On Tue, Oct 24, 2017 at 01:05:00PM +0200, Michael Haggerty wrote: > > I'd expect one of: > > > > 1. We delete "foo" before updating "foo/bar", and we end up with a > > single ref. > > I don't think that this is possible in the general case in a single > transaction. The problem is that the code would need to take locks > > refs/tags/foo.lock > refs/tags/foo/bar.lock > > But the latter couldn't coexist with the loose reference file > > refs/tags/foo > > , which might already exist.
Yeah, you're right. I was thinking of the opposite case (where you could create "foo.lock" even though "foo/bar" exists), but this one is impossible with filesystem semantics. > It is only imaginable to do this in a single transaction if you pack and > prune `refs/tags/foo` first, to get the loose reference out of the way, > before executing the transaction. Even then, you would have to beware of > a race where another process writes a loose version of `refs/tags/foo` > between the time that `pack-refs` prunes it and the time that the > transaction obtains the lock again. Yeah, it's probably better to avoid playing games here. Moving to a non-filesystem storage backend would just make the problem go away. -Peff
