<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-all</artifactId>
    <version>4.1.45.Final</version>
</dependency>

@Bean("hashedWheelTimer")
public HashedWheelTimer hashedWheelTimer(){
    return new HashedWheelTimer(100, TimeUnit.MILLISECONDS, 512);
}

//訂單下單操作
void order(String orderInfo) {
  //下單的時候，向時間輪中添加一個30分鐘的延時任務
  hashedWheelTimer.newTimeout(task -> {
    //注意這里使用異步任務線程池或者開啟線程進行訂單取消任務的處理
    cancelOrder(orderInfo);
  }, 30, TimeUnit.MINUTES);
}

@Async("test")
public void cancelOrder(String orderInfo){
  //查詢訂單支付信息，如果用戶未支付，關閉訂單
}

    public HashedWheelTimer(
            ThreadFactory threadFactory,
            long tickDuration, TimeUnit unit, int ticksPerWheel, boolean leakDetection,
            long maxPendingTimeouts) {

        if (threadFactory == null) {
            throw new NullPointerException("threadFactory");
        }
        if (unit == null) {
            throw new NullPointerException("unit");
        }
        if (tickDuration <= 0) {
            throw new IllegalArgumentException("tickDuration must be greater than 0: " + tickDuration);
        }
        if (ticksPerWheel <= 0) {
            throw new IllegalArgumentException("ticksPerWheel must be greater than 0: " + ticksPerWheel);
        }

        // 初始化時間輪數(shù)組，時間輪大小為大于等于 ticksPerWheel 的第一個 2 的冪，和 HashMap 類似
        wheel = createWheel(ticksPerWheel);
        // 取模用，用來定位數(shù)組中的槽
        mask = wheel.length - 1;

        // 為了保證精度，時間輪內(nèi)的時間單位為納秒
        long duration = unit.toNanos(tickDuration);

        // 時間輪內(nèi)的時鐘撥動頻率不宜太大也不宜太小
        if (duration >= Long.MAX_VALUE / wheel.length) {
            throw new IllegalArgumentException(String.format(
                    "tickDuration: %d (expected: 0 < tickDuration in nanos < %d",
                    tickDuration, Long.MAX_VALUE / wheel.length));
        }

        if (duration < MILLISECOND_NANOS) {
            logger.warn("Configured tickDuration {} smaller then {}, using 1ms.",
                        tickDuration, MILLISECOND_NANOS);
            this.tickDuration = MILLISECOND_NANOS;
        } else {
            this.tickDuration = duration;
        }

        // 創(chuàng)建工作線程
        workerThread = threadFactory.newThread(worker);


        // 非守護線程且 leakDetection 為 true 時檢測內(nèi)存是否泄漏
        leak = leakDetection || !workerThread.isDaemon() ? leakDetector.track(this) : null;

        // 初始化最大等待任務數(shù)
        this.maxPendingTimeouts = maxPendingTimeouts;

        // 如果創(chuàng)建的時間輪實例大于 64，打印日志，并且這個日志只會打印一次
        if (INSTANCE_COUNTER.incrementAndGet() > INSTANCE_COUNT_LIMIT &&
            WARNED_TOO_MANY_INSTANCES.compareAndSet(false, true)) {
            reportTooManyInstances();
        }
    }