Java中的CyclicBarrier循环栅栏解析

public CyclicBarrier(int parties)
public CyclicBarrier(int parties, Runnable barrierAction)

public int await() throws InterruptedException, BrokenBarrierException
public int await(long timeout, TimeUnit unit) throws InterruptedException, BrokenBarrierException, TimeoutException

public class KaneCyclicBarrier {
    private final ReentrantLock lock = new ReentrantLock();
    private final Condition condition = lock.newCondition();
    private int count =0; //批次
    private final int parties; //多少线程准备就绪？
    private Object generation = new Object();
    public KaneCyclicBarrier(int parties) {
        this.parties = parties;
    }
    public  void await(){
        final ReentrantLock lock = this.lock;
        lock.lock();
       try {
            final  Object g = generation;
           int index = ++count;
           if (index == parties) {
             nextGeneration();
             return;
           }
           while (true) {
               try {
                   condition.await();
               } catch (InterruptedException e) {
                   e.printStackTrace();
               }
               if(g!=generation){
                   return;
               }
           }
       }finally {
           lock.unlock();
       }
    }
    public void nextGeneration(){
        condition.signalAll();
        count=0;
        generation = new Object();
    }
}

public class CyclicBarrier_Demo {
    public CyclicBarrier_Demo() {
    }
    public static void main(String[] args) throws InterruptedException {
        KaneCyclicBarrier barrier = new KaneCyclicBarrier(4);
        for(int i = 0; i < 100; ++i) {//假设有100个任务，每次只能有固定数量的线程去执行，可以使用这个
            (new Thread(() -> {
                barrier.await();
                System.out.println("任务开始执行");
            })).start();
            Thread.sleep(500L);
        }
    }
}