Git has become the most popular version control system and you can now make use of it when working with the Google Code Project Hosting system.
If you’ve not encountered Git (and this is becoming increasingly unlikely), it’s a distributed version control system (DVCS) like Mercurial that is used by some big name projects including the Linux kernel and Android. Invented by Linus Torvalds it is occasionally said to be his greatest innovation and easily more important than Linux!
A recent survey showed Git to be the preferred source control system among developers irrespective of operating system while Google Code was the preferred code hosting site of only 6-7% of them - suggesting that the non-availability of Git was holding back the Google hosting facility.
The reason Google can start supporting it is because from version 1.6.6. onwards, Git has added a ‘smart’ HTTP protocol that works with Google’s HTTP-based infrastructure.
According to the announcement from Google, the Git implementation stores object data in a custom data store built on Bigtable, which provides efficient, scalable source code repositories with near-instantaneous replication to multiple datacenters around the world. To fit with Google’s existing Python-based system, their Git server implementation is powered in part by Dulwich - a PHP version of Git.
If you create a project or choose to administer the source for an existing project, you can now decide to use Git as your version control system. This gives you the same options as with existing source control systems available in Google Project Hosting, so you get project updates, advanced issue tracking, and a VCS-backed wiki. You can also create an instant server-side clone of any existing Git repository by clicking the “Create a clone” button on the project’s checkout page.
There’s more information on Git and converting to Git from existing Subversion and Mercurial repositories on the Google Project Hosting support wiki.