Qt timer can't stop bleak's notify.

[ChienHao-Hung]

• bleak version:0.20.0
• Python version: 3.11.4
• Operating System: windows 11

Description

I integrated Bleak into a Qt application. I found that when using Qtimer to close the notification, there will be a problem and notify cannot be stopped.

What I Did

My code

class MainWindow(QMainWindow):
    # device discovery signal
    devices_discovery_signal = Signal()
    devices_discovery_end_signal = Signal()
    connect_signal = Signal()
    disconnect_signal = Signal()
    start_notify_signal = Signal()
    start_notify_end_signal = Signal()
    stop_notify_signal = Signal()
    stop_notify_end_signal = Signal()

    def __init__(self):
        super().__init__()
        self.devices = []
        self.devices_addr = []
        self.ui = Ui_VTCSensorEvaluation()
        self.ui.setupUi(self)
        self.ui.pushButton_3.clicked.connect(self.async_start_device_discovery)
        self.ui.pushButton.clicked.connect(self.connect_device_click)
        self.ui.pushButton_2.clicked.connect(self.start_notify_click)
        self.ui.pushButton_2.setEnabled(False)
        self.myclass = myclass()
        self.update_timer = QTimer(self)
        self.ui.pushButton_5.clicked.connect(self.calculate_data_bias)
        self.bias_num = 0
        self.call_num = 0
        
        self.Ble = Ble_inst(self.update_device_list ,self.connect_status_update,self.receive_data_cb)
        self.ui.ini_ui()
    
    def update_data_timer_func(self):
        datas = self.myclass.ret_cali_data()
        if(datas == None):
            return
        self.ui.sensor_message_update("acc = {},{},{}".format(round(datas[0],2),round(datas[1],2),round(datas[2],2)))
        self.ui.sensor_message_update("mag = {},{},{}".format(round(datas[3],2),round(datas[4],2),round(datas[5],2)))
        self.ui.sensor_message_update("gyro = {},{},{}".format(round(datas[6],2),round(datas[7],2),round(datas[8],2)))
        self.ui.sensor_message_update("")
        return
    def close_notify(self):
        self.start_notify_end_signal.emit()
        self.stop_notify_signal.emit()
        self.stop_notify_end_signal.emit()
        return 
    

        

    def update_device_list(self,dev_list):
        self.ui.common_message_update("search the device")
        self.ui.comboBox.clear()
        self.ui.comboBox.addItems(dev_list)
        self.devices_discovery_end_signal.emit()
        return
    @Slot()
    def async_start_device_discovery(self):
        self.devices_discovery_signal.emit()
        return
    def connect_status_update(self,flag):
        self.ui.pushButton.setEnabled(flag)
        self.ui.pushButton_2.setEnabled(not(flag))
        self.ui.pushButton_2.setText("Run Compass")
        if(flag == False):
            self.ui.common_message_update("Connect Successfully....")
        else :
            self.ui.common_message_update("Connect Failed.....")
        return
    def receive_data_cb(self,ax,ay,az,mx,my,mz,gx,gy,gz):
        self.myclass.do_cali_data(ax,ay,az,mx,my,mz,gx,gy,gz)        
        # print("acc data:",round(ax,2),round(ay,2),round(az,2))
        # print("mag data:",round(mx,2),round(my,2),round(mz,2))
        # print("gyro data:",round(gx,2),round(gy,2),round(gz,2))
        return 
    def connect_device_click(self):
        self.ui.pushButton.setEnabled(False)
        ind = self.ui.comboBox.currentIndex()
        if(ind == 0):
            return 
        self.Ble.set_con_index(ind)
        self.ui.common_message_update("connect the device({})".format(self.ui.comboBox.currentText()))
        self.connect_signal.emit()
        return
    
    def start_notify_click(self):
        print("click Run")
        if(self.ui.pushButton_2.text() == "Run Compass"):
            print("Run select A")
            self.ui.common_message_update("start the notification....")
            self.stop_notify_end_signal.emit()
            self.start_notify_signal.emit()
            self.ui.pushButton_2.setText("Stop Compass")
            self.update_timer.timeout.connect(self.update_data_timer_func)
            self.update_timer.start(10)
            # self.start_notify_end_signal.emit()
        elif(self.ui.pushButton_2.text() == "Stop Compass"):
            print("Run select B")
            self.ui.common_message_update("stop the notification....")
            self.close_notify()
            self.ui.pushButton_2.setText("Run Compass")
            self.update_timer.stop()
        return
    
    def calculate_data_bias(self):
        tmp_txt = self.ui.plainTextEdit_30.toPlainText()
        try:
            self.bias_num = int(tmp_txt)
            if(self.bias_num > 1024):
                self.ui.common_message_update("The number is bigger than 1024.")
                return
            if(self.bias_num <= 0):
                self.ui.common_message_update("The number is less than 1.")
                return
        except:
            self.ui.common_message_update("Text cannot be converted to a number")
            return
        self.call_num = 0
        self.myclass.init_bias_container()
        self.start_notify_signal.emit()
        self.update_timer.timeout.connect(self.close_notify)
        self.update_timer.start(1000)
        return

 class Ble_inst(QObject):

    def __init__(self, update_func ,connect_status_func,rec_func):
        super().__init__()
        self.devices_addr = []
        self.devices = []
        self.client = bleak.BleakClient("FF:FF:FF:FF:FF:FF")
        self.list_upadte = update_func
        self.con_status_func = connect_status_func
        self.con_index = -1
        self.recieve_data = rec_func
        return
    
    async def add_device(self):
        devices = await bleak.BleakScanner.discover()
        self.devices = [""]
        self.devices_addr = [""]
        for d in devices:
            if(d.name != None):
                self.devices.append(d.name)
                self.devices_addr.append(d.address)
                print(d.name)
        self.list_upadte(self.devices)
    
    def disconnect_cb(self,client):
        self.con_status_func(True)
        print("connect loss....")
        return
    def set_con_index(self,index):
        self.con_index = index
        return 

    async def connect_device_func(self):
        self.client = bleak.BleakClient(self.devices_addr[self.con_index],disconnected_callback=self.disconnect_cb)
        await self.client.connect()
        if(self.client.is_connected):
            self.con_status_func(False)
        return
    
    def receive_notify_cb(self,uuid,barray):
        ........
        return 
    async def stop_notify(self):
        print("stop notify....")
        await self.client.stop_notify(target_char)
        return
    async def start_notify(self):
        print("start notify.....")
        await self.client.start_notify(target_char,self.receive_notify_cb)
        return

Logs

Error Log

Task exception was never retrieved
future: <Task finished name='Task-38' coro=<Ble_inst.stop_notify() done, defined at d:\workstation\VTC_display\Ble_instance.py:71> exception=KeyError(15)>      
Traceback (most recent call last):
  File "d:\workstation\VTC_display\Ble_instance.py", line 73, in stop_notify
    await self.client.stop_notify(target_char)
  File "C:\Users\isly8\anaconda3\Lib\site-packages\bleak\__init__.py", line 852, in stop_notify
    await self._backend.stop_notify(char_specifier)
  File "C:\Users\isly8\anaconda3\Lib\site-packages\bleak\backends\winrt\client.py", line 1020, in stop_notify
    event_handler_token = self._notification_callbacks.pop(characteristic.handle)
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: 15
Task exception was never retrieved
future: <Task finished name='Task-39' coro=<Ble_inst.stop_notify() done, defined at d:\workstation\VTC_display\Ble_instance.py:71> exception=KeyError(15)>      
Traceback (most recent call last):
  File "d:\workstation\VTC_display\Ble_instance.py", line 73, in stop_notify
    await self.client.stop_notify(target_char)
  File "C:\Users\isly8\anaconda3\Lib\site-packages\bleak\__init__.py", line 852, in stop_notify
    await self._backend.stop_notify(char_specifier)
  File "C:\Users\isly8\anaconda3\Lib\site-packages\bleak\backends\winrt\client.py", line 1020, in stop_notify
    event_handler_token = self._notification_callbacks.pop(characteristic.handle)
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: 15

[dlech]

Since self.client can get replaced with a new object, I'm guessing stop_notify is getting called on a new instance where start_notify hasn't been called.