Milter-greylist

Oliver Fromme wrote:
>
> 
> Oh by the way, I wasn't able to measure any difference
> between "*" and "{,}".  They perform exactly at the
> same speed, at least with regex(3) on FreeBSD 6.

You shouldn't notice any difference unless the input is patterned it the right
way to cause a lot of backtracking. In that case {n,m} will limit your backtrack
to at most m characters. * is only limited by the amount of matching input.


> 
> (If anything, I would have expected "{,}" to be slower
> because it requires either more states in the DFA/NFA,
> or additional bookkeeping within the state, compared
> to "*".)

In the simple case, yes * can be faster. In the worst case, it can be much
slower. Thousands of times slower.