code: public Disruptor createSingleDisruptor(String topic) {
  		TreeSet handlers = getHandles(topic);
  		if (handlers == null)
  			return null;
  		Disruptor dw = createSingleDw(topic);
  		Disruptor disruptor = addEventMessageHandler(dw, topic, handlers);
  		if (disruptor == null)
  			return null;
  		disruptor.start();
  		return disruptor;
  	}
docs: single producer :single consumer
  
  no lock
  
  @param topic
  @return