[vlc-devel] [PATCH 2/7] core: utils: add vlc_qsort

[Hugo Beauzée-Luyssen]

On Tue, Jan 22, 2019, at 12:59 PM, Rémi Denis-Courmont wrote:
> I am more concerned about the real problem that some craptastic libc do 
> not provide <threads.h> and thus thread_local, than that the compiler 
> does not support C11.
> 
> Le 22 janvier 2019 12:12:46 GMT+02:00, "Hugo Beauzée-Luyssen" 
> <hugo at beauzee.fr> a écrit :
> >
> >
> >On Tue, Jan 22, 2019, at 10:34 AM, Thomas Guillem wrote:
> >> On Mon, Jan 21, 2019, at 18:09, Hugo Beauzée-Luyssen wrote:
> >> > 
> >> > Any reason not to use "thread_local" ?
> >> 
> >> No, no idea, just copied the code from Rémi compat code.
> >> 
> >
> >Since _Thread_local might be missing on some platform, I'd be in favor
> >of using thread_local instead
> >
> >> > 
> >> > > +{
> >> > > +    int (*compar)(const void *, const void *, void *);
> >> > > +    void *arg;
> >> > > +} state;
> >> > > +
> >> > > +static int compar_wrapper(const void *a, const void *b)
> >> > > +{
> >> > > +    return state.compar(a, b, state.arg);
> >> > > +}
> >> > > +
> >> > > +/* Follow the upcoming POSIX prototype, coming from GNU/libc.
> >> > > + * Note that this differs from the BSD prototype. */
> >> > > +
> >> > > +VLC_WEAK void vlc_qsort(void *base, size_t nmemb, size_t size,
> >> > > +                        int (*compar)(const void *, const void
> >*, void *),
> >> > > +                        void *arg)
> >> > 
> >> > Any particular reason to use VLC_WEAK instead of the usual
> >per-platform 
> >> > implementation?
> >> 
> >> It's more future proof for me. We could add more utility functions to
> >
> >> misc/utils.c. Some of these functions could be implemented
> >differently 
> >> depending of the OS or not. With VLC_WEAK, we don't have to play with
> >
> >> conditions in the Makefile.am, this seems more convenient.
> >> 
> >
> >Fair enough, the question is mostly that we don't use it much but more
> >often use multiple source files. Your point is very valid IMO, I just
> >find weak symbols harder to reason about, or less intuitive, than a
> >plain different source file, but I'm absolutely fine with your solution
> >:)
> >
> >> As you want, I don't have strong opinions about wether we should use 
> >> VLC_WEAK in that case.
> >> 
> >
> >
> >-- 
> >  Hugo Beauzée-Luyssen
> >  hugo at beauzee.fr
> >_______________________________________________
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> 
> -- 
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> ma brièveté.
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I can't remember which platform this was added for (it helps for some versions of MSVC, but I'm pretty sure there were some others), but it definitely helped in the past.
If thread_local is provided, we use it as is anyway.

-- 
  Hugo Beauzée-Luyssen
  hugo at beauzee.fr