[pulseaudio-discuss] [PATCH] module-gsettings: new module to store configuration using gsettings

[Tanu Kaskinen]

On Wed, 2016-10-05 at 12:14 -0300, Felipe Sateler wrote:
> On 5 October 2016 at 05:17, Sylvain Baubeau <lebauce at gmail.com> wrote:
> > 
> > 
> > 
> > 2016-10-04 13:04 GMT+02:00 Tanu Kaskinen <tanuk at iki.fi>:
> > > 
> > > 
> > > On Fri, 2016-09-30 at 23:21 +0200, Sylvain Baubeau wrote:
> > > > Thanks for pointing this out. I updated my paprefs patch to apply
> > > > paprefs.convert at startup.
> > > 
> > > Would it be feasible for you to make it a build time option to use
> > > gconf or gsettings in paprefs?
> > 
> > 
> > Yes, I think it's feasible but the code would need quite a lot of rework.
> 
> I don't think this is necessary.

If it's not configurable, that will force the gsettings transition on
all distros. But I think I agree that it's good enough if the data gets
moved on the first run of the new paprefs version, even if paprefs
won't necessarily work before pulseaudio gets restarted.

> > > > > However that leaves us with another problem, as the pulseaudio daemon
> > > > > is not restarted automatically after an upgrade, and thus gsettings
> > > > > module might not be loaded. But, I hope paprefs can already deal with
> > > > > such a scenario and prompt the user accordingly.
> > > > > 
> > > > 
> > > > Unfortunately, paprefs does not deal with such a scenario. It will
> > > > therefore be able to modify the configuration but this configuration
> > > > will
> > > > only take effect when pulseaudio is restarted. What do you suggest
> > > > prompting the user with ?
> > > 
> > > Figuring out a good message is tricky. paprefs could just say "module-
> > > gsettings not loaded", but it would be nice to able to tell the user
> > > what to do. However, module-gsettings not being loaded may be because
> > > the server is too old version and doesn't support module-gsettings at
> > > all (distributions can deal this by depending on new enough server,
> > > though), or it has been removed from default.pa and needs to be added
> > > there, or the server has been updated but not restarted. The last
> > > reason is the most likely one in the beginning, but over time it
> > > becomes less and less likely, so just saying "restart pulseaudio" or
> > > "reboot the machine" probably isn't a good idea.
> > > 
> > > > 
> > > > > 
> > > > > In debian there is only paprefs depending on module-gconf. I don't
> > > > > think we'll keep module-gconf after paprefs has migrated.
> > > 
> > > If we release a pulseaudio version with module-gsettings before we
> > > release paprefs with gsettings support, will you run pulseaudio with
> > > both gconf and gsettings enabled, or only with gconf? Running with both
> > > would have the benefit that if everything goes well, the data will be
> > > migrated without any glitch when the new paprefs version is run for the
> > > first time, because module-gsettings will be already loaded. The risk
> > > with that is that the migration can't be tested at the time you enable
> > > module-gsettings, since paprefs isn't ready. If there's some unforeseen
> > > problem when paprefs is finally updated, and module-gsettings needs to
> > > be fixed in some way, the migration might become even more complex,
> > > because you need to deal with detecting a situation where the server is
> > > running with a broken version of module-gsettings.
> > > 
> > 
> > You're right, it's probably too complicated. It's better to stick with
> > GConf.
> 
> FWIW, I'd rather face a one-time upgrade glitch[1] than be stuck
> forever with an unmaintained stack. So I don't agree that it is better
> to stick with GConf.
> 
> From my POV, making paprefs do the migration automatically is all that
> is missing to perform an upgrade that is as seamless as possible.

(I'm not sure my nitpicking is productive, but here it goes anyway:)
It's not as seamless as possible, because there's a chance that paprefs
won't work before pulseaudio gets updated. Also, the data move itself
can cause glitching, because the modules loaded by module-gconf will be
unloaded and then reloaded by module-gsettings.

Maybe you're arguing that it's not possible to get rid of these
glitches, but I think it is possible. Whether it makes sense to spend
time implementing a "perfect" solution is a different question,
however.

-- 
Tanu