Xa mode explanation and code implementation of four Seata modes

@ author ： Suddenly

@ Home page ： https://blog.csdn.net/zhuocailing3390

@ Community ： Java Technology stack communication

@ The theme ： Seata One of the four modes XA Mode explanation and code implementation

️ @ Creation time ： 2022 year 06 month 22 Japan

1、 Implementation mechanism

Realization XA Pattern , Need to support XA Transaction database

AT The pattern is Seata Default mode , Meet the two-phase submission agreement ：

• A stage ( Execution phase )：XA Start + perform SQL( The transaction will not be committed )+XA End, Register branch transactions ;XA prepare, Ensure branch status .
• Two stages ( Completion stage )：
  • Submit ： perform XA The branch commit.
  • Roll back ： perform XA The branch rollback.

2、 Advantages and disadvantages

• advantage ：
  • XA In mode , All transactions will wait for each other , achieve Strong consistency The effect of .
• shortcoming ：
  • It will occupy the database lock , Waste of resources , Performance degradation , It needs the support of the database itself XA.

3、 Code implementation

Create two SpringBoot engineering , Respectively storage-service And order-service, Simulation from on order-service New orders in the service , And then call storage-service Service new inventory deduction record ; The core code is as follows , Refer to the end of the text for the complete code github Address ;

In coding mode ,XA Pattern And AT Pattern bring into correspondence with , You only need to change the data source proxy configuration to XA that will do , Revised as follows ：

seata:	
	data-source-proxy-mode: XA

3.1 Create table statement

--  Database name ： seata-xa-demo.sql

--  The order sheet 
CREATE TABLE `tb_order`
(
    `id`    int(11) NOT NULL COMMENT ' Primary key ',
    `count` int(11) NULL DEFAULT 0 COMMENT ' Order quantity ',
    `money` int(11) NULL DEFAULT 0 COMMENT ' amount of money ',
    PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 1 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = COMPACT;


--  An inventory statement 
CREATE TABLE `tb_storage`
(
    `id`       int(11) NOT NULL COMMENT ' Primary key ',
    `order_id` int(11) NOT NULL COMMENT ' Order ID',
    `count`    int(11) NOT NULL DEFAULT 0 COMMENT ' stock ',
    PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 2 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = COMPACT;

Be careful ： If you use a higher version of mysql The drive may appear com.mysql.cj.conf.PropertySet.getBooleanReadableProperty(java.lang.String) abnormal , Need to put mysql Version back to 8.0.11 edition ;

3.2 order-service service

3.2.1 yaml To configure

server:
  port: 8082
spring:
  application:
    name: order-service
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3307/seata-at-demo?useUnicode=true&useSSL=false&characterEncoding=UTF-8&allowMultiQueries=true&serverTimezone=Asia/Shanghai
    username: root
    password: lhzlx
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
        namespace: 64ed9ca7-d705-4655-b4e4-f824e420a12a
        group: test

seata:
  enabled: true
  #  Use XA Pattern 
  data-source-proxy-mode: XA
  application-id: ${
    spring.application.name}
  #  The name of the transaction group , Corresponding service.vgroupMapping.default_tx_group=xxx Configured in default_tx_group
  tx-service-group: default_tx_group
  #  Configure the correspondence between the transaction group and the cluster 
  service:
    vgroup-mapping:
      # default_tx_group Is the name of the transaction Group ,default Name the cluster 
      default_tx_group: default
    disable-global-transaction: false
  registry:
    type: nacos
    nacos:
      application: seata-server
      server-addr: 127.0.0.1:8848
      group: SEATA_GROUP
      namespace: 64ed9ca7-d705-4655-b4e4-f824e420a12a
      username: nacos
      password: nacos
      cluster: default
  config:
    type: nacos
    nacos:
      server-addr: 162.14.115.18:8848
      group: SEATA_GROUP
      namespace: 64ed9ca7-d705-4655-b4e4-f824e420a12a
      username: nacos
      password: nacos
      data-id: seataServer.properties

3.2.2 Service

Upstream services through @GlobalTransactional Annotations enable global transactions , Use storageClient Conduct feign call

@Slf4j
@Service
public class OrderServiceImpl implements OrderService {
    

    @Resource
    private StorageClient storageClient;

    @Resource
    private OrderMapper orderMapper;


    /** *  Create order  * * @param order * @return */
    @Override
    @GlobalTransactional
    public Long create(Order order) {
    
        //  Create order 
        long id = new Random().nextInt(999999999);
        order.setId(id);
        orderMapper.insert(order);
        try {
    
            //  Record inventory information 
            storageClient.deduct(order.getId(), order.getCount());
			//  Simulate anomalies 
            // int a = 1 / 0;
        } catch (FeignException e) {
    
            log.error(" Order failure , reason :{}", e.contentUTF8(), e);
            throw new RuntimeException(e.contentUTF8(), e);
        }
        return order.getId();
    }

}

3.2.3 StorageClient

@FeignClient("storage-service")
public interface StorageClient {
    
    /** *  Deducting the inventory  * * @param orderId * @param count */
    @PostMapping("/storage")
    void deduct(@RequestParam("orderId") Long orderId, @RequestParam("count") Integer count);
}

3.3 storage-service service

3.3.1 yaml To configure

server:
  port: 8081
spring:
  application:
    name: storage-service
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3307/seata-xa-demo?useUnicode=true&useSSL=false&characterEncoding=UTF-8&allowMultiQueries=true&serverTimezone=Asia/Shanghai
    username: root
    password: lhzlx

  cloud:
    nacos:
      discovery:
        server-addr: 162.14.115.18:8848
        namespace: 64ed9ca7-d705-4655-b4e4-f824e420a12a
        group: test
        #  stay dev Environment debug when , You can set the time to be longer 
        #heart-beat-interval: 1000 # Heartbeat interval . The unit is millisecond , Default 5*1000
        heart-beat-timeout: 300000 # Cardiac arrest , No heartbeat , Will set the instance as unhealthy . The unit is millisecond , Default 15*1000
        ip-delete-timeout: 4000000 #Ip Delete timeout , No heartbeat , The instance will be deleted . The unit is millisecond , Default 30*1000


seata:
  enabled: true
  #  Turn on XA Pattern 
  data-source-proxy-mode: XA
  application-id: ${
    spring.application.name}
  #  The name of the transaction group , Corresponding service.vgroupMapping.default_tx_group=xxx Configured in default_tx_group
  tx-service-group: default_tx_group
  #  Configure the correspondence between the transaction group and the cluster 
  service:
    vgroup-mapping:
      # default_tx_group Is the name of the transaction Group ,default Name the cluster 
      default_tx_group: default
    disable-global-transaction: false
  registry:
    type: nacos
    nacos:
      application: seata-server
      server-addr: 127.0.0.1:8848
      group: SEATA_GROUP
      namespace: 64ed9ca7-d705-4655-b4e4-f824e420a12a
      username: nacos
      password: nacos
      cluster: default
  config:
    type: nacos
    nacos:
      server-addr: 162.14.115.18:8848
      group: SEATA_GROUP
      namespace: 64ed9ca7-d705-4655-b4e4-f824e420a12a
      username: nacos
      password: nacos
      data-id: seataServer.properties

3.3.2 StorageService

@Slf4j
@Service
public class StorageServiceImpl implements StorageService {
    

    @Resource
    private StorageMapper storageMapper;

    /** *  Deduct the amount of storage  * * @param orderId * @param count */
    @Override
    public void deduct(Long orderId, int count) {
    
        log.info(" Start recording inventory information ");
        try {
    
            long id = new Random().nextInt(999999999);
            Storage storage = new Storage();
            storage.setId(id);
            storage.setOrderId(orderId);
            storage.setCount(count);

            storageMapper.insert(storage);
			//  Simulate anomalies 
            // int a = 1 / 0;
        } catch (Exception e) {
    
            throw new RuntimeException(" Inventory deduction failed , It may be that the inventory is insufficient ！", e);
        }
        log.info(" Inventory information recorded successfully ");
    }
}

3.4 test

There is no screenshot for demonstration during the test , It only shows the result , You can run code to set exceptions to verify

3.4.1 Downstream service is abnormal

stay order-service The service is normal , stay storage-service Service service Exception thrown in , Observe whether the data is successfully rolled back ; If tb_order And tb_storage There is no data , Indicates that the global transaction is successful ;

3.4.2 The upstream service is abnormal

order-service The service is executing storageClient.deduct() Method to throw an exception , stay storage-service The service is normal , Observe whether the data is successfully rolled back ; If tb_order And tb_storage There is no data , Indicates that the global transaction is successful ;

3.4.3 Strong data consistency verification

XA Patterns and AT The pattern differs in ,XA Is strongly consistent and AT It's ultimate consistency ;

We can complete the upstream service orderMapper.insert(order); Enter the breakpoint immediately after , The test will find that tb_order No data in , Re release breakpoints enable normal program execution , If you look at the database again, you will find tb_order There's data in , It means that strong consistency of data is achieved instead of final consistency ;

4、 Source code address

Seata value AT Pattern code implementation ：《seata-xa-demo》