Re: [PATCH v2 3/3] builtin/repack.c: implement support for `--max-cruft-size`

> diff --git a/Documentation/git-gc.txt b/Documentation/git-gc.txt
> index 90806fd26a..fa0541b416 100644
> --- a/Documentation/git-gc.txt
> +++ b/Documentation/git-gc.txt
> @@ -59,6 +59,13 @@ be performed as well.
>  	cruft pack instead of storing them as loose objects. `--cruft`
>  	is on by default.
>  
> +--max-cruft-size=<n>::
> +	When packing unreachable objects into a cruft pack, limit the
> +	size of new cruft packs to be at most `<n>`. Overrides any

> @@ -806,6 +846,72 @@ static void remove_redundant_bitmaps(struct string_list *include,
>  	strbuf_release(&path);
>  }
>  
> +static int existing_cruft_pack_cmp(const void *va, const void *vb)
> +{
> +	struct packed_git *a = *(struct packed_git **)va;
> +	struct packed_git *b = *(struct packed_git **)vb;
> +
> +	if (a->pack_size < b->pack_size)
> +		return -1;
> +	if (a->pack_size > b->pack_size)
> +		return 1;
> +	return 0;
> +}
> +
> +static void collapse_small_cruft_packs(FILE *in, size_t max_size,
> +				       struct existing_packs *existing)
> +{
> +	struct packed_git **existing_cruft, *p;
> +	struct strbuf buf = STRBUF_INIT;
> +	size_t total_size = 0;
> +	size_t existing_cruft_nr = 0;
> +	size_t i;
> +
> +	ALLOC_ARRAY(existing_cruft, existing->cruft_packs.nr);
> +
> +	for (p = get_all_packs(the_repository); p; p = p->next) {
> +		if (!(p->is_cruft && p->pack_local))
> +			continue;
> +
> +		strbuf_reset(&buf);
> +		strbuf_addstr(&buf, pack_basename(p));
> +		strbuf_strip_suffix(&buf, ".pack");
> +
> +		if (!string_list_has_string(&existing->cruft_packs, buf.buf))
> +			continue;
> +
> +		if (existing_cruft_nr >= existing->cruft_packs.nr)
> +			BUG("too many cruft packs (found %"PRIuMAX", but knew "
> +			    "of %"PRIuMAX")",
> +			    (uintmax_t)existing_cruft_nr + 1,
> +			    (uintmax_t)existing->cruft_packs.nr);
> +		existing_cruft[existing_cruft_nr++] = p;
> +	}
> +
> +	QSORT(existing_cruft, existing_cruft_nr, existing_cruft_pack_cmp);
> +
> +	for (i = 0; i < existing_cruft_nr; i++) {
> +		size_t proposed;
> +
> +		p = existing_cruft[i];
> +		proposed = st_add(total_size, p->pack_size);
> +
> +		if (proposed <= max_size) {
> +			total_size = proposed;
> +			fprintf(in, "-%s\n", pack_basename(p));
> +		} else {
> +			retain_cruft_pack(existing, p);
> +			fprintf(in, "%s\n", pack_basename(p));
> +		}
> +	}
> +
> +	for (i = 0; i < existing->non_kept_packs.nr; i++)
> +		fprintf(in, "-%s.pack\n",
> +			existing->non_kept_packs.items[i].string);

> +	strbuf_release(&buf);
> +}
> +
>  static int write_cruft_pack(const struct pack_objects_args *args,
>  			    const char *destination,
>  			    const char *pack_prefix,
> @@ -853,10 +959,14 @@ static int write_cruft_pack(const struct pack_objects_args *args,
>  	in = xfdopen(cmd.in, "w");
>  	for_each_string_list_item(item, names)
>  		fprintf(in, "%s-%s.pack\n", pack_prefix, item->string);
> -	for_each_string_list_item(item, &existing->non_kept_packs)
> -		fprintf(in, "-%s.pack\n", item->string);
> -	for_each_string_list_item(item, &existing->cruft_packs)
> -		fprintf(in, "-%s.pack\n", item->string);
> +	if (args->max_pack_size && !cruft_expiration) {
> +		collapse_small_cruft_packs(in, args->max_pack_size, existing);
> +	} else {
> +		for_each_string_list_item(item, &existing->non_kept_packs)
> +			fprintf(in, "-%s.pack\n", item->string);
> +		for_each_string_list_item(item, &existing->cruft_packs)
> +			fprintf(in, "-%s.pack\n", item->string);
> +	}
>  	for_each_string_list_item(item, &existing->kept_packs)
>  		fprintf(in, "%s.pack\n", item->string);
>  	fclose(in);