sclass OnOffOscillator is AutoCloseable {
  double percentageOn = 50;
  Frequency frequency = freq(50);
  
  transient PingSource clientPingSource;
  transient Schedule<Runnable> schedule;
  transient Thread thread;
  transient new BoolVar on;
  
  *(PingSource *clientPingSource) {}
  
  void init {
    schedule = new Schedule<Runnable>;
    schedule.add(0, r {
      clientPingSource?.action(null);
      on.set();
    });
    schedule.add(percentageOn/100, r {
      on.unset();
      clientPingSource?.action(-> {
        temp tempPingPrivileged();
        on.waitUntilTrue();
        true;
      });
    });
    schedule.jumpFromTo(1, 0);
    schedule.speedUp(frequency!);
  }
  
  void start {
    init();
    thread = startThread("OnOffOscillator", r { schedule.run(); });
  }
  
  // Note: May leave switch in on or off state
  public void stop aka close() {
    interruptThread(thread);
    thread = null;
  }
}