Disruptor

一、简介

LMAX是一家外汇黄金交易所，Disruptor是由LMAX公司开发的可信消息传递架构的一部分
以便用非常快速的方法来在多组件之间传递数据。
核心思想是理解并适应硬件工作方式来达到最优的效果。
github地址:https://github.com/LMAX-Exchange/disruptor
LMAX架构:https://martinfowler.com/articles/lmax.html

二、架构图

结构图

三、成员

sequencer:序列号分配
sequence:序号，自增不减
MultiProducerSequencer 多生产者序列分配器
SingleProducerSequencer 单生产者序列分配器
ProcessingSequenceBarrier 管理消费者和生产者的依赖关系，
Ring Buffer:负责存储和更新事件的数据
Sequence Barrier:由Sequencer生成，它包含此Sequencer发布的Sequence指针以及依赖的其它消费者的Sequence。 它包含为消费者检查是否有可用的事件的代码逻辑。
Wait Strategy: 消费者等待事件的策略， 这些事件由生产者放入。
Event:传递的事件，完全有用户定义
EventProcessor:处理事件的主要循环，包含一个Sequence。有一个具体的实现类BatchEventProcessor.
EventHandler: 用户实现的接口，代表一个消费者
Producer:生产者，先获得占位，然后提交事件。

四、示例

maven依赖

        
            com.lmax
            disruptor
            3.3.6
        

消息体：

import lombok.Data;
/**
 * Created by yangzaining on 2020-04-06.
 */
@Data
public class LongEvent {
    private Long id;
}

消息工厂

import com.lmax.disruptor.EventFactory;
import lombok.Data;

/**
 * Created by yangzaining on 2020-04-06.
 */
@Data
public class LongEventFactory implements EventFactory {
    @Override
    public LongEvent newInstance() {
        return new LongEvent();
    }
}

消费者

import com.lmax.disruptor.EventHandler;
import lombok.extern.slf4j.Slf4j;

/**
 * Created by yangzaining on 2020-04-06.
 */
@Slf4j
public class LongEventHandler implements EventHandler {
    @Override
    public void onEvent(LongEvent event, long sequence, boolean endOfBatch) throws Exception {
        log.info("event = {},sequence = {}, endOfBatch = {}", event.getId(), sequence, endOfBatch);
    }
}

生产者

package demo;

import com.lmax.disruptor.RingBuffer;
import com.lmax.disruptor.dsl.Disruptor;
import com.lmax.disruptor.util.DaemonThreadFactory;

/**
* Created by yangzaining on 2020-04-06.
*/
public class LongEventPusher {

   private RingBuffer ringBuffer;

   LongEventPusher(RingBuffer ringBuffer) {
       this.ringBuffer = ringBuffer;
   }

   public void push(Long id) {
       long sequence = ringBuffer.next();
       try {
           LongEvent event = ringBuffer.get(sequence);
           event.setId(id);
       } finally {
           ringBuffer.publish(sequence);
       }
   }
}

    public static void main(String[] args) throws InterruptedException {
        LongEventFactory factory = new LongEventFactory();
        int bufferSize = 1024;
        Disruptor disruptor = new Disruptor<>(factory, bufferSize, DaemonThreadFactory.INSTANCE);
        disruptor.handleEventsWith(new LongEventHandler(), new LongEventHandler());
        disruptor.start();

        RingBuffer ringBuffer = disruptor.getRingBuffer();
        LongEventPusher pusher = new LongEventPusher(ringBuffer);//java 8可以用pushEvent
        for (long l = 0; l < 100; l++) {
//            long finalL = l;
//            disruptor.publishEvent((eventWrapper, sequence) -> eventWrapper.setId(finalL));
            pusher.push(l);
        }
        Thread.sleep(10000);
    }

producer.png

    /**
     * @see Sequencer#next(int)
     */
    @Override
    public long next(int n)
    {
        if (n < 1)
        {
            throw new IllegalArgumentException("n must be > 0");
        }

        long current;
        long next;

        do
        {
            current = cursor.get();
            next = current + n;

            long wrapPoint = next - bufferSize;
            long cachedGatingSequence = gatingSequenceCache.get();

            if (wrapPoint > cachedGatingSequence || cachedGatingSequence > current)
            {
                long gatingSequence = Util.getMinimumSequence(gatingSequences, current);

                if (wrapPoint > gatingSequence)
                {
                    waitStrategy.signalAllWhenBlocking();
                    LockSupport.parkNanos(1); // TODO, should we spin based on the wait strategy?
                    continue;
                }

                gatingSequenceCache.set(gatingSequence);
            }
            else if (cursor.compareAndSet(current, next))
            {
                break;
            }
        }
        while (true);

        return next;
    }

consumer.png

           while (true)
            {
                try
                {
                    final long availableSequence = sequenceBarrier.waitFor(nextSequence);

                    while (nextSequence <= availableSequence)
                    {
                        event = dataProvider.get(nextSequence);
                        eventHandler.onEvent(event, nextSequence, nextSequence == availableSequence);
                        nextSequence++;
                    }

                    sequence.set(availableSequence);
                }
                catch (final TimeoutException e)
                {
                    notifyTimeout(sequence.get());
                }

消费图解.png

注：以上全凭自己对Disruptor的理解，有不对的地方欢迎指正