Re: [PATCH v2 3/3] glossary: add reachability bitmap description

From: Abhradeep Chakraborty <chakrabortyabhradeep79@gmail.com>
Date: Oct 24, 2022, 07:43 UTC
Message-ID: <CAPOJW5zmYC9q8+aXh9-kZnvT28GQ1ud3LenFi9qxV4DVdCWKxg@mail.gmail.com>
In-Reply-To: <20221022222539.2333-4-philipoakley@iee.email>

Hey Philip, Glad that you're working on this :)

On Sun, Oct 23, 2022 at 3:55 AM Philip Oakley <philipoakley@iee.email> wrote:

Show 20 quoted lines

>
> Describe the purpose of the reachability bitmap.
>
> Signed-off-by: Philip Oakley <philipoakley@iee.email>
> ---
>  Documentation/glossary-content.txt | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/Documentation/glossary-content.txt b/Documentation/glossary-content.txt
> index 97050826e5..3d67b452aa 100644
> --- a/Documentation/glossary-content.txt
> +++ b/Documentation/glossary-content.txt
> @@ -508,6 +508,14 @@ exclude;;
>         <<def_tree_object,trees>> to the trees or <<def_blob_object,blobs>>
>         that they contain.
>
> +[[def_reachability_bitmap]]reachability bitmaps::
> +       Reachability bitmaps store information about the
> +       <<def_reachable,reachability>> of a selected set of objects in
> +       a packfile, or a multi-pack index (MIDX) to speed up object search.

Looks good to me. Initially I thought that we could explain it more but as you already linked the "reachability" here, we don't need to.

> +       A repository may have at
> +       most one bitmap. The bitmap may belong to either one pack, or the
> +       repository's multi-pack index (if it exists).
> +

Small correction here - A repository may have multiple bitmaps (one for each selected commit from the preferred packfile or a multi-pack-index) but it can have only one ".bitmap" file (as of now). Bitmaps for the selected commits are stored in that ".bitmap" file. So I think the below lines (or similar) will work -

    The bitmaps are stored in a ".bitmap" file. A repository may have
    at most one ".bitmap" file. The file may belong to either one pack, or the
    repository's multi-pack-index (if it exists).

Feel free to rephrase it accordingly.

Thanks :)