分布式事务 - Rocketmq

[TOC] # 目录 ## 准备工作 [基础代码](https://blog.eddilee.cn/archives/%E5%88%86%E5%B8%83%E5%BC%8F%E4%BA%8B%E5%8A%A1-%E6%9C%AC%E5%9C%B0%E6%B6%88%E6%81%AF%E8%A1%A8) ## MQ - 原理、流程与本地消息表 - 不同点 - 本地消息表改为MQ - 定时任务改为MQ的消费者 - 不依赖定时任务，基于MQ更高效、更可靠 - 适合于公司内的系统 - 不同公司之间无法基于MQ，本地消息表更合适 DB1 --> 支付系统 --> 支付成功消息 --> 消费者 --> DB2 （订单更新为已支付） ### RocketMQ的安装 http://rocketmq.apache.org/docs/quick-start/ ```shell unzip rocketmq-all-4.7.1-source-release.zip mv rocketmq-all-4.7.1-source-release rocketmq-all-4.7.1 cd rocketmq-all-4.7.1/ && mvn -Prelease-all -DskipTests clean install -U cd distribution/target/rocketmq-4.7.1/rocketmq-4.7.1 ``` #### Linux Server ```shell nohup sh bin/mqnamesrv & tail -f ~/logs/rocketmqlogs/namesrv.log ``` Broker ```shell nohup sh bin/mqbroker -n 192.168.8.246:9876 & tail -f ~/logs/rocketmqlogs/broker.log ``` 问题汇总： ```shell 一、内存问题 [eddie@tracker rocketmq-4.7.1]# sh bin/mqbroker -n localhost:9876 Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x00000005c0000000, 8589934592, 0) failed; error='Cannot allocate memory' (errno=12) # # There is insufficient memory for the Java Runtime Environment to continue. # Native memory allocation (mmap) failed to map 8589934592 bytes for committing reserved memory. # An error report file with more information is saved as: # /opt/rocketmq-all-4.7.1/distribution/target/rocketmq-4.7.1/rocketmq-4.7.1/hs_err_pid22425.log 修改内存 vim /opt/rocketmq-all-4.7.1/distribution/target/rocketmq-4.7.1/rocketmq-4.7.1/bin/runserver.sh JAVA_OPT="${JAVA_OPT} -server -Xms128m -Xmx256m -Xmn256m -XX:MetaspaceSize=128m -XX:MaxMetaspaceSize=320m" vim /opt/rocketmq-all-4.7.1/distribution/target/rocketmq-4.7.1/rocketmq-4.7.1/bin/runbroker.sh JAVA_OPT="${JAVA_OPT} -server -Xms256m -Xmx256m -Xmn256m" 二、SpringBoot启动提示"close the connection to remote address[] result: true" 和 The broker[tracker, 172.19.0.1:10911] boot success. serializeType=JSON and name server is localhost:9876 综合两个提示，明显没有找到IP地址开始我是用两台服务器分别安装 mqbroker 和 namesrv 后来只能安装在一台，在使用下面方法解决： echo 'brokerIP1=192.168.8.246' > conf/broker.properties nohup sh bin/mqbroker -n localhost:9876 -c conf/broker.properties autoCreateTopicEnable=true & ``` ### 代码部分 #### Maven依赖 ```xml <dependency> <groupId>org.apache.rocketmq</groupId> <artifactId>rocketmq-client</artifactId> <version>4.7.1</version>  </dependency> ``` #### 配置类 ```java package com.example.tccdemo.config; import org.apache.rocketmq.client.consumer.DefaultMQPushConsumer; import org.apache.rocketmq.client.consumer.listener.MessageListenerConcurrently; import org.apache.rocketmq.client.exception.MQClientException; import org.apache.rocketmq.client.producer.DefaultMQProducer; import org.springframework.beans.factory.annotation.Qualifier; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; /** * @author eddie.lee * @ProjectName tcc-demo * @Package com.example.tccdemo.config * @ClassName RocketMQConfig * @description http://rocketmq.apache.org/docs/simple-example/ * @date created in 2020-11-30 14:14 * @modified by */ @Configuration public class RocketMQConfig { /** * 生产者 * Send Messages Synchronously 同步发送消息 * * @return producer */ @Bean(initMethod = "start", destroyMethod = "shutdown") public DefaultMQProducer producer() { //Instantiate with a producer group name. DefaultMQProducer producer = new DefaultMQProducer("paymentGroup"); // Specify name server addresses. producer.setNamesrvAddr("192.168.8.246:9876"); return producer; } /** * 消费者 * * @param messageListener * @return consumer * @throws MQClientException * @description @Qualifier("messageListener") 之后需要单独写一个Bean注入 */ @Bean(initMethod = "start", destroyMethod = "shutdown") public DefaultMQPushConsumer consumer(@Qualifier("messageListener") MessageListenerConcurrently messageListener) throws MQClientException { // Instantiate with specified consumer group name. DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("paymentConsumerGroup"); // Specify name server addresses. consumer.setNamesrvAddr("192.168.8.246:9876"); // Subscribe one more more topics to consume. consumer.subscribe("payment", "*"); // Register callback to execute on arrival of messages fetched from brokers. consumer.registerMessageListener(messageListener); return consumer; } } ``` #### 支付消息队列 com.example.tccdemo.service.PaymenService 新增方法 ```java /** * 支付接口 (消息队列：生产者) * * @param userId * @param orderId * @param amount * @return 0:代表成功、1: 用户不存在、2: 余额不足 */ @Transactional(transactionManager = "tm246", rollbackFor = Exception.class) public int pamentMQ(int userId, int orderId, BigDecimal amount) throws Exception { /** * 账户的扣减操作 */ // 账户是否存在 AccountA accountA = accountAMapper.selectByPrimaryKey(userId); if (accountA == null) { return 1; } // 账户的余额小于你扣减的金额 if (accountA.getBalance().compareTo(amount) < 0) { return 2; } // 账户余额减去传入的金额 accountA.setBalance(accountA.getBalance().subtract(amount)); accountAMapper.updateByPrimaryKey(accountA); Message message = new Message(); // 必须项：分类 message.setTopic("payment"); message.setKeys(orderId + ""); message.setBody("订单已支付".getBytes()); try { SendResult result = producer.send(message); if (result.getSendStatus() == SendStatus.SEND_OK) { return 0; } else { // 如果状态不是 SEND_OK 就直接抛出异常, 回滚整个方法. 保证原子性 throw new Exception("消息发送失败!"); } } catch (MQClientException | RemotingException | MQBrokerException | InterruptedException e) { e.printStackTrace(); // 必需抛出, 不能让方法正常结束, 不然就不会触发事务的回滚 throw e; } } ``` @Qualifier("messageListener") 单独写一个Bean注入 ```java package com.example.tccdemo.consumer; import com.example.tccdemo.db247.dao.OrderMapper; import com.example.tccdemo.db247.model.Order; import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyContext; import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyStatus; import org.apache.rocketmq.client.consumer.listener.MessageListenerConcurrently; import org.apache.rocketmq.common.message.MessageExt; import org.springframework.stereotype.Component; import javax.annotation.Resource; import java.util.Date; import java.util.List; import static org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyStatus.CONSUME_SUCCESS; import static org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyStatus.RECONSUME_LATER; /** * @author eddie.lee * @ProjectName tcc-demo * @Package com.example.tccdemo.consumer * @ClassName ChangeOrderStatus * @description * @date created in 2020-11-30 15:14 * @modified by */ @Component("messageListener") public class ChangeOrderStatus implements MessageListenerConcurrently { @Resource private OrderMapper orderMapper; /** * @param list 取得多个消息 * @param consumeConcurrentlyContext * @return */ @Override public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> list, ConsumeConcurrentlyContext consumeConcurrentlyContext) { if (list == null || list.size() == 0) { // 返回消费成功 return CONSUME_SUCCESS; } /** * 取到消费是一个集合 * 比如：获取了两条消息队列的消息, * 第一个消息消费成功 * 第二个消息消费失败，返回再次消费(RECONSUME_LATER) * 但是第一个消息是成功的 * * MessageListenerConcurrently：不建议抛出异常，而不是在以下情况下返回ConsumeConcurrentlyStatus.RECONSUME_LATER * DefaultMQPushConsumer.consumeMessageBatchMaxSize = 1，您可以在此处修改 * * 按 MessageListenerConcurrently 意思，就是每次取一条，所以不用担心第二条失败而导致第一条出现问题 */ for (MessageExt item : list) { String orderId = item.getKeys(); byte[] body = item.getBody(); String msg = new String(body); System.out.println("msg=" + msg); Order order = orderMapper.selectByPrimaryKey(Integer.parseInt(orderId)); if (order == null) { // 返回再次消费 return RECONSUME_LATER; } try { // 已支付 order.setOrderStatus(1); order.setUpdateTime(new Date()); // 更新操作时间 order.setUpdateUser(0); orderMapper.updateByPrimaryKey(order); } catch (Exception e) { e.printStackTrace(); return RECONSUME_LATER; } } // 返回消费成功 return CONSUME_SUCCESS; } } ``` ### 测试 #### 控制层 ```java @RequestMapping("/payment") private String payment(int userId, int orderId, BigDecimal amount) throws Exception { int result = paymenService.pamentMQ(userId, orderId, amount); return "支付结果：" + result; } ``` ##### GET http://localhost:8080/payment?userId=1&orderId=100&amount=200 ##### 数据库变化 account_a 扣减金额 t_order 状态更改=1 ### 总结 - 请求接口 - com.example.tccdemo.controller.PaymenController#payment - 生产者部分 - 支付接口：com.example.tccdemo.service.PaymenService#pamentMQ - 扣减操作 - 订单号和主题消息“订单已支付”，放入消息队列（主要部分是MQ出错的逻辑判断） - 消费者部分 - com.example.tccdemo.config.RocketMQConfig#consumer -- @Qualifier("messageListener") - 编写 messageListener 的 @Bean -- com.example.tccdemo.consumer.ChangeOrderStatus#consumeMessage - 从**List**中获取订单号(OrderId)、消息(msg=订单已支付) - 通过获取到OrderId查询订单，修改支付状态 (关键点：ConsumeConcurrentlyStatus的枚举状态)

幂等性是什么？

分布式事务 - 本地消息表