Re: [PATCH 4/6] builtin/pack-objects.c: learn pack.writeBitmapLookupTable

[Taylor Blau <me@ttaylorr.com>]

On Mon, Jun 20, 2022 at 12:33:12PM +0000, Taylor Blau via GitGitGadget wrote:
> From: Taylor Blau <ttaylorr@github.com>
>
> Teach git to provide a way for users to enable/disable bitmap lookup
> table extension by providing a config option named 'writeBitmapLookupTable'.
>
> Signed-off-by: Taylor Blau <ttaylorr@github.com>
> Signed-off-by: Abhradeep Chakraborty <chakrabortyabhradeep79@gmail.com>
> ---
>  Documentation/config/pack.txt | 7 +++++++
>  builtin/pack-objects.c        | 8 ++++++++
>  2 files changed, 15 insertions(+)
>
> diff --git a/Documentation/config/pack.txt b/Documentation/config/pack.txt
> index ad7f73a1ead..e12008d2415 100644
> --- a/Documentation/config/pack.txt
> +++ b/Documentation/config/pack.txt
> @@ -164,6 +164,13 @@ When writing a multi-pack reachability bitmap, no new namehashes are
>  computed; instead, any namehashes stored in an existing bitmap are
>  permuted into their appropriate location when writing a new bitmap.
>
> +pack.writeBitmapLookupTable::
> +	When true, git will include a "lookup table" section in the

s/git/Git (I typically use "git" when talking about the command-line
tool, and Git when talking about the project as a proper noun).

> +	bitmap index (if one is written). This table is used to defer
> +	loading individual bitmaps as late as possible. This can be
> +	beneficial in repositories which have relatively large bitmap
> +	indexes. Defaults to false.

Is there a reason that we would want to default to "false" here? Perhaps
in the first version of two we would want this to be an opt-in (since
there is no publicly documented way to opt-out of reading the extension
once it is written).

We should make sure to enable this by default at some point in the
future.

>  pack.writeReverseIndex::

...since it's easy to forget ;-).

Thanks,
Taylor