权重轮询调度算法(WeightedRound-RobinScheduling)-Java实现
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry; /**
* 权重轮询调度算法(WeightedRound-RobinScheduling)-Java实现
* @author huligong
* */
public class WeightedRoundRobinScheduling { private int currentIndex = -1;// 上一次选择的服务器
private int currentWeight = 0;// 当前调度的权值
private int maxWeight = 0; // 最大权重
private int gcdWeight = 0; //所有服务器权重的最大公约数
private int serverCount = 0; //服务器数量
private List<Server> serverList; //服务器集合 /**
* 返回最大公约数
* @param a
* @param b
* @return
*/
private static int gcd(int a, int b) {
BigInteger b1 = new BigInteger(String.valueOf(a));
BigInteger b2 = new BigInteger(String.valueOf(b));
BigInteger gcd = b1.gcd(b2);
return gcd.intValue();
} /**
* 返回所有服务器权重的最大公约数
* @param serverList
* @return
*/
private static int getGCDForServers(List<Server> serverList ) {
int w = 0;
for (int i = 0, len = serverList.size(); i < len - 1; i++) {
if (w == 0) {
w = gcd(serverList.get(i).weight, serverList.get(i + 1).weight);
} else {
w = gcd(w, serverList.get(i + 1).weight);
}
}
return w;
} /**
* 返回所有服务器中的最大权重
* @param serverList
* @return
*/
public static int getMaxWeightForServers(List<Server> serverList) {
int w = 0;
for (int i = 0, len = serverList.size(); i < len - 1; i++) {
if (w == 0) {
w = Math.max(serverList.get(i).weight, serverList.get(i + 1).weight);
} else {
w = Math.max(w, serverList.get(i + 1).weight);
}
}
return w;
} /**
* 算法流程：
* 假设有一组服务器 S = {S0, S1, …, Sn-1}
* 有相应的权重，变量currentIndex表示上次选择的服务器
* 权值currentWeight初始化为0，currentIndex初始化为-1 ，当第一次的时候返回 权值取最大的那个服务器，
* 通过权重的不断递减 寻找 适合的服务器返回，直到轮询结束，权值返回为0
*/
public Server GetServer() {
while (true) {
currentIndex = (currentIndex + 1) % serverCount;
if (currentIndex == 0) {
currentWeight = currentWeight - gcdWeight;
if (currentWeight <= 0) {
currentWeight = maxWeight;
if (currentWeight == 0)
return null;
}
}
if (serverList.get(currentIndex).weight >= currentWeight) {
return serverList.get(currentIndex);
}
}
} class Server {
public String ip;
public int weight;
public Server(String ip, int weight) {
super();
this.ip = ip;
this.weight = weight;
}
public String getIp() {
return ip;
}
public void setIp(String ip) {
this.ip = ip;
}
public int getWeight() {
return weight;
}
public void setWeight(int weight) {
this.weight = weight;
}
} public void init() {
Server s1 = new Server("192.168.0.100", 3);//
Server s2 = new Server("192.168.0.101", 2);//
Server s3 = new Server("192.168.0.102", 6);//
Server s4 = new Server("192.168.0.103", 4);//
Server s5 = new Server("192.168.0.104", 1);//
serverList = new ArrayList<Server>();
serverList.add(s1);
serverList.add(s2);
serverList.add(s3);
serverList.add(s4);
serverList.add(s5); currentIndex = -1;
currentWeight = 0;
serverCount = serverList.size();
maxWeight = getMaxWeightForServers(serverList);
gcdWeight = getGCDForServers(serverList);
} public static void main(String[] args) {
WeightedRoundRobinScheduling obj = new WeightedRoundRobinScheduling();
obj.init(); Map<String,Integer> countResult = new HashMap<String,Integer>(); for (int i = 0; i < 100; i++) {
Server s = obj.GetServer();
String log = "ip:"+s.ip+";weight:"+s.weight;
if(countResult.containsKey(log)){
countResult.put(log,countResult.get(log)+1);
}else{
countResult.put(log,1);
}
System.out.println(log);
} for(Entry<String, Integer> map : countResult.entrySet()){
System.out.println("服务器 "+map.getKey()+" 请求次数： "+map.getValue());
}
} }