[vlc-devel] [RFC PATCH 2/2] decoder: interruptible mwait

[Thomas Guillem]

On Tue, Dec 1, 2015, at 11:43, Thomas Guillem wrote:
> mwait (called from Audio and SPU DecoderThread) can now be interrupted
> when
> flushing or closing.
> 
> This fixes a too long closing/flushing time when the next spu or audio
> block is
> too distant.
> ---
>  src/input/decoder.c | 39 ++++++++++++++++++++++++++++++++++-----
>  1 file changed, 34 insertions(+), 5 deletions(-)
> 
> diff --git a/src/input/decoder.c b/src/input/decoder.c
> index c4fb6a1..aa36aec 100644
> --- a/src/input/decoder.c
> +++ b/src/input/decoder.c
> @@ -30,6 +30,7 @@
>  # include "config.h"
>  #endif
>  #include <assert.h>
> +#include <errno.h>
>  
>  #include <vlc_common.h>
>  
> @@ -91,6 +92,7 @@ struct decoder_owner_sys_t
>      vlc_cond_t  wait_request;
>      vlc_cond_t  wait_acknowledge;
>      vlc_cond_t  wait_fifo; /* TODO: merge with wait_acknowledge */
> +    vlc_cond_t  wait_timed;

I don't like adding a new cond...
But it's either adding a new cond or adding a new boolean that is owned
by the owner->lock (and then, you have to lock, reset the boolean,
unlock from the DecoderThread when flushing is done).

>  
>      /* -- These variables need locking on write(only) -- */
>      audio_output_t *p_aout;
> @@ -619,6 +621,25 @@ static void DecoderWaitUnblock( decoder_t *p_dec )
>      }
>  }
>  
> +/* DecoderTimedWait: Interruptible wait
> + * Returns VLC_SUCCESS if wait was not interrupted, and VLC_EGENERIC
> otherwise */
> +static int DecoderTimedWait( decoder_t *p_dec, mtime_t deadline )
> +{
> +    decoder_owner_sys_t *p_owner = p_dec->p_owner;
> +
> +    if (deadline - mdate() <= 0)
> +        return VLC_SUCCESS;

I also added a deadline check in order to don't lock and wait for
nothing.

> +
> +    vlc_fifo_Lock( p_owner->p_fifo );
> +    int ret = 0;
> +    while( !p_owner->flushing && ret != ETIMEDOUT )
> +        ret = vlc_fifo_TimedWaitCond( p_owner->p_fifo,
> &p_owner->wait_timed,
> +                                      deadline );
> +    vlc_fifo_Unlock( p_owner->p_fifo );
> +
> +    return ret == ETIMEDOUT ? VLC_SUCCESS : VLC_EGENERIC;
> +}
> +
>  static inline void DecoderUpdatePreroll( int64_t *pi_preroll, const
>  block_t *p )
>  {
>      if( p->i_flags & (BLOCK_FLAG_PREROLL|BLOCK_FLAG_DISCONTINUITY) )
> @@ -1022,7 +1043,8 @@ static void DecoderPlayAudio( decoder_t *p_dec,
> block_t *p_audio,
>  
>      if( p_aout == NULL || p_audio->i_pts <= VLC_TS_INVALID
>       || i_rate < INPUT_RATE_DEFAULT/AOUT_MAX_INPUT_RATE
> -     || i_rate > INPUT_RATE_DEFAULT*AOUT_MAX_INPUT_RATE )
> +     || i_rate > INPUT_RATE_DEFAULT*AOUT_MAX_INPUT_RATE
> +     || DecoderTimedWait( p_dec, p_audio->i_pts - AOUT_MAX_PREPARE_TIME
> ) )
>      {
>          msg_Dbg( p_dec, "discarded audio buffer" );
>          *pi_lost_sum += 1;
> @@ -1030,8 +1052,6 @@ static void DecoderPlayAudio( decoder_t *p_dec,
> block_t *p_audio,
>          return;
>      }
>  
> -    mwait( p_audio->i_pts - AOUT_MAX_PREPARE_TIME );
> -
>      if( aout_DecPlay( p_aout, p_audio, i_rate ) == 0 )
>          *pi_played_sum += 1;
>  
> @@ -1156,13 +1176,13 @@ static void DecoderPlaySpu( decoder_t *p_dec,
> subpicture_t *p_subpic )
>                    NULL, INT64_MAX );
>      vlc_mutex_unlock( &p_owner->lock );
>  
> -    if( p_subpic->i_start <= VLC_TS_INVALID )
> +    if( p_subpic->i_start <= VLC_TS_INVALID
> +     || DecoderTimedWait( p_dec, p_subpic->i_start -
> SPU_MAX_PREPARE_TIME ) )
>      {
>          subpicture_Delete( p_subpic );
>          return;
>      }
>  
> -    mwait( p_subpic->i_start - SPU_MAX_PREPARE_TIME );
>      vout_PutSubpicture( p_vout, p_subpic );
>  }
>  
> @@ -1499,6 +1519,7 @@ static decoder_t * CreateDecoder( vlc_object_t
> *p_parent,
>      vlc_cond_init( &p_owner->wait_request );
>      vlc_cond_init( &p_owner->wait_acknowledge );
>      vlc_cond_init( &p_owner->wait_fifo );
> +    vlc_cond_init( &p_owner->wait_timed );
>  
>      /* Set buffers allocation callbacks for the decoders */
>      p_dec->pf_aout_format_update = aout_update_format;
> @@ -1642,6 +1663,7 @@ static void DeleteDecoder( decoder_t * p_dec )
>          vlc_object_release( p_owner->p_packetizer );
>      }
>  
> +    vlc_cond_destroy( &p_owner->wait_timed );
>      vlc_cond_destroy( &p_owner->wait_fifo );
>      vlc_cond_destroy( &p_owner->wait_acknowledge );
>      vlc_cond_destroy( &p_owner->wait_request );
> @@ -1757,6 +1779,12 @@ void input_DecoderDelete( decoder_t *p_dec )
>  
>      vlc_cancel( p_owner->thread );
>  
> +    vlc_fifo_Lock( p_owner->p_fifo );
> +    /* Signal DecoderTimedWait */
> +    p_owner->flushing = true;
> +    vlc_cond_signal( &p_owner->wait_timed );
> +    vlc_fifo_Unlock( p_owner->p_fifo );
> +
>      /* Make sure we aren't waiting/decoding anymore */
>      vlc_mutex_lock( &p_owner->lock );
>      p_owner->b_waiting = false;
> @@ -1891,6 +1919,7 @@ void input_DecoderFlush( decoder_t *p_dec )
>          p_owner->frames_countdown++;
>  
>      vlc_fifo_Signal( p_owner->p_fifo );
> +    vlc_cond_signal( &p_owner->wait_timed );
>  
>      vlc_fifo_Unlock( p_owner->p_fifo );
>  }
> -- 
> 2.1.4
>