Re: What's cooking in git.git (Dec 2023, #01; Sat, 9)

From: Jeff Hostetler <git@jeffhostetler.com>
Date: Dec 14, 2023, 15:19 UTC
Message-ID: <e5295dbe-94d2-3186-5663-2466eba4bdde@jeffhostetler.com>
In-Reply-To: <xmqqa5qknnej.fsf@gitster.g>

On 12/8/23 9:02 PM, Junio C Hamano wrote:

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> * jc/diff-cached-fsmonitor-fix (2023-09-15) 3 commits
>   - diff-lib: fix check_removed() when fsmonitor is active
>   - Merge branch 'jc/fake-lstat' into jc/diff-cached-fsmonitor-fix
>   - Merge branch 'js/diff-cached-fsmonitor-fix' into jc/diff-cached-fsmonitor-fix
>   (this branch uses jc/fake-lstat.)
> 
>   The optimization based on fsmonitor in the "diff --cached"
>   codepath is resurrected with the "fake-lstat" introduced earlier.
> 
>   It is unknown if the optimization is worth resurrecting, but in case...
>   source: <xmqqr0n0h0tw.fsf@gitster.g>
> 
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> * jc/fake-lstat (2023-09-15) 1 commit
>   - cache: add fake_lstat()
>   (this branch is used by jc/diff-cached-fsmonitor-fix.)
> 
>   A new helper to let us pretend that we called lstat() when we know
>   our cache_entry is up-to-date via fsmonitor.
> 
>   Needs review.
>   source: <xmqqcyykig1l.fsf@gitster.g>
> 
>

I think these look good. And yes, it is better to insure that the stat struct is always well-defined rather than sometimes uninitialized.

FWIW, in f954c7b8ff3 (fsmonitor: never set CE_FSMONITOR_VALID on submodules, 2022-05-26) we try to never set the CE_FSMONITOR_VALID bit on submodules (because status on a submodule is much more than just an lstat check on the submodule root directory and we always should recursively ask Git to compute the submodule's status).

I haven't had time to investigate, but I wonder if the original complaint on `diff-lib` was due to another code path that allowed the CE_FSMONITOR_VALID bit to get set on a submodule entry.

Jeff