[rrd-developers] rrdtool: update fails on negative timestamp

[Sebastian Harl]

Hi Tobi,

On Fri, Apr 10, 2009 at 09:57:30PM +0200, Tobias Oetiker wrote:
> Today Sebastian Harl wrote:
> > On Tue, Apr 07, 2009 at 10:11:57PM +0200, Sebastian Harl wrote:
> > > On Tue, Apr 07, 2009 at 07:35:30PM +0200, Tobias Oetiker wrote:
> > > > Today Sebastian Harl wrote:
> > > > >   $ rrdtool update file.rrd -t ds -- -5:42 && date
> > > > >   ERROR: file.rrd: illegal attempt to update using time -5 when last update
> > > > >   time is 1239115940 (minimum one second step)
> > > > >   1239116951
> > > > >
> > > > > Apparently, this feature got lost somewhere on the way.
[...]
> > The rrdupdate(1) manpage states the following:
> >
> >   N|timestamp:value[:value...]
> >
> >   The data used for updating the RRD was acquired at a certain time.
> >   This time can either be defined in seconds since 1970-01-01 or by
> >   using the letter ?N?, in which case the update time is set to be the
> >   current time. Negative time values are subtracted from the current
> >   time. [...]
> >
> > So, I'd expect the following to happen:
> >
> > When using N:<values>, RRDtool calls time() to get the current time (in
> > seconds since the epoch) and uses that as timestamp when storing the
> > values. That works fine.
> >
> > When using 1234567890:<values>, RRDtool uses the given timestamp (in
> > seconds since the epoch). That works fine as well.
> >
> > When using -5:<values>, RRDtool calls time() to get the current time (in
> > seconds since the epoch) and subtracts 5 (in this case) from it. The
> > result will be used as timestamp when storing the values. That does not
> > currently work, but, instead, fails with the error mentioned in the
> > example above.
> >
> > So, now, the question is: Did I misunderstand the manpage? I'm not sure
> > how to interpret the last sentence (from the quote above) then and I'd
> > appreciate an explanation. Else, did that feature ever exist? If not,
> > why is it documented in the manpage? How should it behave in the future?
> > I.e., either the manpage or rrdupdate(1) should be fixed ...
> 
> ah ... now I get it ... the -5 should work ... will check ...

Any news on that?

Cheers,
Sebastian

-- 
Sebastian "tokkee" Harl +++ GnuPG-ID: 0x8501C7FC +++ http://tokkee.org/

Those who would give up Essential Liberty to purchase a little Temporary
Safety, deserve neither Liberty nor Safety.         -- Benjamin Franklin

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