// Note: Costs one thread while it exists
sclass RunnablesReferenceQueue is AutoCloseable {
  new ReferenceQueue queue;
  volatile Thread thread;
  new Flag closed;
  
  settable int timeout = 60000; // just for safety
  
  *() {
    thread = startThread("RunnablesReferenceQueue", l0 _run);
  }
  
  void _run() ctex {
    try {
      while (ping() && !closed!) {
        Reference<?> ref = queue.remove(timeout);
        if (ref != null) {
          if (ref cast Runnable)
            pcallF(ref);
          else
            warn("RunnablesReferenceQueue: Reference not runnable - "
              + className(ref));
        }
      }
    } catch InterruptedException e {
    } finally {
      thread = null;
    }
  }
  
  close {
    closed.raise();
    interruptThread(thread);
  }
  
  ReferenceQueue queue aka get() { ret queue; }
}