[vlc-devel] [PATCH 3/3] fingerprinter: use vlc_cond_t instead of sleep

[Rémi Denis-Courmont]

Le sunnuntaina 22. maaliskuuta 2020, 17.21.22 EET Alexandre Janniaux a écrit :
> Instead of checking new requests every seconds, wait for actual new
> requests to be enqueued before trying to do any processing. This avoid
> the harmful sleep warning

I agree, but what was the rationale for this?

> on vlc_tick_sleep as well as providing better
> latency for new fingerprinting requests on a cold fingerprinter.
> ---
>  modules/misc/fingerprinter.c | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/modules/misc/fingerprinter.c b/modules/misc/fingerprinter.c
> index 99a05346f0..18cc83bc2c 100644
> --- a/modules/misc/fingerprinter.c
> +++ b/modules/misc/fingerprinter.c
> @@ -51,6 +51,8 @@ struct fingerprinter_sys_t
>          vlc_mutex_t         lock;
>      } incoming, results;
> 
> +    vlc_cond_t              incoming_cond;
> +
>      struct
>      {
>          vlc_array_t         queue;
> @@ -85,14 +87,13 @@ static int EnqueueRequest( fingerprinter_thread_t *f,
> fingerprint_request_t *r ) fingerprinter_sys_t *p_sys = f->p_sys;
>      vlc_mutex_lock( &p_sys->incoming.lock );
>      int i_ret = vlc_array_append( &p_sys->incoming.queue, r );
> +    vlc_cond_signal( &p_sys->incoming_cond );
>      vlc_mutex_unlock( &p_sys->incoming.lock );
>      return i_ret;
>  }
> 
>  static void QueueIncomingRequests( fingerprinter_sys_t *p_sys )
>  {
> -    vlc_mutex_lock( &p_sys->incoming.lock );
> -
>      for( size_t i = vlc_array_count( &p_sys->incoming.queue ); i > 0 ; i--
> ) {
>          fingerprint_request_t *r = vlc_array_item_at_index(
> &p_sys->incoming.queue, i - 1 ); @@ -100,7 +101,6 @@ static void
> QueueIncomingRequests( fingerprinter_sys_t *p_sys )
> fingerprint_request_Delete( r );
>      }
>      vlc_array_clear( &p_sys->incoming.queue );
> -    vlc_mutex_unlock(&p_sys->incoming.lock);
>  }
> 
>  static fingerprint_request_t * GetResult( fingerprinter_thread_t *f )
> @@ -250,6 +250,7 @@ static int Open(vlc_object_t *p_this)
> 
>      vlc_array_init( &p_sys->incoming.queue );
>      vlc_mutex_init( &p_sys->incoming.lock );
> +    vlc_cond_init( &p_sys->incoming_cond );
> 
>      vlc_array_init( &p_sys->processing.queue );
>      vlc_cond_init( &p_sys->processing.cond );
> @@ -344,12 +345,19 @@ static void *Run( void *opaque )
>      /* main loop */
>      for (;;)
>      {
> -        vlc_tick_sleep( VLC_TICK_FROM_SEC(1) );
> -
> -        QueueIncomingRequests( p_sys );
> -
>          vlc_testcancel();

This becomes useless.

> 
> +        vlc_mutex_lock( &p_sys->incoming.lock );
> +        mutex_cleanup_push( &p_sys->incoming.lock );
> +
> +        while( vlc_array_count( &p_sys->incoming.queue ) == 0 )
> +            vlc_cond_wait( &p_sys->incoming_cond, &p_sys->incoming.lock );
> +
> +        QueueIncomingRequests( p_sys );
> +
> +        vlc_cleanup_pop();
> +        vlc_mutex_unlock( &p_sys->incoming.lock );
> +
>          bool results_available = false;
>          while( vlc_array_count( &p_sys->processing.queue ) )
>          {


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