文章目录
- 16. SpringCloud Alibaba Seata处理分布式事务
- 16.1 分布式事务问题
- 16.2 Seata简介
- 16.2.1 是什么
- 16.2.2 能干嘛
- 16.2.3 去哪下
- 16.2.4 怎么玩
- 16.3 Seata-Server安装
- 16.3.1 官网地址
- 16.3.2 下载版本
- 16.3.3 seata-server-0.9.0.zip解压到指定目录并修改conf目录下的file.conf配置文件
- 16.3.4 mysql5.7数据库新建库seata
- 16.3.5 修改seata-server-0.9.0\seata\conf目录下的registry.conf配置文件
- 16.3.6 启动seata-server
- 16.4 订单/库存/账户业务数据库准备
- 16.4.1 分布式事务业务说明
- 16.4.2 创建业务数据库
- 16.4.3 按照上述3库分别建对应业务表
- 16.4.4 按照上述3库分别建对应的回滚日志表
- 16.4.5 最终效果
- 16.5 订单/库存/账户业务微服务准备
- 16.5.1 新建订单Order-Module
- 16.5.2 新建库存Storage-Module
- 16.5.3 新建账户Account-Module
- 16.6 Test
- 16.6.1 数据库初始情况
- 16.6.2 正常下单
- 16.6.3 超时异常，没加@GlobalTransactional
- 16.6.4 超时异常，添加@GlobalTransactional
- 16.7 补充
- 16.7.1 Seata
- 16.7.2 再看TC/TM/RM三大组件
- 16.7.3 AT模式如何做到对业务的无侵入
- 16.7.4 Debug过程分析
16. SpringCloud Alibaba Seata处理分布式事务
16.1 分布式事务问题
分布式前:
单机单库没这个分布式事务问题,但是随着项目的业务不断增多,微服务与数据库的关系从1：1 -> 1：N -> N：N
分布式后:
单体应用被拆分成微服务应用，原来的三个模块被拆分成三个独立的应用，分别使用三个独立的数据源，
业务操作需要调用三个服务来完成。此时每个服务内部的数据一致性由本地事务来保证，但是全局的数据一致性问题没法保证。
一句话:一次业务操作需要跨多个数据源或需要跨多个系统进行远程调用，就会产生分布式事务问题
16.2 Seata简介
16.2.1 是什么
Seata是一款开源的分布式事务解决方案，致力于在微服务架构下提供高性能和简单易用的分布式事务服务。
官网地址:http://seata.io/zh-cn/
16.2.2 能干嘛
一个典型的分布式事务过程
1.分布式事务处理过程的一ID+三组件模型
- Transaction ID XID: 全局唯一的事务ID
- Transaction Coordinator (TC):事务协调器，维护全局事务的运行状态，负责协调并驱动全局事务的提交或回滚；
- Transaction Manager ™: 控制全局事务的边界，负责开启一个全局事务，并最终发起全局提交或全局回滚的决议；
- Resource Manager (RM): 控制分支事务，负责分支注册、状态汇报，并接收事务协调器的指令，驱动分支（本地）事务的提交和回滚
2.处理过程
- TM 向 TC 申请开启一个全局事务，全局事务创建成功并生成一个全局唯一的 XID；
- XID 在微服务调用链路的上下文中传播；
- RM 向 TC 注册分支事务，将其纳入 XID 对应全局事务的管辖；
- TM 向 TC 发起针对 XID 的全局提交或回滚决议；
- TC 调度 XID 下管辖的全部分支事务完成提交或回滚请求。
16.2.3 去哪下
发布说明: https://github.com/seata/seata/releases
16.2.4 怎么玩
单机版使用==@Transactional==,分布式事务使用==@GlobalTransactional==
SEATA 的分布式交易解决方案
16.3 Seata-Server安装
16.3.1 官网地址
http://seata.io/zh-cn/
16.3.2 下载版本
https://github.com/seata/seata/releases ,本次学习使用的是seata-server-0.9.0.zip
16.3.3 seata-server-0.9.0.zip解压到指定目录并修改conf目录下的file.conf配置文件
- 先备份原始file.conf文件
- 主要修改：自定义事务组名称+事务日志存储模式为db+数据库连接信息
file.conf 主要修改service模块和store模块
service {
###################给事务组起一个名字(啥都行,但是后期要在项目中进行对应)
vgroup_mapping.my_test_tx_group = "fsp_tx_group"
default.grouplist = "127.0.0.1:8091"
enableDegrade = false
disable = false
max.commit.retry.timeout = "-1"
max.rollback.retry.timeout = "-1"
}
## transaction log store
store {
## store mode: file、db
#############修改存储模式为数据库
mode = "db"
## file store
file {
dir = "sessionStore"
# branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
max-branch-session-size = 16384
# globe session size , if exceeded throws exceptions
max-global-session-size = 512
# file buffer size , if exceeded allocate new buffer
file-write-buffer-cache-size = 16384
# when recover batch read size
session.reload.read_size = 100
# async, sync
flush-disk-mode = async
}
## database store
db {
## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
datasource = "dbcp"
## mysql/oracle/h2/oceanbase etc.
db-type = "mysql"
###########修改自己数据库的相关信息
driver-class-name = "com.mysql.jdbc.Driver"
url = "jdbc:mysql://127.0.0.1:3306/seata"
user = "root"
password = "root"
min-conn = 1
max-conn = 3
global.table = "global_table"
branch.table = "branch_table"
lock-table = "lock_table"
query-limit = 100
}
}16.3.4 mysql5.7数据库新建库seata
先建立数据库seata.建表db_store.sql在\seata-server-0.9.0\seata\conf目录里面
16.3.5 修改seata-server-0.9.0\seata\conf目录下的registry.conf配置文件
目的是：指明注册中心为nacos，及修改nacos连接信息
registry {
# file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
type = "nacos"
nacos {
serverAddr = "localhost:8848"
namespace = ""
cluster = "default"
}
16.3.6 启动seata-server
16.4 订单/库存/账户业务数据库准备
以下演示都需要先启动Nacos后启动Seata，保证两个都OK. Seata没启动报错no available server to connect
16.4.1 分布式事务业务说明
主要业务:下订单—>扣库存—>减账户(余额)
这里我们会创建三个服务，一个订单服务，一个库存服务，一个账户服务。
当用户下单时，会在订单服务中创建一个订单，然后通过远程调用库存服务来扣减下单商品的库存，
再通过远程调用账户服务来扣减用户账户里面的余额，最后在订单服务中修改订单状态为已完成。
该操作跨越三个数据库，有两次远程调用，很明显会有分布式事务问题。
16.4.2 创建业务数据库
- seata_order：存储订单的数据库；
- seata_storage：存储库存的数据库；
- seata_account：存储账户信息的数据库。
- 建库SQL
CREATE DATABASE seata_order;
CREATE DATABASE seata_storage;
CREATE DATABASE seata_account;
16.4.3 按照上述3库分别建对应业务表
- seata_order库下建t_order表
- seata_storage库下建t_storage 表
- seata_account库下建t_account 表
- 建表Sql
###########################t_order################################################
CREATE TABLE t_order (
`id` BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
`user_id` BIGINT(11) DEFAULT NULL COMMENT '用户id',
`product_id` BIGINT(11) DEFAULT NULL COMMENT '产品id',
`count` INT(11) DEFAULT NULL COMMENT '数量',
`money` DECIMAL(11,0) DEFAULT NULL COMMENT '金额',
`status` INT(1) DEFAULT NULL COMMENT '订单状态：0：创建中；1：已完结'
) ENGINE=INNODB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;
SELECT * FROM t_order;
###########################t_storage#############################################
CREATE TABLE t_storage (
`id` BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
`product_id` BIGINT(11) DEFAULT NULL COMMENT '产品id',
`total` INT(11) DEFAULT NULL COMMENT '总库存',
`used` INT(11) DEFAULT NULL COMMENT '已用库存',
`residue` INT(11) DEFAULT NULL COMMENT '剩余库存'
) ENGINE=INNODB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
INSERT INTO seata_storage.t_storage(`id`, `product_id`, `total`, `used`, `residue`)
VALUES ('1', '1', '100', '0', '100');
SELECT * FROM t_storage;
###########################t_account###############################################
CREATE TABLE t_account (
`id` BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY COMMENT 'id',
`user_id` BIGINT(11) DEFAULT NULL COMMENT '用户id',
`total` DECIMAL(10,0) DEFAULT NULL COMMENT '总额度',
`used` DECIMAL(10,0) DEFAULT NULL COMMENT '已用余额',
`residue` DECIMAL(10,0) DEFAULT '0' COMMENT '剩余可用额度'
) ENGINE=INNODB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
INSERT INTO seata_account.t_account(`id`, `user_id`, `total`, `used`, `residue`) VALUES ('1', '1', '1000', '0', '1000');
SELECT * FROM t_account;
16.4.4 按照上述3库分别建对应的回滚日志表
- 订单-库存-账户3个库下都需要建各自的回滚日志表
- \seata-server-0.9.0\seata\conf目录下的db_undo_log.sql
-- the table to store seata xid data
-- 0.7.0+ add context
-- you must to init this sql for you business databese. the seata server not need it.
-- 此脚本必须初始化在你当前的业务数据库中，用于AT 模式XID记录。与server端无关（注：业务数据库）
-- 注意此处0.3.0+ 增加唯一索引 ux_undo_log
DROP TABLE `undo_log`;
CREATE TABLE `undo_log` (
`id` BIGINT(20) NOT NULL AUTO_INCREMENT,
`branch_id` BIGINT(20) NOT NULL,
`xid` VARCHAR(100) NOT NULL,
`context` VARCHAR(128) NOT NULL,
`rollback_info` LONGBLOB NOT NULL,
`log_status` INT(11) NOT NULL,
`log_created` DATETIME NOT NULL,
`log_modified` DATETIME NOT NULL,
`ext` VARCHAR(100) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `ux_undo_log` (`xid`,`branch_id`)
) ENGINE=INNODB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
16.4.5 最终效果
16.5 订单/库存/账户业务微服务准备
业务需求:下订单->减库存->扣余额->改(订单)状态
16.5.1 新建订单Order-Module
- 建Module—seata-order-service2001
- POM
<dependencies>
<!--nacos-->
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
<!--seata-->
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-seata</artifactId>
<exclusions>
<!--排除自带的版本-->
<exclusion>
<artifactId>seata-all</artifactId>
<groupId>io.seata</groupId>
</exclusion>
<exclusion>
<groupId>io.seata</groupId>
<artifactId>seata-spring-boot-starter</artifactId>
</exclusion>
<exclusion>
<artifactId>spring-boot-starter</artifactId>
<groupId>org.springframework.boot</groupId>
</exclusion>
</exclusions>
</dependency>
<!--携带上使用的版本-->
<dependency>
<groupId>io.seata</groupId>
<artifactId>seata-all</artifactId>
<version>0.9.0</version>
<exclusions>
<exclusion>
<artifactId>fastjson</artifactId>
<groupId>com.alibaba</groupId>
</exclusion>
</exclusions>
</dependency>
<!--feign-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<!--web-actuator-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<!--mysql-druid-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.10</version>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.0.0</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
</dependencies>
- YML
server:
port: 2001
spring:
application:
name: seata-order-service
cloud:
alibaba:
seata:
#自定义事务组名称需要与seata-server中的对应
tx-service-group: fsp_tx_group
nacos:
discovery:
server-addr: 192.168.174.128:8848
datasource:
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://192.168.174.128:3306/seata_order?useSSL=false
username: root
password: root
feign:
hystrix:
enabled: false
logging:
level:
io:
seata: info
mybatis:
mapperLocations: classpath:mapper/*.xml
configuration:
map-underscore-to-camel-case: true
- file.conf以及registry.conf
file.conf :从seata软件中拷贝出来,然后需要修改的如下所示
.....................
service {
vgroup_mapping.fsp_tx_group = "default" #修改自定义事务组名称
##################修改IP名称为使用的
default.grouplist = "192.168.174.128:8091"
enableDegrade = false
disable = false
max.commit.retry.timeout = "-1"
max.rollback.retry.timeout = "-1"
disableGlobalTransaction = false
}
## transaction log store
store {
## store mode: file、db
#####修改模式为db
mode = "db"
## file store
file {
dir = "sessionStore"
# branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
max-branch-session-size = 16384
# globe session size , if exceeded throws exceptions
max-global-session-size = 512
# file buffer size , if exceeded allocate new buffer
file-write-buffer-cache-size = 16384
# when recover batch read size
session.reload.read_size = 100
# async, sync
flush-disk-mode = async
}
## database store
db {
## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
datasource = "dbcp"
## mysql/oracle/h2/oceanbase etc.
db-type = "mysql"
#############修改数据库的相关信息
driver-class-name = "com.mysql.jdbc.Driver"
url = "jdbc:mysql://192.168.174.128:3306/seata"
user = "root"
password = "root"
min-conn = 1
max-conn = 3
global.table = "global_table"
branch.table = "branch_table"
lock-table = "lock_table"
query-limit = 100
}
}
........
registry.conf:从seata软件中拷贝出来,然后需要修改的如下所示
registry {
# file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
###################### 类型修改为nacos
type = "nacos"
#############修改nacos的相关信息
nacos {
serverAddr = "192.168.174.128:8848"
namespace = ""
cluster = "default"
}
....
}
config {
# file、nacos 、apollo、zk、consul、etcd3
type = "file"
nacos {
#############进行修改
serverAddr = "192.168.174.128"
namespace = ""
}
....
}
.....
- domain
CommonResult类
@Data
@AllArgsConstructor
@NoArgsConstructor
public class CommonResult<T>
{
private Integer code;
private String message;
private T data;
public CommonResult(Integer code, String message)
{
this(code,message,null);
}
}
Order类
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Order
{
private Long id;
private Long userId;
private Long productId;
private Integer count;
private BigDecimal money;
/**
* 订单状态：0：创建中；1：已完结
*/
private Integer status;
}
- Dao接口及实现
OrderDao接口
@Mapper
public interface OrderDao {
/**
* 创建订单
*/
void create(Order order);
/**
* 修改订单金额
*/
void update(@Param("userId") Long userId, @Param("status") Integer status);
}
resources文件夹下新建mapper文件夹后添加
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.rg.cloudalibaba.dao.OrderDao">
<!--便于后期进行扩展-->
<resultMap id="BaseResultMap" type="com.rg.cloudalibaba.domain.Order">
<id column="id" property="id" jdbcType="BIGINT"/>
<result column="user_id" property="userId" jdbcType="BIGINT"/>
<result column="product_id" property="productId" jdbcType="BIGINT"/>
<result column="count" property="count" jdbcType="INTEGER"/>
<result column="money" property="money" jdbcType="DECIMAL"/>
<result column="status" property="status" jdbcType="INTEGER"/>
</resultMap>
<insert id="create">
INSERT INTO t_order(id,user_id,product_id,`count`,money,`status`)
VALUES(NULL,#{user_id},#{product_id},#{count},#{money},0);
</insert>
<update id="update">
UPDATE `t_order`
SET `status` = 1
WHERE user_id = #{user_id}
AND `status` = #{status};
</update>
</mapper>
- Service接口及实现
OrderService
public interface OrderService {
/**
* 创建订单
*/
void create(Order order);
}
OrderServiceImpl
@Service
@Slf4j
public class OrderServiceImpl implements OrderService {
/**
* 创建订单->调用库存服务扣减库存->调用账户服务扣减账户余额->修改订单状态
* 简单说：
* 下订单->减库存->减余额->改状态
*/
@Resource
private OrderDao orderDao;
@Resource
private AccountService accountService;
@Resource
private StorageService storageService;
//@GlobalTransactional(name = "fsp-create-order",rollbackFor = Exception.class)
public void create(Order order){
log.info("--------------->下单开始");
orderDao.create(order);
//远程调用库存服务扣减库存
log.info("----------------->order-service中扣减库存开始");
storageService.decrease(order.getProductId(), order.getCount());
log.info("----------------->order-service中扣减库存结束");
//远程调用账户服务扣减余额
log.info("----------------->order-service中扣减余额开始");
accountService.decrease(order.getUserId(), order.getMoney());
log.info("----------------->order-service中扣减余额结束");
//修改订单状态
log.info("----------------->order-service中修改订单状态开始");
orderDao.update(order.getUserId(), 0);
log.info("----------------->order-service中修改订单状态结束");
log.info("--------------->下单结束");
}
}
StorageService
@FeignClient(value = "seata-storage-service")
public interface StorageService {
/**
* 扣减库存
* @param productId
* @param count
* @return
*/
@PostMapping(value = "/storage/decrease")
CommonResult decrease(@RequestParam("productId") Long productId, @RequestParam("count") Integer count);
}
AccountService
@FeignClient(value = "seata-account-service")
public interface AccountService {
@PostMapping("/account/decrease")
CommonResult decrease(@RequestParam("userId") Long userId, @RequestParam("money") BigDecimal money);
}
- controller
@RestController
public class OrderController {
@Autowired
private OrderService orderService;
/**
* 创建订单
*/
@GetMapping("/order/create")
public CommonResult create( Order order) {
orderService.create(order);
return new CommonResult(200, "订单创建成功!");
}
}
- config
DataSourceProxyConfig:自定义数据源配置类
@Configuration
public class DataSourceProxyConfig {
@Value("${mybatis.mapperLocations}")
private String mapperLocations;
@Bean
@ConfigurationProperties(prefix = "spring.datasource")
public DataSource druidDataSource(){
return new DruidDataSource();
}
@Bean
public DataSourceProxy dataSourceProxy(DataSource dataSource) {
return new DataSourceProxy(dataSource);
}
@Bean
public SqlSessionFactory sqlSessionFactoryBean(DataSourceProxy dataSourceProxy) throws Exception {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSourceProxy);
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(mapperLocations));
sqlSessionFactoryBean.setTransactionFactory(new SpringManagedTransactionFactory());
return sqlSessionFactoryBean.getObject();
}
}
MyBatisConfig:数据源配置类
@Configuration
@MapperScan({"com.rg.cloudalibaba.dao"})
public class MyBatisConfig {
}
- 主启动
@EnableDiscoveryClient
@EnableFeignClients
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)//取消数据源的自动创建
public class SeataOrderMainApp2001 {
public static void main(String[] args) {
SpringApplication.run(SeataOrderMainApp2001.class, args);
}
}
16.5.2 新建库存Storage-Module
- 建Module—seata-storage-service2002
- POM—同order2001
- YML—同order2001,只是服务name以及连接的DB需要切换下
- file.conf和registry.conf—同order2001
- domain
CommonResult—同order2001
Storage类
@Data
public class Storage {
private Long id;
//产品id
private Long productId;
//总库存
private Integer total;
//已用库存
private Integer used;
//剩余库存
private Integer residue;
}
- Dao接口及实现
StorageDao
@Mapper
public interface StorageDao {
/**
* 扣减库存
*/
void decrease(@Param("productId") Long productId, @Param("count") Integer count);
}
resources文件夹下新建mapper文件夹后添加StorageMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.rg.cloudalibaba.dao.StorageDao">
<resultMap id="BaseResultMap" type="com.rg.cloudalibaba.domain.Storage">
<id column="id" property="id" jdbcType="BIGINT"/>
<result column="product_id" property="productId" jdbcType="BIGINT"/>
<result column="total" property="total" jdbcType="INTEGER"/>
<result column="used" property="used" jdbcType="INTEGER"/>
<result column="residue" property="residue" jdbcType="INTEGER"/>
</resultMap>
<update id="decrease">
UPDATE t_storage
SET used = used+#{count},
residue = residue - #{count}
WHERE product_id = #{product_id};
</update>
</mapper>
- Service接口及实现
StorageService类
public interface StorageService {
/**
* 扣减库存
*/
void decrease(Long productId, Integer count);
}
StorageServiceImpl类
@Service
@Slf4j
public class StorageServiceImpl implements StorageService {
@Autowired
private StorageDao storageDao;
@Override
public void decrease(Long productId, Integer count) {
log.info("------------------------->storage-service中扣减库存开始");
storageDao.decrease(productId,count);
log.info("------------------------->storage-service中扣减库存结束");
}
}
- controller
@RestController
public class StorageController {
@Autowired
private StorageService storageService;
@RequestMapping("/storage/decrease")
public CommonResult decrease(Long productId,Integer count){
storageService.decrease(productId,count);
return new CommonResult(200, "扣减库存成功!");
}
}
- Config—同order2001
- 主启动
@EnableDiscoveryClient
@EnableFeignClients
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)//取消数据源的自动创建
public class SeataStorageMainApp2002 {
public static void main(String[] args) {
SpringApplication.run(SeataStorageMainApp2002.class, args);
}
}
16.5.3 新建账户Account-Module
- 建Module—seata-account-service2003
- POM—同order2001
- YML—同order2001,只是服务name以及连接的DB需要切换下
- file.conf和registry.conf—同order2001
- domain
CommonResult—同order2001
Account类
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Account {
private Long id;
//用户id
private Long userId;
//总额度
private BigDecimal total;
//已用额度
private BigDecimal used;
//剩余额度
private BigDecimal residue;
}
- Dao接口及实现
AccountDao
@Mapper
public interface AccountDao {
/**
* 扣减账户余额
*/
void decrease(@Param("userId") Long userId, @Param("money") BigDecimal money);
}
resources文件夹下新建mapper文件夹后添加AccountMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.rg.cloudalibaba.dao.AccountDao">
<update id="decrease">
UPDATE t_account
SET residue = residue - #{money},
used = used+#{money}
WHERE user_id = #{user_id};
</update>
</mapper>
- Service接口及实现
AccountService
public interface AccountService {
/**
* 扣减账户余额
* @param userId 用户id
* @param money 金额
*/
void decrease(@RequestParam("userId") Long userId, @RequestParam("money") BigDecimal money);
}
AccountServiceImpl
@Service
@Slf4j
public class AccountServiceImpl implements AccountService {
@Autowired
private AccountDao accountDao;
@Override
public void decrease(Long userId, BigDecimal money) {
log.info("-------------------account-service扣减账号余额开始");
accountDao.decrease(userId,money);
log.info("-------------------account-service扣减账号余额结束");
}
}
- controller
@RestController
public class AccountController {
@Autowired
private AccountService accountService;
@RequestMapping("/account/decrease")
CommonResult decrease(@RequestParam("userId") Long userId, @RequestParam("money") BigDecimal money){
accountService.decrease(userId,money);
return new CommonResult(200, "扣减账号余额成功!");
}
}
- Config配置—同order2001
- 主启动
@EnableDiscoveryClient
@EnableFeignClients
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)//取消数据源的自动创建
public class SeataAccountMainApp2003 {
public static void main(String[] args) {
SpringApplication.run(SeataAccountMainApp2003.class, args);
}
}
16.6 Test
16.6.1 数据库初始情况
SELECT * FROM seata_order.t_order
SELECT * FROM seata_storage.t_storage
SELECT * FROM seata_account.t_account;
16.6.2 正常下单
访问: http://localhost:2001/order/create?userId=1&productId=1&count=10&money=100
数据库情况:
16.6.3 超时异常，没加@GlobalTransactional
AccountServiceImpl添加超时
数据库情况:
故障情况:
当库存和账户金额扣减后，订单状态并没有设置为已经完成，没有从零改为1.而且由于feign的重试机制，账户余额还有可能被多次扣减
16.6.4 超时异常，添加@GlobalTransactional
AccountServiceImpl添加超时
OrderServiceImpl添加@GlobalTransactional
结果:下单后数据库数据并没有任何改变,记录都添加不进来
16.7 补充
16.7.1 Seata
- 2019年1月份蚂蚁金服和阿里巴巴共同开源的分布式事务解决方案
- Simple Extensible Autonomous Transaction Architecture，简单可扩展自治事务框架
- 2020起始，参加工作后用1.0以后的版本
16.7.2 再看TC/TM/RM三大组件
省略…
16.7.3 AT模式如何做到对业务的无侵入
- 是什么
- 一阶段加载
在一阶段，Seata 会拦截“业务 SQL”，
1 解析 SQL 语义，找到“业务 SQL”要更新的业务数据，在业务数据被更新前，将其保存成“before image”，
2 执行“业务 SQL”更新业务数据，在业务数据更新之后，
3 其保存成“after image”，最后生成行锁。
以上操作全部在一个数据库事务内完成，这样保证了一阶段操作的原子性。
- 二阶段提交
二阶段是顺利提交的情况
因为“业务 SQL”在一阶段已经提交至数据库，所以Seata框架只需将一阶段保存的快照数据和行锁删掉，完成数据清理即可。
- 二阶段回滚
二阶段如果是回滚的话，Seata 就需要回滚一阶段已经执行的“业务 SQL”，还原业务数据。
回滚方式便是用“before image”还原业务数据；但在还原前要首先要校验脏写，对比“数据库当前业务数据”和 “after image”，如果两份数据完全一致就说明没有脏写，可以还原业务数据，如果不一致就说明有脏写，出现脏写就需要转人工处理。
16.7.4 Debug过程分析
