public final double sampleCount(){
synchronized (_lock) {
    long count=_count.get();
    long lastCount=_lastCount;
    _lastCount=count;
    return count - lastCount;
  }
}

public final double sampleCount ( ) { synchronized ( _lock ) { long count = _count . get ( ) ; long lastCount = _lastCount ; _lastCount = count ; return count - lastCount ; } }
return the probe ' s next sample .
