Re: [PATCH v6 14/42] sequencer.c: use ref transactions for all ref updates

From: Jonathan Nieder <jrnieder@gmail.com>
To: Ronnie Sahlberg <sahlberg@google.com>
Cc: git@vger.kernel.org, mhagger@alum.mit.edu
Subject: Re: [PATCH v6 14/42] sequencer.c: use ref transactions for all ref updates
Date: Thu, 15 May 2014 10:35:57 -0700	[thread overview]
Message-ID: <20140515173557.GL9218@google.com> (raw)
In-Reply-To: <1398976662-6962-15-git-send-email-sahlberg@google.com>

Ronnie Sahlberg wrote:

> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -272,23 +272,31 @@ static int error_dirty_index(struct replay_opts *opts)
>  static int fast_forward_to(const unsigned char *to, const unsigned char *from,
>  			int unborn, struct replay_opts *opts)
>  {
> -	struct ref_lock *ref_lock;
> +	struct ref_transaction *transaction;
>  	struct strbuf sb = STRBUF_INIT;
> -	int ret;
> +	struct strbuf err = STRBUF_INIT;
>  
>  	read_cache();
>  	if (checkout_fast_forward(from, to, 1))
>  		exit(1); /* the callee should have complained already */
> -	ref_lock = lock_any_ref_for_update("HEAD", unborn ? null_sha1 : from,
> -					   0, NULL);
> -	if (!ref_lock)
> -		return error(_("Failed to lock HEAD during fast_forward_to"));
>  
>  	strbuf_addf(&sb, "%s: fast-forward", action_name(opts));
> -	ret = write_ref_sha1(ref_lock, to, sb.buf);
> +
> +	transaction = ref_transaction_begin();
> +	if ((!transaction ||
> +	    ref_transaction_update(transaction, "HEAD", to, from,
> +				   0, !unborn)) ||

These parentheses make it harder to parse.  Other patches in this
series do

	if (!transaction ||
	    ref_transaction_update(...) ||
	    ref_transaction_commit(...)) {

so this could do

	if (!transaction ||
	    ref_transaction_update(...) ||
	    (ref_transaction_commit(...) && !(transaction = NULL))) {

> +	    (ref_transaction_commit(transaction, sb.buf, &err) &&
> +	     !(transaction = NULL))) {
> +		ref_transaction_rollback(transaction);

Earlier patches in the series didn't bother rolling back.  Should they
have?

Thanks,
Jonathan