GDScript: Fix lambda hot reloading

modules/gdscript/gdscript.cpp

@@ -1386,6 +1386,36 @@ String GDScript::debug_get_script_name(const Ref<Script> &p_script) {
 }
 #endif
 
+thread_local GDScript::UpdatableFuncPtr GDScript::func_ptrs_to_update_thread_local;
+
+GDScript::UpdatableFuncPtrElement GDScript::_add_func_ptr_to_update(GDScriptFunction **p_func_ptr_ptr) {
+	UpdatableFuncPtrElement result = {};
+
+	{
+		MutexLock lock(func_ptrs_to_update_thread_local.mutex);
+		result.element = func_ptrs_to_update_thread_local.ptrs.push_back(p_func_ptr_ptr);
+		result.mutex = &func_ptrs_to_update_thread_local.mutex;
+
+		if (likely(func_ptrs_to_update_thread_local.initialized)) {
+			return result;
+		}
+
+		func_ptrs_to_update_thread_local.initialized = true;
+	}
+
+	MutexLock lock(func_ptrs_to_update_mutex);
+	func_ptrs_to_update.push_back(&func_ptrs_to_update_thread_local);
+
+	return result;
+}
+
+void GDScript::_remove_func_ptr_to_update(const UpdatableFuncPtrElement p_func_ptr_element) {
+	ERR_FAIL_NULL(p_func_ptr_element.element);
+	ERR_FAIL_NULL(p_func_ptr_element.mutex);
+	MutexLock lock(*p_func_ptr_element.mutex);
+	p_func_ptr_element.element->erase();
+}
+
 void GDScript::clear(ClearData *p_clear_data) {
 	if (clearing) {
 		return;
@@ -1403,6 +1433,16 @@ void GDScript::clear(ClearData *p_clear_data) {
 		is_root = true;
 	}
 
+	{
+		MutexLock outer_lock(func_ptrs_to_update_mutex);
+		for (UpdatableFuncPtr *updatable : func_ptrs_to_update) {
+			MutexLock inner_lock(updatable->mutex);
+			for (GDScriptFunction **func_ptr_ptr : updatable->ptrs) {
+				*func_ptr_ptr = nullptr;
+			}
+		}
+	}
+
 	RBSet<GDScript *> must_clear_dependencies = get_must_clear_dependencies();
 	for (GDScript *E : must_clear_dependencies) {
 		clear_data->scripts.insert(E);

modules/gdscript/gdscript.h

@@ -86,6 +86,8 @@ class GDScript : public Script {
 	friend class GDScriptAnalyzer;
 	friend class GDScriptCompiler;
 	friend class GDScriptDocGen;
+	friend class GDScriptLambdaCallable;
+	friend class GDScriptLambdaSelfCallable;
 	friend class GDScriptLanguage;
 	friend struct GDScriptUtilityFunctionsDefinitions;
 
@@ -108,6 +110,30 @@ class GDScript : public Script {
 	HashMap<StringName, MethodInfo> _signals;
 	Dictionary rpc_config;
 
+	struct LambdaInfo {
+		int capture_count;
+		bool use_self;
+	};
+
+	HashMap<GDScriptFunction *, LambdaInfo> lambda_info;
+
+	// List is used here because a ptr to elements are stored, so the memory locations need to be stable
+	struct UpdatableFuncPtr {
+		List<GDScriptFunction **> ptrs;
+		Mutex mutex;
+		bool initialized = false;
+	};
+	struct UpdatableFuncPtrElement {
+		List<GDScriptFunction **>::Element *element = nullptr;
+		Mutex *mutex = nullptr;
+	};
+	static thread_local UpdatableFuncPtr func_ptrs_to_update_thread_local;
+	List<UpdatableFuncPtr *> func_ptrs_to_update;
+	Mutex func_ptrs_to_update_mutex;
+
+	UpdatableFuncPtrElement _add_func_ptr_to_update(GDScriptFunction **p_func_ptr_ptr);
+	static void _remove_func_ptr_to_update(const UpdatableFuncPtrElement p_func_ptr_element);
+
 #ifdef TOOLS_ENABLED
 	// For static data storage during hot-reloading.
 	HashMap<StringName, MemberInfo> old_static_variables_indices;

modules/gdscript/gdscript_compiler.cpp

@@ -1371,6 +1371,7 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 				return GDScriptCodeGenerator::Address();
 			}
 
+			main_script->lambda_info.insert(function, { lambda->captures.size(), lambda->use_self });
 			gen->write_lambda(result, function, captures, lambda->use_self);
 
 			for (int i = 0; i < captures.size(); i++) {
@@ -2631,6 +2632,7 @@ Error GDScriptCompiler::_prepare_compilation(GDScript *p_script, const GDScriptP
 	p_script->implicit_ready = nullptr;
 	p_script->static_initializer = nullptr;
 	p_script->rpc_config.clear();
+	p_script->lambda_info.clear();
 
 	p_script->clearing = false;
 
@@ -3040,6 +3042,128 @@ void GDScriptCompiler::make_scripts(GDScript *p_script, const GDScriptParser::Cl
 	}
 }
 
+GDScriptCompiler::FunctionLambdaInfo GDScriptCompiler::_get_function_replacement_info(GDScriptFunction *p_func, int p_index, int p_depth, GDScriptFunction *p_parent_func) {
+	FunctionLambdaInfo info;
+	info.function = p_func;
+	info.parent = p_parent_func;
+	info.script = p_parent_func;
+	info.name = p_func->get_name();
+	info.line = p_func->_initial_line;
+	info.index = p_index;
+	info.depth = p_depth;
+	info.capture_count = 0;
+	info.use_self = false;
+	info.arg_count = p_func->_argument_count;
+	info.default_arg_count = p_func->_default_arg_count;
+	info.sublambdas = _get_function_lambda_replacement_info(p_func, p_depth, p_parent_func);
+
+	GDScript::LambdaInfo *extra_info = main_script->lambda_info.getptr(p_func);
+	if (extra_info != nullptr) {
+		info.capture_count = extra_info->capture_count;
+		info.use_self = extra_info->use_self;
+	}
+
+	return info;
+}
+
+Vector<GDScriptCompiler::FunctionLambdaInfo> GDScriptCompiler::_get_function_lambda_replacement_info(GDScriptFunction *p_func, int p_depth, GDScriptFunction *p_parent_func) {
+	Vector<FunctionLambdaInfo> result;
+	// Only scrape the lambdas inside p_func.
+	for (int i = 0; i < p_func->lambdas.size(); ++i) {
+		result.push_back(_get_function_replacement_info(p_func->lambdas[i], i, p_depth + 1, p_func));
+	}
+	return result;
+}
+
+GDScriptCompiler::ScriptLambdaInfo GDScriptCompiler::_get_script_lambda_replacement_info(GDScript *p_script) {
+	ScriptLambdaInfo info;
+
+	if (p_script->implicit_initializer) {
+		info.implicit_initializer_info = _get_function_lambda_replacement_info(p_script->implicit_initializer);
+	}
+	if (p_script->implicit_ready) {
+		info.implicit_ready_info = _get_function_lambda_replacement_info(p_script->implicit_ready);
+	}
+	if (p_script->static_initializer) {
+		info.static_initializer_info = _get_function_lambda_replacement_info(p_script->static_initializer);
+	}
+
+	for (const KeyValue<StringName, GDScriptFunction *> &E : p_script->member_functions) {
+		info.member_function_infos.insert(E.key, _get_function_lambda_replacement_info(E.value));
+	}
+
+	for (const KeyValue<StringName, Ref<GDScript>> &KV : p_script->get_subclasses()) {
+		info.subclass_info.insert(KV.key, _get_script_lambda_replacement_info(KV.value.ptr()));
+	}
+
+	return info;
+}
+
+bool GDScriptCompiler::_do_function_infos_match(const FunctionLambdaInfo &p_old_info, const FunctionLambdaInfo *p_new_info) {
+	if (p_new_info == nullptr) {
+		return false;
+	}
+
+	if (p_new_info->capture_count != p_old_info.capture_count || p_new_info->use_self != p_old_info.use_self) {
+		return false;
+	}
+
+	int old_required_arg_count = p_old_info.arg_count - p_old_info.default_arg_count;
+	int new_required_arg_count = p_new_info->arg_count - p_new_info->default_arg_count;
+	if (new_required_arg_count > old_required_arg_count || p_new_info->arg_count < old_required_arg_count) {
+		return false;
+	}
+
+	return true;
+}
+
+void GDScriptCompiler::_get_function_ptr_replacements(HashMap<GDScriptFunction *, GDScriptFunction *> &r_replacements, const FunctionLambdaInfo &p_old_info, const FunctionLambdaInfo *p_new_info) {
+	ERR_FAIL_COND(r_replacements.has(p_old_info.function));
+	if (!_do_function_infos_match(p_old_info, p_new_info)) {
+		p_new_info = nullptr;
+	}
+
+	r_replacements.insert(p_old_info.function, p_new_info != nullptr ? p_new_info->function : nullptr);
+	_get_function_ptr_replacements(r_replacements, p_old_info.sublambdas, p_new_info != nullptr ? &p_new_info->sublambdas : nullptr);
+}
+
+void GDScriptCompiler::_get_function_ptr_replacements(HashMap<GDScriptFunction *, GDScriptFunction *> &r_replacements, const Vector<FunctionLambdaInfo> &p_old_infos, const Vector<FunctionLambdaInfo> *p_new_infos) {
+	for (int i = 0; i < p_old_infos.size(); ++i) {
+		const FunctionLambdaInfo &old_info = p_old_infos[i];
+		const FunctionLambdaInfo *new_info = nullptr;
+		if (p_new_infos != nullptr && p_new_infos->size() == p_old_infos.size()) {
+			// For now only attempt if the size is the same.
+			new_info = &p_new_infos->get(i);
+		}
+		_get_function_ptr_replacements(r_replacements, old_info, new_info);
+	}
+}
+
+void GDScriptCompiler::_get_function_ptr_replacements(HashMap<GDScriptFunction *, GDScriptFunction *> &r_replacements, const ScriptLambdaInfo &p_old_info, const ScriptLambdaInfo *p_new_info) {
+	_get_function_ptr_replacements(r_replacements, p_old_info.implicit_initializer_info, p_new_info != nullptr ? &p_new_info->implicit_initializer_info : nullptr);
+	_get_function_ptr_replacements(r_replacements, p_old_info.implicit_ready_info, p_new_info != nullptr ? &p_new_info->implicit_ready_info : nullptr);
+	_get_function_ptr_replacements(r_replacements, p_old_info.static_initializer_info, p_new_info != nullptr ? &p_new_info->static_initializer_info : nullptr);
+
+	for (const KeyValue<StringName, Vector<FunctionLambdaInfo>> &old_kv : p_old_info.member_function_infos) {
+		_get_function_ptr_replacements(r_replacements, old_kv.value, p_new_info != nullptr ? p_new_info->member_function_infos.getptr(old_kv.key) : nullptr);
+	}
+	for (int i = 0; i < p_old_info.other_function_infos.size(); ++i) {
+		const FunctionLambdaInfo &old_other_info = p_old_info.other_function_infos[i];
+		const FunctionLambdaInfo *new_other_info = nullptr;
+		if (p_new_info != nullptr && p_new_info->other_function_infos.size() == p_old_info.other_function_infos.size()) {
+			// For now only attempt if the size is the same.
+			new_other_info = &p_new_info->other_function_infos[i];
+		}
+		// Needs to be called on all old lambdas, even if there's no replacement.
+		_get_function_ptr_replacements(r_replacements, old_other_info, new_other_info);
+	}
+	for (const KeyValue<StringName, ScriptLambdaInfo> &old_kv : p_old_info.subclass_info) {
+		const ScriptLambdaInfo &old_subinfo = old_kv.value;
+		const ScriptLambdaInfo *new_subinfo = p_new_info != nullptr ? p_new_info->subclass_info.getptr(old_kv.key) : nullptr;
+		_get_function_ptr_replacements(r_replacements, old_subinfo, new_subinfo);
+	}
+}
+
 Error GDScriptCompiler::compile(const GDScriptParser *p_parser, GDScript *p_script, bool p_keep_state) {
 	err_line = -1;
 	err_column = -1;
@@ -3050,6 +3174,8 @@ Error GDScriptCompiler::compile(const GDScriptParser *p_parser, GDScript *p_scri
 
 	source = p_script->get_path();
 
+	ScriptLambdaInfo old_lambda_info = _get_script_lambda_replacement_info(p_script);
+
 	// Create scripts for subclasses beforehand so they can be referenced
 	make_scripts(p_script, root, p_keep_state);
 
@@ -3065,6 +3191,27 @@ Error GDScriptCompiler::compile(const GDScriptParser *p_parser, GDScript *p_scri
 		return err;
 	}
 
+	ScriptLambdaInfo new_lambda_info = _get_script_lambda_replacement_info(p_script);
+
+	HashMap<GDScriptFunction *, GDScriptFunction *> func_ptr_replacements;
+	_get_function_ptr_replacements(func_ptr_replacements, old_lambda_info, &new_lambda_info);
+
+	{
+		MutexLock outer_lock(main_script->func_ptrs_to_update_mutex);
+		for (GDScript::UpdatableFuncPtr *updatable : main_script->func_ptrs_to_update) {
+			MutexLock inner_lock(updatable->mutex);
+			for (GDScriptFunction **func_ptr_ptr : updatable->ptrs) {
+				GDScriptFunction **replacement = func_ptr_replacements.getptr(*func_ptr_ptr);
+				if (replacement != nullptr) {
+					*func_ptr_ptr = *replacement;
+				} else {
+					// Probably a lambda from another reload, ignore.
+					*func_ptr_ptr = nullptr;
+				}
+			}
+		}
+	}
+
 	if (has_static_data && !root->annotated_static_unload) {
 		GDScriptCache::add_static_script(p_script);
 	}

modules/gdscript/gdscript_compiler.h

@@ -44,6 +44,34 @@ class GDScriptCompiler {
 	HashSet<GDScript *> parsing_classes;
 	GDScript *main_script = nullptr;
 
+	struct FunctionLambdaInfo {
+		GDScriptFunction *function;
+		GDScriptFunction *parent;
+		Ref<GDScript> script;
+		StringName name;
+		int line;
+		int index;
+		int depth;
+		//uint64_t code_hash;
+		//int code_size;
+		int capture_count;
+		int use_self;
+		int arg_count;
+		int default_arg_count;
+		//Vector<GDScriptDataType> argument_types;
+		//GDScriptDataType return_type;
+		Vector<FunctionLambdaInfo> sublambdas;
+	};
+
+	struct ScriptLambdaInfo {
+		Vector<FunctionLambdaInfo> implicit_initializer_info;
+		Vector<FunctionLambdaInfo> implicit_ready_info;
+		Vector<FunctionLambdaInfo> static_initializer_info;
+		HashMap<StringName, Vector<FunctionLambdaInfo>> member_function_infos;
+		Vector<FunctionLambdaInfo> other_function_infos;
+		HashMap<StringName, ScriptLambdaInfo> subclass_info;
+	};
+
 	struct CodeGen {
 		GDScript *script = nullptr;
 		const GDScriptParser::ClassNode *class_node = nullptr;
@@ -137,6 +165,13 @@ class GDScriptCompiler {
 	Error _parse_setter_getter(GDScript *p_script, const GDScriptParser::ClassNode *p_class, const GDScriptParser::VariableNode *p_variable, bool p_is_setter);
 	Error _prepare_compilation(GDScript *p_script, const GDScriptParser::ClassNode *p_class, bool p_keep_state);
 	Error _compile_class(GDScript *p_script, const GDScriptParser::ClassNode *p_class, bool p_keep_state);
+	FunctionLambdaInfo _get_function_replacement_info(GDScriptFunction *p_func, int p_index = -1, int p_depth = 0, GDScriptFunction *p_parent_func = nullptr);
+	Vector<FunctionLambdaInfo> _get_function_lambda_replacement_info(GDScriptFunction *p_func, int p_depth = 0, GDScriptFunction *p_parent_func = nullptr);
+	ScriptLambdaInfo _get_script_lambda_replacement_info(GDScript *p_script);
+	bool _do_function_infos_match(const FunctionLambdaInfo &p_old_info, const FunctionLambdaInfo *p_new_info);
+	void _get_function_ptr_replacements(HashMap<GDScriptFunction *, GDScriptFunction *> &r_replacements, const FunctionLambdaInfo &p_old_info, const FunctionLambdaInfo *p_new_info);
+	void _get_function_ptr_replacements(HashMap<GDScriptFunction *, GDScriptFunction *> &r_replacements, const Vector<FunctionLambdaInfo> &p_old_infos, const Vector<FunctionLambdaInfo> *p_new_infos);
+	void _get_function_ptr_replacements(HashMap<GDScriptFunction *, GDScriptFunction *> &r_replacements, const ScriptLambdaInfo &p_old_info, const ScriptLambdaInfo *p_new_info);
 	int err_line = 0;
 	int err_column = 0;
 	StringName source;