我复制
CountDownLatch并实现了
reset()一种将内部
Sync类重置为其初始状态（开始计数）的方法：)看起来可以正常工作。不再需要创建不必要的对象
o /因为
sync是私有的，所以无法进行子类化。嘘
import java.util.concurrent.CyclicBarrier;import java.util.concurrent.TimeUnit;import java.util.concurrent.locks.AbstractQueuedSynchronizer;public class ResettableCountDownLatch { private static final class Sync extends AbstractQueuedSynchronizer { private static final long serialVersionUID = 4982264981922014374L; public final int startCount; Sync(int count) { this.startCount = count; setState(startCount); } int getCount() { return getState(); } public int tryAcquireShared(int acquires) { return getState() == 0? 1 : -1; } public boolean tryReleaseShared(int releases) { // Decrement count; signal when transition to zero for (;;) { int c = getState(); if (c == 0) return false; int nextc = c-1; if (compareAndSetState(c, nextc)) return nextc == 0; } } public void reset() { setState(startCount); } } private final Sync sync; public ResettableCountDownLatch(int count) { if (count < 0) throw new IllegalArgumentException("count < 0"); this.sync = new Sync(count); } public void await() throws InterruptedException { sync.acquireSharedInterruptibly(1); } public void reset() { sync.reset(); } public boolean await(long timeout, TimeUnit unit) throws InterruptedException { return sync.tryAcquireSharedNanos(1, unit.tonanos(timeout)); } public void countDown() { sync.releaseShared(1); } public long getCount() { return sync.getCount(); } public String toString() { return super.toString() + "[Count = " + sync.getCount() + "]"; }}
