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FreeBSD Begins Switch to Subversion
An anonymous reader writes "The FreeBSD Project has begun the switch of its source code management system from CVS to Subversion. At this point in time, FreeBSD's developers are making changes to the base system in the Subversion repository. We have a replication system in place that exports our work to the legacy CVS tree on a continuous basis.
People who are using our extensive CVS based distribution network (including anoncvs, CVSup, cvsweb, ftp) will not be interrupted by our work-in-progress. We are committed to maintaining the existing CVS based distribution system for at least the support lifetime of all existing 'stable' branches. Security and errata patches will continue to be made available in their usual CVS locations."
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They don't use git because FreeBSD development has traditionally been "centralized". They use a model where patches are fed to a group of core developers with "commit permission" to the tree, and all source changes are vetted and fed through that funnel. Subversion's centralized source control methodology works well with the FreeBSD development process, and the decentralized aspects of git is not needed.
However, of course, there is still some distributed coding going on at the edges, but they tend to be peripheral and experimental. The developers working on these experimental branches can choose to use whatever source control system they wish. Many FreeBSD developers prefer perforce for their experimental work, but they can use git or mercurial if they wish.
Subversion has an Apache/BSD type license. GIT does not.
GIT lost the version control war early on. Its focus on Linux development with little to no support for Windows and Mac made it unpopular. That's a situation that has changed (somewhat), but the stigma is still attached to it. Which is not really a problem. GIT was developed to meet the needs of the Linux Kernel Project. If it happens to meet the needs of other projects, great. If it doesn't, that's just as fine.
In any case, Mercurial ended up being the "best of breed" solution. It offered all the features of the competing version control systems, was portable across platforms, had a significant toolchain appear practically overnight, and is used by HUGE OSS companies like Sun and Mozilla. I've used it in my own projects and have found that it is much easier and more dynamic than the classic, monolithic model of CVS.
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Path of least resistance; it works much like CVS, it fits in with existing infrastructure, and everyone knows how to use it.
git isn't terribly well suited to very large monolithic projects; you need to split into multiple smaller projects since it tracks entire trees rather than single files. When your tree is 1.3GB+ and has upwards of quarter of a million files that's rather painful either way.
It also isn't well suited to rewriting history, e.g. in the case when you have to remove a changeset because it violates someone's patent or copyright; you can rewrite the repository to remove it, but you end up renaming every commit afterwards, since their names are SHA1's dependent on every previous commit, generating tonnes of churn in many different places as the whole of history basically disappears and reappears elsewhere.
Many of git's advantages can still be leveraged with SVN; git-svn works pretty well, and it doesn't require massive upheavals in all areas of the project.
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Well, if you believe Linus, it must be because they are ugly and stupid :)
Mercurial is the solution currently in use at Mozilla, Sun, and quite a few Linux projects. (Though not the main kernel branch. That's GIT. Think something more along the lines of ALSA.)
Mercurial is interesting because it encourages teams to work together, pushing and pulling source code from each other. When the source reaches a stable point, you can push that to a central repository for building and archiving.
The interesting aspect about this design is that it actively encourages branching! Rather than treating branches as a special thing that needs to be done under a certain set of circumstances, it treats every copy of the repository as a branch. So developers can work independently. When they come back together, the tool is able to auto-merge most projects back into a single whole.
Mercurial is able to do this because it tracks the point of divergence. With that information, it can see if any of the changes truly conflict. 95% of the time, there is no conflict and Mercurial is able to merge the files auto-magically. The other 5% of the time, Mercurial will launch a merge tool and make you answer YES/NO to each difference. This process is amazingly smooth.
The key thing to keep in mind with Mercurial is that you won't want to keep all your source in one repository. (Like most companies do with CVS.) Keep a separate repository for each project or module. You can keep the repositories all in the same path, but it's much easier to work with only the code you need rather than copying around a 10GB source tree from developer to developer.
If you do decide to try Mercurial and are given a Windows development machine, I highly recommend TortoiseHG. You'll occasionally have to run 'hg update' from the command line (the tool will prompt you), but it's otherwise a very slick way of working with Mercurial repositories.
Oh, and don't use the CVS->Mercurial conversion tools. It leaves CVS-style droppings all over creation. Just import the latest codebase and keep CVS running in read-only mode for as long as you need historical data.
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Googlefight!
git tutorial: 512,000 results
mercurial tutorial: 1,100,000 results
Winner: Mercurial!
Google doesn't provide JACK for GIT. GIT uses SVN. In order to use GIT with Google, you need to have a GIT->SVN translator:
http://nigel.mcnie.name/blog/using-git-for-your-sourceforgegoogle-code-project Installing a Cygwin environment is not a supportable solution for most corporations. They needed native solutions. Something which has begun to appear.I agree with you wholeheartedly. The target audience is Linux hackers. They are the ones using GIT. The business world, OTOH, has chosen Mercurial. Such is the way of things.
Javascript + Nintendo DSi = DSiCade
If you are used to CVS then Subversion is definitely a step up, and it will be very familiar to your users. What's more it is well supported by IDEs and has piles of other tools like Tortoise that makes it easy for non-developers to use. Heck, if push comes to shove it can even be used as a WebDAV share with the advantage that it will automagically version your files.
The downside of Subversion is that it isn't very good at merging. Merging branches in current versions of Subversion is a manual process that is ridiculously painful. This can be mitigated somewhat using the svnmerge Python script, but even with the script merging still isn't as easy as any of the distributed version control systems. For people like Linus Torvalds that's basically a showstopper for Subversion. To them merging is basically the whole point of a version control system.
It's quite possible, however, that you have different needs than the Linux kernel. For example, none of the distributed version control systems deal well with large files. If you want to store multi-media files along with your source then Subversion is basically your only option. Likewise, if you plan on having designers or random office workers use your repository then you can forget about the distributed tools.
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