Single Latch - thread wait for "open" or pass through await() instantly if latch open

SingleLatch.java

public class SingleLatch {

    static final int STATE_OPEN = 0;
    static final int STATE_CLOSED = 1;

    public enum State {
        OPEN(STATE_OPEN),
        CLOSED(STATE_CLOSED);

        int state;
        State(int state) {
            this.state = state;
        }

        int getInt() {
            return state;
        }

        static State valueOf(int state) {
            switch (state) {
                case STATE_OPEN: return OPEN;
                case STATE_CLOSED: return CLOSED;
                default:
                    throw new IllegalStateException("state "+state+" not declared");
            }
        }
    }

    /**
     * Synchronization control For SingleLatch.
     * Uses AQS state to represent count.
     */
    private static final class Sync extends AbstractQueuedSynchronizer {
        private static final long serialVersionUID = 4982267854940614374L;

        Sync() {
            setState(State.CLOSED.getInt());
        }

        State getSyncState() {
            return  State.valueOf(getState());
        }

        @Override
        protected int tryAcquireShared(int acquires) {
            return (getState() == STATE_OPEN) ? 1 : -1;
        }

        @Override
        protected boolean tryReleaseShared(int releases) {
            setState(STATE_OPEN);
            return true;
        }
    }

    private final SingleLatch.Sync sync;


    public SingleLatch() {
        this.sync = new SingleLatch.Sync();
    }

    public void await() throws InterruptedException {
        sync.acquireSharedInterruptibly(State.OPEN.getInt());
    }

    public boolean await(long timeout, TimeUnit unit) throws InterruptedException {
        return sync.tryAcquireSharedNanos(State.OPEN.getInt(), unit.toNanos(timeout));
    }

    public void open() {
        sync.releaseShared(State.OPEN.getInt());
    }

    public boolean isClosed() {
        return State.CLOSED.equals(sync.getSyncState());
    }

    public String toString() {
        return super.toString() + "[Count = " + sync.getSyncState() + "]";
    }
}