Re: [PATCH 04/15] reftable/stack: gracefully handle failed auto-compaction due to locks

> Whenever we commit a new table to the reftable stack we will end up
> invoking auto-compaction of the stack to keep the total number of tables
> at bay. This auto-compaction may fail though in case at least one of the
> tables which we are about to compact is locked. This is indicated by the
> compaction function returning a positive value. We do not handle this

> case though, and thus bubble that return value up the calling chain,
> which will ultimately cause a failure.
>
> Fix this bug by handling positive return values.
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  reftable/stack.c           | 13 ++++++++++++-
>  t/t0610-reftable-basics.sh | 20 ++++++++++++++++++++
>  2 files changed, 32 insertions(+), 1 deletion(-)
>
> diff --git a/reftable/stack.c b/reftable/stack.c
> index ba15c48ddd..dd5160d751 100644
> --- a/reftable/stack.c
> +++ b/reftable/stack.c
> @@ -680,8 +680,19 @@ int reftable_addition_commit(struct reftable_addition *add)
>  	if (err)
>  		goto done;
>
> -	if (!add->stack->disable_auto_compact)
> +	if (!add->stack->disable_auto_compact) {
> +		/*
> +		 * Auto-compact the stack to keep the number of tables in
> +		 * control. Note that we explicitly ignore locking issues which
> +		 * may indicate that a concurrent process is already trying to
> +		 * compact tables. This is fine, so we simply ignore that error
> +		 * condition.
> +		 */
>

>  		err = reftable_stack_auto_compact(add->stack);
> +		if (err < 0 && err != REFTABLE_LOCK_ERROR)
> +			goto done;
> +		err = 0;
> +	}
>
>  done:
>  	reftable_addition_close(add);
> diff --git a/t/t0610-reftable-basics.sh b/t/t0610-reftable-basics.sh
> index 686781192e..5f2f9baa9b 100755
> --- a/t/t0610-reftable-basics.sh
> +++ b/t/t0610-reftable-basics.sh
> @@ -340,6 +340,26 @@ test_expect_success 'ref transaction: empty transaction in empty repo' '
>  	EOF
>  '
>
> +test_expect_success 'ref transaction: fails gracefully when auto compaction fails' '
> +	test_when_finished "rm -rf repo" &&
> +	git init repo &&
> +	(
> +		cd repo &&
> +
> +		test_commit A &&
> +		for i in $(test_seq 10)
> +		do
> +			git branch branch-$i &&
> +			for table in .git/reftable/*.ref
> +			do
> +				touch "$table.lock" || exit 1
> +			done ||
> +			exit 1
> +		done &&
> +		test_line_count = 13 .git/reftable/tables.list
> +	)
> +'