sclass PerSecondCounter {
  double interval = 1; // seconds
  long time = sysNow(), count, lastCount, lastDiff;
  
  *() {}
  *(double *interval) {}
  
  void inc() { inc(1); }
  synchronized void inc(int n) { count += n; }
  
  synchronized double getLast() {
    double fps = lastDiff == 0 ? 0 : lastCount*1000.0/lastDiff;
    update(sysNow()-time);
    ret fps;
  }
  
  synchronized double get() {
    long diff = sysNow()-time;
    double fps = (count+lastCount)*1000.0/(diff+lastDiff);
    update(diff);
    ret fps;
  }
  
  void update(long diff) {
    if (diff >= toMS(interval)) {
      lastDiff = diff;
      lastCount = count;
      time = sysNow();
      count = 0;
    }
  }
}