SpringBoot分布式事务之可靠消息最终一致性-51CTO.COM

环境：springboot2.3.9 + RocketMQ4.8.0

可靠消息最终一致性原理

执行流程

Producer发送Prepare message到broker。
Prepare Message发送成功后开始执行本地事务。
如果本地事务执行成功的话则返回commit，如果执行失败则返回rollback。（这个是在事务消息的回调方法里由开发者自己决定commit or rollback）
Producer发送上一步的commit还是rollback到broker，这里有以下两种情况：

1、如果broker收到了commit/rollback消息：

如果收到了commit，则broker认为整个事务是没问题的，执行成功的。那么会下发消息给Consumer端消费。

如果收到了rollback，则broker认为本地事务执行失败了，broker将会删除Half Message，不下发给Consumer端。

2、如果broker未收到消息（如果执行本地事务突然宕机了，相当执行本地事务(executeLocalTransaction)执行结果返回unknow，则和broker未收到确认消息的情况一样处理。）：

broker会定时回查本地事务的执行结果：如果回查结果是本地事务已经执行则返回commit，若未执行，则返回unknow。

Producer端回查的结果发送给Broker。Broker接收到的如果是commit，则broker视为整个事务执行成功，如果是rollback，则broker视为本地事务执行失败，broker删除Half Message，不下发给consumer。如果broker未接收到回查的结果（或者查到的是unknow），则broker会定时进行重复回查，以确保查到最终的事务结果。重复回查的时间间隔和次数都可配。

工程结构

图片

建立父子工程，两个子项目account-manager，integral-manager。

依赖

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
  <groupId>org.apache.rocketmq</groupId>
  <artifactId>rocketmq-spring-boot-starter</artifactId>
  <version>2.2.0</version>
</dependency>

Account子模块

配置文件

server:
  port: 8081
---
rocketmq:
  nameServer: localhost:9876
  producer:
    group: pack-mq
---
spring:
  jpa:
    generateDdl: false
    hibernate:
      ddlAuto: update
    openInView: true
    show-sql: true
---
spring:
  datasource:
    driverClassName: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/account?serverTimeznotallow=GMT%2B8
    username: root
    password: ******
    type: com.zaxxer.hikari.HikariDataSource
    hikari:
      minimumIdle: 10
      maximumPoolSize: 200
      autoCommit: true
      idleTimeout: 30000
      poolName: MasterDatabookHikariCP
      maxLifetime: 1800000
      connectionTimeout: 30000
      connectionTestQuery: SELECT 1

业务实体类

// 用户表
@Entity
@Table(name = "t_account")
public class Account {
  @Id
  private Long id;
  private String name ;
}
// 业务记录表（用来查询去重）
@Entity
@Table(name = "t_account_log")
public class AccountLog {
  @Id
  private Long txid;
  private Date createTime ;
}

DAO相关类

public interface AccountRepository extends JpaRepository<Account, Long> {
}
public interface AccountLogRepository extends JpaRepository<AccountLog, Long> {
}

Service相关类

@Resource
private AccountRepository accountRepository ;
@Resource
private AccountLogRepository accountLogRepository ;
  
// 该方法保存业务数据，同时保存操作记录；操作记录用来回查。
@Transactional
public boolean register(Account account) {
  accountRepository.save(account) ;
  AccountLog accountLog = new AccountLog(account.getId(), new Date()) ;
  accountLogRepository.save(accountLog) ;
  return true ;
}
  
public AccountLog existsTxId(Long txid) {
  return accountLogRepository.findById(txid).orElse(null) ;
}

发送消息方法

@Resource
private RocketMQTemplate rocketMQTemplate ;
  
public String sendTx(String topic, String tags, Account account) {
  String uuid = UUID.randomUUID().toString().replaceAll("-", "") ;
  TransactionSendResult result =rocketMQTemplate.sendMessageInTransaction(topic + ":" + tags, MessageBuilder.withPayload(account).
      setHeader("tx_id", uuid).build(), uuid) ;
  return result.getSendStatus().name() ;
}

消息监听（生产者监听）

@RocketMQTransactionListener
public class ProducerMessageListener implements RocketMQLocalTransactionListener {
  
  @Resource
  private AccountService accountService ;


  @Override
  public RocketMQLocalTransactionState executeLocalTransaction(Message msg, Object arg) {
    try {
      Account account = new JsonMapper().readValue((byte[])msg.getPayload(), Account.class) ;
      accountService.register(account) ;
    } catch (Exception e) {
      e.printStackTrace() ;
      return RocketMQLocalTransactionState.ROLLBACK ;
    }
    return RocketMQLocalTransactionState.COMMIT ;
  }


  @Override
  public RocketMQLocalTransactionState checkLocalTransaction(Message msg) {
  // 这里检查本地事务是否执行成功
    try {
      Account account = new JsonMapper().readValue((byte[])msg.getPayload(), Account.class) ;
      System.out.println("执行查询ID为：" + account.getId() + " 的数据是否存在") ;
      AccountLog accountLog = accountService.existsTxId(account.getId()) ;
      if (accountLog == null) {
        return RocketMQLocalTransactionState.UNKNOWN ;
      }
    } catch (Exception e) {
      e.printStackTrace() ;
      return RocketMQLocalTransactionState.UNKNOWN ;
    }
    return RocketMQLocalTransactionState.COMMIT ;
  }


}

Controller接口

@RestController
@RequestMapping("/accounts")
public class AccountController {
  @Resource
  private ProducerMessageService messageService ;
  @PostMapping("/send")
  public Object sendMessage(@RequestBody Account account) {
    return messageService.sendTx("tx-topic", "mks", account) ;
  }
}

Integral子模块

业务实体类

@Entity
@Table(name = "t_integral")
public class Integral {
  @Id
  private Long id;
  private Integer score ;
  private Long acccountId ;
}

DAO相关类

public interface IntegralRepository extends JpaRepository<Integral, Long> {
}

Service相关类

@Resource
private IntegralRepository integralRepository ;
  
@Transactional
public Integral saveIntegral(Integral integral) {
  return integralRepository.save(integral) ;
}

消息监听

@RocketMQMessageListener(topic = "tx-topic", consumerGroup = "consumer05-group", selectorExpression = "mks")
@Component
public class IntegralMessageListener implements RocketMQListener<String> {


  @Resource
  private IntegralService integralService ;
  
  @SuppressWarnings("unchecked")
  @Override
  public void onMessage(String message) {
    System.out.println("Integral接收到消息：" + message) ;
    try {
      Map<String, Object> jsonMap = new JsonMapper().readValue(message, Map.class) ;
      Integer id = (Integer) jsonMap.get("id") ;
      integralService.saveIntegral(new Integral(1L, 1000, id + 0L)) ;
    } catch (Exception e) {
      throw new RuntimeException(e) ;
    }
  }


}