pthread_cleanup_push & pthread_cleanup_pop usage

[Alfred Perlstein]

* John Hein <jhein at timing.com> [081007 21:45] wrote:
> In June pthread_cleanup_push & pthread_cleanup_pop were changed to macros
> that look like so...

Hey John, I found the same problem when working on QNX a while back,
however that is really how it's supposed to be set up.

I would suggest the following construct to fix the problem,
make your own per-thread stack of destructors that are callable
as functions and not macros.

It's not too hard to do.

Just use a pthread_key and pthread_once thingy to write a library
to do it, shouldn't take more than a hundred lines of code.

FWIW, OS X and QNX have the same set of macros, not sure about
other OSes.

-Alfred

> 
> +#define        pthread_cleanup_push(cleanup_routine, cleanup_arg)              \
> +               {                                                               \
> +                       struct _pthread_cleanup_info __cleanup_info__;          \
> +                       __pthread_cleanup_push_imp(cleanup_routine, cleanup_arg,\
> +                               &__cleanup_info__);                             \
> +                       {
> +
> +#define        pthread_cleanup_pop(execute)                                    \
> +                       }                                                       \
> +                       __pthread_cleanup_pop_imp(execute);                     \
> +               }
> +
> 
> 
> This breaks code where the pop is done in an inner block level.
> 
> simplified example:
> 
>     pthread_cleanup_push(docleanup, &foo);
>     try
>     {   
>         dostuff();
>     }
>     catch (...)
>     {   
>         pthread_cleanup_pop(1);
>         throw;
>     }
>     pthread_cleanup_pop(1);
> 
> Does anyone have a recommended fix?
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-- 
- Alfred Perlstein