Subject: Re: [PATCH 8/8] git-repack --max-pack-size: add option parsing to enable feature

From: "Shawn O. Pearce" <[email-masked]>
Date: Tue, 1 May 2007 01:45:28 -0400

Dana How <[email-masked]> wrote:
> Add --max-pack-size parsing and usage messages.
> Upgrade git-repack.sh to handle multiple packfile names.
...
> diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
...
> +		if (!prefixcmp(arg, "--max-pack-size=")) {
> +			char *end;
> +			pack_size_limit = strtoul(arg+16, &end, 0) * 1024 * 1024;
> +			if (!arg[16] || *end)
> +				usage(pack_usage);
> +			no_reuse_delta = 1;

Wow, are you serious?  This entire change is about making repack
automatically split large projects into multiple packfiles.  If
that happens are you intending that the caller will mark all of
those packfiles with .keep files immediately after repacking them?
If you want users to create .keep files, can git-repack.sh do that
for them when more than one packfile was output?

Because otherwise a "quick" git-gc will not be quick because the
reuse delta feature (which is a massive performance improvement for
repack/gc) will always be disabled.  But odds are a future repack
of the same project will generally keep things that are in the
same packfile already in the same packfile again, so delta reuse is
actually possible for most objects.  I think you should find a way
to make this change work without needing to force no_reuse_delta
just because this limit was added.

> diff --git a/git-repack.sh b/git-repack.sh
...
> +names=$(git-pack-objects --non-empty --all --reflog $args </dev/null "$PACKTMP") ||
>  	exit 1
> -if [ -z "$name" ]; then
> +if [ -z "$names" ]; then
>  	echo Nothing new to pack.
> -else
> +fi
> +for name in $names ; do

I think this particular change needs to either preceed the prior
commit, or be part of it.  If someone tries to bisect this patch
series with a large enough project that multiple packfiles are being
produced then you run into some ugly problems in this repack script.

-- 
Shawn.