Re: [PATCH v4 09/10] builtin/history: split handling of ref updates into two phases

[Junio C Hamano <gitster@pobox.com>]

Patrick Steinhardt <ps@pks.im> writes:

> The function `handle_reference_updates()` is used by git-history(1) to
> update all references that refer to commits that have been rewritten. As
> such, it performs two steps:
>
>   - It gathers the references that need to be updated in the first
>     place.
>
>   - It prepares and commits the reference transaction.
>
> In a subsequent commit we'll want to handle those two steps separately.
> Prepare for this by splitting up the function into two.

OK.  I can sees how this will help doing a dry-run mode.

> +static int apply_pending_ref_updates(struct repository *repo,
> +				     const struct replay_result *result,
> +				     const char *reflog_msg,
> +				     int dry_run)
> +{
> +	struct ref_transaction *transaction = NULL;
> +	struct strbuf err = STRBUF_INIT;
> +	int ret;
> +
> +	if (!dry_run) {
> +		transaction = ref_store_transaction_begin(get_main_ref_store(repo),
> +							  0, &err);
> +		if (!transaction) {
> +			ret = error(_("failed to begin ref transaction: %s"), err.buf);
> +			goto out;
> +		}
> +	}
> +
> +	for (size_t i = 0; i < result->updates_nr; i++) {
>  		ret = handle_ref_update(transaction,
> -					decoration->name,
> -					&rewritten->object.oid,
> -					&original->object.oid,
> +					result->updates[i].refname,
> +					&result->updates[i].new_oid,
> +					&result->updates[i].old_oid,
>  					reflog_msg, &err);

Cute.

handle_ref_update() uses transaction==NULL not as a signal to update
each ref as request comes (i.e., non-transactional updates) but as a
singal to perform a dry-run, which was unexpected to my taste but it
has been that way since at least February this year ;-)

Looking good.

Thanks.