令牌桶算法
import java.util.concurrent.*;
public class MyRateLimiter {
//令牌桶
BlockingQueue<Integer>TOKEN_BUCKET=new LinkedBlockingDeque<>(5);
public static void main(String[] args) {
MyRateLimiter myRateLimiter=new MyRateLimiter();
myRateLimiter.addTokenFixedRate();
for(int i=0;i<10;i++){
myRateLimiter.acqurie();
System.out.println("第几次执行i:" + i + ",执行时间为：" + System.currentTimeMillis());
}
}
/**
* 定时添加令牌
*/
public void addTokenFixedRate(){
ScheduledExecutorService scheduledExecutorService= Executors.newSingleThreadScheduledExecutor();
scheduledExecutorService.scheduleAtFixedRate(()->{
boolean suc=TOKEN_BUCKET.offer(1);
if(!suc){
System.out.println("令牌桶满了丢弃");
}
},0,200,TimeUnit.MILLISECONDS);
}
public void acqurie(){
while (TOKEN_BUCKET.poll()==null){};
}
}
@CanIgnoreReturnValue
public double acquire(int permits) {
long microsToWait = reserve(permits);
stopwatch.sleepMicrosUninterruptibly(microsToWait);
return 1.0 * microsToWait / SECONDS.toMicros(1L);
}
//Reserve 一路向下能查到如下代码 reserveEarliestAvailable
final long reserveEarliestAvailable(int requiredPermits, long nowMicros) {
resync(nowMicros);
long returnValue = nextFreeTicketMicros;
// 现存令牌可以提供的令牌数
double storedPermitsToSpend = min(requiredPermits, this.storedPermits);
//需要刷新的令牌数
double freshPermits = requiredPermits - storedPermitsToSpend;
//等待时间=需要刷新的令牌数*固定间隔+存储许可等待时间
long waitMicros =
storedPermitsToWaitTime(this.storedPermits, storedPermitsToSpend)
+ (long) (freshPermits * stableIntervalMicros);
//下次令牌生产时间=本次令牌生产时间+等待时间
this.nextFreeTicketMicros = LongMath.saturatedAdd(nextFreeTicketMicros, waitMicros);
this.storedPermits -= storedPermitsToSpend;
return returnValue;
}