[devel] [gmane.comp.freedesktop.xorg] Re: Xlib moved to git

[Anton Farygin]

On Sun, 19 Feb 2006 12:40:14 -0800, Keith Packard wrote:

> On Sun, 2006-02-19 at 08:47 -0800, Alan Coopersmith wrote:
> 
>> Since the decision to do this seems to have been made in private
>> discussions, can you explain to the rest of us why git was chosen for us
>> over subversion or mercurial, which seemed to be the leading contenders
>> to replace CVS in discussions until very recently?
> 
> One of the advantages of our new modular world is that we needn't use the
> same version control system everywhere, so this isn't some kind of
> 'global' choice.
> 
> In this particular case, we want to provide two parallel versions of the
> same library, an XCB version (as discussed at the X developers conference)
> and the existing version. Without some reasonable revision management, it
> wasn't going to be easy to deal with.
> 
> So, a move from CVS was warranted, but perhaps a bit more email-based
> warning would have been helpful in this case.
> 
> As to the selection of which SCMS to choose, I've frankly never seen any
> group build a credible concensus around any useful system. In fact, I've
> seen several groups (Gnome, recently) make ill-informed choices for
> political rather than technical reasons.
> 
> I've selected GIT for my work for many reasons:
> 
>  1)	It has a credible track record with a real, large project.
> 
> This rules out things like Darcs, monotone, bzr, etc.
> 
>  2)	It has an obviously robust repository structure
> 
> This rules out svn, mercurial, CVS. Yes, mercurial is better than CVS, but
> it still modifies existing files, rather than only writing new ones.
> 
>  3)	I have local support available (price == sushi).
> 
> The only local SCMS developer I know wrote git.
> 
>  4)	The CVS import tool captures the whole repository
> 
> Tailor doesn't handle branches, ruling out mercurial and bzr
> 
>  5)	It's very fast
> 
> This rules out svn+svk
>  
>  6)	The distributed model provides new developers tools.
> 
> Allowing all developers to share the SCMS, whether or not they have commit
> access is a huge feature. New features can be developed and distributed by
> people with no commit access as if they were peers in the project, and not
> second-class citizens.
> 
> Now, the real key is that because the git import tools capture the whole
> repository in a change-set manner, we can move from git to any of the
> modern revision control systems in a straightforward fashion. So, if it
> turns out one of the other systems, or some completely new one becomes teh
> b0mb in the future, we can easily migrate from git.
> 
> My primary hesitancy in moving from CVS was repository-lockin, every one
> of these new projects advertised CVS import capacity, but not perfect
> cross-product compatibility.
> 
> We're now at the point where a substantial group of systems offer
> essentially identical mechanisms, making moving among them easy if we want
> to in the future.
> 
> Right now, git provides the capability, reliability and developer momentum
> that we need to solve our immediate issues with some assurances that
> future concerns will be addressed as well. In fact, with the import of
> cairo into GIT, when concerns were raised about git on the git mailing
> list, the developers addressed them responsibly.
> 
> I am not recommending a wholesale conversion from CVS to git; using a few
> relatively low-velocity projects should help us decide where to apply this
> particular tool, and how to manage migration of other parts of the
> distribution.
>  
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