multiscreen logging

[Martin Klapetek]

On Tue, Jul 26, 2016 at 8:03 AM, Sebastian Kügler <sebas at kde.org> wrote:

> Hey,
>
> [Please keep both lists addressed.]
>
> Debugging multiscreen issues is a nightmare:
>
> - there are at least 4 different processes involved (kded, kcmshell /
>   systemsettings, kscreen_backend_launcher and plasmashell)
> - some are critical during log in
> - they IPC with each other
> - especially the backend launcher's debug is really hard to get at
>
> This means that:
> - it's hard (almost impossible) for users to get us good and useful logs
> - it's hard for ourselves to debug and find out what's exactly going on,
> especially when multiple components need to play in tune
>
> Yesternight, after debugging the so-many-th issue, it occurred to me that
> we
> need to make this way easier to debug. Q(C)Debug falls short in that we get
> logs of individual components, if we're lucky. If we're really lucky, we
> get
> timestamps, so we can get a rough idea of what is going down when.
>
> All of these problems can be solved with a relatively simple, shared log
> file.
>
> So I'd like to switch most of (lib)kscreen's debug output to logging to a
> file. The files has then logs from multiple processes and will be much
> easier
> to go through.
>

Wouldn't this create a possible concurrency issues when multiple processes
write to the same file?


> What do you think? If you like the idea, I'll polish up my branch and will
> post it for review, so we can discuss the actual implementation.
>

I think a possible better way could be to log each component into each own
file (in the same dir) with timestamps and function stamps and process
stamps
and everything and then merge those files using some automation and sort by
timestamp. Unless Qt on Linux actually handles concurrent write access just
fine
and in the correct order (I know it didn't on Windows last time I looked).

Cheers
-- 
Martin Klapetek
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