Re: [PATCH v2 1/3] t7519: avoid file to index mtime race for untracked cache

From: Tao Klerks <tao@klerks.biz>
Date: Feb 27, 2022, 22:12 UTC
Message-ID: <CAPMMpoi4oQ4nORc-Jq00pFQq7eFYe0mZhwdU7fvTabvCdL1Okw@mail.gmail.com>
In-Reply-To: <xmqqr17qbw8l.fsf@gitster.g>

On Fri, Feb 25, 2022 at 8:07 PM Junio C Hamano <gitster@pobox.com> wrote:

Show 8 quoted lines

>
> "Tao Klerks via GitGitGadget" <gitgitgadget@gmail.com> writes:
>
> > In t7519 there is a test that writes files to disk, and immediately
> > writes the untracked index. Because of mtime-comparison logic that
>
> "untracked cache", I think.
>

Yep, fixed, thx.

Show 10 quoted lines

> > uses a 1-second resolution, this means the cached entries are not
> > trusted/used under some circumstances
> > (see read-cache.c#is_racy_stat()).
> >
> > Untracked cache tests in t7063 use a 1-second delay to avoid this
> > issue, but we don't want to introduce arbitrary slowdowns, so instead
> > use test-tool chmtime to backdate the files slightly.
>
> Good approach.  Perhaps fixing 7063 can be marked as #leftoverbit?
>

Sure. Updated the commit msg.

I also started another thread with what that looks like - it's not very pretty in the end because of Windows compatibility issues, and still incomplete because (as far as I can tell) the sleep is used for a couple of different purposes, and only one of them lends itself to chmtime manipulation.