Re: [PATCH/RFC 2/2] git-p4: Add complex test case for branch import

vitor.hda@gmail.com wrote on Tue, 23 Aug 2011 23:02 +0100:

On Tue, Aug 23, 2011 at 3:27 AM, Pete Wyckoff [off-list ref] wrote:

quoted

I think I understand the problem now, and have a small test case
to see what's going wrong.  Your solution is definitely
sub-optimal.  :)  Is there anything that can be done with
--import-marks and --export-marks?

Don't know if you agree, but I think it would be better to keep git-p4
from storing extra files in the filesystem. And, as far as I understood,
these two options require extra files.
But I don't think marks would help us that much. We already have
something similar: the changelist number in the commit log. The big
problem is that P4 does not store a pointer to the previous changelist.

Agreed.

quoted

Could you guess at the branch point using p4?  I.e. for each file
in the new branch, grab the change that caused its most recent
revision (the #xx part).  Pick the max of those changes.  In git,
find the commit whith "change = ..." that you just discovered.
That's the parent.

Yes, I think this would work. Nevertheless, I would prefer not to do so
much pooling on the P4 server because when we're in a remote location in
regards to the P4 proxy server this kind of command becomes rather slow.
And if the branch has many files this may become cumbersome.

quoted

Even this won't be perfect, and I'm not even sure if it's less
icky than diff-tree.

From what I can see, the two possible solutions would be:

a) Running a "filelog" on all files. This may become slower when the
   branch has lots of files. There's also the problem in needing to
   contact the P4 proxy server every time.

b) Using diff-tree. This will be slower if the original changelist is
   very far from the latest one, but has the advantage of being run
   locally. It has the disadvantage of not having an apparent
   compatibility with fast-import.

In my personal point of view, diff-tree solution still looks better, if
it weren't for the fast-import issue. Now if we could just figure out
how to overcome this issue...

Nice analysis.  P4 can indeed be the bottleneck, even on near
servers if there are lots of files.  Diff-tree seems like the
better choice to find the branch point.  I don't understand fully
why the way we are using fast-import causes these problems.  Will
look at that next.

		-- Pete