[vlc-devel] [PATCH 1/6] os2: implement vlc_once()

[Rémi Denis-Courmont]

Le jeudi 22 mars 2018, 16:41:29 EET KO Myung-Hun a écrit :
> ---
>  include/vlc_threads.h |  6 ++++++
>  src/os2/thread.c      | 17 +++++++++++++++++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/include/vlc_threads.h b/include/vlc_threads.h
> index 37054a3ded..b7505da266 100644
> --- a/include/vlc_threads.h
> +++ b/include/vlc_threads.h
> @@ -125,6 +125,12 @@ typedef struct
>  #define VLC_STATIC_COND { NULLHANDLE, 0, NULLHANDLE, 0 }
>  #define LIBVLC_NEED_SEMAPHORE
>  #define LIBVLC_NEED_RWLOCK
> +typedef struct
> +{
> +    unsigned done;
> +    vlc_mutex_t mutex;
> +} vlc_once_t;
> +#define VLC_STATIC_ONCE { 0, VLC_STATIC_MUTEX }
>  typedef struct vlc_threadvar *vlc_threadvar_t;
>  typedef struct vlc_timer *vlc_timer_t;
> 
> diff --git a/src/os2/thread.c b/src/os2/thread.c
> index 8f7b335ea4..52f58023b8 100644
> --- a/src/os2/thread.c
> +++ b/src/os2/thread.c
> @@ -427,6 +427,23 @@ int vlc_cond_timedwait_daytime (vlc_cond_t *p_condvar,
> vlc_mutex_t *p_mutex, return vlc_cond_wait_common (p_condvar, p_mutex,
> ulTimeout);
>  }
> 
> +void vlc_once(vlc_once_t *once, void (*cb)(void))
> +{
> +    if( !once->done )

This looks like a violation of the memory model.

> +    {
> +        vlc_mutex_lock( &once->mutex );
> +
> +        if( !once->done )
> +        {
> +            cb();
> +
> +            once->done = 1;
> +        }
> +
> +        vlc_mutex_unlock( &once->mutex );
> +    }
> +}
> +
>  /*** Thread-specific variables (TLS) ***/
>  struct vlc_threadvar
>  {


-- 
Rémi Denis-Courmont