Fix/workaround for issue #21667

When a Reference managed instance is garbage collected and its finalizer is called, it could happen that the native instance is referenced once again before the finalizer can unreference and memdelete it. The workaround is to create a new managed instance when this happens (at least for now).

1 files changed, 59 insertions, 61 deletions

diff --git a/modules/mono/mono_gd/gd_mono.cpp b/modules/mono/mono_gd/gd_mono.cpp
index f1dbb5c514..833aa23820 100644
--- a/modules/mono/mono_gd/gd_mono.cpp
+++ b/modules/mono/mono_gd/gd_mono.cpp
@@ -639,9 +639,7 @@ Error GDMono::_unload_scripts_domain() {
 
 	mono_gc_collect(mono_gc_max_generation());
 
-	finalizing_scripts_domain = true;
 	mono_domain_finalize(scripts_domain, 2000);
-	finalizing_scripts_domain = false;
 
 	mono_gc_collect(mono_gc_max_generation());
 
@@ -837,7 +835,6 @@ GDMono::GDMono() {
 	gdmono_log = memnew(GDMonoLog);
 
 	runtime_initialized = false;
-	finalizing_scripts_domain = false;
 
 	root_domain = NULL;
 	scripts_domain = NULL;
@@ -866,7 +863,7 @@ GDMono::GDMono() {
 
 GDMono::~GDMono() {
 
-	if (runtime_initialized) {
+	if (is_runtime_initialized()) {
 
 		if (scripts_domain) {
 
@@ -891,8 +888,9 @@ GDMono::~GDMono() {
 
 		print_verbose("Mono: Runtime cleanup...");
 
-		runtime_initialized = false;
 		mono_jit_cleanup(root_domain);
+
+		runtime_initialized = false;
 	}
 
 	if (gdmono_log)
@@ -903,33 +901,12 @@ GDMono::~GDMono() {
 
 _GodotSharp *_GodotSharp::singleton = NULL;
 
-void _GodotSharp::_dispose_object(Object *p_object) {
-
-	if (p_object->get_script_instance()) {
-		CSharpInstance *cs_instance = CAST_CSHARP_INSTANCE(p_object->get_script_instance());
-		if (cs_instance) {
-			cs_instance->mono_object_disposed();
-			return;
-		}
-	}
-
-	// Unsafe refcount decrement. The managed instance also counts as a reference.
-	// See: CSharpLanguage::alloc_instance_binding_data(Object *p_object)
-	if (Object::cast_to<Reference>(p_object)->unreference()) {
-		memdelete(p_object);
-	}
-}
-
 void _GodotSharp::_dispose_callback() {
 
 #ifndef NO_THREADS
 	queue_mutex->lock();
 #endif
 
-	for (List<Object *>::Element *E = obj_delete_queue.front(); E; E = E->next()) {
-		_dispose_object(E->get());
-	}
-
 	for (List<NodePath *>::Element *E = np_delete_queue.front(); E; E = E->next()) {
 		memdelete(E->get());
 	}
@@ -938,7 +915,6 @@ void _GodotSharp::_dispose_callback() {
 		memdelete(E->get());
 	}
 
-	obj_delete_queue.clear();
 	np_delete_queue.clear();
 	rid_delete_queue.clear();
 	queue_empty = true;
@@ -958,52 +934,69 @@ void _GodotSharp::detach_thread() {
 	GDMonoUtils::detach_current_thread();
 }
 
-bool _GodotSharp::is_finalizing_domain() {
+int32_t _GodotSharp::get_domain_id() {
 
-	return GDMono::get_singleton()->is_finalizing_scripts_domain();
+	MonoDomain *domain = mono_domain_get();
+	CRASH_COND(!domain); // User must check if runtime is initialized before calling this method
+	return mono_domain_get_id(domain);
 }
 
-bool _GodotSharp::is_domain_loaded() {
+int32_t _GodotSharp::get_scripts_domain_id() {
 
-	return GDMono::get_singleton()->get_scripts_domain() != NULL;
+	MonoDomain *domain = SCRIPTS_DOMAIN;
+	CRASH_COND(!domain); // User must check if scripts domain is loaded before calling this method
+	return mono_domain_get_id(domain);
 }
 
-#define ENQUEUE_FOR_DISPOSAL(m_queue, m_inst)                                   \
-	m_queue.push_back(m_inst);                                                  \
-	if (queue_empty) {                                                          \
-		queue_empty = false;                                                    \
-		if (!is_finalizing_domain()) { /* call_deferred may not be safe here */ \
-			call_deferred("_dispose_callback");                                 \
-		}                                                                       \
-	}
+bool _GodotSharp::is_scripts_domain_loaded() {
 
-void _GodotSharp::queue_dispose(MonoObject *p_mono_object, Object *p_object) {
+	return GDMono::get_singleton()->is_runtime_initialized() && SCRIPTS_DOMAIN != NULL;
+}
 
-	if (GDMonoUtils::is_main_thread() && !GDMono::get_singleton()->is_finalizing_scripts_domain()) {
-		_dispose_object(p_object);
-	} else {
-#ifndef NO_THREADS
-		queue_mutex->lock();
-#endif
+bool _GodotSharp::_is_domain_finalizing_for_unload(int32_t p_domain_id) {
 
-		// This is our last chance to invoke notification predelete (this is being called from the finalizer)
-		// We must use the MonoObject* passed by the finalizer, because the weak GC handle target returns NULL at this point
-		CSharpInstance *si = CAST_CSHARP_INSTANCE(p_object->get_script_instance());
-		if (si) {
-			si->call_notification_no_check(p_mono_object, Object::NOTIFICATION_PREDELETE);
-		}
+	return is_domain_finalizing_for_unload(p_domain_id);
+}
 
-		ENQUEUE_FOR_DISPOSAL(obj_delete_queue, p_object);
+bool _GodotSharp::is_domain_finalizing_for_unload() {
 
-#ifndef NO_THREADS
-		queue_mutex->unlock();
-#endif
-	}
+	return is_domain_finalizing_for_unload(mono_domain_get());
+}
+
+bool _GodotSharp::is_domain_finalizing_for_unload(int32_t p_domain_id) {
+
+	return is_domain_finalizing_for_unload(mono_domain_get_by_id(p_domain_id));
+}
+
+bool _GodotSharp::is_domain_finalizing_for_unload(MonoDomain *p_domain) {
+
+	if (!p_domain)
+		return true;
+	return mono_domain_is_unloading(p_domain);
+}
+
+bool _GodotSharp::is_runtime_shutting_down() {
+
+	return mono_runtime_is_shutting_down();
+}
+
+bool _GodotSharp::is_runtime_initialized() {
+
+	return GDMono::get_singleton()->is_runtime_initialized();
 }
 
+#define ENQUEUE_FOR_DISPOSAL(m_queue, m_inst)                                                            \
+	m_queue.push_back(m_inst);                                                                           \
+	if (queue_empty) {                                                                                   \
+		queue_empty = false;                                                                             \
+		if (!is_domain_finalizing_for_unload(SCRIPTS_DOMAIN)) { /* call_deferred may not be safe here */ \
+			call_deferred("_dispose_callback");                                                          \
+		}                                                                                                \
+	}
+
 void _GodotSharp::queue_dispose(NodePath *p_node_path) {
 
-	if (GDMonoUtils::is_main_thread() && !GDMono::get_singleton()->is_finalizing_scripts_domain()) {
+	if (GDMonoUtils::is_main_thread() && !is_domain_finalizing_for_unload(SCRIPTS_DOMAIN)) {
 		memdelete(p_node_path);
 	} else {
 #ifndef NO_THREADS
@@ -1020,7 +1013,7 @@ void _GodotSharp::queue_dispose(NodePath *p_node_path) {
 
 void _GodotSharp::queue_dispose(RID *p_rid) {
 
-	if (GDMonoUtils::is_main_thread() && !GDMono::get_singleton()->is_finalizing_scripts_domain()) {
+	if (GDMonoUtils::is_main_thread() && !is_domain_finalizing_for_unload(SCRIPTS_DOMAIN)) {
 		memdelete(p_rid);
 	} else {
 #ifndef NO_THREADS
@@ -1040,8 +1033,13 @@ void _GodotSharp::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("attach_thread"), &_GodotSharp::attach_thread);
 	ClassDB::bind_method(D_METHOD("detach_thread"), &_GodotSharp::detach_thread);
 
-	ClassDB::bind_method(D_METHOD("is_finalizing_domain"), &_GodotSharp::is_finalizing_domain);
-	ClassDB::bind_method(D_METHOD("is_domain_loaded"), &_GodotSharp::is_domain_loaded);
+	ClassDB::bind_method(D_METHOD("get_domain_id"), &_GodotSharp::get_domain_id);
+	ClassDB::bind_method(D_METHOD("get_scripts_domain_id"), &_GodotSharp::get_scripts_domain_id);
+	ClassDB::bind_method(D_METHOD("is_scripts_domain_loaded"), &_GodotSharp::is_scripts_domain_loaded);
+	ClassDB::bind_method(D_METHOD("is_domain_finalizing_for_unload", "domain_id"), &_GodotSharp::_is_domain_finalizing_for_unload);
+
+	ClassDB::bind_method(D_METHOD("is_runtime_shutting_down"), &_GodotSharp::is_runtime_shutting_down);
+	ClassDB::bind_method(D_METHOD("is_runtime_initialized"), &_GodotSharp::is_runtime_initialized);
 
 	ClassDB::bind_method(D_METHOD("_dispose_callback"), &_GodotSharp::_dispose_callback);
 }