Java Memory Model Tests

JMM.java

class DataRace {
  // Make volatile
  boolean ready = false;
  int answer  = 0;

  void thread1() {
      // Spin Lock
     while(!ready);
     assert answer == 42
  }

  void thread2() {
    answer = 42;
    ready = true
  }

}


/**
 * Double checked locking.
 */
class DoubleChecked {

  static volatile DoubleChecked instance;
 
  static DoubleChecked getInstance() {
      // Lazy initialization
      if(instance ==null) {
         synchronized(DoubleChecked.class) {
             if(instance == null) {
              instance = new DoubleChecked();
             }
         }
      }
  }

  int foo = 0;
  DoubleChecked() { foo = 42; }
  void method() {
      assert foo == 42;
  }
}

// AtomicIntegerArray