Re: Need GDBus Service file for org.gnome.Shell

[Simon McVittie <simon mcvittie collabora co uk>]

On 20/06/13 11:24, Bazon Bloch wrote:
> I got the Error: 
> "GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name
> org.gnome.Shell was not provided by any service files" 

That doesn't necessarily mean it *should* be provided by a .service
file, just that something tried to communicate with gnome-shell and
didn't find one. Creating a .service file is a way to cause the service
to be started automatically, which is often appropriate for non-GUI
services - but attempting to run a new copy of GNOME Shell is not the
right thing to happen here.

> I still got the flat-CPU-graph-problem
> with https://extensions.gnome.org/extension/120/system-monitor/ after
> resume from suspend. Thanks to this list, I now how to restart that via
> dbus:
> gdbus call --session --dest org.gnome.Shell --object-path
> /org/gnome/Shell --method org.gnome.Shell.Extensions.ReloadExtension
> system-monitor paradoxxx zero gmail com

Right, that's a workaround. The correct solution is to fix the extension
so it doesn't need reloading.

One possible route towards achieving this would be to have the extension
watch the system bus for a signal indicating a resume from suspend, and
do what it would have done when the Shell disabled and re-enabled it;
the next refinement of that would be to reduce what is done after 10
seconds to the absolute minimum to make it work, which would hopefully
indicate what was wrong in a specific enough way to be able to fix it
correctly.

> I would like to have this executed automatically about 10s after each
> resume, and so I created a systemd service:
...
> Environment=DISPLAY=:0
> ExecStart=/usr/bin/sh -c "/path/to/reload-sys-mon.sh"

System-level services connecting to a user session service are not
something that is, or should be, supported. Something in the user
session (like the extension itself) should monitor the system bus to
detect a resume.

>   Process: 1548 ExecStart=/usr/bin/sh -c /path/to/reload-sys-mon.sh
> (code=exited, status=0/SUCCESS)
>    CGroup: name=systemd:/system/resume  service/resume carl service
>            └─1554 dbus-launch
> --autolaunch=0b13b59cd91045ad9b746f7b36da8550 --binary-syntax --close-stderr

The system service is creating a tiny user-level D-Bus session
containing nothing except your shell script, and trying to talk to a
GNOME Shell instance in that session. Your GNOME Shell is in a different
session, created when you logged in. Creating a .service file would
result in your script trying to start a second GNOME Shell instance,
sharing the $DISPLAY with the real one, but in a different login session
- that's never going to work very well.

    S