Re: Need help for migration from CVS to git in one go (ie, FORGETTING CVS history)

On Thu, 6 Nov 2008, Francis Galiegue wrote:

Le Thursday 06 November 2008 04:08:16 Jakub Narebski, vous avez écrit :
Hello,
[...]

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* 52 CVS modules, fine; but then this can become one and 52
  subdirectories in them and still act as separate modules from
  the build system point of view (which I have implemented, so
  I can change it);

I think that those CVS modules should become separate repositories,
perhaps joined together using submodules. This is one of more
difficult things during conversion.

Note that in Git commits are always whole tree (whole project)
commits.

Honestly, I'm not fond of this approach. The problem with submodules as far as 
I'm concerned is that documentation is "not really there", and (unless the 
README of egit is _really_ outdated) that there's no support in egit.

I know about commits affecting the whole tree, and even branches and tags, and 
that's more of an advantage to my eyes, for two reasons:

* 99+% of queries currently done on the CVS tree (with Bonsai) cover all 
modules; only rarely is a single module concerned, and in this case you just 
fill in the appropriate field in the search page anyway;

Well, the mapping of CVS modules into Git repositories, and perhaps
also later binding those Git repositories together using submodules
support is IMHO one of more difficult decisions when deciding on
migration from CVS to Git.

What you would have to ask yourself is which of those CVS modules
are independent, for example having independent version numbers (tags)
and independent branches. And if commit really affects whole tree...

* creating a branch is one command and that's it. It may also be one command 
with submodules, but again, the documentation makes me uncomfortable; with 
CVS, well... You get the picture.

Submodules are Git repositories of their own. So you have branching
there (almost) as easy as otherwise in Git. The only problem is a bit
lacking UI for binding those submodules together.

What's more, I don't think we have the requirement of making specific 
per-module tags. Not as far as this has been discussed so far, anyway, and 
not as far as the history shows.

Well, that is one issue that would help in mapping CVS modules to Git
repositories (and submodules).

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* second: even though this may be a "non problem", we use Bonsai,
which has the ability to see what was commited by whom, given a time
interval (from d1 to d2): the base gitweb allows to search by
commiter, which is good, but it has no date boundaries: do tools
exist for git that can do this? If not, that wouldn't be a big deal,
however...

First, there are more web interfaces than gitweb, see
http://git.or.cz/gitweb/InterfacesFrontendsAndTools

Yep, I've yet to try those... There are quite a few!

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Second, you can do this from command line, using combination of commit
limiting a..b and a...b, or --since=<date> or --after=<date> and
--before=<date>, commit message searching --author, --committer, and
--grep, and path limiting "git log -- <pathspec>".

Well, a Web-based search engine is kind of a requirement. I'm the only one to 
do command line... Thanks for the hints, though!

You can also use one of GUI; qgit and gitk + git-gui seems to be quite
mature and cross-platform.

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Third, it would be not that hard to add more advanced search support
to gitweb; this is even one of planned features.

I think there are two possible ways of doing it: have a kind of
"advanced search" form, where one can have fill search terms, like
date limit, path limiting etc; or have an option to limit search to
current view context (for example current file or current directory).

Which brings back to the subject of submodules, since as I said above, we 
generally search on the entire tree, and per-module searches are rare.

Hmmm...

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* third: also Bonsai-related; Bonsai can link to Bugzilla by
matching (wild guess) /\b(?:#?)(\d+)\b/ and transforming this into
http://your.bugzilla.fqdn.here/show_bug.cgi?id=$1. Does gitweb have
this built-in? (haven't looked yet) Is this planned, or has it been
discussed and been considered not worth the hassle?

This is (under name of 'committags') in gitweb TODO; gitweb-xmms2
support this IIRC or supported this (for Mantis and not Bugzilla
though...)

Interesting... I'll have a look at it.

Well, now I have bumped priority of this item in my gitweb TODO list...

-- 
Jakub Narebski
Poland