[vlc-devel] [PATCH] clock: don't return invalid ts when paused

[Thomas Guillem]

This commit is wrong. When unpaused, the vout can request a time to the clock while the clock is still paused (but will soon be unpaused, threading...). In that case, the converted time will be delayed by the pause delay.

On Wed, Sep 4, 2019, at 14:35, Thomas Guillem wrote:
> vlc_clock_ConvertToSystem() could return INT64_MAX when paused, this was not
> documented and not handled at all by the aout and the vout.
> 
> To fix this issue, I first tried the obvious choice: handling this INT64_T
> value from both outputs. The problem is that I don't really know how to handle
> it. Indeed, the main clock and every outputs are requested to pause at the same
> time, but they all run on different thread and will process this request on
> their own timeline. Therefore, the output might be still running when the clock
> is paused. Handling 2 different pause state from the output is not a good idea.
> 
> So I decided a simpler fix: the clock will act as it's not paused and will
> always return valid values. Indeed, both outputs are very likely to be in the
> pause state anyway and will stop requesting/updating time to the clock.
> 
> PS: The pause state from the clock is now only used to apply the pause delay on
> the reference point.
> ---
>  src/clock/clock.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/src/clock/clock.c b/src/clock/clock.c
> index 15a6cf68e4..cfaef7b151 100644
> --- a/src/clock/clock.c
> +++ b/src/clock/clock.c
> @@ -227,8 +227,6 @@ static vlc_tick_t 
> vlc_clock_slave_to_system_locked(vlc_clock_t *clock,
>                                                     vlc_tick_t ts, 
> double rate)
>  {
>      vlc_clock_main_t *main_clock = clock->owner;
> -    if (main_clock->pause_date != VLC_TICK_INVALID)
> -        return INT64_MAX;
>  
>      vlc_tick_t system = main_stream_to_system(main_clock, ts);
>      if (system == VLC_TICK_INVALID)
> @@ -300,10 +298,7 @@ int vlc_clock_Wait(vlc_clock_t *clock, vlc_tick_t 
> system_now, vlc_tick_t ts,
>      while (!main_clock->abort)
>      {
>          vlc_tick_t deadline;
> -        if (main_clock->pause_date != VLC_TICK_INVALID)
> -            deadline = INT64_MAX;
> -        else
> -            deadline = clock->to_system_locked(clock, system_now, ts, 
> rate);
> +        deadline = clock->to_system_locked(clock, system_now, ts, 
> rate);
>          deadline = __MIN(deadline, max_deadline);
>  
>          if (vlc_cond_timedwait(&main_clock->cond, &main_clock->lock, deadline))
> -- 
> 2.20.1
> 
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