gatt_notification: Use thread pool of one thread to ensure serial processing of notification

common/gattlib_callback_notification_device.c

@@ -48,12 +48,13 @@ struct gattlib_notification_device_thread_args {
 	size_t data_length;
 };
 
-static gpointer _gattlib_notification_device_thread(gpointer data) {
+void gattlib_notification_device_thread(gpointer data, gpointer user_data) {
 	struct gattlib_notification_device_thread_args* args = data;
+	struct gattlib_handler* handler = user_data;
 
-	args->connection->notification.callback.notification_handler(
+	handler->callback.notification_handler(
 		args->uuid, args->data, args->data_length,
-		args->connection->notification.user_data
+		handler->user_data
 	);
 
 	if (args->uuid != NULL) {
@@ -62,15 +63,9 @@ static gpointer _gattlib_notification_device_thread(gpointer data) {
 	if (args->data != NULL) {
 		free(args->data);
 	}
-	return NULL;
 }
 
-static void* _notification_device_thread_args_allocator(va_list args) {
-	gatt_connection_t* connection = va_arg(args, gatt_connection_t*);
-	const uuid_t* uuid = va_arg(args, const uuid_t*);
-	const uint8_t* data = va_arg(args, const uint8_t*);
-	size_t data_length = va_arg(args, size_t);
-
+static void* _notification_device_thread_args_allocator(gatt_connection_t* connection, const uuid_t* uuid, const uint8_t* data, size_t data_length) {
 	struct gattlib_notification_device_thread_args* thread_args = malloc(sizeof(struct gattlib_notification_device_thread_args));
 	thread_args->connection = connection;
 	thread_args->uuid = malloc(sizeof(uuid_t));
@@ -87,11 +82,17 @@ static void* _notification_device_thread_args_allocator(va_list args) {
 }
 
 void gattlib_on_gatt_notification(gatt_connection_t* connection, const uuid_t* uuid, const uint8_t* data, size_t data_length) {
-	gattlib_handler_dispatch_to_thread(
-		&connection->on_connection,
-		gattlib_notification_device_python_callback /* python_callback */,
-		_gattlib_notification_device_thread /* thread_func */,
-		"gattlib_notification_device" /* thread_name */,
-		_notification_device_thread_args_allocator /* thread_args_allocator */,
-		connection, uuid, data, data_length);
+	GError *error = NULL;
+
+	assert(connection->notification.thread_pool != NULL);
+
+	void* arg = _notification_device_thread_args_allocator(connection, uuid, data, data_length);
+	if (arg == NULL) {
+		GATTLIB_LOG(GATTLIB_ERROR, "gattlib_on_gatt_notification: Failed to allocate arguments for thread");
+		return;
+	}
+	g_thread_pool_push(connection->notification.thread_pool, arg, &error);
+	if (error != NULL) {
+		GATTLIB_LOG(GATTLIB_ERROR, "gattlib_on_gatt_notification: Failed to push thread in pool: %s", error->message);
+	}
 }

common/gattlib_common.c

@@ -9,21 +9,47 @@
 #include "gattlib_internal.h"
 
 int gattlib_register_notification(gatt_connection_t* connection, gattlib_event_handler_t notification_handler, void* user_data) {
+	GError *error = NULL;
+
 	if (connection == NULL) {
 		return GATTLIB_INVALID_PARAMETER;
 	}
+
 	connection->notification.callback.notification_handler = notification_handler;
 	connection->notification.user_data = user_data;
-	return GATTLIB_SUCCESS;
+
+	connection->notification.thread_pool = g_thread_pool_new(
+		gattlib_notification_device_thread,
+		&connection->notification,
+		1 /* max_threads */, FALSE /* exclusive */, &error);
+	if (error != NULL) {
+		GATTLIB_LOG(GATTLIB_ERROR, "gattlib_register_notification: Failed to create thread pool: %s", error->message);
+		return GATTLIB_ERROR_INTERNAL;
+	} else {
+		assert(connection->notification.thread_pool != NULL);
+		return GATTLIB_SUCCESS;
+	}
 }
 
 int gattlib_register_indication(gatt_connection_t* connection, gattlib_event_handler_t indication_handler, void* user_data) {
+	GError *error = NULL;
+
 	if (connection == NULL) {
 		return GATTLIB_INVALID_PARAMETER;
 	}
 	connection->indication.callback.notification_handler = indication_handler;
 	connection->indication.user_data = user_data;
-	return GATTLIB_SUCCESS;
+
+	connection->indication.thread_pool = g_thread_pool_new(
+		gattlib_notification_device_thread,
+		&connection->indication,
+		1 /* max_threads */, FALSE /* exclusive */, &error);
+	if (error != NULL) {
+		GATTLIB_LOG(GATTLIB_ERROR, "gattlib_register_indication: Failed to create thread pool: %s", error->message);
+		return GATTLIB_ERROR_INTERNAL;
+	} else {
+		return GATTLIB_SUCCESS;
+	}
 }
 
 int gattlib_register_on_disconnect(gatt_connection_t *connection, gattlib_disconnection_handler_t handler, void* user_data) {
@@ -119,16 +145,18 @@ void gattlib_handler_free(struct gattlib_handler* handler) {
 	// Reset callback to stop calling it after we stopped
 	handler->callback.callback = NULL;
 
-	if (handler->python_args == NULL) {
-		return;
+	if (handler->python_args != NULL) {
+		struct gattlib_python_args* args = handler->python_args;
+		Py_DECREF(args->callback);
+		Py_DECREF(args->args);
+		handler->python_args = NULL;
+		free(handler->python_args);
 	}
 
-	struct gattlib_python_args* args = handler->python_args;
-	Py_DECREF(args->callback);
-	Py_DECREF(args->args);
-	free(args);
-
-	handler->python_args = NULL;
+	if (handler->thread_pool != NULL) {
+		g_thread_pool_free(handler->thread_pool, FALSE /* immediate */, TRUE /* wait */);
+		handler->thread_pool = NULL;
+	}
 }
 
 bool gattlib_has_valid_handler(struct gattlib_handler* handler) {

common/gattlib_internal_defs.h

@@ -33,6 +33,8 @@ struct gattlib_handler {
 	void* user_data;
 	// We create a thread to ensure the callback is not blocking the mainloop
 	GThread *thread;
+	// Thread pool
+	GThreadPool *thread_pool;
 	// In case of Python callback and argument, we keep track to free it when we stopped to discover BLE devices
 	void* python_args;
 };
@@ -52,6 +54,8 @@ void gattlib_handler_dispatch_to_thread(struct gattlib_handler* handler, void (*
 void gattlib_handler_free(struct gattlib_handler* handler);
 bool gattlib_has_valid_handler(struct gattlib_handler* handler);
 
+void gattlib_notification_device_thread(gpointer data, gpointer user_data);
+
 #if defined(WITH_PYTHON)
 // Callback used by Python to create arguments used by native callback
 void* gattlib_python_callback_args(PyObject* python_callback, PyObject* python_args);