Subject: Re: [PATCH v3 04/11] reftable/stack: verify that `reftable_stack_add()` uses auto-compaction

From: Taylor Blau <[email-masked]>
Date: Mon, 11 Dec 2023 15:15:19 -0500

On Mon, Dec 11, 2023 at 10:07:42AM +0100, Patrick Steinhardt wrote:
> While we have several tests that check whether we correctly perform
> auto-compaction when manually calling `reftable_stack_auto_compact()`,
> we don't have any tests that verify whether `reftable_stack_add()` does
> call it automatically. Add one.
>
> Signed-off-by: Patrick Steinhardt <[email-masked]>
> ---
>  reftable/stack_test.c | 49 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
>
> diff --git a/reftable/stack_test.c b/reftable/stack_test.c
> index 0644c8ad2e..52b4dc3b14 100644
> --- a/reftable/stack_test.c
> +++ b/reftable/stack_test.c
> @@ -850,6 +850,54 @@ static void test_reftable_stack_auto_compaction(void)
>  	clear_dir(dir);
>  }
>
> +static void test_reftable_stack_add_performs_auto_compaction(void)
> +{
> +	struct reftable_write_options cfg = { 0 };
> +	struct reftable_stack *st = NULL;
> +	struct strbuf refname = STRBUF_INIT;
> +	char *dir = get_tmp_dir(__LINE__);
> +	int err, i, n = 20;
> +
> +	err = reftable_new_stack(&st, dir, cfg);
> +	EXPECT_ERR(err);
> +
> +	for (i = 0; i <= n; i++) {
> +		struct reftable_ref_record ref = {
> +			.update_index = reftable_stack_next_update_index(st),
> +			.value_type = REFTABLE_REF_SYMREF,
> +			.value.symref = "master",
> +		};
> +
> +		/*
> +		 * Disable auto-compaction for all but the last runs. Like this
> +		 * we can ensure that we indeed honor this setting and have
> +		 * better control over when exactly auto compaction runs.
> +		 */
> +		st->disable_auto_compact = i != n;
> +
> +		strbuf_reset(&refname);
> +		strbuf_addf(&refname, "branch-%04d", i);
> +		ref.refname = refname.buf;

Does the reftable backend take ownership of the "refname" field? If so,
then I think we'd want to use strbuf_detach() here to avoid a
double-free() when you call strbuf_release() below.

Thanks,
Taylor