safeCounter() is not thread-safe.

[ohyoung79]

The current implementation of safeCounter() seems not to be thread-safe. "counter = counter <DISCRETE? counter: 0" and "return counter ++" are likely to work separately. "return counter ++" itself is not thread-safe either. The Orignal program is written in a javascript language that works only in single-thread, it is thread-safe by default. But the java program must be implemented thread-safe. The simplest is to safecounter() synchronized, and if you want to implement lock-free, you'll have to fix it like this:

private static int counter = 0; ==> private static AtomicInteger counter = new AtomicInteger (0);

private static int safeCounter () {     counter = counter <DISCRETE_VALUES? counter: 0;     return counter ++; } ==> private static int safeCounter () {     int oldVal = 0;     int newVal = 0;     for (;;) {         oldVal = counter.get ();         newVal = oldVal < DISCRETE_VALUES ? oldVal : 0;         newVal ++;         if (counter.compareAndSet (oldVal, newVal)) return newVal - 1;     } }