[Buildbot-devel] p4poller.py changes detection since last sync

[Yasser LEBON]

After clarification with team responsible of Perforce in my company it
seems that using @HEAD or @NOW the scanning occurs at the level of the
db.rev instead of db.change that gives differents impacts on Perforce
server. I contacted Perforce and here is their answer:
"The difference has to do with the query being different since you are
using different arguments. The result may be the same but dealing with the
internals is very different, if you are familiar with relational database
you know that the way you construct your query has a lot to do with the
performance.

Actually, I made a patch to change the p4poller.py behaviour. I used "p4
changes -m1" to have the last revision and use the result output  to get
the changelists range "p4 changes @%d, @%d" % (lastChange, headRevision)

Regards
Yasser



2013/9/27 William Deegan <bill at baddogconsulting.com>

> Yasser,
> On Sep 19, 2013, at 2:14 PM, Yasser LEBON <yasser.lebon at gmail.com> wrote:
>
> >
> > Hello,
> >
> > I noticed that buildbot use the following command to get perforce depot
> list of changes since last sync:
> >
> > 'p4 changes %s...@%d,now' % (self.p4base, self.last_change+1)
> >
> > Is there any reason why we use 'now' instead of '#head'? Thanks
>
> I'm not sure why the previous maintainer used ,now, but the result should
> be the same.
>
> From p4 docs:
> * The datespec @now can be used as a synonym for the current date
> and time.
> * file#head The head revision (latest version) of file. Except where
> explicitly
> noted, this is equivalent to referring to the file without a revision
> specifier.
>
> Are you aware of any functional difference?
> -Bill
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