[p4] Guidelines for codelines?

Rick Macdonald rickmacd at shaw.ca
Thu Nov 20 12:30:37 PST 2008


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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