wacom: disconnect when we have finished retrieving the data

There is no point keeping the connection alive just to drain the battery.

README.md

@@ -77,10 +77,11 @@ org.freedesktop.tuhi1.Device
       interactivity (e.g. the user may need to press the sync button).
 
       When the device connects, the daemon downloads all drawings from the
-      device. If successfull, the drawings are deleted from the device. The
-      data is held by the daemon in non-persistent storage until the daemon
-      is stopped or we run out of memory, whichever happens earlier.  Use
-      GetJSONData() to retrieve the data from the daemon.
+      device and disconnects from the device. If successfull, the drawings
+      are deleted from the device. The data is held by the daemon in
+      non-persistent storage until the daemon is stopped or we run out of
+      memory, whichever happens earlier.  Use GetJSONData() to retrieve the
+      data from the daemon.
 
       When drawings become available from the device, the DrawingsAvailable
       property updates to the number of available drawings.

tuhi.py

@@ -78,6 +78,7 @@ class TuhiDevice(GObject.Object):
         self._tuhi_dbus_device = tuhi_dbus_device
         self._wacom_device = WacomDevice(bluez_device)
         self._wacom_device.connect('drawing', self._on_drawing_received)
+        self._wacom_device.connect('done', self._on_fetching_finished, bluez_device)
         self.drawings = []
 
         bluez_device.connect('connected', self._on_bluez_device_connected)
@@ -123,6 +124,9 @@ class TuhiDevice(GObject.Object):
 
         self._tuhi_dbus_device.add_drawing(d)
 
+    def _on_fetching_finished(self, device, bluez_device):
+        bluez_device.disconnect_device()
+
 
 class Tuhi(GObject.Object):
     __gsignals__ = {

tuhi/ble.py

@@ -202,6 +202,24 @@ class BlueZDevice(GObject.Object):
         if isinstance(result, Exception):
             logger.error('Connection failed: {}'.format(result))
 
+    def disconnect_device(self):
+        """
+        Disconnect the bluetooth device via bluez. This function is
+        asynchronous and returns immediately.
+        """
+        i = self.obj.get_interface(ORG_BLUEZ_DEVICE1)
+        if not i.get_cached_property('Connected').get_boolean():
+            logger.info('{}: Device is already disconnected'.format(self.address))
+            self.emit('disconnected')
+            return
+
+        logger.info('{}: Disconnecting'.format(self.address))
+        i.Disconnect(result_handler=self._on_disconnect_result)
+
+    def _on_disconnect_result(self, obj, result, user_data):
+        if isinstance(result, Exception):
+            logger.error('Disconnection failed: {}'.format(result))
+
     def _on_properties_changed(self, obj, properties, invalidated_properties):
         properties = properties.unpack()
 

tuhi/wacom.py

@@ -121,6 +121,8 @@ class WacomDevice(GObject.Object):
     __gsignals__ = {
         "drawing":
             (GObject.SIGNAL_RUN_FIRST, None, (GObject.TYPE_PYOBJECT,)),
+        "done":
+            (GObject.SIGNAL_RUN_FIRST, None, ()),
     }
 
     def __init__(self, device):
@@ -570,7 +572,10 @@ class WacomDevice(GObject.Object):
 
     def run(self):
         logger.debug('{}: starting'.format(self.device.address))
-        self.retrieve_data()
+        try:
+            self.retrieve_data()
+        finally:
+            self.emit("done")
 
     def start(self):
         self.thread = threading.Thread(target=self.run)