Martin Englund's Blog

Migrating from TeamWare to a new SCM

As Mark pointed out, I'm investigating the technical details on how we should migrate from TeamWare to a more recent SCM.

At the moment I'm busy gathering data about Mercurial to determine the impact it will have on disk usage and time it takes to bringover (the TeamWare equivalent of the Mercurial clone command).

I am also working with Kelly on how we should go about an migrate all information in TeamWare and SCCS to Mercurial. Right now I'm not worrying about non-technical details, e.g. if the SCCS comments are encumbered, i.e. if they contain information which can not be open sourced. I've written a simple Perl script, reusing what Steve have done for OpenSolaris, which allows me to iterate over all SCCS revisions, and do a "hg add" of revision 1.1 and then "hg commit" on all the following revisions.

Doing a simple migration like that is not a problem, but we'd like to group each TeamWare putback into a change set, and that requires some magic. One problem is that TeamWare records time in local time of the engineer who ran the "sccs delget" command, so when you have many engineers working on code that gets integrated at the same time, we can not use the timestamp to group the entries.

Another problem is that the Java SE source have had very relaxed requirements on the SCCS comments, especially if you compare it to Solaris. Lately it has gotten a lot better, but it is far from as stringent as what you find in the ON RTI process.

You can find other random notes about Mercurial on my other blog.

[Technorati Tags: Java SCM Mercurial ]

Comments

• Being a non-sfbay guy, I hope you've already considered cross-continent bringover/putback performance issues.

  Posted by: weijun on September 27, 2006 at 08:14 AM

• 
  Yes, the distributed part of the new SCM is a very important part of the equation.

  First of all, we tried a bringover (clone) over VPN and DSL, which took about 8 minutes for the whole of the JDK, secondly we plan to put clone gates at all major development sites.

  I'm also a remote developer, so I suffer from the TeamWare bringover sluggishness too, and will be very happy if we chose Mercurial.
  

  Posted by: martin on September 27, 2006 at 09:35 AM

• I have a similar Perl script that takes changes from ClearCase, collects them into change sets, and imports into some other SCM system (several possible targets). I am using the commit message (check-in
  message) together with a time windows to build the change sets.

  The
  tricky part is that there may be dependencies, e.g. if you have two
  changes to the same file with a comment of "cool feature X", then they
  cannot be rolled into a single change set (they were different changes
  to the *same file*). Also I want to preserve the ordering, so I want to
  collect the change sets roughly in chronological order, but still if one
  change set is dependent upon another (because that other had
  changed the same file at a lower rev) I want to respect that.

  I think I could share my script if you are interested. Let me know.

  Posted by: gwk on October 02, 2006 at 02:17 AM

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