On Thu, May 15, 2014 at 5:20 PM, Jonathan Nieder <jrnieder@xxxxxxxxx> wrote:
> Ronnie Sahlberg wrote:
>
>> Change ref_transaction_commit so that it does not free the transaction.
>> Instead require that a caller will end a transaction by either calling
>> ref_transaction_rollback or ref_transaction_free.
>
> Can I always use ref_transaction_rollback instead of ref_transaction_free?
> It would be convenient if my cleanup code could always call _rollback
> instead of having to do something different for success and errors.
Currently, yes.
But it might make sense to change these so rollback only clears the
updates that are in flight from the transaction and
free only frees the transaction itself iff there are no updates in flight.
I.e. the success and error would then differ like this :
...
if (transaction_commit()) {
transaction_rollback()
transaction_free()
return error("some error")
}
transaction_free()
>
> Another way to ask the question: what is it valid to do with a
> transaction after commiting?
Right now the only valid thing to do is either rollback or free. But
we could allow other things too :
re-usable transactions.
---------------------------------
I don't know if this is a good reason or not, but one reason we might
want to keep
two different names could be if we want to start allowing to re-use
transactions.
For example for cases/backends where transaction_begin() might be very
expensive.
For that case I would imagine we could allow to do things such as
t = transaction_begin()
...
/* first transaction */
transaction_update(...)
transaction_commit(...)
if transaction failed transaction_rollback(...)
/* second transaction, first transaction cleared all updates in
flight either through commit or through rollback */
transaction_update()
transaction_commit()
if transaction failed transaction_rollback(...)
...
transaction_free()
(In order to do something like this we would still need to do some
changes so that rollback will only free the updates that were in
flight but not free the transaction itself.)
>
> Thanks,
> Jonathan
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