Re: branch creation uses wrong starting point

Jamma Tino Schwarze wrote:
> I'm preparing migration of a rather large codebase and I came across an
> issue. I'll try to summarize it briefly.
> 
> Suppose, I've got three branches in CVS (plus HEAD) with the following
> anchestry:
> HEAD
> +- 5_4_branch
> ...+- 5_4_customer_production_branch
> ......+- 5_4_customer_test_branch
> 
> I'm mapping these to
> /c4u/MODULES
> /c4u/5.4/MODULES
> /customer/old_branches/5_4_customer_production/MODULES
> /customer/old_branches/5_4_customer_test/MODULES
> 
> I looked into symbol-info.txt and found that all parent-relations are
> correctly recognized:
> 0     5_4_branch            branch     c4u/5.4/MODULES .trunk.
> 0     5_4_customer_production_branch branch customer/old_branches/5_4_customer_production/MODULES 5_4_branch
> 0     5_4_customer_test_branch    branch customer/old_branches/5_4_customer_test/MODULES 5_4_customer_production_branch
> 
> But it looks like the commit for the creation of
> "5_4_customer_test_branch" is wrong. I come to that conclusion since
> svnsync-ing the converted repository fails and reports a missing file
> right at that commit. The log message also does not make sense:
> 
> ----
> r24870 | cvs2svn | 2009-09-30 10:51:17 +0200 (Wed, 30 Sep 2009) | 2 lines
> Changed paths:
>    A /customer/old_branches/5_4_customer_test
>    A /customer/old_branches/5_4_customer_test/MODULES (from /c4u/MODULES:15273)
> [...]
> This commit was manufactured by cvs2svn to create branch
> '5_4_customer_test_branch'.
> ----
> 
> It looks like it copies the test-branch from trunk instead of it's
> parent which has just been correctly created the revision before:
> ------------------------------------------------------------------------
> r24869 | cvs2svn | 2009-09-30 10:51:16 +0200 (Wed, 30 Sep 2009) | 2 lines
> Changed paths:
>    A /customer/old_branches/5_4_customer_production
>    A /customer/old_branches/5_4_customer_production/MODULES (from /c4u/5.4/MODULES:24860)
>    D /customer/old_branches/5_4_customer_production/MODULES/c4u_tools 
> 
> This commit was manufactured by cvs2svn to create branch
> '5_4_customer_production_branch'.
> ------------------------------------------------------------------------
> -> copied correctly from 5_4_branch, removing that one module which does
> not have that branch.

Your analysis is helpful, but it would be more helpful if you would also
provide a test repository that we can use to reproduce your problem.
Reasoning about problems like this is much easier with a concrete
example.  See the FAQ for instructions for how to make a test repo.

> I'm a bit lost and suspect a cvs2svn bug (I'm using 2.3.0). Is it worth
> to try cvs2svn from trunk?

It can't hurt, though offhand I can't think of any changes in trunk that
would affect this.

> I was able to reproduce the problem using a clean repository, performing
> only the following operations: [...]
> -> both production and test branch are created at the same time, with no
> changes inbetween. It looks like cvs2svn uses the CVS-revision number
> for determining from where to copy files, but they do not show the
> parent-child relationship:
> cvs log
>     5_4_customer_test_branch:       1.1.1.1.2.1.0.4
>     5_4_customer_production_branch: 1.1.1.1.2.1.0.2
>     5_4_branch: 1.1.1.1.0.2

There is no unambiguous way to determine the relationship between
branches in cases like these.  So cvs2svn uses some heuristics, *not*
just basing its decision on the version numbers.  (These heuristics
don't work so well for vendor branches, so if your real example involves
vendor branches that could be part of the problem.)

It is alarming that svnsync reports an error on the converted
repository, and we should get to the bottom of that problem.  It is
definitely a bug, either in "svnadmin load", or in svnsync, or in
cvs2svn *and* "svnadmin load" (because "svnadmin load" should refuse to
load invalid data into the repository regardless of where it comes from).

But otherwise the most important criterion for the correctness of a
conversion is whether checking a branch/tag out of Subversion gives the
same files and contents as checking the same branch/tag out of CVS.  Is
this the case with your repo?

Michael

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