Re: [chrony-dev] Patch for adding leap seconds in the PPS refclock

[Miroslav Lichvar <mlichvar@xxxxxxxxxx>]

On Thu, May 22, 2014 at 09:00:33AM +0200, Hattink, Tjalling [FINT] wrote:
> I've pasted a patch below that fixes leap second handling for the PPS
> refclock. Without the patch the PPS refclock will always report
> LEAP_normal. But if a locked refclock (the SHM clock in my case) does
> report a leap state it should also be taken over by the PPS refclock,
> otherwise chrony will still use LEAP_normal when the PPS clock is used
> as reference source.

Nice find. The patch looks good to me, but can you please send a
version against current git with "git send-email" so I can apply it
with "git am"? You get the credit and I don't mess up your commit
message. Thanks.

> The patch will copy the leap state from the refclock. In case the PPS
> clock is not specifically locked to another refclock it will take over
> the leap state from the local clock.
> 
> I've tested this patch by simulating a leap second through the samples
> for the SHM clock, and with the patch you will see chrony properly jump
> forward or backward on the leap second. Without the patch it will not do
> this and the clock becomes desynchronized and no leap state is reported
> upstream to other NTP clients.
> 
> Kind regards,
> 
> Tjalling Hattink
> 
> 
> --- a/refclock.c
> +++ b/refclock.c
> @@ -378,7 +378,9 @@ RCL_AddPulse(RCL_Instance instance, stru
>    double correction, dispersion, offset;
>    struct timeval cooked_time;
>    int rate;
> +  NTP_Leap leap;
>  
> +  leap = LEAP_Normal;
>    LCL_GetOffsetCorrection(pulse_time, &correction, &dispersion);
>    UTI_AddDoubleToTimeval(pulse_time, correction, &cooked_time);
>    dispersion += instance->precision +
> filter_get_avg_sample_dispersion(&instance->filter);
> @@ -421,6 +423,8 @@ RCL_AddPulse(RCL_Instance instance, stru
>      if (fabs(ref_offset - offset) + ref_dispersion + dispersion >= 0.2
> / rate)
>        return 0;
>  
> +    leap = refclocks[instance->lock_ref].leap_status;
> +
>  #if 0
>      LOG(LOGS_INFO, LOGF_Refclock, "refclock pulse second=%.9f
> offset=%.9f offdiff=%.9f samplediff=%.9f",
>          second, offset, ref_offset - offset, sample_diff);
> @@ -429,7 +433,6 @@ RCL_AddPulse(RCL_Instance instance, stru
>      struct timeval ref_time;
>      int is_synchronised, stratum;
>      double root_delay, root_dispersion, distance;
> -    NTP_Leap leap;
>      uint32_t ref_id;
>  
>      /* Ignore the pulse if we are not well synchronized */
> @@ -450,7 +453,7 @@ RCL_AddPulse(RCL_Instance instance, stru
>    }
>  
>    filter_add_sample(&instance->filter, &cooked_time, offset,
> dispersion);
> -  instance->leap_status = LEAP_Normal;
> +  instance->leap_status = leap;
>  
>    log_sample(instance, &cooked_time, 0, 1, offset + correction -
> instance->offset, offset, dispersion);
> 

-- 
Miroslav Lichvar

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