[Qt-interest] Fwd: QAtomicInt and QThread

[Thiago Macieira]

Em Friday, 24 de June de 2011, às 18:42:26, Mandeep Sandhu escreveu:
> >> What you need for protecting the atomicity of read/write ops between
> >> threads is mutex. eg: you use QMutex from serializing access to the
> >> shared data.
> > 
> > Is it not enough to use a QAtomicInt? From the docs the "=" and "=="
> > operators seems to be atomic on QAtomicInt. So that way at least the
> > last example should work.
> 
> For your specific case of reading/writing integer values, it might
> suffice. Though I've never used it myself so maybe someone else on the
> list can confirm?

It's not.

Reading a 64-bit integer on a 32-bit platform is not atomic, much less thread-
safe.

The entire example is thread-unsafe and will produce weird values.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
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