From: Phil Hord <phil.hord@gmail.com>
Date: Wed, 07 Mar 2012 22:33:39 GMT
Subject: Re: Approaches to SVN to Git conversion
Message-ID: <CABURp0pLnMdFVgQ2+S_rW-KEjUBjKbEbMepEdPUkRJD+JQ_Ehg@mail.gmail.com>
In-Reply-To: <4F5690FB.9060800@pileofstuff.org>

On Tue, Mar 6, 2012 at 5:34 PM, Andrew Sayers
<andrew-git@pileofstuff.org> wrote:
> This is quite close to the implementation I've got.  The SVN exporter
> runs in two stages:
>
> In the first stage, the script treats any non-blacklisted file as a
> marker file, but only looks for trunk branches.  It looks all through
> the history, traces back through the copyfroms, and tries to find the
> original directory associated with the file.  Usually it decides that
> the only branch without a copyfrom is /trunk.  Searching just for trunks
> with this weak heuristic makes it much easier to hand-verify the result.
>
> In the second stage, the script looks through the history again, tracing
> the copies of known branches in a slightly less clever way than
> described in my previous e-mail.  There's no need for marker files this
> time round, as we just assume any `svn cp /trunk
> /directory/not/within/a/branch` is a new branch.  In my experiments this
> has been a pretty solid way of detecting branches without too much human
> input - I might be missing something (or have mis-explained something),
> but I'd be interested to hear examples of where this would go wrong.

I think what you're describing would work perfectly for my weird svn
repo.  I have branches named like this:

branches/developer/hordp/foo
branches/developer/hordp/bar
etc.

Since these were created with 'svn cp' originally, they would be
properly considered branches by your algorithm, right?    If so,
sweet!

> Having said that, here's a dodgy example I'd like to pre-emptively defend:
>
>        svn add tronk
>        svn ci -m "Created trunk" # r1
>        svn cp tronk trunk
>        svn ci -m "D'oh" # r2
>        svn rm tronk
>        svn add trunk/markerFile.txt
>        svn ci -m "Double d'oh!" # r3
>
> You could argue that the correct branch history description for the
> above would be:
>
>        In r3, create branch "trunk"
>
> In other words, ignore everything that happened before the marker file
> was created.  However, I would argue the following representation is
> more correct:
>
>        In r1, create branch "tronk"
>        In r2, create branch "trunk" from "tronk" r1
>        In r3, delete branch "tronk"
>

I prefer your interpretation. It doesn't look dodgy at all.

Phil