Review Request 121134: make KGlobal reference counting threadsafe

[René J.V. Bertin]

> On Nov. 16, 2014, 9:29 p.m., David Faure wrote:
> > kdecore/kernel/kglobal.cpp, line 332
> > <https://git.reviewboard.kde.org/r/121134/diff/6/?file=328847#file328847line332>
> >
> >     Would s_allowQuit.load() compile? I forgot the Qt4 API since it changed in Qt5.
> >     
> >     It would be slightly better imho, for readability.

Nope, sorry.


- René J.V.


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On Nov. 16, 2014, 9:22 p.m., René J.V. Bertin wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/121134/
> -----------------------------------------------------------
> 
> (Updated Nov. 16, 2014, 9:22 p.m.)
> 
> 
> Review request for KDE Software on Mac OS X, kdelibs and David Faure.
> 
> 
> Repository: kdelibs
> 
> 
> Description
> -------
> 
> I have been experiencing unexpected exits from KDevelop that were not due to any kind of error in the KDevelop code; it was as if someone told the application to exit normally. This happens mostly on OS X, but also sometimes on Linux.
> I finally traced this to `KGlobal::deref` reaching a zero reference count and invoking `QCoreApplication::quit` when called from one of KDevelop's KJob dtors. There does not appear to be a reference counting mismatch in the code, so the issue might be due to a race condition in KGlobal::ref/deref.
> 
> This patch introduces thread-safety to KGlobal's reference counting by turning the simple global `static int s_refCount` into a `static QAtomicInt s_refCount`. I consider this an important bug fix regardless of whether it corrects the issue I have with KDevelop.
> 
> 
> Diffs
> -----
> 
>   kdecore/kernel/kglobal.cpp cf003a4 
> 
> Diff: https://git.reviewboard.kde.org/r/121134/diff/
> 
> 
> Testing
> -------
> 
> On OS X 10.6.8 only for now.
> 
> NB: Qt itself uses the QAtomicInt's parent class (QBasicAtomicInt) for its own reference counter used for implicit sharing. This is thus well-tested code that is unlikely to introduce regressions to a core KDE feature.
> 
> 
> Thanks,
> 
> René J.V. Bertin
> 
>

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