Thanks.
I used your improved text in the commit message.
On Thu, May 15, 2014 at 11:15 AM, Jonathan Nieder <jrnieder@xxxxxxxxx> wrote:
> Ronnie Sahlberg wrote:
>
>> Allow ref_transaction_free to be called with NULL and as a result allow
>> ref_transaction_rollback to be called for a NULL transaction.
>>
>> This allows us to write code that will
>> if ( (!transaction ||
>> ref_transaction_update(...)) ||
>> (ref_transaction_commit(...) && !(transaction = NULL)) {
>> ref_transaction_rollback(transaction);
>> ...
>> }
>>
>> In this case transaction is reset to NULL IFF ref_transaction_commit() was
>> invoked and thus the rollback becomes ref_transaction_rollback(NULL) which
>> is safe. IF the conditional triggered prior to ref_transaction_commit()
>> then transaction is untouched and then ref_transaction_rollback(transaction)
>> will rollback the failed transaction.
>
> I still think these last two paragraphs confuse more than enlighten
> here. There's plenty of time to explain them in the patch that uses
> that code.
>
> I'd just say something like
>
> Allow ref_transaction_free(NULL) and hence ref_transaction_rollback(NULL)
> as no-ops.
>
> This makes ref_transaction_rollback easier to use and more similar to
> plain 'free'.
>
> And maybe:
>
> In particular, it lets us rollback unconditionally as part of cleanup
> code after setting 'transaction = NULL' if a transaction has been
> committed or rolled back already.
>
> Thanks,
> Jonathan
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