1public void await() throws InterruptedException {
2    sync.acquireSharedInterruptibly(1);
3}

1public final void acquireSharedInterruptibly(int arg) throws InterruptedException {
2    if (Thread.interrupted()) throw new InterruptedException();
3    if (tryAcquireShared(arg) < 0)
4        doAcquireSharedInterruptibly(arg);
5}

1protected int tryAcquireShared(int acquires) {
2    return (getState() == 0) ? 1 : -1;
3}

1public void countDown() {
2    sync.releaseShared(1);
3}

1public final boolean releaseShared(int arg) {
2    if (tryReleaseShared(arg)) {
3        doReleaseShared();
4        return true;
5    }
6    return false;
7}

 1protected boolean tryReleaseShared(int releases) {
 2    // Decrement count; signal when transition to zero
 3    for (;;) {
 4        int c = getState();
 5        if (c == 0)
 6            return false;
 7        int nextc = c-1;
 8        if (compareAndSetState(c, nextc))
 9            return nextc == 0;
10    }
11}

1public CountDownLatch(int count) {
2    this.sync = new Sync(count);
3}

1Sync(int count) {
2    setState(count);
3}