golang实现权重轮询调度算法

package main

    import (
    	"fmt"
    	"time"
    )

    var slaveDns = map[int]map[string]interface{}{
    	0: {"connectstring": "root@tcp(172.16.0.164:3306)/shiqu_tools?charset=utf8", "weight": 2},
    	1: {"connectstring": "root@tcp(172.16.0.165:3306)/shiqu_tools?charset=utf8", "weight": 4},
    	2: {"connectstring": "root@tcp(172.16.0.166:3306)/shiqu_tools?charset=utf8", "weight": 8},
    }

    var i int = -1 //表示上一次选择的服务器
    var cw int = 0 //表示当前调度的权值
    var gcd int = 2 //当前所有权重的最大公约数 比如 2，4，8 的最大公约数为：2

    func getDns() string {
    	for {
    		i = (i + 1) % len(slaveDns)
    		if i == 0 {
    			cw = cw - gcd
    			if cw <= 0 {
    				cw = getMaxWeight()
    				if cw == 0 {
    					return ""
    				}
    			}
    		}

    		if weight, _ := slaveDns[i]["weight"].(int); weight >= cw {
    			return slaveDns[i]["connectstring"].(string)
    		}
    	}
    }

    func getMaxWeight() int {
    	max := 0
    	for _, v := range slaveDns {
    		if weight, _ := v["weight"].(int); weight >= max {
    			max = weight
    		}
    	}

    	return max
    }

    func main() {

    	note := map[string]int{}

    	s_time := time.Now().Unix()

    	for i := 0; i < 100; i++ {
    		s := getDns()
    		fmt.Println(s)
    		if note[s] != 0 {
    			note[s]++
    		} else {
    			note[s] = 1
    		}
    	}

    	e_time := time.Now().Unix()

    	fmt.Println("total time: ", e_time-s_time)

    	fmt.Println("--------------------------------------------------")

    	for k, v := range note {
    		fmt.Println(k, " ", v)
    	}
    }

来源： http://studygolang.com/articles/8924