Re: Main event loop in networkmanager.

["Andrew Bird (Sphere Systems)" <ajb spheresystems co uk>]

On Wednesday 03 August 2011, Anders Gnistrup wrote:
> Hi
> 
> FIrst post to this maillist.
> 
> My problem is that I need to receive signal from the networkmanager.
> This is done using connect_to_signal and it seems quite easy.
> But when testing I get the error message -> create a glib event loop.
> And thats My problem. I already have a loop.
> 
> The short description of my application is a interface able to configure
> some wireless network interfaces from a remote host using a XMLrpc from
> twisted. (There is no screen on target platform)
> 
> the application loop is a XMLrpc interface (reactor), where several rpc is
> available. Some of these graps information from the networkmanager dbus
> interface. This is OK, because it is a synchronous API. But when adding a
> new connection (using addConnection), the succes/fail is a signal
> (networkmanager version 0.84). So I need to create a asynchronous loop. (I
> know this is changed in networkmanager version 0.9)
> 
> So I have two solutions:
> 1) Tell the networkmanger signal to use my loop. (seems impossible, if
> please tell me how) 2) Create a second thread and start a loop using:
>    from dbus.mainloop.glib import DBusGMainLoop
>    DBusGMainLoop(set_as_default=True)
>    additional code ......
>    loop = gobject.MainLoop()
>    loop.run
> 
> The second solution creates new problems. I need to make data thread safe,
> and there is no need for two thread. It's only signals!
> 
> I have searched the net for a solution for (1), but I can't find any
> (2) is possible but does not seems "right"
> 

Hi Anders,
	Can't you select the glib loop in twisted? Here's a test program I just 
wrote that works for me.

Hope it helps,

Andrew


import dbus
from dbus.mainloop.glib import DBusGMainLoop
from twisted.application.service import Application, Service
from twisted.python import log

NM_SERVICE = 'org.freedesktop.NetworkManager'
NM_OBJPATH = '/org/freedesktop/NetworkManager'
NM_INTFACE = NM_SERVICE

loop = DBusGMainLoop(set_as_default=True)
bus = dbus.SystemBus(mainloop=loop)

obj = bus.get_object(NM_SERVICE, NM_OBJPATH)


class MyService(Service):

    def method_cb(self, arg):
        print "method returned %s" % str(arg)

    def signal_cb(self, arg):
        print "signal fired with %s" % str(arg)

    def startService(self):
        print "startService"

        obj.GetDevices(dbus_interface=NM_INTFACE,
                       reply_handler=self.method_cb,
                       error_handler=log.err)

        obj.connect_to_signal('DeviceAdded', self.signal_cb,
                                dbus_interface=NM_INTFACE)

service = MyService()
application = Application('Mytest')
service.setServiceParent(application)


# start as follows
# /usr/bin/twistd --nodaemon --python=mytest.py --reactor=glib2


2011-08-03 09:55:03+0100 [-] Log opened.
2011-08-03 09:55:03+0100 [-] twistd 10.2.0 (/usr/bin/python 2.7.1) starting 
up.
2011-08-03 09:55:03+0100 [-] reactor class: 
twisted.internet.glib2reactor.Glib2Reactor.
2011-08-03 09:55:03+0100 [-] startService
2011-08-03 09:55:04+0100 [-] method returned 
dbus.Array([dbus.ObjectPath('/org/freedesktop/NetworkManager/Devices/0')], 
signature=dbus.Signature('o'))
2011-08-03 09:55:34+0100 [-] signal fired with 
/org/freedesktop/NetworkManager/Devices/1