KStringHandler: stateless/reentrant/thread-safe?

Frank Reininghaus frank78ac at googlemail.com
Sun Oct 28 16:12:31 GMT 2012

2012/10/27 Thiago Macieira:
> On sexta-feira, 26 de outubro de 2012 22.44.23, Thiago Macieira wrote:
>> On sexta-feira, 26 de outubro de 2012 21.06.35, Frank Reininghaus wrote:
>> > Yes, I thought the same, but then I wasn't entirely sure if all these
>> > functions really are thread-safe. Some of them have const static
>> > variables,
>> > which might be initialised the first time the function is called AFAIK. I
>> > don't know if that's guaranteed to work if the functions can be called
>> > from
>> > multiple threads. But you can probably answer that question
>> Caching some global information which could be recreated on every call is
>> stateless and thread-safe.
> Actually, this is wrong. Caching is a good thing, but it could cause a thread-
> safety issue if not implemented correctly.
> The presence of statics probably requires a good investigation to check if
> it's thread-safe. And removing the "stateless" requirement is still a good
> idea.

The functions with statics are:

1. KStringHandler::isUtf8(const char *)


2. KStringHandler::from8Bit(const char *)


The first one contains a static array of chars, which looks safe to
me. The second has a static reference to a QString which is generated
using KGlobal::staticQString(const char*). I'm not entirely sure if
that is safe as well.


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