This Week in Bazaar

This is the seventh in a series of posts about current topics in the development world of the Bazaar distributed version control system. The series is co-authored by John Arbash Meinel, one of the primary developers on Bazaar, and Elliot Murphy, who is sentimental today.

MySQL Switches to Bazaar

Very big news for the Bazaar team today, as MySQL announces switching from Bitkeeper to Bazaar.

One of the things that was important in doing this conversion was doing a very high quality import of all the existing history. John did a great job working on that, and even added a new feature to Bazaar and bzr-gtk to enable this: per-file commit messages. Since per-file commit messages had been used for years in the MySQL code base, it was not acceptable to lose them, and none of the DVCS systems under consideration supported these messages. Although this feature is debated by some, it was important to preserve that history, and so support for per-file commit messages was added to Bazaar in a non-invasive way, where projects who wanted to use them could, but existing projects were not forced to adopt them. At the moment, to enter per-file commit messages you need to use the bzr-gtk GUI commit tool, but we'd love it if someone came up with a clean way to enable this in the standard CLI also.

It was also important to have a smooth transition period that did not interrupt delivering MySQL releases. This meant we needed a stable importer where the imports could be periodically refreshed without causing all of the developers around the world working on the project to re-download all their trees. At one point we were doing continuous imports of over 30 trees.

It's been a fun and challenging project providing support to MySQL during this time. Although we're really excited about this milestone, we still have plenty of work to do. Here are a few things we've learned, where we are working to make Bazaar even better.

Stacked Branches. We've talked previously about stacked branches, and for a project like MySQL this new feature will make uploading a new branch to Launchpad much faster.

Merging - Bazaar has several good merge algorithms, but we still have some ideas to make merging go even smoother, particularly for some of the complicated ancestries that MySQL has. All merge algorithms have their own set of trade offs, edge cases that they handle better or worse than other algorithms.

We also need to continue to add GUI tools, and make further enhancements to existing tools. If you are looking for a valuable way to contribute to Bazaar, try lending a hand to one of the Bazaar GUI projects.

Last week we asked about bzr screencasts, and James Westby told me about a screencast that he recorded - if anyone else is interested in getting involved in producing a series of screencasts, please do let us know.

This Week In Bazaar First Edition

This is the first in a mostly-every-week series of posts about whats been happening in the development world of the Bazaar distributed version control system. The series is co-authored by John Arbash Meinel, one of the primary developers on Bazaar, and Elliot Murphy, Launchpad developer and wanted criminal.

We get to talk about anything we want. This week:

• What's been happening for a better GUI on Windows
• What's new in the 1.4 release
• Importing from other VCS's with bzr fast-import

... details ...

GUI on Windows

We found this guy named Mark Hammond who claims to know how to make python stuff work well on windows. There is an existing GUI tool for Bazaar on Windows called TortoiseBZR now, modeled after TortoiseSVN. If you haven't used a Tortoise before, they are extensions that integrate into Windows Explorer; allowing you to see and control the versioning of your files without needing to change to a separate tool.

Mark has taken a look and proposed a series of enhancements to make the tool work even better. Bazaar already works very well from the Windows command prompt, but we want to provide excellent GUI tools as well. Take a look at the TortoiseBZR web page for screenshots of it in action.

What's new in the 1.4 release

The Bazaar team releases a new version of Bazaar just about every month, with both bugfixes and new features. The bzr-1.4 release came out last Thursday, May 1st.

The major changes for 1.4 include improvements in performance of 'log' and 'status', and a new Branch hook called post-change-branch-tip, which will trigger any time a Branch is modified (push, commit, etc). This should enable server generated emails whenever somebody publishes their changes. Write something cool with it and tell us what you did!

The full list of changes for 1.4 can be found at: https://launchpad.net/bzr/1.4/1.4
The list of all changes is at http://doc.bazaar-vcs.org/bzr.dev/en/release-notes/NEWS.html

bzr fast-import

Bazaar fast-import is a plugin for bazaar that allows you to import from many different version control systems. The fast-import stuff is intended to support any system that can use the fast-export format. This format was originated by git developers, and quickly adopted elsewhere. So if a source format can generate a "fast-import" stream, you should be able
to import it into Bazaar.

• CVS
  To convert from cvs, you currently use the cvs2svn converter. Which has a flag to generate a "fast-import" stream.
• Mercurial
  There is a script called hg-fast-export.py bundled with the plugin (in the exporters/ directory).
• SVN
  The svn-fast-export script is also bundled with the bzr-fastimport plugin.
• git
  Bundled with the standard git distribution is the git-fast-export command.
• Your own exotic system here.

Give fast-import a try. It's mostly designed for 1-time conversions, rather than mirroring, but there are already some rudimentary mirroring capabilities.


That's all for the first installment of "This Week in Bazaar".

(edited for formatting)