[dnsdist] about addPoolRule() performance

[Wang Jian]

Hi,

For dnsdist, addPoolRule() has two forms for domain, such as

  addPoolRule("google.com", "googledns")
  addPoolRule("facebook.com", "googledns")

vs

  addPoolRule({"google.com", "facebook.com"}, "googledns")

The first form has 2 rules and second form has 1 rule. There is
difference in rule management apparently.

The thing is, there can be huge performance difference too, if the
domain set is large and hash table lookup is used. I look through code
and think current implementation doesn't use hash table lookup. Am I
correct? If so, I suggest adding hash table lookup.

Regards