050a6d70b94ae7857910dd01217:/include/simgrid/simix.hpp

diff --git a/include/simgrid/simix.hpp b/include/simgrid/simix.hpp
index fb8addfb3c..9e3ec63a77 100644
--- a/include/simgrid/simix.hpp
+++ b/include/simgrid/simix.hpp
@@ -18,6 +18,8 @@ XBT_PUBLIC void simcall_run_answered(std::function<void()> const& code,
                                      simgrid::kernel::actor::SimcallObserver* observer);
 XBT_PUBLIC void simcall_run_blocking(std::function<void()> const& code,
                                      simgrid::kernel::actor::SimcallObserver* observer);
+XBT_PUBLIC void simcall_run_object_access(std::function<void()> const& code,
+                                          simgrid::kernel::actor::ObjectAccessSimcallItem* item);
 
 namespace simgrid {
 namespace kernel {
@@ -26,7 +28,7 @@ namespace actor {
 /** Execute some code in kernel context on behalf of the user code.
  *
  * Every modification of the environment must be protected this way: every setter, constructor and similar.
- * Getters don't have to be protected this way.
+ * Getters don't have to be protected this way, and setters may use the simcall_object_access() variant (see below).
  *
  * This allows deterministic parallel simulation without any locking, even if almost nobody uses parallel simulation in
  * SimGrid. More interestingly it makes every modification of the simulated world observable by the model-checker,
@@ -58,9 +60,32 @@ template <class F> typename std::result_of_t<F()> simcall_answered(F&& code, Sim
   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 occure 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);
+
+  return result.get();
+}
+
 /** Execute some code (that does not return immediately) in kernel context
  *
- * This is very similar to simcall() right above, but the calling actor will not get rescheduled until
+ * This is very similar to simcall_answered() above, but the calling actor will not get rescheduled until
  * actor->simcall_answer() is called explicitly.
  *
  * This is meant for blocking actions. For example, locking a mutex is a blocking simcall.
@@ -91,8 +116,8 @@ auto simcall_blocking(F&& code, Observer* observer) -> decltype(observer->get_re
   simcall_blocking(std::forward<F>(code), static_cast<SimcallObserver*>(observer));
   return observer->get_result();
 }
+// compact namespaces are C++17 and this is a public header file so let's stick to C++14
 } // namespace actor
 } // namespace kernel
 } // namespace simgrid
-
 #endif