notes/resource/java/令牌桶算法谷歌实现.md

概念

令牌桶是一种用于分组交换和电信网络的算法。它可用于检查数据包形式的数据传输是否符合定义的带宽和突发性限制（流量不均匀或变化的度量)

maven 依赖

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>30.1-jre</version>
</dependency>

代码实现

import com.google.common.util.concurrent.ListeningExecutorService;  
import com.google.common.util.concurrent.MoreExecutors;  
import com.google.common.util.concurrent.RateLimiter;  
  
import java.text.SimpleDateFormat;  
import java.util.Date;  
import java.util.concurrent.Executors;  
  
public class Main {  
    public static void main(String[] args) {  
        ListeningExecutorService executorService = MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(100));  
  
        RateLimiter limiter = RateLimiter.create(1);  
        for (int i = 1; i < 50; i++) {  
            Double acquire = limiter.acquire(10);  
            executorService.submit(new PrintTask(String.format("get token，token:%s consumer：%s, taskId:%s", acquire, acquire, i)));  
        }  
    }  
  
    static class PrintTask implements Runnable {  
        String out;  
  
        public PrintTask(String out) {  
            this.out = out;  
        }  
  
        @Override  
        public void run() {  
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");  
            System.out.println(sdf.format(new Date()) + " -> " + Thread.currentThread().getName() + out);  
        }  
    }  
}

总结

其中核心 RateLimiter limiter = RateLimiter.create(1); 和 Double acquire = limiter.acquire(10); 相当于是实现 qps 的标准比值。

前者为生成令牌的个数每秒，后者为获取令牌的个数。