RocketMQ源码 发送顺序消息源码分析

发布时间:2024年01月07日

前言

rocketmq 发送顺序消息和普通消息的主流程区别大部分一致的,区别在于:普通消息发送时,从所有broker的队列集合中 轮询选择一个队列,而顺序队列可以提供用户自定义消息队列选择器,从NameServer 分配的顺序 broker集合中选择一个队列。

源码版本:4.9.3

源码架构图

源码分析

发送普通消息源码在另外一篇文章https://blog.csdn.net/hzwangmr/article/details/135411495,这里主要阅读和普通消息有差异的部分。

顺序消息源码入口

org.apache.rocketmq.client.producer.DefaultMQProducer#send(org.apache.rocketmq.common.message.Message, org.apache.rocketmq.client.producer.MessageQueueSelector, java.lang.Object)

可以看到系统提供了一个 MessageQueueSelector 消息队列选择器,用于自定义选择队列的逻辑。

    /**
     * Same to {@link #send(Message)} with message queue selector specified.
     *
     * @param msg Message to send.
     * @param selector Message queue selector, through which we get target message queue to deliver message to.
     * @param arg Argument to work along with message queue selector.
     * @return {@link SendResult} instance to inform senders details of the deliverable, say Message ID of the message,
     * {@link SendStatus} indicating broker storage/replication status, message queue sent to, etc.
     * @throws MQClientException if there is any client error.
     * @throws RemotingException if there is any network-tier error.
     * @throws MQBrokerException if there is any error with broker.
     * @throws InterruptedException if the sending thread is interrupted.
     */
    @Override
    public SendResult send(Message msg, MessageQueueSelector selector, Object arg)
        throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
        msg.setTopic(withNamespace(msg.getTopic()));
        return this.defaultMQProducerImpl.send(msg, selector, arg);
    }

触发队列选择器源码

org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl#sendSelectImpl

这里可以看到在调用发送消息核心 sendKernelImpl() 方法之前,会调用 selector.select() 函数,执行我们自定的选择逻辑。那么自定义的逻辑具体是什么呢?接着往下看

    private SendResult sendSelectImpl(
        Message msg,
        MessageQueueSelector selector,
        Object arg,
        final CommunicationMode communicationMode,
        final SendCallback sendCallback, final long timeout
    ) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
        long beginStartTime = System.currentTimeMillis();
        this.makeSureStateOK();
        Validators.checkMessage(msg, this.defaultMQProducer);

        // 获取topic路由数据
        TopicPublishInfo topicPublishInfo = this.tryToFindTopicPublishInfo(msg.getTopic());
        if (topicPublishInfo != null && topicPublishInfo.ok()) {
            MessageQueue mq = null;
            try {
                // 解析发布消息队列
                List<MessageQueue> messageQueueList =
                    mQClientFactory.getMQAdminImpl().parsePublishMessageQueues(topicPublishInfo.getMessageQueueList());
                // 克隆消息
                Message userMessage = MessageAccessor.cloneMessage(msg);
                String userTopic = NamespaceUtil.withoutNamespace(userMessage.getTopic(), mQClientFactory.getClientConfig().getNamespace());
                userMessage.setTopic(userTopic);

                // 利用消息队列选择器,选择一个队列
                mq = mQClientFactory.getClientConfig().queueWithNamespace(
                        // 自定义选择队列
                        selector.select(messageQueueList, userMessage, arg)
                );
            } catch (Throwable e) {
                throw new MQClientException("select message queue threw exception.", e);
            }

            long costTime = System.currentTimeMillis() - beginStartTime;
            if (timeout < costTime) {
                throw new RemotingTooMuchRequestException("sendSelectImpl call timeout");
            }
            if (mq != null) {
                // 如果选择出来的 MessageQueue 存在,这调用核心发送消息函数,发送消息
                return this.sendKernelImpl(msg, mq, communicationMode, sendCallback, null, timeout - costTime);
            } else {
                throw new MQClientException("select message queue return null.", null);
            }
        }

        validateNameServerSetting();
        throw new MQClientException("No route info for this topic, " + msg.getTopic(), null);
    }

源码工程自带发送顺序消息实例

可以看到,工程自带的发送顺序消息的example实例,针对 id相同的数据,选择了相同的消息队列,这样对于同一个实体的数据变化一定是有顺序的。

public class Producer {
    public static void main(String[] args) throws UnsupportedEncodingException {
        try {
            DefaultMQProducer producer = new DefaultMQProducer("please_rename_unique_group_name");
            producer.start();

            String[] tags = new String[] {"TagA", "TagB", "TagC", "TagD", "TagE"};
            for (int i = 0; i < 100; i++) {
                int orderId = i % 10;
                Message msg =
                    new Message("TopicTestjjj", tags[i % tags.length], "KEY" + i,
                        ("Hello RocketMQ " + i).getBytes(RemotingHelper.DEFAULT_CHARSET));
                SendResult sendResult = producer.send(msg, new MessageQueueSelector() {
                    @Override
                    public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
                        // 自定义选择逻辑,可以理解为将相同的 orderId订单id,投递到相同的队列中
                        Integer id = (Integer) arg;
                        int index = id % mqs.size();
                        return mqs.get(index);
                    }
                }, orderId);

                System.out.printf("%s%n", sendResult);
            }

            producer.shutdown();
        } catch (MQClientException | RemotingException | MQBrokerException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

其他

topic对应的顺序队列怎么来的?

mq生产者客户端,在发送消息前,会从 NameServer中读取消息队里指定 topic对应的 topic路由信息,然后写到转换和缓存在内存多个数据结构里。其中,有一处就是下方的将 topic路由数据转换为topic 已发布信息,这里写入了messageQueueList (顺序消息待选择队列)。

转换逻辑是:

  1. 将路由信息写入topic发布信息;
  2. 判断当前路由信息是不是顺序 topic 配置;
  3. 解析顺序消息 topic配置;
  4. 遍历 broker,遍历broker 队列数量;
    1. 封装消息队列数据。topic -> broker ->队里id;
  5. 顺序队列数据,添加到 MessageQueueList 集合中;
    public static TopicPublishInfo topicRouteData2TopicPublishInfo(final String topic, final TopicRouteData route) {
        TopicPublishInfo info = new TopicPublishInfo();
        // 写入路由数据
        info.setTopicRouteData(route);
        // 顺序消息配置,顺序消息分配了多少个broker
        if (route.getOrderTopicConf() != null && route.getOrderTopicConf().length() > 0) {
            // 是顺序消息
            // 解析顺序消息topic配置
            String[] brokers = route.getOrderTopicConf().split(";");

            // 遍历顺序 broker,从namersrv拿到的broker数量
            for (String broker : brokers) {
                String[] item = broker.split(":");

                // 特定broker中的队列数量
                int nums = Integer.parseInt(item[1]);
                for (int i = 0; i < nums; i++) {
                    // 分装队列数据,topic--brokerName--队列id
                    MessageQueue mq = new MessageQueue(topic, item[0], i);
                    info.getMessageQueueList().add(mq);
                }
            }
            // 是顺序topic,打标
            info.setOrderTopic(true);
        }
    }
文章来源:https://blog.csdn.net/hzwangmr/article/details/135418962
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