CyclicBarrier简单模拟订单对账流程

CyclicBarrier简单模拟订单对账流程

代码

/**
 * 主要针对CyclicBarrier的使用进行模拟
 */
public class CyclicBarrierDemo {
    //预先设定好模拟数据量
    private static final int TICKET_NUM = 20;
    //模拟数据库中的订单和发货单数据
    private static final List<Integer> ORDER = Collections.synchronizedList(new ArrayList<>());
    private static final List<Integer> SENDER = Collections.synchronizedList(new ArrayList<>());
    //假设订单库中每个订单都需要去比较是否相同，模拟需要被比较的数据的队列
    private static final List<Integer> DIFFER_ORDER = Collections.synchronizedList(new ArrayList<>());
    private static final List<Integer> DIFFER_SENDER = Collections.synchronizedList(new ArrayList<>());
    //给订单和发货单计数
    private static final AtomicInteger ORDER_COUNT = new AtomicInteger(TICKET_NUM);
    private static final AtomicInteger SENDER_COUNT = new AtomicInteger(TICKET_NUM);
    //为什么用Pool而不直接传Runnable,若直接传R，是同步执行，必须要一个订单比较完后才能执行下一个比较
    //即barrierAction执行完后才能执行下一次barrierAction
    //为什么POOL的大小置为一，因为check()方法线程不安全，置为1保证，每次只有一个线程去队列中取数据
    private static final ThreadPoolExecutor POOL = (ThreadPoolExecutor) Executors.newFixedThreadPool(1);
    private final CyclicBarrier notify = new CyclicBarrier(2, () -> {
        POOL.execute(this::check);
    });

    //初始化订单和发货单
    static {
        for (int i = 0; i < 20; i++) {
            ORDER.add(i);
            SENDER.add(new Random().nextInt(TICKET_NUM));
        }
        System.out.println("初始化订单数据: ");
        System.out.println(ORDER);
        System.out.println("初始化发货单数据: ");
        System.out.println(SENDER);
    }

    public void check() {
        int orderNum = DIFFER_ORDER.remove(0);
        int senderNum = DIFFER_SENDER.remove(0);
        if (orderNum == senderNum) {
            System.out.println(orderNum + " == " + senderNum + " 订单和发货单无差异，无需处理...");
        } else {
            System.out.println(orderNum + " != " + senderNum + ", Order = " + orderNum + " 订单和发货单存在差异，需要调用对账方法...");
        }
    }

    public void checkAll() {
        //有未校验订单时，将未校验订单放入比较队列
        new Thread(() -> {
            while (ORDER_COUNT.get() != 0) {
                try {
                    Thread.sleep((long) (Math.random() * 300));
                    DIFFER_ORDER.add(ORDER.get(TICKET_NUM - 1 - ORDER_COUNT.decrementAndGet()));
                    notify.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }
        }).start();
        //有未校验发货单时，将未校验订单放入比较队列
        new Thread(() -> {
            while (SENDER_COUNT.get() > 0) {
                try {
                    Thread.sleep((long) (Math.random() * 300));
                    DIFFER_SENDER.add(SENDER.get(TICKET_NUM - 1 - SENDER_COUNT.decrementAndGet()));
                    notify.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    public static void main(String[] args) {
        CyclicBarrierDemo demo = new CyclicBarrierDemo();
        demo.checkAll();
    }
}

Run