From: Amisha Chhajed <amishhhaaaa@gmail.com>
Date: Sun, 18 Jan 2026 13:09:58 GMT
Subject: Re: [PATCH v3] sparse-checkout: optimize string_list construction
Message-ID: <CAPvEtreFgpVLG7WsJsJLjSA0_x0S3vh=PXa+VqmVnxjRTJ7WGA@mail.gmail.com>
In-Reply-To: <c5631f7d-72ff-4876-9b68-ea4a70fde501@gmail.com>

On Sun, 18 Jan 2026 at 08:16, Derrick Stolee <stolee@gmail.com> wrote:
>
> On 1/16/26 12:17 PM, Junio C Hamano wrote:
> > Amisha Chhajed <amishhhaaaa@gmail.com> writes:
> >
> >> It was assumed to be safe under the notion that our entries are not
> >> duplicate but as already pointed out, our entries are not unique so we
> >> need one of those two ways either insert or remove_duplicates, this
> >> can be a trivial question but i wonder how are the tests passing by
> >> removing these lines, i was actually researching about it.
> >
> > ... suspense.  And the result of the research was???
> >
> > If the answer was simply "we lack test coverage", it may make sense
> > to add a test taken from Peff's earlier response to increase test
> > coverage, perhaps?
>
> In addition to adding more tests to t/t1091-sparse-checkout-builtin.sh
> to cover these duplicate cases. To demonstrate your quadratic perf
> improvement, a test in t/perf/p2000-sparse-operations.sh or similar
> would be good to add.
>
> I expect that the test you would add doesn't matter too much about
> the data shape, but would look very different from most tests in
> p2000. You can make use of the constructed repo's directory structure
> that has nesting directories with name f1, f2, f3, or f4.
>
> Here's something to get you started that I haven't tested myself:
>
> test_perf 'duplicate sparse directories' '
>         (
>                 cd full-v4 &&
>
>                 for i in $(test_seq 1000)
>                 do
>                         printf "f1/f2/f3/f4\n"
>                 done >in &&
>                 git sparse-checkout set --stdin <in
>         )
> '
>
> That should test the logic with 1000 identical directories, which
> should be enough to have the quadratic growth show up.
>
> Thanks,
> -Stolee


Thank you so much for pointing me in the right direction.