Solve memory leak with return values related to functions, now instead of deleting the return value (which forces to delete the lambda callback when it is anonymous as it does not have references to any handle) we created a finalizer (for old NodeJS versions and newer ones) which deletes the value when it is garbage collected instead of inmedietly after the return.

Author: viferga

source/ports/node_port/source/node_port.cpp

@@ -677,7 +677,9 @@ napi_value metacall_node_call(napi_env env, napi_callback_info info)
 	char name[FUNCTION_NAME_LENGTH];
 	size_t name_length;
 
-	napi_get_value_string_utf8(env, argv[0], name, FUNCTION_NAME_LENGTH, &name_length);
+	napi_status status = napi_get_value_string_utf8(env, argv[0], name, FUNCTION_NAME_LENGTH, &name_length);
+
+	metacall_node_exception(env, status);
 
 	for (size_t i = 1; i < argc; i++)
 	{
@@ -693,7 +695,47 @@ napi_value metacall_node_call(napi_env env, napi_callback_info info)
 
 	napi_value result = metacall_node_value_to_napi(env, ret);
 
-	metacall_value_destroy(ret);
+	auto finalizer = [](napi_env, void * finalize_data, void *)
+	{
+		metacall_value_destroy(finalize_data);
+	};
+
+	// Create a finalizer for the value
+	#if (NAPI_VERSION < 5)
+	{
+		napi_value symbol, external;
+
+		status = napi_create_symbol(env, nullptr, &symbol);
+
+		metacall_node_exception(env, status);
+
+		status = napi_create_external(env, ret, finalizer, nullptr, &external);
+
+		metacall_node_exception(env, status);
+
+		napi_property_descriptor desc =
+		{
+			nullptr,
+			symbol,
+			nullptr,
+			nullptr,
+			nullptr,
+			external,
+			napi_default,
+			nullptr
+		};
+
+		status = napi_define_properties(env, result, 1, &desc);
+
+		metacall_node_exception(env, status);
+	}
+	#else // NAPI_VERSION >= 5
+	{
+		status = napi_add_finalizer(env, result, ret, finalizer, nullptr, nullptr);
+
+		metacall_node_exception(env, status);
+	}
+	#endif
 
 	return result;
 }
@@ -727,7 +769,7 @@ napi_value metacall_node_load_from_file(napi_env env, napi_callback_info info)
 	int met_result = metacall_load_from_file(tagBuf, file_name_strings, sizeof(file_name_strings)/sizeof(file_name_strings[0]), NULL);
 	if (met_result > 0)
 	{
-		napi_throw_error(env, NULL, "Metacall could not load from file");
+		napi_throw_error(env, NULL, "MetaCall could not load from file");
 		return NULL;
 	}
 
@@ -773,7 +815,7 @@ napi_value metacall_node_load_from_memory(napi_env env, napi_callback_info info)
 
 	if (tag == NULL)
 	{
-		napi_throw_error(env, NULL, "Metacall could not load from memory, tag allocation failed");
+		napi_throw_error(env, NULL, "MetaCall could not load from memory, tag allocation failed");
 		return NULL;
 	}
 
@@ -792,7 +834,7 @@ napi_value metacall_node_load_from_memory(napi_env env, napi_callback_info info)
 
 	if (script == NULL)
 	{
-		napi_throw_error(env, NULL, "Metacall could not load from memory, script allocation failed");
+		napi_throw_error(env, NULL, "MetaCall could not load from memory, script allocation failed");
 		return NULL;
 	}
 
@@ -804,7 +846,7 @@ napi_value metacall_node_load_from_memory(napi_env env, napi_callback_info info)
 	// Load script from memory
 	if (metacall_load_from_memory(tag, script, script_length, NULL) != 0)
 	{
-		napi_throw_error(env, NULL, "Metacall could not load from memory");
+		napi_throw_error(env, NULL, "MetaCall could not load from memory");
 		return NULL;
 	}
 

source/ports/node_port/test/index.js

@@ -124,11 +124,9 @@ describe('metacall', () => {
 			}, 2, 3), 10);
 
 			// Passing callback as a return value
-			/*
 			const callback = f.function_ret_lambda(10);
 			assert.notStrictEqual(callback, undefined);
 			assert.strictEqual(callback(3), 30);
-			*/
 		});
 	});
 });