That's a great question and I've been wondering about it myself. It goes
all the way to the initial commit where multixacts were introduced, and
I don't see any particular reason for it even back then. Even in the
very first version of multixact.c, IMO it would've been simpler to have
the writer handle the wraparound.
+1 This code is quite old. I don't see any particular reason for doing
it that way. Unfortunately, we were unable to prove the absence of
something, namely errors, in this instance. But there were no obvious
statements on why it should be in this manner. So, for me, it's much
clearer to increment and handle wraparound in one place rather
than spread it across multiple calls in the module.
-- Best regards,
Maxim Orlov.
