app doesn't recieve signal DeviceDisappeared

Hi!

Excuse me for my English.

I need help with using Bluez and dbus. Here is my small program in Python:

------------

import dbus
import dbus.glib
import gobject

def device_found(addr, values):
print 'Found:', addr

def device_disapp(addr):
print 'Disappeared:', addr

bus = dbus.SystemBus()
obj = bus.get_object('org.bluez', '/org/bluez/hci0') adapter = dbus.Interface(obj, 'org.bluez.Adapter') adapter.connect_to_signal('DeviceFound', device_found) adapter.connect_to_signal('DeviceDisappeared', device_disapp)

adapter.StartDiscovery()

gobject.threads_init()
dbus.glib.init_threads()
main_loop = gobject.MainLoop()
main_loop.run()

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And I have problem with DeviceDisappeared signal. I run program, then it finds my bluetooth enabled phone and prints it's address every ~10 seconds (periodical discovery). Than I turn off bluetooth in phone, but Bluez doesn't send signal 'DeviceDisappeared', so program doesn't print "Disappeared: ...". What's wrong in my program? Do I have misunderstanding of Bluez Adapter API?

Hi Ilya,

this might be a bug. Not many applications are actually making full use of the DeviceDisappeared signal. Please run dbus-monitor and check if it is really not present.

On another note, you can _NOT_ hardcode /org/bluez/hci0 path in your apps. Nowadays they are totally random. Use FindAdapter() instead.

Regards

Marcel

Marcel Holtmann пишет:

I run 'dbus-monitor --system'. Now I'm sure there are no DeviceDisappeared signal.
Besides, I found that the adapter's Discovering property changes to True only _right before_ any device is found. If there are no devices in the field, this property will be False permanently.

I use BlueZ 4.12. I understand that before reporting any bug I should update my system with the lastest versions of packages, so if this bug was fixed between 4.12 an current 4.27 version - excuse me and sorry for disturbing.

Now I use this method instead of hardcoding paths. Thanks!

Hi,

I also recognized, that the signal DeviceDisappeared never gets thrown. I need this Signal for KBlueLock (Screen lock, when your BT device disappeares)
Right now i have located the problem a little deeper and did some tests. I am using bluez-4.27 and use the test-discovery script in the test directory. I expanded the testscript, to also listen for the DeviceDisappeared Signals.

With a normal discovery, the signal gets never thrown (dbus-monitor). And the curious thing is, that the 'Discovering' value always switches between true and false ... so the discovery gets enabled and disabled automatically. But jhe told me, this is intended to provide a PeriodicDiscovery.

In adapter.c there is a function 'void adapter_set_state(struct btd_adapter *adapter, int state)'. This function anyhow clears the List with out of reach (oor) devices, depending on the discovery state. If i comment out this if clause 'if (!discov_active && adapter->oor_devices)' to not free the oor device list, the Signal gets thrown properly.
It gets thrown only once and the list of oor devices is also freed after that (dont know where).
So my guess is, that the 'discov_active' boolean is set wrong (?), so that this if clause is reached, but it should not.

This variable gets set depending on macros PERIODIC_INQUIRY and STD_INQUIRY. What are these ?
So maybe the state is set wrong, but i do not know what the state should be.

Also strange is, that this DeviceDisappeared signal (with commented out freeing of the oor list) only works, if more than one devices are in the area. Because of the automatic stop/start of the 'Discovering' value. If your one and only device gets disappeared the 'Discovering' value switches to false and never starts searching again ( so it does not recognize, that the device disappeared). The Discovery starts again, when you device is visible again ...

I hope this helps, to find the problem.
I would also fix it, but i do not know which discovery state must be set and which not, and when the oor list has to be freed and when not.

Regards,

Tom

Hi Tom,

It should've been fixed now. Note that you only got those signals while a discovery session is active (someone called Adapter.StartDiscovery()).

--=20
Luiz Augusto von Dentz
Engenheiro de Computa=E7=E3o

Hi,

Thanks a lot. Works great.
Now i just need to wait for the next bluez release, to make use of it in KBlueLock :)

Tom