Re: [Monotone-devel] Monotone to and from Subversion

[William Uther]

Hi,
  I was looking at the same thing.  Tailor did not seem a 100%  
satisfactory solution, although it could be worse.

  I was thinking at one point of using the same idea used in the  
cvssync.attrs branch.  It would be much easier with subversion.

  Basically, you have one micro-branch that is the 'subversion'  
line.  There is a cert attached to the any monotone revision that  
corresponds to a subversion revision.  The cert contains the  
subversion repository and revision information.

  To do a 'pull' from subversion into monotone, you find the last  
monotone revision with a cert from the repository you're pulling  
from.  You read from the cert which revision it is up to.  You loop  
forward from there checking out from subversion and checking in to  
monotone.  I don't know how you can easily get diffs out of  
subversion, but you could do the check-ins to monotone without a  
workspace which should speed things up.

  To do a 'push' from monotone into subversion, you first find the  
last monotone revision with a cert from the repository you're pulling  
from.  If the subversion revision in that cert doesn't match the head  
revision of the repository then you need to abort and tell the user to  
pull first.  If it does match, then you can push all descendants of  
that revision (you might want to warn the user if they're not  
merged).  Loop through the descendants of the last synced revision and  
find the longest path (to the head?).  That will be the set of  
revisions you'll commit.  Loop along this path towards the head,  
committing each monotone revision in turn.  Each time you commit a  
monotone revision to subversion, you can attach a cert to it marking  
it as committed.

  Note that this does NOT commit every revision in monotone into  
subversion.  Subversion can only hold a linear history.  If there is a  
non-linear history in monotone, then only one line of that history  
will be committed as separate revisions.  The other line will be  
committed as one great diff when the merge revision is committed.

  The only other tricky bit is the log messages to use in a push.   
You could just use the corresponding monotone log messages, but this  
loses log messages when merge revisions are pushed.  In this  
situation, cvssync makes a composite commit message.  Every revision  
that has multiple parents will get a composite commit message.  The  
message is the concatenation of the log messages of every ancestor of  
the merge revision that is not also the ancestor of an already synced  
revision.  This makes sure that log messages go with the revision that  
commits the diffs, even if they are lumped together because of the non- 
linear history.

  I have other things to do right now :)

Cheers,

Will        :-}

On 22/01/2008, at 3:32 PM, Grahame Bowland wrote:

> Hey guys
>
> I'm going to be in a situation where getting to a subversion
> repository is a pain. I'd like to export from subversion into monotone
> and then work committing to the the monotone database, but in a way
> which makes it easy for me to pull updates from subversion upstream
> and also commit my patches back (with changelog entries, etc).
>
> Does anyone have a way of doing this that they've found works well? It
> seems like I could just hack something together with a few scripts and
> tailor, but I thought I'd ask in case someone else has already done
> it!
>
> Thanks
> Grahame
>
>
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