java - 我怎样才能在没有发生之前获得锁？

Question

我想在没有发生之前锁定java来测试内存可见性的其他规则。而且我已经尝试过Unsafe#compareAndswapInteger，AtomicInteger#weakCompareAndSet他们似乎仍然保证发生之前的规则？

这是我的测试代码：

    @Test
    public void testUnsafeMutex_case2() throws InterruptedException {
        class A {
            String name;
            A(String name) {this.name = name;}
        }
        class B{A a;}
        UnsafeMutex unsafeMutex = new UnsafeMutex();
        final B b = new B();
        Thread thread = new Thread(() -> {
            unsafeMutex.lock();
            System.out.println(b.a.name); // **I wanna NPE here**
            unsafeMutex.unlock();
        });
        unsafeMutex.lock(); // put it before Thread#start, and by happens-before rule, it should run first
        thread.start();
        b.a = new A("name"); // after Thread#start, to avoid happens-before
        unsafeMutex.unlock();
        thread.join();
    }

    static class UnsafeMutex {

        /**
         * no adding key word volatile for avoiding happens before piggy backing
         */
        private AtomicInteger state = new AtomicInteger(0);

        public void lock() {
            while(!state.weakCompareAndSet(0, 1));
        }

        public void unlock() {
            while(!state.weakCompareAndSet(1, 0));
        }
    }