Looking for appropriate newsgroup

[Josef Moellers]

'morning,

I have some problems with a qt application that needs to receive data
from an MQTT broker and display it on a KDE desktop.
Whenever I quit the application, it crashes the desktop.

Anyone have a hint as to where this problem might be more appropriate?

netscape.public.mozilla.qt is rather quiet ;-)
and I was unable to find anything else.

Josef

[Jorgen Grahn]

On Fri, 2018-08-03, Josef Moellers wrote:
> 'morning,
>
> I have some problems with a qt application that needs to receive data
> from an MQTT broker and display it on a KDE desktop.

Does "display it on a KDE desktop" mean something special? I.e. if
you open an xterm or a web browser, is that the same thing?

> Whenever I quit the application, it crashes the desktop.
>
> Anyone have a hint as to where this problem might be more appropriate?
>
> netscape.public.mozilla.qt is rather quiet ;-)

Yeah, things like Qt are probably not discussed on Usenet these days.
I'm not sure where that happens.

> and I was unable to find anything else.

If "crashes the KDE desktop" means some important KDE process crashes,
then it sounds like something the KDE developers should be feel very
responsible for. I assume there's information about how to contact
them.

Although chances are your code is buggy, and does something which
triggers a bug in KDE, in which case getting the KDE people to fix
/their/ part isn't enough still won't make you happy.

/Jorgen

--
// Jorgen Grahn <grahn@ Oo o. . .
\X/ snipabacken.se> O o .

[Josef Moellers]

On 03.08.2018 09:44, Jorgen Grahn wrote:
> On Fri, 2018-08-03, Josef Moellers wrote:
>> 'morning,
>>
>> I have some problems with a qt application that needs to receive data
>> from an MQTT broker and display it on a KDE desktop.
>
> Does "display it on a KDE desktop" mean something special? I.e. if
> you open an xterm or a web browser, is that the same thing?

No, the application receives some MQTT messages (mainly referring to
temperatures and humidities in various locations) and displays them in
its own window.

>> Whenever I quit the application, it crashes the desktop.
>>
>> Anyone have a hint as to where this problem might be more appropriate?
>>
>> netscape.public.mozilla.qt is rather quiet ;-)
>
> Yeah, things like Qt are probably not discussed on Usenet these days.
> I'm not sure where that happens.
>
>> and I was unable to find anything else.
>
> If "crashes the KDE desktop" means some important KDE process crashes,
> then it sounds like something the KDE developers should be feel very
> responsible for. I assume there's information about how to contact
> them.
>
> Although chances are your code is buggy, and does something which
> triggers a bug in KDE, in which case getting the KDE people to fix
> /their/ part isn't enough still won't make you happy.

I assume the latter, eg leaving the MQTT subscription active such that
messages keep coming in, confusing KDE or some background process keeps
running.

The C++ MQTT interface blocks until a message arrives. For each topic, I
open a pipe and spawn a child process which blocks until a message is
received which will then be put into the pipe. The main application
registers a notify on the pipe fds and updates the values in the window.

Josef

[Josef Moellers]

F'up to self:

I did away with the forking as the mosquitto class implements
multi-threading, so a loop_start() at the end of the constructor was all
that is required.

Josef

[James Kuyper]

https://forum.qt.io/

[Jorgen Grahn]

Yeah, but how can you confuse KDE? I don't use KDE: my desktop is an
X11 display, a simple window manager and various programs having
windows open. It's impossible for these programs to break the desktop
environment, or should be.

> The C++ MQTT interface blocks until a message arrives. For each topic, I
> open a pipe and spawn a child process which blocks until a message is
> received which will then be put into the pipe. The main application
> registers a notify on the pipe fds and updates the values in the window.

Sounds like my prejudice against such APIs: designed to be the only
I/O the program does, so in practice everyone has to run them in
threads which tunnel the data into a more realistic event loop.

But I suggest we stop here. Everything so far has been offtopic for
comp.lang.c++. The only group I frequent where it's partly ontopic
is comp.unix.programmer, and there mostly for troubleshooting tips.

[Josef Moellers]

Thanks!
As I have already solved my problem, I'll just keep that in mind, if you
don't mind ;-)

Josef

[Reinhardt Behm]

There is also a mailing list for Qt.

--
Reinhardt