Be ready: We're switching version control systems

[Nick Mathewson <nickm@xxxxxxxxxxxxx>]

Hello, everyone!  Sometime in the next week or two, I am planning to
move the repository for Tor software from Subversion to Git.  This will
only affect the Tor program itself -- other software in the Tor
Project's Subversion repository will stay where it is for now.

WHAT DOES THAT MEAN?

When we develop software, we use a tool called a version control system
to keep track of all of the changes we have made to it.  Right now, we
use Subversion, which is a pretty conservative centralized version
control design: it manages everything in a big repository on our
Subversion server.  We're switching to Git, which is a decentralized
version control system (DVCS): it allows for many repositories existing
in parallel on different computers.

For more info on Git and its advantages, see http://git-scm.com/ .
We're mainly switching for:

- Better support for branch merging.
- Better support for distributed collaboration.
- Better support for offline development.
- Better support for security fix development.
- Cryptographic confirmation of repository integrity.

NOTES:

- Yes, we'll back up before we start.
- No, I don't know which day the switch will happen on yet.
- No, the website is not moving out of svn.
- Yes, this might be a good time to think about the story of the bike shed.
  [http://www.bikeshed.com/]

HOW DOES THIS AFFECT YOU?

== If you download Tor as a package

  It doesn't affect you at all, except inasmuch as it helps us develop
  Tor more effectively and get you better work faster.

== If you have been tracking Tor from subversion, but not changing it

  Instead of checking out the repository using "svn checkout", you'll
  clone it out with "git clone".  Instead of saying "svn update" to
  see the latest version, you'll say "git pull".

== If you have been writing patches for Tor against subversion, and
   mailing them in.

  As above, you'll need to use git to get the latest development
  version, not subversion.  If you do your work on a local git branch,
  though, you have a better ability to make sure that your patches
  form a logical sequence, and that they apply cleanly against the
  latest Tor before you send them in.

  Of course, you can still just do your patches against a working copy,
  use "git diff" to generate a patch, and email it in.  Just because
  you have support for local branches and versioning doesn't mean you
  need to use it.

  We'll be glad to work with people on the mailing lists and the IRC
  channels to help folks transition along with us.  I'll be sending out
  links to more detailed instructions as the transition occurs.

For more reading on Git, see:

The Git Tutorial
  http://www.kernel.org/pub/software/scm/git/docs/gittutorial.html
  http://www.kernel.org/pub/software/scm/git/docs/gittutorial-2.html

Git for Computer scientists
  http://eagain.net/articles/git-for-computer-scientists/

The "Everyday Git" quick-reference:
  http://www.kernel.org/pub/software/scm/git/docs/everyday.html

Git for SVN users:
  http://www.gnome.org/~newren/eg/git-for-svn-users.html

Two very opinionated Google Tech Talks talks about Git:
  Randal Schwartz:
     http://video.google.com/videoplay?docid=-3999952944619245780
  Linus Torvalds
     http://www.youtube.com/watch?v=4XpnKHJAok8

Our handy repository of (supposedly) useful Git tools.
  git://git.torproject.org/git/githax
See in particular the documentation on using Git with our Thandy
project; the instructions for Tor should be similar.
  http://git.torproject.org/checkout/githax/master/doc/Howto-thandy.txt

And of course, the delightful Git Manual:
  http://www.kernel.org/pub/software/scm/git/docs/user-manual.html

yrs,
-- 
Nick Mathewson