findLabel and the selector about geodns HOT 3 OPEN

On Mar 8, 2013, at 23:46, Miek Gieben [email protected] wrote:

The selector in findLabel generates garbage. It would be beter to completely remove this from this (often called) function.

Using the new data structure we've talked about should fix that.

It's interesting (but makes sense) that "creating garbage" is a significant overhead. The things you pointed out also explains, I think, how the 32-bit servers ran out of memory so quickly when the query rate went way up.

Ask

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Since you made this ticket I've dug myself deeper in, rather than working towards getting rid of it. Can you outline what you had in my for getting rid of it? Currently the code making the list of "targets" is in "GetTargets()" in targeting.go and serve.go passes that list to findLabels that then just iterates over it.

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[ Quoting [email protected] in "Re: [geodns] findLabel and the sele..." ]

Since you made this ticket I've dug myself deeper in, rather than working towards getting rid of it. Can you outline what you had in my for getting rid of it? Currently the code making the list of "targets" is in "GetTargets()" in targeting.go and serve.go passes that list to findLabels that then just iterates over it.

Thought I mentioned it, because of the string var 'name', which probably
isn't a real big issue. The following patch captures what I had in mind
to change it. Note: untested! Only thing going for it, is that it
compiles.

grtz Miek
@@ -125,23 +125,30 @@ func (z _Zone) SoaRR() dns.RR {
// first available qType at each targeting level. Return a Label
// and the qtype that was "found"
func (z *Zone) findLabels(s string, targets []string, qts qTypes) (_Label, uint16) {

• return z.findLabelsN(s, targets, qts, 0)
  +}

- for _, target := range targets {

•   var name string
  

  +func (z _Zone) findLabelsN(s string, targets []string, qts qTypes, x int) (_Label, uint16) {
• if x > 7 {

•   return z.Labels[s], 0
  

• }
• name := make([]byte, 256)
• for _, target := range targets {
  switch target {
  case "@":

•       name = s
  

•       copy(name, s)
  default:
      if len(s) > 0 {
  

•           name = s + "." + target
  

•           copy(name, s)
  

•           name[len(s)+1] = '.'
  

•           copy(name[:len(s)+2], target)
      } else {
  

•           name = target
  

•           copy(name, target)
      }
  }
  

•   if label, ok := z.Labels[name]; ok {
  

•   if label, ok := z.Labels[string(name)]; ok {
  
      for _, qtype := range qts {
  

@@ -153,9 +160,7 @@ func (z _Zone) findLabels(s string, targets []string, qts qTypes) (_Label, uint1
return z.Labels[s], qtype
case dns.TypeMF:
if label.Records[dns.TypeMF] != nil {

•                   name = label.firstRR(dns.TypeMF).(*dns.MF).Mf
  

•                   // TODO: need to avoid loops here somehow
  

•                   return z.findLabels(name, targets, qts)
  

•                   return z.findLabelsN(label.firstRR(dns.TypeMF).(*dns.MF).Mf, targets, qts, x+1)
              }
          default:
              // return the label if it has the right record
  

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