fixed race condition when writing prefabs during fbx import

src/engine/job_system.cpp

@@ -379,7 +379,7 @@ bool init(u8 workers_count, IAllocator& allocator)
 
 	int count = maximum(1, int(workers_count));
 	for (int i = 0; i < count; ++i) {
-		WorkerTask* task = LUMIX_NEW(getAllocator(), WorkerTask)(*g_system, i < 64 ? u64(1) << i : 0);
+		WorkerTask* task = LUMIX_NEW(getAllocator(), WorkerTask)(*g_system, i);
 		if (task->create("Worker", false)) {
 			task->m_is_enabled = true;
 			g_system->m_workers.push(task);
@@ -499,4 +499,45 @@ void wait(Signal* handle) {
 	waitEx(handle, false);
 }
 
+u32 getWorkerIndex() {
+	return getWorker()->m_worker_index;
+}
+
+void moveJobToWorker(u8 worker_index) {
+	g_system->m_sync.enter();
+	FiberDecl* this_fiber = getWorker()->m_current_fiber;
+	WorkerTask* worker = g_system->m_workers[worker_index % g_system->m_workers.size()];
+	worker->m_work_queue.push(this_fiber, &g_system->m_job_queue_sync);
+	wake();
+	FiberDecl* new_fiber = g_system->m_free_fibers.back();
+	g_system->m_free_fibers.pop();
+	if (!Fiber::isValid(new_fiber->fiber)) {
+		new_fiber->fiber = Fiber::create(64 * 1024, manage, new_fiber);
+	}
+	getWorker()->m_current_fiber = new_fiber;
+	this_fiber->current_job.worker_index = worker_index;
+	Fiber::switchTo(&this_fiber->fiber, new_fiber->fiber);
+	getWorker()->m_current_fiber = this_fiber;
+	ASSERT(getWorker()->m_worker_index == worker_index);
+	g_system->m_sync.exit();
+}
+
+void yield() {
+	g_system->m_sync.enter();
+	FiberDecl* this_fiber = getWorker()->m_current_fiber;
+	g_system->m_work_queue.push(this_fiber, &g_system->m_job_queue_sync);
+
+	wake();
+	FiberDecl* new_fiber = g_system->m_free_fibers.back();
+	g_system->m_free_fibers.pop();
+	if (!Fiber::isValid(new_fiber->fiber)) {
+		new_fiber->fiber = Fiber::create(64 * 1024, manage, new_fiber);
+	}
+	this_fiber->current_job.worker_index = ANY_WORKER;
+	getWorker()->m_current_fiber = new_fiber;
+	Fiber::switchTo(&this_fiber->fiber, new_fiber->fiber);
+	g_system->m_sync.exit();
+}
+
+
 } // namespace Lumix::jobs

src/engine/job_system.h

@@ -19,6 +19,10 @@ LUMIX_ENGINE_API void shutdown();
 LUMIX_ENGINE_API u8 getWorkersCount();
 
 LUMIX_ENGINE_API void enableBackupWorker(bool enable);
+// yield current job and push it to worker queue
+LUMIX_ENGINE_API void moveJobToWorker(u8 worker_index);
+// yield current job, push it to global queue
+LUMIX_ENGINE_API void yield();
 
 LUMIX_ENGINE_API void enter(Mutex* mutex);
 LUMIX_ENGINE_API void exit(Mutex* mutex);

src/renderer/editor/fbx_importer.cpp

@@ -2586,7 +2586,6 @@ bool FBXImporter::writePhysicsPrefab(const Path& src, const ImportConfig& cfg) {
 
 bool FBXImporter::writePrefab(const Path& src, const ImportConfig& cfg)
 {
-	// TODO this is not threadsafe, since it can load/unload assets, access lua state, ...
 	Engine& engine = m_app.getEngine();
 	World& world = engine.createWorld(false);
 
@@ -2625,7 +2624,6 @@ bool FBXImporter::writePrefab(const Path& src, const ImportConfig& cfg)
 
 	world.serialize(blob, WorldSerializeFlags::NONE);
 	engine.destroyWorld(world);
-
 	if (!file.write(blob.data(), blob.size())) {
 		logError("Could not write ", tmp);
 		file.close();

src/renderer/editor/render_plugins.cpp

@@ -66,6 +66,7 @@
 
 
 using namespace Lumix;
+	static AtomicI32 xx = 0;
 
 static Animation::Flags operator | (Animation::Flags a, Animation::Flags b) {
 	return Animation::Flags(u32(a) | u32(b));
@@ -2687,7 +2688,10 @@ struct ModelPlugin final : AssetBrowser::IPlugin, AssetCompiler::IPlugin {
 		if (meta.split) {
 			cfg.origin = FBXImporter::ImportConfig::Origin::CENTER_EACH_MESH;
 			any_written = importer.writeSubmodels(filepath, cfg) || any_written;
+			// writePrefab is not threadsafe, run on "main thread"
+			jobs::moveJobToWorker(0);
 			any_written = importer.writePrefab(filepath, cfg) || any_written;
+			jobs::yield();
 		}
 		cfg.origin = meta.origin;
 		any_written = importer.writeModel(src, cfg) || any_written;
@@ -2697,7 +2701,9 @@ struct ModelPlugin final : AssetBrowser::IPlugin, AssetCompiler::IPlugin {
 		}
 		any_written = importer.writePhysics(filepath, cfg) || any_written;
 		if (meta.create_prefab_with_physics) {
+			jobs::moveJobToWorker(0);
 			importer.writePhysicsPrefab(filepath, cfg);
+			jobs::yield();
 		}
 		return any_written;
 	}