Allow threads to mark themselves as safe for nodes

core/io/resource_loader.cpp

@@ -302,6 +302,7 @@ void ResourceLoader::_thread_load_function(void *p_userdata) {
 		if (!Thread::is_main_thread()) {
 			mq_override = memnew(CallQueue);
 			MessageQueue::set_thread_singleton_override(mq_override);
+			set_current_thread_safe_for_nodes(true);
 		}
 	} else {
 		DEV_ASSERT(load_task.dependent_path.is_empty());
@@ -357,6 +358,7 @@ void ResourceLoader::_thread_load_function(void *p_userdata) {
 
 	if (load_nesting == 0 && mq_override) {
 		memdelete(mq_override);
+		set_current_thread_safe_for_nodes(false);
 	}
 }
 

core/os/thread_safe.cpp

@@ -0,0 +1,46 @@
+/**************************************************************************/
+/*  thread_safe.cpp                                                       */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#ifndef THREAD_SAFE_CPP
+#define THREAD_SAFE_CPP
+
+#include "thread_safe.h"
+
+static thread_local bool current_thread_safe_for_nodes = false;
+
+bool is_current_thread_safe_for_nodes() {
+	return current_thread_safe_for_nodes;
+}
+
+void set_current_thread_safe_for_nodes(bool p_safe) {
+	current_thread_safe_for_nodes = p_safe;
+}
+
+#endif // THREAD_SAFE_CPP

core/os/thread_safe.h

@@ -38,4 +38,7 @@
 #define _THREAD_SAFE_LOCK_ _thread_safe_.lock();
 #define _THREAD_SAFE_UNLOCK_ _thread_safe_.unlock();
 
+bool is_current_thread_safe_for_nodes();
+void set_current_thread_safe_for_nodes(bool p_safe);
+
 #endif // THREAD_SAFE_H

editor/plugins/tiles/tiles_editor_plugin.cpp

@@ -59,6 +59,7 @@ void TilesEditorPlugin::_pattern_preview_done() {
 
 void TilesEditorPlugin::_thread_func(void *ud) {
 	TilesEditorPlugin *te = static_cast<TilesEditorPlugin *>(ud);
+	set_current_thread_safe_for_nodes(true);
 	te->_thread();
 }
 

main/main.cpp

@@ -512,6 +512,7 @@ void Main::print_help(const char *p_binary) {
 // are initialized here. This also combines `Main::setup2()` initialization.
 Error Main::test_setup() {
 	Thread::make_main_thread();
+	set_current_thread_safe_for_nodes(true);
 
 	OS::get_singleton()->initialize();
 
@@ -723,6 +724,7 @@ int Main::test_entrypoint(int argc, char *argv[], bool &tests_need_run) {
 
 Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_phase) {
 	Thread::make_main_thread();
+	set_current_thread_safe_for_nodes(true);
 
 	OS::get_singleton()->initialize();
 
@@ -1990,6 +1992,7 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	engine->startup_benchmark_end_measure(); // core
 
 	Thread::release_main_thread(); // If setup2() is called from another thread, that one will become main thread, so preventively release this one.
+	set_current_thread_safe_for_nodes(false);
 
 	if (p_second_phase) {
 		return setup2();
@@ -2055,6 +2058,7 @@ error:
 
 Error Main::setup2() {
 	Thread::make_main_thread(); // Make whatever thread call this the main thread.
+	set_current_thread_safe_for_nodes(true);
 
 	// Print engine name and version
 	print_line(String(VERSION_NAME) + " v" + get_full_version_string() + " - " + String(VERSION_WEBSITE));

scene/gui/rich_text_label.cpp

@@ -2691,9 +2691,11 @@ bool RichTextLabel::_find_layout_subitem(Item *from, Item *to) {
 }
 
 void RichTextLabel::_thread_function(void *p_userdata) {
+	set_current_thread_safe_for_nodes(true);
 	_process_line_caches();
 	updating.store(false);
 	call_deferred(SNAME("thread_end"));
+	set_current_thread_safe_for_nodes(false);
 }
 
 void RichTextLabel::_thread_end() {

scene/main/node.h

@@ -539,7 +539,7 @@ public:
 		if (current_process_thread_group == nullptr) {
 			// Not thread processing. Only accessible if node is outside the scene tree,
 			// if accessing from the main thread or being loaded.
-			return !data.inside_tree || Thread::is_main_thread() || ResourceLoader::is_within_load();
+			return !data.inside_tree || is_current_thread_safe_for_nodes();
 		} else {
 			// Thread processing
 			return current_process_thread_group == data.process_thread_group_owner;
@@ -548,7 +548,7 @@ public:
 
 	_FORCE_INLINE_ bool is_readable_from_caller_thread() const {
 		if (current_process_thread_group == nullptr) {
-			return Thread::is_main_thread() || ResourceLoader::is_within_load();
+			return Thread::is_main_thread() || is_current_thread_safe_for_nodes();
 		} else {
 			return true;
 		}
@@ -727,8 +727,8 @@ Error Node::rpc_id(int p_peer_id, const StringName &p_method, VarArgs... p_args)
 #ifdef DEBUG_ENABLED
 #define ERR_THREAD_GUARD ERR_FAIL_COND_MSG(!is_accessible_from_caller_thread(), "Caller thread can't call this function in this node. Use call_deferred() or call_thread_group() instead.");
 #define ERR_THREAD_GUARD_V(m_ret) ERR_FAIL_COND_V_MSG(!is_accessible_from_caller_thread(), (m_ret), "Caller thread can't call this function in this node. Use call_deferred() or call_thread_group() instead.")
-#define ERR_MAIN_THREAD_GUARD ERR_FAIL_COND_MSG(is_inside_tree() && !Thread::is_main_thread(), "This function in this node can only be accessed from the main thread. Use call_deferred() instead.");
-#define ERR_MAIN_THREAD_GUARD_V(m_ret) ERR_FAIL_COND_V_MSG(is_inside_tree() && !Thread::is_main_thread(), (m_ret), "This function in this node can only be accessed from the main thread. Use call_deferred() instead.")
+#define ERR_MAIN_THREAD_GUARD ERR_FAIL_COND_MSG(is_inside_tree() && !is_current_thread_safe_for_nodes(), "This function in this node can only be accessed from the main thread. Use call_deferred() instead.");
+#define ERR_MAIN_THREAD_GUARD_V(m_ret) ERR_FAIL_COND_V_MSG(is_inside_tree() && !is_current_thread_safe_for_nodes(), (m_ret), "This function in this node can only be accessed from the main thread. Use call_deferred() instead.")
 #define ERR_READ_THREAD_GUARD ERR_FAIL_COND_MSG(!is_readable_from_caller_thread(), "This function in this node can only be accessed from either the main thread or a thread group. Use call_deferred() instead.")
 #define ERR_READ_THREAD_GUARD_V(m_ret) ERR_FAIL_COND_V_MSG(!is_readable_from_caller_thread(), (m_ret), "This function in this node can only be accessed from either the main thread or a thread group. Use call_deferred() instead.")
 #else