Fix BLE companion transport reliability

scripts/pi-car-companion-bluetooth

@@ -21,8 +21,6 @@ DBUS_PROPERTIES = "org.freedesktop.DBus.Properties"
 GATT_MANAGER = "org.bluez.GattManager1"
 GATT_SERVICE = "org.bluez.GattService1"
 GATT_CHARACTERISTIC = "org.bluez.GattCharacteristic1"
-AD_MANAGER = "org.bluez.LEAdvertisingManager1"
-ADVERTISEMENT = "org.bluez.LEAdvertisement1"
 
 SERVICE_UUID = "6c7a0001-7c6d-4f74-9bb0-c5a4e5efc001"
 RX_UUID = "6c7a0002-7c6d-4f74-9bb0-c5a4e5efc001"
@@ -103,19 +101,30 @@ class Characteristic(dbus.service.Object):
 
 class TxCharacteristic(Characteristic):
     def __init__(self, bus, service):
-        super().__init__(bus, 1, TX_UUID, ["notify"], service)
+        super().__init__(bus, 1, TX_UUID, ["indicate"], service)
         self.notifying = False
         self.queue = deque()
         self.sending = False
 
-    @dbus.service.method(GATT_CHARACTERISTIC, in_signature="a{sv}")
-    def StartNotify(self, _options):
+    @dbus.service.method(GATT_CHARACTERISTIC)
+    def StartNotify(self):
         self.notifying = True
+        if self.queue and not self.sending:
+            self.sending = True
+            GLib.idle_add(self._send_next)
 
-    @dbus.service.method(GATT_CHARACTERISTIC, in_signature="a{sv}")
-    def StopNotify(self, _options):
+    @dbus.service.method(GATT_CHARACTERISTIC)
+    def StopNotify(self):
         self.notifying = False
         self.queue.clear()
+        self.sending = False
+
+    @dbus.service.method(GATT_CHARACTERISTIC)
+    def Confirm(self):
+        if self.queue:
+            GLib.idle_add(self._send_next)
+        else:
+            self.sending = False
 
     def send(self, message):
         encoded = (json.dumps(message, separators=(",", ":")) + "\n").encode("utf-8")
@@ -123,7 +132,7 @@ class TxCharacteristic(Characteristic):
             self.queue.append(encoded[offset:offset + NOTIFY_CHUNK_BYTES])
         if not self.sending:
             self.sending = True
-            GLib.timeout_add(20, self._send_next)
+            GLib.idle_add(self._send_next)
 
     def _send_next(self):
         if not self.notifying or not self.queue:
@@ -132,7 +141,7 @@ class TxCharacteristic(Characteristic):
         chunk = self.queue.popleft()
         value = dbus.Array([dbus.Byte(byte) for byte in chunk], signature="y")
         self.PropertiesChanged(GATT_CHARACTERISTIC, {"Value": value}, [])
-        return bool(self.queue)
+        return False
 
 
 class RxCharacteristic(Characteristic):
@@ -216,26 +225,10 @@ def call_api(method, path, body, token):
         raise ProtocolError("PI_SERVICE_UNAVAILABLE", "The Pi companion service is unavailable") from error
 
 
-class Advertisement(dbus.service.Object):
-    def __init__(self, bus):
-        self.path = "/org/pi_car_companion/advertisement0"
-        super().__init__(bus, self.path)
-
-    @dbus.service.method(DBUS_PROPERTIES, in_signature="s", out_signature="a{sv}")
-    def GetAll(self, interface):
-        if interface != ADVERTISEMENT:
-            raise InvalidArgs()
-        return {"Type": "peripheral", "ServiceUUIDs": dbus.Array([SERVICE_UUID], signature="s"), "LocalName": "Pi Car"}
-
-    @dbus.service.method(ADVERTISEMENT)
-    def Release(self):
-        pass
-
-
 def find_adapter(bus):
     objects = dbus.Interface(bus.get_object(BLUEZ, "/"), DBUS_OM).GetManagedObjects()
     for path, interfaces in objects.items():
-        if GATT_MANAGER in interfaces and AD_MANAGER in interfaces:
+        if GATT_MANAGER in interfaces:
             return path
     raise RuntimeError("No Bluetooth LE adapter with GATT server support was found")
 
@@ -253,10 +246,22 @@ def main():
     service.add_characteristic(rx)
     service.add_characteristic(tx)
     application.add_service(service)
-    advertisement = Advertisement(bus)
-    dbus.Interface(adapter, GATT_MANAGER).RegisterApplication(application.path, {}, reply_handler=lambda: None, error_handler=lambda error: (_ for _ in ()).throw(error))
-    dbus.Interface(adapter, AD_MANAGER).RegisterAdvertisement(advertisement.path, {}, reply_handler=lambda: None, error_handler=lambda error: (_ for _ in ()).throw(error))
-    GLib.MainLoop().run()
+    loop = GLib.MainLoop()
+    registration_errors = []
+
+    def registration_failed(error):
+        registration_errors.append(error)
+        loop.quit()
+
+    dbus.Interface(adapter, GATT_MANAGER).RegisterApplication(
+        application.path,
+        {},
+        reply_handler=lambda: None,
+        error_handler=registration_failed,
+    )
+    loop.run()
+    if registration_errors:
+        raise registration_errors[0]
 
 
 if __name__ == "__main__":