[vlc-devel] [RFC PATCH] decoder: do not depend on allocated block for flush

[Thomas Guillem]

On Wed, Nov 18, 2015, at 18:24, Thomas Guillem wrote:
> With this patch, a flush won't fail because of a block_Alloc failure.

The question is: Are there some decoder/packetizer modules than need a
flush block with an aligned size of 128 ?

> ---
>  src/input/decoder.c | 46 ++++++++++++++--------------------------------
>  1 file changed, 14 insertions(+), 32 deletions(-)
> 
> diff --git a/src/input/decoder.c b/src/input/decoder.c
> index c9f401b..24e70e9 100644
> --- a/src/input/decoder.c
> +++ b/src/input/decoder.c
> @@ -109,6 +109,7 @@ struct decoder_owner_sys_t
>      bool b_has_data;
>  
>      /* Flushing */
> +    block_t flush_block;
>      bool flushing;
>      bool b_draining;
>      atomic_bool drained;
> @@ -209,18 +210,8 @@ static void DecoderUpdateFormatLocked( decoder_t
> *p_dec )
>      p_owner->b_fmt_description = true;
>  }
>  
> -static block_t *DecoderBlockFlushNew()
> +static void BlockNoRelease( block_t *b )
>  {
> -    block_t *p_null = block_Alloc( 128 );
> -    if( !p_null )
> -        return NULL;
> -
> -    p_null->i_flags |= BLOCK_FLAG_DISCONTINUITY |
> -                       BLOCK_FLAG_CORRUPTED |
> -                       BLOCK_FLAG_CORE_FLUSH;
> -    memset( p_null->p_buffer, 0, p_null->i_buffer );
> -
> -    return p_null;
>  }
>  
>  /*****************************************************************************
> @@ -984,11 +975,7 @@ static void DecoderProcessVideo( decoder_t *p_dec,
> block_t *p_block, bool b_flus
>          /* The packetizer does not output a block that tell the decoder
>          to flush
>           * do it ourself */
>          if( b_flush )
> -        {
> -            block_t *p_null = DecoderBlockFlushNew();
> -            if( p_null )
> -                DecoderDecodeVideo( p_dec, p_null );
> -        }
> +            DecoderDecodeVideo( p_dec, &p_owner->flush_block );
>      }
>      else
>      {
> @@ -1136,11 +1123,7 @@ static void DecoderProcessAudio( decoder_t *p_dec,
> block_t *p_block, bool b_flus
>          /* The packetizer does not output a block that tell the decoder
>          to flush
>           * do it ourself */
>          if( b_flush )
> -        {
> -            block_t *p_null = DecoderBlockFlushNew();
> -            if( p_null )
> -                DecoderDecodeAudio( p_dec, p_null );
> -        }
> +            DecoderDecodeAudio( p_dec, &p_owner->flush_block );
>      }
>      else
>      {
> @@ -1261,9 +1244,8 @@ static void DecoderProcess( decoder_t *p_dec,
> block_t *p_block )
>          return;
>      }
>  
> -    if( p_block && p_block->i_buffer <= 0 )
> +    if( p_block && p_block->i_buffer <= 0 && !b_flush_request )
>      {
> -        assert( !b_flush_request );
>          block_Release( p_block );
>          return;
>      }
> @@ -1271,7 +1253,7 @@ static void DecoderProcess( decoder_t *p_dec,
> block_t *p_block )
>  #ifdef ENABLE_SOUT
>      if( p_owner->b_packetizer )
>      {
> -        if( p_block )
> +        if( p_block && p_block != &p_owner->flush_block )
>              p_block->i_flags &= ~BLOCK_FLAG_CORE_PRIVATE_MASK;
>  
>          DecoderProcessSout( p_dec, p_block );
> @@ -1288,7 +1270,8 @@ static void DecoderProcess( decoder_t *p_dec,
> block_t *p_block )
>  
>              b_flush = !b_flushing && b_flush_request;
>  
> -            p_block->i_flags &= ~BLOCK_FLAG_CORE_PRIVATE_MASK;
> +            if( p_block != &p_owner->flush_block )
> +                p_block->i_flags &= ~BLOCK_FLAG_CORE_PRIVATE_MASK;
>          }
>  
>          if( p_dec->fmt_out.i_cat == AUDIO_ES )
> @@ -1334,16 +1317,10 @@ static void *DecoderThread( void *p_data )
>               * for the sake of flushing (glitches could otherwise
>               happen). */
>              int canc = vlc_savecancel();
>  
> -            /* TODO: add a flush callback to decoder, do not depend on
> an
> -             * allocated block */
> -            block_t *dummy = DecoderBlockFlushNew();
> -            if( unlikely(dummy == NULL) )
> -                msg_Err( p_dec, "cannot flush" );
> -
>              vlc_fifo_Unlock( p_owner->p_fifo );
>  
>              /* Flush the decoder (and the output) */
> -            DecoderProcess( p_dec, dummy );
> +            DecoderProcess( p_dec, &p_owner->flush_block );
>  
>              vlc_fifo_Lock( p_owner->p_fifo );
>              vlc_restorecancel( canc );
> @@ -1481,6 +1458,11 @@ static decoder_t * CreateDecoder( vlc_object_t
> *p_parent,
>      p_owner->b_first = true;
>      p_owner->b_has_data = false;
>  
> +    block_Init( &p_owner->flush_block, NULL, 0 );
> +    p_owner->flush_block.pf_release = BlockNoRelease;
> +    p_owner->flush_block.i_flags = BLOCK_FLAG_DISCONTINUITY |
> +                                   BLOCK_FLAG_CORRUPTED |
> +                                   BLOCK_FLAG_CORE_FLUSH;
>      p_owner->flushing = false;
>      p_owner->b_draining = false;
>      atomic_init( &p_owner->drained, false );
> -- 
> 2.1.4
>