[p4] Guidelines for codelines?

Matt Craighead matt.craighead at conifersystems.com
Fri Nov 21 10:45:41 PST 2008


> Where
> you have a team of programmers it is a massive help in preventing them
> stomping all over each other and breaking the build.

If commits (integrates or otherwise) frequently result in build breaks, I
would suggest that you have a much bigger process problem.

Again, I've worked on projects with hundreds of people committing to the
same "main" tree, where all build configurations passed the vast majority of
the time, and when they did break they were rapidly fixed.  It can be
done... it just requires tools to detect and prevent build breaks.


On Fri, Nov 21, 2008 at 3:22 AM, Greg Whitfield <
Greg.Whitfield at lightworkdesign.com> wrote:

> I'll backup what Rick says - using development branches has been a huge
> plus, and I could not imagine working effectively without them. Where
> you have a team of programmers it is a massive help in preventing them
> stomping all over each other and breaking the build. Mostly his approach
> of merge-down/copy up works quite trivially. I have found it useful
> occasionally to do per-changelist integrations but that is normally in
> situations where code has been restructured in a  dev branch and you
> want to ensure feature enhancements in mainline make their way up
> properly. In this situation, "p4 interchanges" is really useful, and I
> recommend you check it out (no pun intended!).
>
> Chris's suggestion of a CGI script may not be needed if "p4
> interchanges" does the job for you. I guess it depends on what specific
> info you want in the reports.
>
> Greg
> ~~~~
>
>
>
> -----Original Message-----
> From: perforce-user-bounces at perforce.com
>  [mailto:perforce-user-bounces at perforce.com] On Behalf Of Chris Helck
> Sent: 20 November 2008 22:26
> To: Rick Macdonald; Matt Craighead
> Cc: perforce-user at perforce.com
> Subject: Re: [p4] Guidelines for codelines?
>
> On a related note, I've been wondering whether some of this can be
> avoided by generating reports. A CGI script could look at all branch
> specs and list all unintegrated changes in the direction of the normal
> flow (release -> main -> development) as well as reverse flow. This
> report might help spot branches that are going to have integration
> problems early on. Thoughts?
> -Chris
>
>
> -----Original Message-----
> From: perforce-user-bounces at perforce.com
> [mailto:perforce-user-bounces at perforce.com] On Behalf Of Rick Macdonald
> Sent: Thursday, November 20, 2008 3:31 PM
> To: Matt Craighead
> Cc: perforce-user at perforce.com
> Subject: Re: [p4] Guidelines for codelines?
>
> Matt, I'm responding to this not to change _your_ mind, but just for
> another viewpoint for the original poster.
>
> Not using development branches seems a severe way to avoid mass
> integrations. You can retain the benefit of having development branches
> without mass integrations simply by making a list of all the changelists
> and integrating them one at a time. Combine this with "Merge down - Copy
> Up" and it is not as traumatic to the mainline as doing development
> directly in the mainline can be.
>
> Having said that, we have always "merged down - copied up" but in 10
> years of Perforce use in our company I've never heard of anybody needing
> to integrate one changelist at a time. I've seen several people here say
> they do, and I think Laura suggests it in her book. A lot of it depends
> on the scope of development tasks. Ours are typically relatively small
> and don't take long to do.
>
> I can't imagine not using branches. It's a big plus to have a different
> codeline policy for my dev branch than for the parent (mainline or
> whatever). I can checkpoint/backup changes to my dev branch even if they
> don't compile. That gives me rollback, history and diff features. Other
> programmers can sync and work with or test other people's branches.
>
> Rick
>
> Matt Craighead wrote:
> > My personal recommendation is to avoid development branches.  I've
> > found development branches to be a lot more trouble than they're
> > worth.  One of the biggest problems is "mass integrates".  I've
> > written about this on my
> > blog:
> > http://www.conifersystems.com/2008/11/05/the-benefits-of-small-commits
> > / http://www.conifersystems.com/2008/11/12/when-are-small-commits-bad/
> >
> > 'One common way people end up committing large changes is the dreaded
> > "mass integrate".  That is, you have two branches, and you want to
> > catch up the one branch with all the changes made to the other branch.
>
> > In a mass integrate, rather than integrating each individual change
> > over by itself, you integrate all of the changes together in one big
> > commit.  Mass integrates may touch hundreds or thousands of files.'
> >
> > Also, in Perforce you can undo a bad change, but you can't
> > simultaneously roll back the integration history -- if you undo the
> > change, the integration history will be wrong.  This makes these
> changes especially dangerous.
> >
> > I would say you are better off having all development take place in
> > the main branch.
> >
> > On Mon, Nov 17, 2008 at 4:45 PM, steve at vance.com <steve at vance.com>
> wrote:
> >
> >
> >> The release codeline should only be for fixes to defects found in QA
> >> on the release. Fixes found in other releases that need to be ported
> >> to that release qualify through integration.
> >>
> >> Think of your use of development codelines (you're really talking
> >> multiple, not just one, right?) as ways to avoid risk to the ongoing
> >> releasability and productivity of your mainline. Some people only
> >> integrate to the mainline because the only want fully qualified and
> >> reviewed changes there and branches help them implement that process.
> >>
> >> Feature that may not be done before next release? Branch it. Project
> >> with significant architectural change? Branch it. Prototype or
> >> one-off development? Branch it. Want to be able to check in without
> >> necessarily following the code quality rules on main (with good
> >> justification, of course)? Branch it.
> >>
> >> Steve
> >>
> >> Original Message:
> >> -----------------
> >> From: Chris Helck Chris.Helck at us.icap.com
> >> Date:   Mon, 17 Nov 2008 15:58:26 -0500
> >>  To: perforce-user at perforce.com
> >> Subject: [p4] Guidelines for codelines?
> >>
> >>
> >> We are following the standard development, main, release model and
> >> I'm trying to create guidelines for our developers to help them
> >> figure out which codeline they should work on. My question is when
> >> can work be done directly on the main line? It seems to me the logic
> >> goes something like
> >> this:
> >>
> >> 1. If the change is for a specific release and the release codeline
> >> exists then the change goes on the release codeline.
> >> 2. If the change is an experiment, a large open ended change, or for
> >> an unscheduled release then it goes on a development codeline.
> >> 3. Everything else can go on the main.
> >>
> >> This isn't very crisp and it's bound to be confusing. Can someone
> >> suggest a clearer statement?
> >>
> >> Also, I understand some people use the main only for integrations.
> >> When/why is this recommended?
> >>
> >> Thanks,
> >> C. Helck
> >>
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> privileged and is the intellectual property of ICAP plc and its
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> lost by any mistransmission. The Information is not, and should not  be
> construed as, an offer, bid or solicitation in relation to any
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-- 
Matt Craighead
Founder/CEO, Conifer Systems LLC
http://www.conifersystems.com
512-772-1834



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