====== Version Control Migration ======

===== Status Quo =====

Currently, gEDA uses CVS.  CVS is the "original" version control system used for collaborating on open source projects.

Unfortunately, CVS has a number of problems:

  - CVS does not support the concept of patch sets.  That is, it's very difficult to work out what changes went into CVS together without using dodgy tools like [[http://www.cobite.com/cvsps/|cvsps]].
  - Merging with CVS is painful, especially when there is keyword expansion brokenness such as the ''Log'' keyword.
  - CVS doesn't support renames preserving history.
  - The overhead involved in creating and managing a branch in CVS is such that people tend to do one of the following:
     - Don't bother
     - Use another VCS locally, then export patches, then commit patches to CVS.  This is a big hassle for everyone.
     - Do II. **and** use a branch in CVS, which is even more hassle, but means people can see the changes in advance.
  - You can't do anything in CVS (view logs, view "blame" for a line of code, create diffs to previous versions) without being online & connecting to the repository.

===== What We Need =====

gEDA has a development process that involves a number of people working independently on separate changes.  Some of these are a single changeset hacked together in a few minutes, some involve several major changes and are developed over a matter of months.  Often,  in order to track down a tricky bug, it is necessary for a developer to try and work out what a fellow developer did several months ago.

The following features would be deemed desirable in a version control system:

  - Free as in beer as well as free as in speech.
  - Actively developed/maintained.
  - Atomic commits (a.k.a. changesets).
  - All users have their own copy of the history.
  - Users can make local branches/commits without being logged onto a remote server ("distributed" repository model).
  - Merge & rename tracking.
  - Easy to transition to from CVS.

Using the [[http://en.wikipedia.org/wiki/Comparison_of_revision_control_software|comparison matrix at Wikipedia]], it looks like only [[http://www.selenic.com/mercurial/wiki/|Mercurial]] and [[http://git.or.cz/|git]] have the features we require.

A number of factors militate in favour of using git:

  * Existing experience within the the gEDA development community.
  * More extensively used by major projects (Linux kernel, X.org X server, OLPC, WINE).