java 加权轮询_Java RPC中的权重轮询-优快云博客

本文介绍了一种基于加权轮询（Weighted Round Robin）的调度算法实现，该算法适用于服务器负载均衡场景，通过为不同的服务器分配权重来实现更合理的请求分配。文章提供了具体的Java代码实现，并展示了如何初始化服务器列表及进行调度。

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定义接口public interface RoundRobin {

T nextData();

}

实现

算法来自nginxpublic class WeightedRoundRobin implements RoundRobin {

private List> items = new ArrayList<>();

public WeightedRoundRobin(Map datas) {

List> initItems = datas.entrySet()

.stream()

.map(e -> new Item<>(e.getKey(), e.getValue()))

.collect(Collectors.toList());

items.addAll(initItems);

}

public T nextData() {

Item bestItem = null;

int total = 0;

for (Item currentItem : items) {

currentItem.currentWeight += currentItem.effectiveWeight;

total += currentItem.effectiveWeight;

if (currentItem.effectiveWeight < currentItem.weight) {

currentItem.effectiveWeight++;

}

if (bestItem == null || currentItem.currentWeight > bestItem.currentWeight) {

bestItem = currentItem;

}

if (bestItem == null) {

return null;

}

bestItem.currentWeight -= total;

return bestItem.getData();

}

public List> getItems() {

return items;

}

public void setItems(List> items) {

this.items = items;

}

public static final class Item {

private T data;

private int weight;

private int effectiveWeight;

private int currentWeight;

public Item(T data, int weight) {

this.data = data;

this.weight = weight;

}

public T getData() {

return data;

}

public void setData(T data) {

this.data = data;

}

public int getWeight() {

return weight;

}

public void setWeight(int weight) {

this.weight = weight;

}

public int getEffectiveWeight() {

return effectiveWeight;

}

public void setEffectiveWeight(int effectiveWeight) {

this.effectiveWeight = effectiveWeight;

}

public int getCurrentWeight() {

return currentWeight;

}

public void setCurrentWeight(int currentWeight) {

this.currentWeight = currentWeight;

}

@Override

public String toString() {

return "Item{" +

"data=" + data +

", weight=" + weight +

", effectiveWeight=" + effectiveWeight +

", currentWeight=" + currentWeight +

'}';

}

使用Map testDatas = new HashMap() {{

put(1, 3); // 权重3

put(2, 5); // 权重5

put(3, 8); // 权重8

}};

WeightedRoundRobin roundRobin = new WeightedRoundRobin<>(testDatas);

for (int i = 0; i < 20; i++) {

LOGGER.info("id: {}", roundRobin.nextData());

}