Re: [PATCH 1/9] refs: make _advance() check struct repo, not flag

From: Jeff King <peff@peff.net>
Date: Sep 24, 2021, 18:13 UTC
Message-ID: <YU4VUF17tyG2AZi3@coredump.intra.peff.net>
In-Reply-To: <493fff7f4716d889da751b5f8c6740cc1e3aa360.1632242495.git.jonathantanmy@google.com>

On Tue, Sep 21, 2021 at 09:51:03AM -0700, Jonathan Tan wrote:

Show 20 quoted lines

> Currently, ref iterators access the object store each time they advance
> if and only if the boolean flag DO_FOR_EACH_INCLUDE_BROKEN is unset.
> (The iterators access the object store because, if
> DO_FOR_EACH_INCLUDE_BROKEN is unset, they need to attempt to resolve
> each ref to determine that it is not broken.)
> 
> Also, the object store accessed is always that of the_repository, making
> it impossible to iterate over a submodule's refs without
> DO_FOR_EACH_INCLUDE_BROKEN (unless add_submodule_odb() is used).
>
> As a first step in resolving both these problems, replace the
> DO_FOR_EACH_INCLUDE_BROKEN flag with a struct repository pointer. This
> commit is a mechanical conversion - whenever DO_FOR_EACH_INCLUDE_BROKEN
> is set, a NULL repository (representing access to no object store) is
> used instead, and whenever DO_FOR_EACH_INCLUDE_BROKEN is unset, a
> non-NULL repository (representing access to that repository's object
> store) is used instead. Right now, the locations in which
> non-the_repository support needs to be added are marked with BUG()
> statements - in a future patch, these will be replaced. (NEEDSWORK: in
> this RFC patch set, this has not been done)

I think your goal here of passing around a repository object is good. But rolling the meaning of DO_FOR_EACH_INCLUDE_BROKEN into an implicit "do we have a non-NULL repository" makes things awkward, I think.

As you noticed, we can't get rid of the flags parameter entirely. We still have DO_FOR_EACH_PER_WORKTREE_ONLY. But I also have a series which adds another flag which pairs with INCLUDE_BROKEN. Having half of the logic implicit in the repository pointer and half in a flag would be weird.

I'll post that series in a moment, but what I'm wondering here is: would it be that big a deal to just pass the repository object around, and it is simply not used if INCLUDE_BROKEN is passed?

-Peff