Mono/C#: Optimize the way we store GC handles for scripts

Don't store GC handles for C# script instances and instance bindings as 'Ref<MonoGCHandle>'; store the raw data instead. Initially this was not possible as we needed to store a Variant, but this had not been the case for a looong time yet the stored type was never updated.

modules/mono/mono_gd/gd_mono_cache.cpp

@@ -186,7 +186,7 @@ void CachedData::clear_godot_api_cache() {
 
 	// End of MarshalUtils methods
 
-	task_scheduler_handle = Ref<MonoGCHandle>();
+	task_scheduler_handle = Ref<MonoGCHandleRef>();
 }
 
 #define GODOT_API_CLASS(m_class) (GDMono::get_singleton()->get_core_api_assembly()->get_class(BINDINGS_NAMESPACE, #m_class))
@@ -316,7 +316,7 @@ void update_godot_api_cache() {
 	// TODO Move to CSharpLanguage::init() and do handle disposal
 	MonoObject *task_scheduler = mono_object_new(mono_domain_get(), GODOT_API_CLASS(GodotTaskScheduler)->get_mono_ptr());
 	GDMonoUtils::runtime_object_init(task_scheduler, GODOT_API_CLASS(GodotTaskScheduler));
-	cached_data.task_scheduler_handle = MonoGCHandle::create_strong(task_scheduler);
+	cached_data.task_scheduler_handle = MonoGCHandleRef::create_strong(task_scheduler);
 
 	cached_data.godot_api_cache_updated = true;
 }

modules/mono/mono_gd/gd_mono_cache.h

@@ -156,7 +156,7 @@ struct CachedData {
 
 	// End of MarshalUtils methods
 
-	Ref<MonoGCHandle> task_scheduler_handle;
+	Ref<MonoGCHandleRef> task_scheduler_handle;
 
 	bool corlib_cache_updated;
 	bool godot_api_cache_updated;

modules/mono/mono_gd/gd_mono_internals.cpp

@@ -75,7 +75,7 @@ void tie_managed_to_unmanaged(MonoObject *managed, Object *unmanaged) {
 		script_binding.inited = true;
 		script_binding.type_name = NATIVE_GDMONOCLASS_NAME(klass);
 		script_binding.wrapper_class = klass;
-		script_binding.gchandle = ref ? MonoGCHandle::create_weak(managed) : MonoGCHandle::create_strong(managed);
+		script_binding.gchandle = ref ? MonoGCHandleData::new_weak_handle(managed) : MonoGCHandleData::new_strong_handle(managed);
 		script_binding.owner = unmanaged;
 
 		if (ref) {
@@ -101,7 +101,7 @@ void tie_managed_to_unmanaged(MonoObject *managed, Object *unmanaged) {
 		return;
 	}
 
-	Ref<MonoGCHandle> gchandle = ref ? MonoGCHandle::create_weak(managed) : MonoGCHandle::create_strong(managed);
+	MonoGCHandleData gchandle = ref ? MonoGCHandleData::new_weak_handle(managed) : MonoGCHandleData::new_strong_handle(managed);
 
 	Ref<CSharpScript> script = CSharpScript::create_for_managed_type(klass, native);
 

modules/mono/mono_gd/gd_mono_utils.cpp

@@ -86,10 +86,9 @@ MonoObject *unmanaged_get_managed(Object *unmanaged) {
 		}
 	}
 
-	Ref<MonoGCHandle> &gchandle = script_binding.gchandle;
-	ERR_FAIL_COND_V(gchandle.is_null(), NULL);
+	MonoGCHandleData &gchandle = script_binding.gchandle;
 
-	MonoObject *target = gchandle->get_target();
+	MonoObject *target = gchandle.get_target();
 
 	if (target)
 		return target;
@@ -106,7 +105,7 @@ MonoObject *unmanaged_get_managed(Object *unmanaged) {
 	MonoObject *mono_object = GDMonoUtils::create_managed_for_godot_object(script_binding.wrapper_class, script_binding.type_name, unmanaged);
 	ERR_FAIL_NULL_V(mono_object, NULL);
 
-	gchandle->set_handle(MonoGCHandle::new_strong_handle(mono_object), MonoGCHandle::STRONG_HANDLE);
+	gchandle = MonoGCHandleData::new_strong_handle(mono_object);
 
 	// Tie managed to unmanaged
 	Reference *ref = Object::cast_to<Reference>(unmanaged);
@@ -156,6 +155,22 @@ bool is_thread_attached() {
 	return mono_domain_get() != NULL;
 }
 
+uint32_t new_strong_gchandle(MonoObject *p_object) {
+	return mono_gchandle_new(p_object, /* pinned: */ false);
+}
+
+uint32_t new_strong_gchandle_pinned(MonoObject *p_object) {
+	return mono_gchandle_new(p_object, /* pinned: */ true);
+}
+
+uint32_t new_weak_gchandle(MonoObject *p_object) {
+	return mono_gchandle_new_weakref(p_object, /* track_resurrection: */ false);
+}
+
+void free_gchandle(uint32_t p_gchandle) {
+	mono_gchandle_free(p_gchandle);
+}
+
 void runtime_object_init(MonoObject *p_this_obj, GDMonoClass *p_class, MonoException **r_exc) {
 	GDMonoMethod *ctor = p_class->get_method(".ctor", 0);
 	ERR_FAIL_NULL(ctor);

modules/mono/mono_gd/gd_mono_utils.h

@@ -92,6 +92,11 @@ _FORCE_INLINE_ bool is_main_thread() {
 	return mono_domain_get() != NULL && mono_thread_get_main() == mono_thread_current();
 }
 
+uint32_t new_strong_gchandle(MonoObject *p_object);
+uint32_t new_strong_gchandle_pinned(MonoObject *p_object);
+uint32_t new_weak_gchandle(MonoObject *p_object);
+void free_gchandle(uint32_t p_gchandle);
+
 void runtime_object_init(MonoObject *p_this_obj, GDMonoClass *p_class, MonoException **r_exc = NULL);
 
 bool mono_delegate_equal(MonoDelegate *p_a, MonoDelegate *p_b);