From: David Turner <dturner@twopensource.com>
To: Duy Nguyen <pclouds@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>,
Michael Haggerty <mhagger@alum.mit.edu>
Subject: Re: [PATCH v5 25/27] refs: add LMDB refs storage backend
Date: Fri, 19 Feb 2016 14:10:39 -0500 [thread overview]
Message-ID: <1455909039.7528.89.camel@twopensource.com> (raw)
In-Reply-To: <CACsJy8AEOzSi-yJo3eJLSv5s6RW1sZBw+G2Y7cypGb2b+p0QLg@mail.gmail.com>
On Fri, 2016-02-19 at 09:54 +0700, Duy Nguyen wrote:
> On Fri, Feb 19, 2016 at 3:23 AM, David Turner <
> dturner@twopensource.com> wrote:
> > > > +static int read_per_worktree_ref(const char *submodule, const
> > > > char
> > > > *refname,
> > > > + struct MDB_val *val, int
> > > > *needs_free)
> > >
> > > From what I read, I suspect these _per_worktree functions will be
> > > identical for the next backend. Should we just hand over the job
> > > for
> > > files backend? For all entry points that may deal with per
> > > -worktree
> > > refs, e.g. lmdb_resolve_ref_unsafe, can we check ref_type() first
> > > thing, if it's per-worktree we call
> > > refs_be_files.resolve_ref_unsafe()
> > > instead? It could even be done at frontend level,
> > > e.g. refs.c:resolve_ref_unsafe().
> > >
> > > Though I may be talking rubbish here because I don't know how
> > > whether
> > > it has anything to do with transactions.
> >
> > The reason I did it this way is that some ref chains cross backend
> > boundaries (e.g. HEAD -> refs/heads/master). But if we have other
> > backends later, we could generalize.
>
> Crossing backends should go through frontend again, imo. But I don't
> really know if it's efficient.
It's pretty tricky to maintain state (e.g. count of symref redirects)
across that barrier. So I'm not sure how to do it cleanly.
> > > > +static int lmdb_create_symref(const char *ref_target,
> > > > + const char *refs_heads_master,
> > > > + const char *logmsg)
> > > > +{
> > > > +
> > > ...
> > > > + mdb_put_or_die(&transaction, &key, &val, 0);
> > > > +
> > > > + /* TODO: Don't create ref d/f conflicts */
> > >
> > > I'm not sure I get this comment. D/F conflicts are no longer a
> > > thing
> > > for lmdb backend, right?
> >
> > I'm trying to avoid the lmdb backend creating a set of refs that
> > the
> > files backend can't handle. This would make collaboration with
> > other
> > versions of git more difficult.
>
> It already is. If you create refs "foo" and "FOO" on case sensitive
> file system and clone it on a case-insensitive one, you face the same
> problem. We may have an optional configuration knob to prevent
> incompatibilities with files backend, but I think that should be done
> (and enforced if necessary) outside backends.
Sure, the current state isn't perfect, but why make it worse?
next prev parent reply other threads:[~2016-02-19 19:10 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-18 5:17 [PATCH v5 00/27] refs backends David Turner
2016-02-18 5:17 ` [PATCH v5 01/27] refs: Move head_ref{,_submodule} to the common code David Turner
2016-02-18 5:17 ` [PATCH v5 02/27] refs: move for_each_*ref* functions into " David Turner
2016-02-18 5:17 ` [PATCH v5 03/27] refs: add a backend method structure with transaction functions David Turner
2016-02-18 5:17 ` [PATCH v5 04/27] refs: add methods for misc ref operations David Turner
2016-02-18 5:17 ` [PATCH v5 05/27] refs: add method for do_for_each_ref David Turner
2016-02-18 5:17 ` [PATCH v5 06/27] refs: add do_for_each_per_worktree_ref David Turner
2016-02-18 5:17 ` [PATCH v5 07/27] refs: add methods for reflog David Turner
2016-02-18 5:17 ` [PATCH v5 08/27] refs: add method for initial ref transaction commit David Turner
2016-02-18 5:17 ` [PATCH v5 09/27] refs: add method for delete_refs David Turner
2016-02-18 5:17 ` [PATCH v5 10/27] refs: add methods to init refs db David Turner
2016-02-18 5:17 ` [PATCH v5 11/27] refs: add method to rename refs David Turner
2016-02-18 5:17 ` [PATCH v5 12/27] refs: forbid cross-backend ref renames David Turner
2016-02-20 4:30 ` Duy Nguyen
2016-02-24 20:48 ` David Turner
2016-02-18 5:17 ` [PATCH v5 13/27] refs: make lock generic David Turner
2016-02-18 5:17 ` [PATCH v5 14/27] refs: move duplicate check to common code David Turner
2016-02-18 5:17 ` [PATCH v5 15/27] refs: allow log-only updates David Turner
2016-02-18 5:17 ` [PATCH v5 16/27] refs: don't dereference on rename David Turner
2016-02-18 5:17 ` [PATCH v5 17/27] refs: on symref reflog expire, lock symref not referrent David Turner
2016-02-18 5:17 ` [PATCH v5 18/27] refs: resolve symbolic refs first David Turner
2016-02-18 5:17 ` [PATCH v5 19/27] refs: always handle non-normal refs in files backend David Turner
2016-02-18 5:17 ` [PATCH v5 20/27] init: allow alternate ref strorage to be set for new repos David Turner
2016-02-18 5:17 ` [PATCH v5 21/27] refs: check submodules' ref storage config David Turner
2016-02-18 5:17 ` [PATCH v5 22/27] clone: allow ref storage backend to be set for clone David Turner
2016-02-18 5:17 ` [PATCH v5 23/27] svn: learn ref-storage argument David Turner
2016-02-20 23:55 ` Eric Wong
2016-02-23 18:08 ` David Turner
2016-02-18 5:17 ` [PATCH v5 24/27] refs: add register_ref_storage_backends() David Turner
2016-02-18 5:17 ` [PATCH v5 25/27] refs: add LMDB refs storage backend David Turner
2016-02-18 8:50 ` Duy Nguyen
2016-02-18 20:23 ` David Turner
2016-02-18 21:15 ` Junio C Hamano
2016-02-19 2:54 ` Duy Nguyen
2016-02-19 19:10 ` David Turner [this message]
2016-02-20 13:14 ` Duy Nguyen
2016-02-24 20:41 ` David Turner
2016-02-20 21:32 ` Junio C Hamano
2016-02-19 22:49 ` David Turner
2016-02-19 23:08 ` Junio C Hamano
2016-02-20 2:58 ` Duy Nguyen
2016-02-24 20:43 ` David Turner
2016-02-25 10:07 ` Duy Nguyen
2016-02-20 8:59 ` Duy Nguyen
2016-02-24 20:37 ` David Turner
2016-02-25 10:12 ` Duy Nguyen
2016-02-25 20:05 ` [PATCH] refs: document transaction semantics David Turner
2016-02-25 20:10 ` David Turner
2016-02-25 20:34 ` Junio C Hamano
2016-02-25 20:50 ` David Turner
2016-02-18 5:17 ` [PATCH v5 26/27] refs: tests for lmdb backend David Turner
2016-02-18 5:17 ` [PATCH v5 27/27] tests: add ref-storage argument David Turner
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