Re: Race condition merging branches

[Carel Fellinger]

On Mon, Aug 27, 2001 at 07:39:07PM +0000, Kaz Kylheku wrote:
> In article <address@hidden>, Carel Fellinger wrote:
> >I've a branch and a trunk and I want to merge things from the branch
> >back into the trunk. I regularly tag the branch with tags like
> >branch_3, the branch tag is branch. I naively thought that the
> >follwing would do:
> >
> >  cvs rtag -r branch branch_n
> >  cvs update -j branch_n-1 -j branch_n
> >
> >but this obviously leaves out the stuff in branch_n, so I have
> 
> It obviously what? You are laboring under some sort of misconception.

Boy do I feel stupid.  As Eric Siegerman pointed out to me it works
just as I thought at first.  Must have been the heat that made me
misinterper what happened to my files.

...
> used by you only.  But in general, this is a race condition; if
> people could be committing to that branch, you could lose merges.
> 
>  That would be really bad, as it would
> >be left out in the next iteration of branch merges were I would do:
> >
> >  cvs update -j branch_n -j branch
> >  cvs rtag -r branch branch_n+1
> 
> You still have a race condition. Because between the update and the
> rtag command, someone could commit changes to the branch, so you
> end up tagging something other than what you merged.

You're right. But fortunately cvs is up to the task of tagging first
and merging from (but excluding) tag_n-1 upto (and including) tag_n. 

-- 
groetjes, carel