package balance

import(
	"errors"
)
type RoundRobinBalance 	struct{
	curIndex int
}
func init(){
	RegisterBalancer("roundrobin",&RoundRobinBalance{})
}
func (p *RoundRobinBalance)DoBalance(insts []*Instance,key ...string) (inst *Instance, err error) {
	if len(insts)==0 {
		err= errors.New("No instance")
		return 
	}


	lens:=len(insts)

	inst=insts[p.curIndex]
	p.curIndex=(p.curIndex+1)%lens
	return
}