From: Michael Haggerty <mhagger@alum.mit.edu>
To: Jeff King <peff@peff.net>, Duy Nguyen <pclouds@gmail.com>
Cc: Johannes Sixt <j6t@kdbg.org>,
Git Mailing List <git@vger.kernel.org>,
David Turner <dturner@twopensource.com>
Subject: Re: git gc and worktrees
Date: Wed, 1 Jun 2016 10:57:08 +0200 [thread overview]
Message-ID: <574EA364.60408@alum.mit.edu> (raw)
In-Reply-To: <20160531221415.GA3824@sigill.intra.peff.net>
On 06/01/2016 12:14 AM, Jeff King wrote:
> [...]
> Michael (cc'd) noted to me off-list recently that there may be some
> special cases there regarding reflogs in other worktrees (i.e., that we
> don't always include them for our reachability checks). I don't know the
> details, though.
That's correct. `for_each_reflog()` does its work by walking the
directory tree under `$GIT_DIR/logs`. So when run in the main
repository, it never looks at the per-worktree reflogs. Therefore,
objects that are only reachable from per-worktree reflogs can end up
getting pruned.
This is closely tangled up with my ref-iterators patch series (which is
why I noticed it), especially with
[PATCH 13/13] for_each_reflog(): reimplement using iterators
[1].
I think reference stores are going to need two distinct types of
reference iteration: one to iterate over the *logical* reference space
of a single repo or worktree, and one to find all *local* references
and/or reachability roots (e.g., when run within a linked repo). The
current approach, where subtrees of the reference namespace are pasted
ad-hoc into each other partly by manhandling the ref_cache and partly
via the hack in `git_path()` is not, I think, a very good long-term design.
I'd prefer the elementary operation on a low-level reference store to be
iterating over all of the references that are stored locally, and to use
`merge_ref_iterator` for pasting together the parts of low-level
reference stores that are needed to form a logical view of the
references in a linked repo.
Michael
[1]
http://thread.gmane.org/gmane.comp.version-control.git/295860/focus=295866
next prev parent reply other threads:[~2016-06-01 8:57 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-31 7:07 git gc and worktrees Johannes Sixt
2016-05-31 12:02 ` Duy Nguyen
2016-05-31 22:14 ` Jeff King
2016-06-01 7:00 ` Johannes Sixt
2016-06-01 8:57 ` Michael Haggerty [this message]
2016-06-01 15:15 ` Junio C Hamano
2016-06-01 16:12 ` Michael Haggerty
2016-06-01 19:39 ` Junio C Hamano
2016-06-02 4:08 ` Michael Haggerty
2016-06-03 16:45 ` Junio C Hamano
2016-06-01 10:45 ` [PATCH 0/4] Fix prune/gc problem with multiple worktrees Nguyễn Thái Ngọc Duy
2016-06-01 10:45 ` [PATCH 1/4] revision.c: move read_cache() out of add_index_objects_to_pending() Nguyễn Thái Ngọc Duy
2016-06-01 10:45 ` [PATCH 2/4] reachable.c: mark reachable objects in index from all worktrees Nguyễn Thái Ngọc Duy
2016-06-01 18:13 ` Eric Sunshine
2016-06-02 9:35 ` Duy Nguyen
2016-06-01 18:57 ` David Turner
2016-06-02 9:37 ` Duy Nguyen
2016-06-01 10:45 ` [PATCH 3/4] reachable.c: mark reachable detached HEAD " Nguyễn Thái Ngọc Duy
2016-06-01 10:45 ` [PATCH 4/4] reachable.c: make reachable reflogs for all per-worktree reflogs Nguyễn Thái Ngọc Duy
2016-06-01 15:51 ` Michael Haggerty
2016-06-01 16:01 ` [PATCH 0/4] Fix prune/gc problem with multiple worktrees Jeff King
2016-06-01 16:06 ` Junio C Hamano
2016-06-02 9:53 ` Duy Nguyen
2016-06-02 11:26 ` Michael Haggerty
2016-06-02 17:44 ` Junio C Hamano
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