[vlc-devel] [RFC PATCH 1/4] decoder: don't wait for flush to complete

[Rémi Denis-Courmont]

Le 2015-11-17 18:16, Thomas Guillem a écrit :
> ---
>  src/input/decoder.c | 31 +++++--------------------------
>  1 file changed, 5 insertions(+), 26 deletions(-)
>
> diff --git a/src/input/decoder.c b/src/input/decoder.c
> index cacf7f2..16c985a 100644
> --- a/src/input/decoder.c
> +++ b/src/input/decoder.c
> @@ -109,8 +109,7 @@ struct decoder_owner_sys_t
>      bool b_has_data;
>
>      /* Flushing */
> -    bool flushing;
> -    bool flushed;
> +    atomic_bool flushing;

Why atomic?

>      bool b_draining;
>      atomic_bool drained;
>      bool b_idle;
> @@ -1330,7 +1329,7 @@ static void *DecoderThread( void *p_data )
>
>      for( ;; )
>      {
> -        if( p_owner->flushing )
> +        if( atomic_load( &p_owner->flushing ) )
>          {   /* Flush before/regardless of pause. We do not want to
> resume just
>               * for the sake of flushing (glitches could otherwise
> happen). */
>              int canc = vlc_savecancel();
> @@ -1341,9 +1340,6 @@ static void *DecoderThread( void *p_data )
>              if( unlikely(dummy == NULL) )
>                  msg_Err( p_dec, "cannot flush" );
>
> -            /* Owner is buggy if it queues data while flushing */
> -            assert( vlc_fifo_IsEmpty( p_owner->p_fifo ) );
> -            p_owner->flushing = false;
>              vlc_fifo_Unlock( p_owner->p_fifo );
>
>              /* Flush the decoder (and the output) */
> @@ -1351,12 +1347,8 @@ static void *DecoderThread( void *p_data )
>
>              vlc_fifo_Lock( p_owner->p_fifo );
>              vlc_restorecancel( canc );
> +            atomic_store( &p_owner->flushing, false );
>
> -            /* Owner is supposed to wait for flush to complete.
> -             * TODO: It might be possible to remove this 
> restriction. */
> -            assert( vlc_fifo_IsEmpty( p_owner->p_fifo ) );
> -            p_owner->flushed = true;
> -            vlc_cond_signal( &p_owner->wait_fifo );
>              continue;
>          }
>
> @@ -1485,9 +1477,8 @@ static decoder_t * CreateDecoder( vlc_object_t
> *p_parent,
>      p_owner->b_first = true;
>      p_owner->b_has_data = false;
>
> -    p_owner->flushing = false;
> -    p_owner->flushed = true;
>      p_owner->b_draining = false;
> +    atomic_init( &p_owner->flushing, false );
>      atomic_init( &p_owner->drained, false );
>      p_owner->b_idle = false;
>
> @@ -1818,7 +1809,6 @@ void input_DecoderDecode( decoder_t *p_dec,
> block_t *p_block, bool b_do_pace )
>              vlc_fifo_WaitCond( p_owner->p_fifo, &p_owner->wait_fifo 
> );
>      }
>
> -    p_owner->flushed = false;
>      vlc_fifo_QueueUnlocked( p_owner->p_fifo, p_block );
>      vlc_fifo_Unlock( p_owner->p_fifo );
>  }
> @@ -1874,16 +1864,9 @@ void input_DecoderFlush( decoder_t *p_dec )
>
>      vlc_fifo_Lock( p_owner->p_fifo );
>
> -    /* Don't flush if already flushed */
> -    if( p_owner->flushed )
> -    {
> -        vlc_fifo_Unlock( p_owner->p_fifo );
> -        return;
> -    }
> -
>      /* Empty the fifo */
>      block_ChainRelease( vlc_fifo_DequeueAllUnlocked( p_owner->p_fifo 
> ) );
> -    p_owner->flushing = true;
> +    atomic_store( &p_owner->flushing, true );
>
>      /* Flushing video decoder when paused: increment
> frames_countdown in order
>       * to display one frame */
> @@ -1893,10 +1876,6 @@ void input_DecoderFlush( decoder_t *p_dec )
>
>      vlc_fifo_Signal( p_owner->p_fifo );
>
> -    /* Monitor for flush end */
> -    while( !p_owner->flushed )
> -        vlc_fifo_WaitCond( p_owner->p_fifo, &p_owner->wait_fifo );
> -
>      vlc_fifo_Unlock( p_owner->p_fifo );
>  }

-- 
Rémi Denis-Courmont
http://www.remlab.net/