Re: Import ClearCaase with history?

From: Charles O'Farrell <charleso@gmail.com>
Date: Mar 31, 2010, 12:16 UTC
Message-ID: <loom.20100331T135240-261@post.gmane.org>
In-Reply-To: <1270035189.2785.11.camel@chumley>

Hi David,

Show 11 quoted lines

> I've seen programs that purport to import Subversion (which is also
> good, as they also are using Subversion for other projects....) but do
> any such programs exist for Clearcase?
> 
> I know that, in theory, it would be possible to 
>   for all checkins to Clearcase
>      check out of Clearcase
>      check into git
>   done
> 
> but that would take an incredibly long time in practice, wouldn't it?

Well it certainly isn't lightning quick, but it's not 'incredibly' slow either.

http://github.com/charleso/git-cc

It uses 'cleartool lshistory' to retrieve the changes to a given view, and then 'cleartool get' to download the contents, which can then be added directly to Git. In practice this is reasonably quick, although it depends on the size of your history. I've seen it take a few hours to complete the first step with a medium sized VOB, but once that's complete it's (relatively) quick to fetch the actual files. Git-cc is actually a bridge, and can be reused in this way to retrieve new content after an initial import (which is much, much quicker). Changes can also be pushed back to Clearcase.

As a word of warning, given the way in which Clearcase works you're not technically retrieving the full and complete history; as such a thing is almost impossible to export from Clearcase. What you see is the history of all the _currently_ visible files in your _current_ view. So, for example, any files that have been deleted or moved are completely ignored in the lshistory output. If this is unacceptable the only other option would be to manually modify the config spec to include this missing elements and take 'snapshots' of the history over time.

It's by no means as good or as complete as git-svn; partly because Clearcase is so tricky and partly because I'm so lazy. I hope this helps in some way though.

Cheers,

Charles

PS. Take a look at the Git tools wiki page for some other alternatives.

https://git.wiki.kernel.org/index.php/Interfaces,_frontends,_and_tools