# 一个按权重（weight）进行LB的算法

package netty;

import lombok.SneakyThrows;

import java.util.List;
import java.util.Objects;
import java.util.Random;

/**
* Test
*
* @author xfyou
*/
public class Test {

@SneakyThrows
public static void main(String[] args) {
List<Integer> weightList = ImmutableList.of(0, 0, 0, 0);
boolean allHaveTheSameWeight = isSameWeight(weightList);
if (!allHaveTheSameWeight) {
selectOneByWeight(weightList);
} else {
selectOneRandom(weightList);
}
}

/**
* 如果所有的权重都是一样的，则随机选择一个
*/
private static void selectOneRandom(List<Integer> weightList) {
System.out.println("selecded list index:" + new Random().nextInt(weightList.size()));
}

/**
* 如果所有的权重不一样，则优化选择权重高的
*/
private static void selectOneByWeight(List<Integer> weightList) {
int offset = new Random().nextInt(weightList.stream().mapToInt(i -> i).sum());
for (int i = 0, len = weightList.size(); i < len; i++) {
offset -= weightList.get(i);
if (offset < 0) {
System.out.println("selected weight:" + weightList.get(i) + ", selected index:" + i);
break;
}
}
}

/**
* 判断所有的权重是否一样
*/
private static boolean isSameWeight(List weightList) {
boolean allHaveTheSameWeight = true;
for (int i = 0, len = weightList.size(); i < len; i++) {
if (i > 0) {
if (!Objects.equals(weightList.get(i), weightList.get(i - 1))) {
allHaveTheSameWeight = false;
break;
}
}
}
return allHaveTheSameWeight;
}

}

posted @ 2019-08-30 16:01  FrankYou  阅读(428)  评论(0编辑  收藏