git svn project shuffle

git svn project shuffle

[Christopher Snapp]

I have used git to interface with an svn repo for some time quite
successfully, but today I've run into a scenario that I'm not sure how
to solve.

The situation is this:
* I have a project (let's call it "oldproj") that has its own
branches, tags, and trunk svn structure
* oldproj is checked out using git svn clone --stdlayout and all has been swell
* due to a CM shuffle oldproj's svn trunk has been copied to a new svn
project (let's call it newproj), so oldproj/trunk has been copied to
newproj/trunk/oldproj
* oldproj's branches and tags directories have been "archived",
meaning it isn't CM guy's intention to bring them over to the newproj
structure.  I don't mind losing the contents of the oldproj's branches
and tags, but I'm not sure how to transition to newproj using my
already checked out git svn clone

My questions are:
# If I try to start from scratch by using git svn clone --stdlayout
the "newproj" location I lose all of the revision history associated
with "oldproj/trunk" that has been copied to newproj/trunk/oldproj.
How can I have git understand the history for the
newproj/trunk/oldproj location?

# An alternative would be if I could somehow reconfigure my already
checked out oldproj git repo so I retain all of the version history
and my local branches and can move forward checking code into the
newproj/trunk/oldproj location?

Regarding the second question, I'd be concerned that the loss of the
branches and tags from the oldproj would confuse things in the future
as the newproj branches and tags are new.

This is probably a simple scenario that many have bumped into but my
searches have so far come up blank.

Thanks very much for any guidance or pointers to previous discussions
regarding this scenario.

--
Chris

Re: git svn project shuffle

[Jonathan Nieder]

Hi Chris,

Christopher Snapp wrote:

> # If I try to start from scratch by using git svn clone --stdlayout
> the "newproj" location I lose all of the revision history associated
> with "oldproj/trunk" that has been copied to newproj/trunk/oldproj.
> How can I have git understand the history for the
> newproj/trunk/oldproj location?

If I were in your situation I would do the following:

 0. Make backups!
 1. git svn init -Rnew ...newproj info...
 2. Edit .git/config to put the new project in a separate
     refs/remotes/newproj/ hierarchy.
 3. git svn -Rnew fetch
 4. gitk --all.  Look around.
 5. For each "tip" of the old history:
     git replace <corresponding new commit> <old branch tip>
 6. gitk --all.  Make sure it looks right.
 7. git filter-branch -- --all
 8. rm -fr .git/svn.  This is destructive, but only of information
    you're probably not using.  (It forgets old properties, for
    example.)
 9. Edit .git/config and use "git branch -r -d" to get rid of references
    to oldproj.  Rename the newproj svn-remote to "svn" again.
10. git svn fetch.
11. gitk --all.  Everything good?  Push.

> # An alternative would be if I could somehow reconfigure my already
> checked out oldproj git repo so I retain all of the version history
> and my local branches and can move forward checking code into the
> newproj/trunk/oldproj location?

If your history in each branch is not published and is linear, you
could also try just putting the old and new histories in one temporary
repo and rebasing your private branches.

Or you can export your own work with "git format-patch" or "git
fast-export" and reimport it with "git am" or "git fast-import".

Hope that helps,
Jonathan

Re: git svn project shuffle

[Christopher Snapp]

Jonathan,

First off, thanks very much for the quick and thorough response.

Sadly, this is outside the norm for me and I'm just not understanding
all the steps.  As a result I've successfully mangled my poor git
repo. Good thing I followed step 0. :)

I'll continue to read up on some of the steps you listed to try and
figure out where I went wrong, but I'm wondering if there might be an
easier way to get back to a stable repo.  The alternative I'd like to
try is to simply clone the new svn location.  What I'm not
understanding is why git will not traverse the svn history properly.
If you remember my old project's trunk has been copied to a
subdirectory of the new project's trunk.  So, oldproj/trunk is now
newproj/trunk/oldproj.  When I do a git svn clone of the newproj I
would expect it to follow the svn copy that created
newproj/trunk/oldproj but it doesn't.  I'm simply left with a couple
of commits and none of the original oldproj history.  If I view the
svn repo using some other tool (e.g. kdesvn) I can see all the history
as expected.  I'm not coming up with anything in my searches that
would give me a reason why git would stop searching history.

Thanks again for the help,




On Mon, Oct 4, 2010 at 2:54 PM, Jonathan Nieder <jrnieder@gmail.com> wrote:
> Hi Chris,
>
> Christopher Snapp wrote:
>
>> # If I try to start from scratch by using git svn clone --stdlayout
>> the "newproj" location I lose all of the revision history associated
>> with "oldproj/trunk" that has been copied to newproj/trunk/oldproj.
>> How can I have git understand the history for the
>> newproj/trunk/oldproj location?
>
> If I were in your situation I would do the following:
>
>  0. Make backups!
>  1. git svn init -Rnew ...newproj info...
>  2. Edit .git/config to put the new project in a separate
>     refs/remotes/newproj/ hierarchy.
>  3. git svn -Rnew fetch
>  4. gitk --all.  Look around.
>  5. For each "tip" of the old history:
>     git replace <corresponding new commit> <old branch tip>
>  6. gitk --all.  Make sure it looks right.
>  7. git filter-branch -- --all
>  8. rm -fr .git/svn.  This is destructive, but only of information
>    you're probably not using.  (It forgets old properties, for
>    example.)
>  9. Edit .git/config and use "git branch -r -d" to get rid of references
>    to oldproj.  Rename the newproj svn-remote to "svn" again.
> 10. git svn fetch.
> 11. gitk --all.  Everything good?  Push.
>
>> # An alternative would be if I could somehow reconfigure my already
>> checked out oldproj git repo so I retain all of the version history
>> and my local branches and can move forward checking code into the
>> newproj/trunk/oldproj location?
>
> If your history in each branch is not published and is linear, you
> could also try just putting the old and new histories in one temporary
> repo and rebasing your private branches.
>
> Or you can export your own work with "git format-patch" or "git
> fast-export" and reimport it with "git am" or "git fast-import".
>
> Hope that helps,
> Jonathan
>



-- 
Chris

Re: git svn project shuffle

[Jonathan Nieder]

Hi again,

Christopher Snapp wrote:

> If you remember my old project's trunk has been copied to a
> subdirectory of the new project's trunk.  So, oldproj/trunk is now
> newproj/trunk/oldproj.

Yeah, I was ignoring this part. :)  git svn is not really wired for
it.

The instructions were meant to also be usable in a case where oldproj
and newproj are entirely independent repositories.

> When I do a git svn clone of the newproj I
> would expect it to follow the svn copy that created
> newproj/trunk/oldproj but it doesn't.

If the layout has been relatively stable before, maybe "git svn
--no-follow-parent" would give some joy.

Still I would be interested in hearing where the grafting procedure
went wrong.  If you end up tracking it down to a single step, do
please let us know.

Regards,
Jonathan