PropertiesChanged signal

Lennart Poettering mzqohf at
Sat May 8 06:19:48 PDT 2010

On Sat, 08.05.10 10:29, Michael 'Mickey' Lauer (mickey at wrote:

> Am Samstag, den 08.05.2010, 09:24 +0200 schrieb Thiago Macieira:
> > Em Sexta-feira 7. Maio 2010, às 23.10.00, Michael 'Mickey' Lauer escreveu:
> > > And while we're there we could/should also fix the client-based signal
> > > matching, which is IMO one of the major design flaws in DBus.
> > > I know that the desktop people don't care, but still...
> > 
> > What is the issue?
> Two issues:
> 1.) Listeners are always woken up on any kind of signals (to run the
> match function), no matter whether they are listening to a certain
> signal or not. That's a waste of CPU hence battery.

My recommendation for this would be to do something that has recently
been done in libudev to minimize wakeups in the monitoring clients there:
pass along pre-calculated bloom filters with the packets and use BSD
socket filters to test them and supress unmatched packets. WHile this
would have little effect on normal clients dbus-daemon would presumably
benefit greatly since it would no longer wake up for every packet it


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net           GnuPG 0x1A015CC4

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