Disruptor框架简介

Disruptor框架内部核心的数据结构是Ring Buffer，Ring Buffer是一个环形的数组，Disruptor框架以Ring Buffer为核心实现了异步事件处理的高性能架构；JDK的BlockingQueue相信大家都用过，其是一个阻塞队列，内部通过锁机制实现生产者和消费者之间线程的同步。跟BlockingQueue一样，Disruptor框架也是围绕Ring Buffer实现生产者和消费者之间数据的交换，只不过Disruptor框架性能更高，笔者曾经在同样的环境下拿Disruptor框架跟ArrayBlockingQueue做过性能测试，Disruptor框架处理数据的性能比ArrayBlockingQueue的快几倍。

Disruptor框架性能为什么会更好呢？其有以下特点：

预加载内存可以理解为使用了内存池；
无锁化
单线程写
消除伪共享
使用内存屏障
序号栅栏机制

快速入门

MQManager启用Disruptor，返回RingBuffer实例。

@Configuration
public class MQManager {

    @Bean("messageModel")
    public RingBuffer<MessageModel> messageModelRingBuffer() {
        //定义用于事件处理的线程池， Disruptor通过java.util.concurrent.ExecutorSerivce提供的线程来触发consumer的事件处理  
        ExecutorService executor = Executors.newFixedThreadPool(2);

        //指定事件工厂  
        HelloEventFactory factory = new HelloEventFactory();

        //指定ringbuffer字节大小，必须为2的N次方（能将求模运算转为位运算提高效率），否则将影响效率  
        int bufferSize = 1024 * 256;

        //单线程模式，获取额外的性能  
        Disruptor<MessageModel> disruptor = new Disruptor<>(factory, bufferSize, executor,
                ProducerType.SINGLE, new BlockingWaitStrategy());

        //设置事件业务处理器---消费者  
        disruptor.handleEventsWith(new HelloEventHandler());

        // 启动disruptor线程  
        disruptor.start();

        //获取ringbuffer环，用于接取生产者生产的事件  
        RingBuffer<MessageModel> ringBuffer = disruptor.getRingBuffer();

        return ringBuffer;
    }
}

MessageModel消息实体类

@Data
public class MessageModel {  
    private String message;  
}

工厂类

public class HelloEventFactory implements EventFactory<MessageModel> {
    @Override  
    public MessageModel newInstance() {  
        return new MessageModel();  
    }  
}

消息处理器

@Slf4j
public class HelloEventHandler implements EventHandler<MessageModel> {
    @Override  
    public void onEvent(MessageModel event, long sequence, boolean endOfBatch) {  
        try {  
            log.info("消费者处理消息开始");  
            if (event != null) {  
                log.info("消费者消费的信息是：{}",event);  
            }  
        } catch (Exception e) {  
            log.info("消费者处理消息失败");  
        }  
        log.info("消费者处理消息结束");  
    }  
}

消息发送

@Slf4j
@Service
public class DisruptorMqServiceImpl implements DisruptorMqService {  
  
    @Autowired
    private RingBuffer<MessageModel> messageModelRingBuffer;
  
    @Override  
    public void sayHelloMq(String message) {  
        log.info("record the message: {}",message);  
        //获取下一个Event槽的下标  
        long sequence = messageModelRingBuffer.next();  
        try {  
            //给Event填充数据  
            MessageModel event = messageModelRingBuffer.get(sequence);  
            event.setMessage(message);  
            log.info("往消息队列中添加消息：{}", event);  
        } catch (Exception e) {  
            log.error("failed to add event to messageModelRingBuffer for : e = {},{}",e,e.getMessage());  
        } finally {  
            //发布Event，激活观察者去消费，将sequence传递给改消费者  
            //注意最后的publish方法必须放在finally中以确保必须得到调用；如果某个请求的sequence未被提交将会堵塞后续的发布操作或者其他的producer  
            messageModelRingBuffer.publish(sequence);  
        }  
    }  
}