[FFmpeg-devel] [PATCH v2 1/4] avcodec/allcodecs: make avcodec_register_all thread safe

[wm4]

On Tue,  7 Mar 2017 16:01:58 +0700
Muhammad Faiz <mfcc64 at gmail.com> wrote:

> use ff_thread_once
> 
> Suggested-by: wm4 <nfxjfg at googlemail.com>
> Signed-off-by: Muhammad Faiz <mfcc64 at gmail.com>
> ---
>  libavcodec/allcodecs.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> index eee322b..6ec7e79 100644
> --- a/libavcodec/allcodecs.c
> +++ b/libavcodec/allcodecs.c
> @@ -25,6 +25,7 @@
>   */
>  
>  #include "config.h"
> +#include "libavutil/thread.h"
>  #include "avcodec.h"
>  #include "version.h"
>  
> @@ -58,14 +59,8 @@
>              av_register_codec_parser(&ff_##x##_parser);                 \
>      }
>  
> -void avcodec_register_all(void)
> +static void register_all(void)
>  {
> -    static int initialized;
> -
> -    if (initialized)
> -        return;
> -    initialized = 1;
> -
>      /* hardware accelerators */
>      REGISTER_HWACCEL(H263_VAAPI,        h263_vaapi);
>      REGISTER_HWACCEL(H263_VIDEOTOOLBOX, h263_videotoolbox);
> @@ -717,3 +712,10 @@ void avcodec_register_all(void)
>      REGISTER_PARSER(VP9,                vp9);
>      REGISTER_PARSER(XMA,                xma);
>  }
> +
> +void avcodec_register_all(void)
> +{
> +    static AVOnce control = AV_ONCE_INIT;
> +
> +    ff_thread_once(&control, register_all);
> +}

Looks all good to me.

Of course this doesn't change that the thread-safety of this whole
"list of components" code is still questionable, but it doesn't hurt to
do this either.