Merge pull request #78974 from RandomShaper/fix_wtp_safe_flag

Fix management of safe-for-nodes flag in ResourceLoader and WorkerThreadPool

core/io/resource_loader.cpp

@@ -309,6 +309,10 @@ void ResourceLoader::_thread_load_function(void *p_userdata) {
 	}
 	// --
 
+	if (!Thread::is_main_thread()) {
+		set_current_thread_safe_for_nodes(true);
+	}
+
 	Ref<Resource> res = _load(load_task.remapped_path, load_task.remapped_path != load_task.local_path ? load_task.local_path : String(), load_task.type_hint, load_task.cache_mode, &load_task.error, load_task.use_sub_threads, &load_task.progress);
 	if (mq_override) {
 		mq_override->flush();

core/object/worker_thread_pool.cpp

@@ -56,6 +56,8 @@ void WorkerThreadPool::_process_task(Task *p_task) {
 	Task *prev_low_prio_task = nullptr; // In case this is recursively called.
 
 	if (!use_native_low_priority_threads) {
+		// Tasks must start with this unset. They are free to set-and-forget otherwise.
+		set_current_thread_safe_for_nodes(false);
 		pool_thread_index = thread_ids[Thread::get_caller_id()];
 		ThreadData &curr_thread = threads[pool_thread_index];
 		task_mutex.lock();
@@ -179,9 +181,6 @@ void WorkerThreadPool::_process_task(Task *p_task) {
 		if (post) {
 			task_available_semaphore.post();
 		}
-
-		// Engine/user tasks can set-and-forget, so we must be sure it's back to normal by the end of the task.
-		set_current_thread_safe_for_nodes(false);
 	}
 }
 
@@ -371,7 +370,9 @@ Error WorkerThreadPool::wait_for_task_completion(TaskID p_task_id) {
 								must_exit = true;
 							} else {
 								// Solve tasks while they are around.
+								bool safe_for_nodes_backup = is_current_thread_safe_for_nodes();
 								_process_task_queue();
+								set_current_thread_safe_for_nodes(safe_for_nodes_backup);
 								continue;
 							}
 						} else if (!use_native_low_priority_threads && task->low_priority) {