[FFmpeg-devel] [PATCH 1/3] avutil/threadmessage: add av_thread_message_flush()

[Nicolas George]

Le quartidi 14 frimaire, an CCXXIV, Clement Boesch a écrit :
> From: Clément Bœsch <clement at stupeflix.com>
> 
> ---
>  libavutil/threadmessage.c | 31 +++++++++++++++++++++++++++++++
>  libavutil/threadmessage.h | 16 ++++++++++++++++
>  2 files changed, 47 insertions(+)
> 
> diff --git a/libavutil/threadmessage.c b/libavutil/threadmessage.c
> index b7fcbe2..a5f1507 100644
> --- a/libavutil/threadmessage.c
> +++ b/libavutil/threadmessage.c
> @@ -40,6 +40,7 @@ struct AVThreadMessageQueue {
>      int err_send;
>      int err_recv;
>      unsigned elsize;
> +    void (*free_func)(void *msg);
>  #else
>      int dummy;
>  #endif
> @@ -81,10 +82,17 @@ int av_thread_message_queue_alloc(AVThreadMessageQueue **mq,
>  #endif /* HAVE_THREADS */
>  }
>  
> +void av_thread_message_queue_set_free_func(AVThreadMessageQueue *mq,
> +                                           void (*free_func)(void *msg))
> +{
> +    mq->free_func = free_func;
> +}
> +
>  void av_thread_message_queue_free(AVThreadMessageQueue **mq)
>  {
>  #if HAVE_THREADS
>      if (*mq) {
> +        av_thread_message_flush(*mq);
>          av_fifo_freep(&(*mq)->fifo);
>          pthread_cond_destroy(&(*mq)->cond);
>          pthread_mutex_destroy(&(*mq)->lock);
> @@ -182,3 +190,26 @@ void av_thread_message_queue_set_err_recv(AVThreadMessageQueue *mq,
>      pthread_mutex_unlock(&mq->lock);
>  #endif /* HAVE_THREADS */
>  }
> +

> +static void free_func_wrap(void *arg, void *msg, int size)
> +{
> +    void (*free_func)(void *msg) = arg;

Technically, this is not legal: void* is a data pointer, it could be smaller
than a function pointer (remember the "medium" memory model for 16-bits
code). I do not object much, but it is easy to fix: just pass &free_func as
argument, or even squarely mq itself.

> +    free_func(msg);
> +}
> +
> +void av_thread_message_flush(AVThreadMessageQueue *mq)
> +{
> +#if HAVE_THREADS
> +    int used, off;
> +    void *free_func = mq->free_func;
> +
> +    pthread_mutex_lock(&mq->lock);
> +    used = av_fifo_size(mq->fifo);
> +    if (free_func)
> +        for (off = 0; off < used; off += mq->elsize)
> +            av_fifo_generic_peek_at(mq->fifo, free_func, off, mq->elsize, free_func_wrap);
> +    av_fifo_drain(mq->fifo, used);
> +    pthread_cond_broadcast(&mq->cond);
> +    pthread_mutex_unlock(&mq->lock);
> +#endif /* HAVE_THREADS */
> +}
> diff --git a/libavutil/threadmessage.h b/libavutil/threadmessage.h
> index a8481d8..e256cae 100644
> --- a/libavutil/threadmessage.h
> +++ b/libavutil/threadmessage.h
> @@ -88,4 +88,20 @@ void av_thread_message_queue_set_err_send(AVThreadMessageQueue *mq,
>  void av_thread_message_queue_set_err_recv(AVThreadMessageQueue *mq,
>                                            int err);
>  
> +/**
> + * Set the optional free message callback function which will be called if an
> + * operation is removing messages from the queue.
> + */
> +void av_thread_message_queue_set_free_func(AVThreadMessageQueue *mq,
> +                                           void (*free_func)(void *msg));
> +
> +/**
> + * Flush the message queue
> + *
> + * This function is mostly equivalent to reading and free-ing every message
> + * except that it will be done in a single operation (no lock/unlock between
> + * reads).
> + */
> +void av_thread_message_flush(AVThreadMessageQueue *mq);
> +
>  #endif /* AVUTIL_THREADMESSAGE_H */

Rest looks good to me, thanks for humouring me.

Regards,

-- 
  Nicolas George
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