On Thu, Jan 04, 2018 at 03:19:01PM -0300, James Almer wrote:
> Signed-off-by: James Almer <jamr...@gmail.com>
> ---
> libavcodec/utils.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
> index dfbfe98d63..61acf36c4b 100644
> --- a/libavcodec/utils.c
> +++ b/libavcodec/utils.c
> @@ -26,7 +26,6 @@
> */
>
> #include "config.h"
> -#include "libavutil/atomic.h"
> #include "libavutil/attributes.h"
> #include "libavutil/avassert.h"
> #include "libavutil/avstring.h"
> @@ -95,7 +94,6 @@ void av_fast_padded_mallocz(void *ptr, unsigned int *size,
> size_t min_size)
>
> /* encoder management */
> static AVCodec *first_avcodec = NULL;
> -static AVCodec **last_avcodec = &first_avcodec;
>
> AVCodec *av_codec_next(const AVCodec *c)
> {
> @@ -127,16 +125,21 @@ int av_codec_is_decoder(const AVCodec *codec)
> return codec && (codec->decode || codec->receive_frame);
> }
>
> +static AVMutex codec_register_mutex = AV_MUTEX_INITIALIZER;
> +
> av_cold void avcodec_register(AVCodec *codec)
> {
> AVCodec **p;
> avcodec_init();
> - p = last_avcodec;
> - codec->next = NULL;
> + ff_mutex_lock(&codec_register_mutex);
> + p = &first_avcodec;
>
> - while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, codec))
> + while (*p)
> p = &(*p)->next;
> - last_avcodec = &codec->next;
> + *p = codec;
> + codec->next = NULL;
> +
> + ff_mutex_unlock(&codec_register_mutex);the code should keep track of the last entry of the list as previously and not search through the list each time for the end, especially not under a mutex this is not as negligible fast as you may think adding 1000 entries to a list like this will need ~ half millon iterations [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Concerning the gods, I have no means of knowing whether they exist or not or of what sort they may be, because of the obscurity of the subject, and the brevity of human life -- Protagoras
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