[arch-mirrors] Syncing

[Pierre Schmitz]

On Sat, 31 Jul 2010 18:08:11 -0300, Carlos Carvalho
<carlos at fisica.ufpr.br> wrote:
> Pierre Schmitz (pierre at archlinux.de) wrote on 31 July 2010 22:47:
>  >I added some titles. For the delay I added "Average difference between
>  >time of probe and last sychronization". This means if I download the
>  >lastsync file at 12:00 from your mirror and the file indicates that you
>  >have synced at 10:00 you got a delay of 2 hours.Of course this is very
>  >rough but should give us an idea how often you sync with the master
>  >server (directly or indirectly). We might update the lastsync file more
>  >often in future to get some better results. For now I would guess we
>  >have an error of about one hour.
> 
> Yes, but the numbers there don't make sense. For our case
> (c3sl.ufpr.br), the delay is 12.92 or 12.72 hours. Since you list us
> as having updated at 2010-07-31 18:01, and now is Jul 31 21:05:23 UTC,
> there are two possibilities. The first is that you're in the past, in
> which case you cannot know we updated at the moment you list. The
> second possibility is that your're in the future :-)

There is a solution which does not involve time travel at all: the
delay value is an average value measured during the last week every
hour. So if you mirrors keeps updating this value should decrease soon.
I did this to get more usable values instead of just snapshots.

Maybe I should just show you the code:

delay = (SELECT AVG(mirror_log.time-mirror_log.lastsync) FROM
mirror_log WHERE mirror_log.host = tmirrors.host AND mirror_log.time >=
'.$range.')

with $range being 1 week and time being the time of probe.

-- 
Pierre Schmitz, https://users.archlinux.de/~pierre