Deffered and DbusMainLoop

[Anders Gnistrup <agn datarespons dk>]

Hi

I have a problem, which I can not solve. I have an application, which have a XML interface (based on twisted.web import xmlrpc)
I have a snippet of code that is be called via the xmlrpc interface.

def ssidList(self):
        def ssid_blocking():
            wlan_list = []
            for apDict in self.wifi.GetAccessPointsInfo():
                if apDict['Ssid'] != None:
                    val = apDict['Ssid']
                    str_val = ""
                    for elt in val:
                        # This test should not be needed, but prevents crashes.
                        if type(elt) == type(dbus.Byte(1)): 
                            str_val += chr(elt)
                wlan_list.append({ 'ssid' : str_val } )
            return wlan_list;

        # return  ssid_blocking()
        d = threads.deferToThread(ssid_blocking) 
        def retResult(var):
            return var
        d.addCallback(retResult)
        return d

If I remove the # before "# return  ssid_blocking()" everything works just fine (no use of deferToThread). If I try to use the defreToThread method, the program crashes. The problem seems to be related to the usage of DBusGMainLoop(set_as_default=True).

My theory is that when entering a deferToThread a new thread is created, but the dbus mainloop lives in another thread.
The call that makes the program crashes is when calling bus.get_object (bus is a dbus.SystemBus())

My goal is to create a nonblocking xmlrpc interface.

Can anyone give an explanation, or describe a alternative solution.

/AG