Re: [Tracker] [Patch] DBus connection lost handling

[Laurent Aguerreche <laurent aguerreche free fr>]

Le lundi 04 septembre 2006 Ã 04:32 +0200, Laurent Aguerreche a Ãcrit :
> Hello,
>
> currently, when DBus connection goes down trackerd exits with status set
> to 1. The culprit is dbus-daemon that runs as a per-user session
> process. When it goes down trackerd follows.
>
> A DBus aware process can avoid this exit with:
> dbus_connection_set_exit_on_disconnect (connection, FALSE);
> (It is required because dbus_bus_get() always set 'exit_on_disconnect'
> to TRUE otherwise it would stay to FALSE)
>
> Now trackerd doesn't crash anymore when it looses its connection to
> DBus... but it won't be able to reconnect to DBus anymore, so trackerd
> has to be shut down.

Perhaps I wrote something wrong here! Finally I think it would be
possible to reconnect to a DBus session but question is: is it useful?
I just stopped DBus on my system with '/etc/init.d/dbus stop' then start
it again and trackerd didn't crash. It seems that stability of trackerd
depends on the dbus daemon attached to user's session.

> In fact, it is also useful to make trackerd exits on a DBus
> disconnection because GNOME, KDE, XFCE, whatever, runs a dbus daemon
> that will exit at end of session. Therefore treackerd is currently
> crashing at end of session (look at trackerd's logs).
>
> It is possible to catch the 'disconnected' signal from DBus and to make
> trackerd exiting after a DBus disconnection. I propose a patch that
> implement this idea.

Of course, if there is a cleaner way to handle/detect the end of a
session I am interested.

> But this patch is not very clean... I added a DBUS_ACTION named
> DBUS_ACTION_DBUS_DISCONNECTED. I do not really like it since a
> disconnection is not a DBUS action from a user... I also wonder if we
> should extend how DBus treat DBus signals.
> If I remember correctly, it is possible to use DBus to catch a signal
> (from I-do-not-remember-what) to know whether a battery is going empty.
> In this case, trackerd could stop to extract data but could continue to
> index files and to answer to user requests.
>
> You also see that I created a sort of new signal, the 'DBus connection
> lost' for do_cleanup() in trackerd.c.  :-)
>
> My patch is mainly to show the DBus/end of session problem and to think
> how to do it cleanly.
>
>
>
> Laurent.
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