Bug#557477: git-svn: git svn dcommit doesn't handle network failure

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Jan 9, 2010, 07:57 UTC
Message-ID: <20100109075743.GA3377@progeny.tock>
In-Reply-To: <20100109021347.GA26520@dcvr.yhbt.net>

Eric Wong wrote:

Show 5 quoted lines

> I agree that error recovery for dcommit sucks right now.
> 
> I think Brice's idea (creating a temporary branch to dcommit from)
> is easier to implement and less likely to break than automatically
> unapplying patches.

Sounds sane to me. Probably that temporary branch could just be a detached HEAD.

Current dcommit:

 diff-index --quiet HEAD || carp "Cannot dcommit with a dirty index"
 if head ne 'HEAD':
	save the old HEAD
	check out the head
 find svn upstream
 decide what commits to push (linearize_history)
 for each commit d to push:
	commit diff from d~ to d to the remote repository
		(this involves applying the diff locally?)
	remember parents
	fetch remote revision, using remembered parents for commit

	unless args include --no-rebase:
		rebase the current HEAD against fetched revision
			(or reset if there are no changes)
		update the list of commits to push
 if head ne 'HEAD':
	let the user know the branch or commit id for the finished dcommit
	check out the old head again

If I understand you correctly, before finding the svn upstream, dcommit would save the HEAD ref name (if any) and detach the HEAD; after pushing the relevant commits, update that ref and reattach the HEAD.

If pushing fails early, what should git-svn do? Leave the HEAD detached, with a message suggesting to return to the old ref? Check out the old ref, with a message suggesting to 'git svn rebase' and try again? Do the 'git svn rebase' automatically?

I guess the safest option is the first one. That would at least be a starting point for experimenting with more friendly behaviors.

I should also mention that there seems to be a little race here: if git-svn dies before (or while) fetching the newly commited revision, when it is fetched later it will have the wrong parents.

Jonathan