59      * compareAndSet for longs. While the intrinsic compareAndSetLong
  60      * method works in either case, some constructions should be
  61      * handled at Java level to avoid locking user-visible locks.
  62      */
  63     static final boolean VM_SUPPORTS_LONG_CAS = VMSupportsCS8();
  64 
  65     /**
  66      * Returns whether underlying JVM supports lockless CompareAndSet
  67      * for longs. Called only once and cached in VM_SUPPORTS_LONG_CAS.
  68      */
  69     private static native boolean VMSupportsCS8();
  70 
  71     /*
  72      * This class intended to be implemented using VarHandles, but there
  73      * are unresolved cyclic startup dependencies.
  74      */
  75     private static final jdk.internal.misc.Unsafe U = jdk.internal.misc.Unsafe.getUnsafe();
  76     private static final long VALUE;
  77 
  78     static {
  79         try {
  80             VALUE = U.objectFieldOffset
  81                 (AtomicLong.class.getDeclaredField("value"));
  82         } catch (ReflectiveOperationException e) {
  83             throw new Error(e);
  84         }
  85     }
  86 
  87     private volatile long value;
  88 
  89     /**
  90      * Creates a new AtomicLong with the given initial value.
  91      *
  92      * @param initialValue the initial value
  93      */
  94     public AtomicLong(long initialValue) {
  95         value = initialValue;
  96     }
  97 
  98     /**
  99      * Creates a new AtomicLong with initial value {@code 0}.
 100      */
 101     public AtomicLong() {
 102     }
 103 
 104     /**

  59      * compareAndSet for longs. While the intrinsic compareAndSetLong
  60      * method works in either case, some constructions should be
  61      * handled at Java level to avoid locking user-visible locks.
  62      */
  63     static final boolean VM_SUPPORTS_LONG_CAS = VMSupportsCS8();
  64 
  65     /**
  66      * Returns whether underlying JVM supports lockless CompareAndSet
  67      * for longs. Called only once and cached in VM_SUPPORTS_LONG_CAS.
  68      */
  69     private static native boolean VMSupportsCS8();
  70 
  71     /*
  72      * This class intended to be implemented using VarHandles, but there
  73      * are unresolved cyclic startup dependencies.
  74      */
  75     private static final jdk.internal.misc.Unsafe U = jdk.internal.misc.Unsafe.getUnsafe();
  76     private static final long VALUE;
  77 
  78     static {
  79         VALUE = U.objectFieldOffset(AtomicLong.class, "value");





  80     }
  81 
  82     private volatile long value;
  83 
  84     /**
  85      * Creates a new AtomicLong with the given initial value.
  86      *
  87      * @param initialValue the initial value
  88      */
  89     public AtomicLong(long initialValue) {
  90         value = initialValue;
  91     }
  92 
  93     /**
  94      * Creates a new AtomicLong with initial value {@code 0}.
  95      */
  96     public AtomicLong() {
  97     }
  98 
  99     /**