Seata
大约 17 分钟
Seata
CloudAlibaba之Seata
问题引出
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，但是，关系型数据库提供的能力是基于单机事务的，一旦遇到分布式事务场景，就需要通过更多其他技术手段来解决问题。
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。此时每个服务自己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。
结论
迫切希望提供一种分布式事务框架，解决微服务架构下的分布式事务问题
简介
是什么？
Simple Extensible Autonomous Transaction Architecture：Seata
Apache Seata(incubating) 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。
能干嘛？
解决分布式事务
去哪下？
官网：Apache Seata
怎么玩？
本地@Transactional
全局@GlobalTransactional
Seata的分布式交易解决方案
3c515c833d82540654e36ad43b6aeb93.png
工作流程简介
1、纵观整个分布式事务的管理，就是全局事务ID的传递和变更,要让开发者无感知。
2、seata对分布式事务的协调和控制就是1+3
一个XID
XID是全局事务的唯一标识，它可以在服务的调用链路中传递，绑定到服务的事务上下文中。
官网版3个概念(TC—>TM—>RM)
个别版3个概念
- TC (Transaction Coordinator) - 事务协调器
- 就是seata，负责维护全局事务和分支事务的状态。驱动全局事务提交或回滚。
- TM (Transaction Manager) - 事务管理器
- 标注全局@GlobalTransactional启动入口动作的微服务模块（比如订单模块），它是事务的发起者，负责定义全局事务的范围，并根据TC维护的全局事务和分支事务状态，做出开始事务、提交事务、回滚事务的决议。
- RM (Resource Manager) - 资源管理器
- 就是mysql数据库本身，可以是多个RM，负责管理分支事务上的资源，向TC注册分支事，汇报分支事务状态，驱动分支事务的提交或回滚。
- TC (Transaction Coordinator) - 事务协调器
3、分布式事务的执行流程———小总结
三个组件相互协作，TC以Seata 服务器(Server)形式独立部署，TM和RM则是以Seata Client的形式集成在微服务中运行，
流程如下：
4、各事务模式
我们以AT模式进行学习
Seata-Server2.0.0安装
下载地址
配置参数参考
https://seata.apache.org/zh-cn/docs/user/configuration
新手部署指南
步骤
建库
1、新建数据库Seata
CREATE DATABASE seata;
USE seata;
SQL建表地址
https://github.com/seata/seata/blob/develop/script/server/db/mysql.sql
SQL脚本
CREATE TABLE IF NOT EXISTS `global_table`
(
`xid` VARCHAR(128) NOT NULL,
`transaction_id` BIGINT,
`status` TINYINT NOT NULL,
`application_id` VARCHAR(32),
`transaction_service_group` VARCHAR(32),
`transaction_name` VARCHAR(128),
`timeout` INT,
`begin_time` BIGINT,
`application_data` VARCHAR(2000),
`gmt_create` DATETIME,
`gmt_modified` DATETIME,
PRIMARY KEY (`xid`),
KEY `idx_status_gmt_modified` (`status` , `gmt_modified`),
KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDB
DEFAULT CHARSET = utf8mb4;
-- the table to store BranchSession data
CREATE TABLE IF NOT EXISTS `branch_table`
(
`branch_id` BIGINT NOT NULL,
`xid` VARCHAR(128) NOT NULL,
`transaction_id` BIGINT,
`resource_group_id` VARCHAR(32),
`resource_id` VARCHAR(256),
`branch_type` VARCHAR(8),
`status` TINYINT,
`client_id` VARCHAR(64),
`application_data` VARCHAR(2000),
`gmt_create` DATETIME(6),
`gmt_modified` DATETIME(6),
PRIMARY KEY (`branch_id`),
KEY `idx_xid` (`xid`)
) ENGINE = InnoDB
DEFAULT CHARSET = utf8mb4;
-- the table to store lock data
CREATE TABLE IF NOT EXISTS `lock_table`
(
`row_key` VARCHAR(128) NOT NULL,
`xid` VARCHAR(128),
`transaction_id` BIGINT,
`branch_id` BIGINT NOT NULL,
`resource_id` VARCHAR(256),
`table_name` VARCHAR(32),
`pk` VARCHAR(36),
`status` TINYINT NOT NULL DEFAULT '0' COMMENT '0:locked ,1:rollbacking',
`gmt_create` DATETIME,
`gmt_modified` DATETIME,
PRIMARY KEY (`row_key`),
KEY `idx_status` (`status`),
KEY `idx_branch_id` (`branch_id`),
KEY `idx_xid` (`xid`)
) ENGINE = InnoDB
DEFAULT CHARSET = utf8mb4;
CREATE TABLE IF NOT EXISTS `distributed_lock`
(
`lock_key` CHAR(20) NOT NULL,
`lock_value` VARCHAR(20) NOT NULL,
`expire` BIGINT,
primary key (`lock_key`)
) ENGINE = InnoDB
DEFAULT CHARSET = utf8mb4;
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('AsyncCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryRollbacking', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('TxTimeoutCheck', ' ', 0);
结果
改配置
修改seata-server-2.O.O\conf\appIication.yml配置，记得先备份
application.yml定稿版(一般使用里面的配置足矣)
# Copyright 1999-2019 Seata.io Group.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Seata控制台访问端口
server:
port: 7091
spring:
application:
name: seata-server
logging:
config: classpath:logback-spring.xml
file:
path: ${log.home:${user.home}/logs/seata}
extend:
logstash-appender:
destination: 127.0.0.1:4560
kafka-appender:
bootstrap-servers: 127.0.0.1:9092
topic: logback_to_logstash
# Seata控制台登录用户密码
console:
user:
username: seata
password: seata
seata:
config:
type: nacos
nacos:
server-addr: 127.0.0.1:8848
namespace:
group: SEATA_GROUP #后续自己在nacos里面新建,不想新建SEATA_GROUP，就写DEFAULT_GROUP
username: nacos
password: nacos
registry:
type: nacos
nacos:
application: seata-server
server-addr: 127.0.0.1:8848
group: SEATA_GROUP #后续自己在nacos里面新建,不想新建SEATA_GROUP，就写DEFAULT_GROUP
namespace:
cluster: default
username: nacos
password: nacos
store:
mode: db
db:
datasource: druid
db-type: mysql
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/seata?characterEncoding=utf8&useSSL=false&serverTimezone=GMT%2B8&rewriteBatchedStatements=true&allowPublicKeyRetrieval=true
user: root
password: '020708'
min-conn: 10
max-conn: 100
global-table: global_table
branch-table: branch_table
lock-table: lock_table
distributed-lock-table: distributed_lock
query-limit: 1000
max-wait: 5000
# server:
# service-port: 8091 #If not configured, the default is '${server.port} + 1000'
security:
secretKey: SeataSecretKey0c382ef121d778043159209298fd40bf3850a017
tokenValidityInMilliseconds: 1800000
ignore:
urls: /,/**/*.css,/**/*.js,/**/*.html,/**/*.map,/**/*.svg,/**/*.png,/**/*.jpeg,/**/*.ico,/api/v1/auth/login,/metadata/v1/**
启动
先启动Nacos
再启动seata-server.bat
访问http://127.0.0.1:7091
再看Nacos，可以看到Seata已经注册到Nacos中了
案例实战
案例实战说明：
即将准备三个微服务模块：订单模块、库存模块、账户余额模块
主要说明演示：使用分布式事务Seata前后的区别说明：不使用分布式事务有什么影响，使用分布式事务可以解决哪些痛点。
数据库和表准备
注意：以下演示Nacos和Seata都要先保证启动ok
案例业务说明：
这里我们创建三个服务，一个订单服务，一个库存服务，一个账户服务。-------最下面还有笔记
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。
下订单 → 减库存 → 扣余额 → 改(订单)状态
建库
针对3个微服务建各自的数据库
SQL脚本
CREATE DATABASE seata_order;
CREATE DATABASE seata_storage;
CREATE DATABASE seata_account;
建表
针对这3个库，各自需要建对应的undo_log回滚日志表
SQL脚本
CREATE TABLE IF NOT EXISTS `undo_log`
(
`branch_id` BIGINT NOT NULL COMMENT 'branch transaction id',
`xid` VARCHAR(128) NOT NULL COMMENT 'global transaction id',
`context` VARCHAR(128) NOT NULL COMMENT 'undo_log context,such as serialization',
`rollback_info` LONGBLOB NOT NULL COMMENT 'rollback info',
`log_status` INT(11) NOT NULL COMMENT '0:normal status,1:defense status',
`log_created` DATETIME(6) NOT NULL COMMENT 'create datetime',
`log_modified` DATETIME(6) NOT NULL COMMENT 'modify datetime',
UNIQUE KEY `ux_undo_log` (`xid`, `branch_id`)
) ENGINE = InnoDB AUTO_INCREMENT = 1 DEFAULT CHARSET = utf8mb4 COMMENT ='AT transaction mode undo table';
ALTER TABLE `undo_log` ADD INDEX `ix_log_created` (`log_created`);
结果
针对这3个库，各自需要建对应的业务表
seata_order库建t_order表
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=1 DEFAULT CHARSET=utf8;
SELECT * FROM t_order;
seata_account建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 '已用账户余额',
`residue` DECIMAL(10,0) DEFAULT '0' COMMENT '剩余可用额度'
)ENGINE=INNODB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
INSERT INTO t_account(`id`,`user_id`,`total`,`used`,`residue`)VALUES('1','1','1000','0','1000');
SELECT * FROM t_account;
seata_storage建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=1 DEFAULT CHARSET=utf8;
INSERT INTO t_storage(`id`,`product_id`,`total`,`used`,`residue`)VALUES('1','1','100','0','100');
SELECT * FROM t_storage;
最终效果
编码落地实现
业务需求：下订单——>减库存——>扣余额——>改订单状态
创建openfeign需要远程调用的一些接口方法
seata-account-service远程接口
/**
* @Author: @weixueshi
* @Create: 2024/4/15 - 13:07
* @Version: v1.0
*/
@FeignClient(value = "seata-account-service")
public interface AccountFeignApi
{
/**
* 扣减账户余额
*/
@PostMapping("/account/decrease")
ResultData decrease(@RequestParam("userId") Long userId, @RequestParam("money") Long money);
}
seata-storage-service远程接口
/**
* @Author: @weixueshi
* @Create: 2024/4/15 - 13:07
* @Version: v1.0
*/
@FeignClient(value = "seata-storage-service")
public interface StorageFeignApi
{
/**
* 扣减库存
*/
@PostMapping(value = "/storage/decrease")
ResultData decrease(@RequestParam("productId") Long productId, @RequestParam("count") Integer count);
}
新建订单Order微服务
建Model
- seata-order-service2001
改pom
<properties> <maven.compiler.source>17</maven.compiler.source> <maven.compiler.target>17</maven.compiler.target> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <!--自定义--> <dependency> <groupId>org.cloud</groupId> <artifactId>cloud-commons</artifactId> <version>1.0-SNAPSHOT</version> </dependency> <!--自定义openfeign服务--> <dependency> <groupId>org.cloud</groupId> <artifactId>cloudAlibaba-openfeign-consumer</artifactId> <version>1.0-SNAPSHOT</version> </dependency> <!--alibaba-seata--> <dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-seata</artifactId> </dependency> <!--openfeign--> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency> <!--loadbalancer--> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-loadbalancer</artifactId> </dependency> <!--nacos--> <dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId> </dependency> <!--SpringBoot通用依赖模块--> <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> <!--SpringBoot集成druid连接池--> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> </dependency> <!--mybatis-plus和springboot整合--> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-spring-boot3-starter</artifactId> </dependency> <!--Mysql数据库驱动8 --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <!--persistence--> <dependency> <groupId>javax.persistence</groupId> <artifactId>persistence-api</artifactId> </dependency> <!--hutool--> <dependency> <groupId>cn.hutool</groupId> <artifactId>hutool-all</artifactId> </dependency> <!-- fastjson2 --> <dependency> <groupId>com.alibaba.fastjson2</groupId> <artifactId>fastjson2</artifactId> </dependency> <!--lombok--> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.18.28</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build>写yml
server: port: 2001 spring: application: name: seata-order-service cloud: nacos: discovery: server-addr: localhost:8848 #Nacos服务注册中心地址 # ==========applicationName + druid-mysql8 driver=================== datasource: type: com.alibaba.druid.pool.DruidDataSource driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/seata_order?characterEncoding=utf8&useSSL=false&serverTimezone=GMT%2B8&rewriteBatchedStatements=true&allowPublicKeyRetrieval=true username: root password: '020708' # ========================mybatis=================== mybatis: mapper-locations: classpath:mapper/*.xml type-aliases-package: org.cloud.entity configuration: map-underscore-to-camel-case: true # ========================seata=================== seata: registry: type: nacos nacos: server-addr: 127.0.0.1:8848 namespace: "" group: SEATA_GROUP application: seata-server tx-service-group: default_tx_group # 事务组，由它获得TC服务的集群名称 service: vgroup-mapping: # 点击源码分析 default_tx_group: default # 事务组与TC服务集群的映射关系 data-source-proxy-mode: AT logging: level: io: seata: info启动类
@SpringBootApplication @MapperScan("org.cloud.mapper") @EnableDiscoveryClient //服务注册和发现 @EnableFeignClients public class SeataOrderServiceApp { public static void main( String[] args ) { SpringApplication.run(SeataOrderServiceApp.class,args); } }业务类
这里省略了mapper等哪些创建
OrderController
@RestController
@RequestMapping("/order")
public class OrderController {
@Resource
private IOrderService orderService;
/**
* 创建订单
*/
@GetMapping("/order/create")
public ResultData create(Order order)
{
orderService.create(order);
return ResultData.success(order);
}
}
OrderServiceImpl
/**
* @author author
* @since 2024-04-15
* 下订单->减库存->扣余额->改(订单)状态
*/
@Slf4j
@Service
public class OrderServiceImpl extends ServiceImpl<OrderMapper, Order> implements IOrderService {
@Resource
private OrderMapper orderMapper;
/**
* 订单微服务通过OpenFeign去调用库存微服务
*/
@Resource
private StorageFeignApi storageFeignApi;
/**
* 订单微服务通过OpenFeign去调用账户微服务
*/
@Resource
private AccountFeignApi accountFeignApi;
@Override
// @GlobalTransactional(name = "swx-create-order",rollbackFor = Exception.class)
public void create(Order order) {
//xid检查
String xid = RootContext.getXID();
//1. 新建订单
log.info("==================>开始新建订单"+"\t"+"xid_order:" +xid);
//订单状态status：0：创建中；1：已完结
order.setStatus(0);
int result = orderMapper.insert(order);
//插入订单成功后获得插入mysql的实体对象
Order orderFromDB = null;
if(result > 0)
{
QueryWrapper<Order> wrapper = new QueryWrapper<>();
wrapper.eq("status", order.getStatus());
orderFromDB = orderMapper.selectOne(wrapper);
//orderFromDB = orderMapper.selectByPrimaryKey(order.getId());
log.info("-------> 新建订单成功，orderFromDB info: "+orderFromDB);
System.out.println();
//2. 扣减库存
log.info("-------> 订单微服务开始调用Storage库存，做扣减count");
storageFeignApi.decrease(orderFromDB.getProductId(), orderFromDB.getCount());
log.info("-------> 订单微服务结束调用Storage库存，做扣减完成");
System.out.println();
//3. 扣减账号余额
log.info("-------> 订单微服务开始调用Account账号，做扣减money");
accountFeignApi.decrease(orderFromDB.getUserId(), orderFromDB.getMoney());
log.info("-------> 订单微服务结束调用Account账号，做扣减完成");
System.out.println();
//4. 修改订单状态
//订单状态status：0：创建中；1：已完结
log.info("-------> 修改订单状态");
orderFromDB.setStatus(1);
int updateResult = baseMapper.updateById(orderFromDB);
log.info("-------> 修改订单状态完成"+"\t"+updateResult);
log.info("-------> orderFromDB info: "+orderFromDB);
}
System.out.println();
log.info("==================>结束新建订单"+"\t"+"xid_order:" +xid);
}
}
新建库存storage微服务
建Model
- seata-storage-service2002
改pom
<properties> <maven.compiler.source>17</maven.compiler.source> <maven.compiler.target>17</maven.compiler.target> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <!--自定义--> <dependency> <groupId>org.cloud</groupId> <artifactId>cloud-commons</artifactId> <version>1.0-SNAPSHOT</version> </dependency> <!--openfeign--> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency> <!--loadbalancer--> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-loadbalancer</artifactId> </dependency> <!--alibaba-seata--> <dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-seata</artifactId> </dependency> <!--nacos--> <dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId> </dependency> <!--SpringBoot通用依赖模块--> <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> <!--SpringBoot集成druid连接池--> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> </dependency> <!--mybatis-plus和springboot整合--> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-spring-boot3-starter</artifactId> </dependency> <!--Mysql数据库驱动8 --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <!--persistence--> <dependency> <groupId>javax.persistence</groupId> <artifactId>persistence-api</artifactId> </dependency> <!--hutool--> <dependency> <groupId>cn.hutool</groupId> <artifactId>hutool-all</artifactId> </dependency> <!-- fastjson2 --> <dependency> <groupId>com.alibaba.fastjson2</groupId> <artifactId>fastjson2</artifactId> </dependency> <!--lombok--> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.18.28</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build>写yml
server: port: 2002 spring: application: name: seata-storage-service cloud: nacos: discovery: server-addr: localhost:8848 #Nacos服务注册中心地址 # ==========applicationName + druid-mysql8 driver=================== datasource: type: com.alibaba.druid.pool.DruidDataSource driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/seata_storage?characterEncoding=utf8&useSSL=false&serverTimezone=GMT%2B8&rewriteBatchedStatements=true&allowPublicKeyRetrieval=true username: root password: '020708' # ========================mybatis=================== mybatis: mapper-locations: classpath:mapper/*.xml type-aliases-package: org.cloud.entity configuration: map-underscore-to-camel-case: true # ========================seata=================== seata: registry: type: nacos nacos: server-addr: 127.0.0.1:8848 namespace: "" group: SEATA_GROUP application: seata-server tx-service-group: default_tx_group # 事务组，由它获得TC服务的集群名称 service: vgroup-mapping: default_tx_group: default # 事务组与TC服务集群的映射关系 data-source-proxy-mode: AT logging: level: io: seata: info启动类
@SpringBootApplication @MapperScan("org.cloud.mapper") @EnableDiscoveryClient @EnableFeignClients public class SeataStorageServiceapp { public static void main( String[] args ) { System.out.println( "Hello World!" ); } }业务类
StorageController
@RestController
@RequestMapping("/storage")
public class StorageController {
@Resource
private IStorageService storageService;
/**
* 扣减库存
*/
@RequestMapping("/decrease")
public ResultData decrease(Long productId, Integer count) {
storageService.decrease(productId, count);
return ResultData.success("扣减库存成功!");
}
}
StorageServiceImpl
@Slf4j
@Service
public class StorageServiceImpl extends ServiceImpl<StorageMapper, Storage> implements IStorageService {
@Resource
private StorageMapper storageMapper;
/**
* 扣减库存
*/
@Override
public void decrease(Long productId, Integer count) {
log.info("------->storage-service中扣减库存开始");
storageMapper.decrease(productId,count);
log.info("------->storage-service中扣减库存结束");
}
}
StorageMapper
<?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="org.cloud.mapper.StorageMapper">
<resultMap id="BaseResultMap" type="org.cloud.model.entity.Storage">
<id column="id" jdbcType="BIGINT" property="id" />
<result column="product_id" jdbcType="BIGINT" property="productId" />
<result column="total" jdbcType="INTEGER" property="total" />
<result column="used" jdbcType="INTEGER" property="used" />
<result column="residue" jdbcType="INTEGER" property="residue" />
</resultMap>
<update id="decrease">
UPDATE
t_storage
SET
used = used + #{count},
residue = residue - #{count}
WHERE product_id = #{productId}
</update>
</mapper>
新建账户Account微服务
建Model
- seata-account-service2003
改pom
<properties> <maven.compiler.source>17</maven.compiler.source> <maven.compiler.target>17</maven.compiler.target> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <!--自定义--> <dependency> <groupId>org.cloud</groupId> <artifactId>cloud-commons</artifactId> <version>1.0-SNAPSHOT</version> </dependency> <!--openfeign--> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency> <!--loadbalancer--> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-loadbalancer</artifactId> </dependency> <!--alibaba-seata--> <dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-seata</artifactId> </dependency> <!--nacos--> <dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId> </dependency> <!--SpringBoot通用依赖模块--> <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> <!--SpringBoot集成druid连接池--> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> </dependency> <!--mybatis-plus和springboot整合--> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-spring-boot3-starter</artifactId> </dependency> <!--Mysql数据库驱动8 --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <!--persistence--> <dependency> <groupId>javax.persistence</groupId> <artifactId>persistence-api</artifactId> </dependency> <!--hutool--> <dependency> <groupId>cn.hutool</groupId> <artifactId>hutool-all</artifactId> </dependency> <!-- fastjson2 --> <dependency> <groupId>com.alibaba.fastjson2</groupId> <artifactId>fastjson2</artifactId> </dependency> <!--lombok--> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.18.28</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build>写yml
server: port: 2003 spring: application: name: seata-account-service cloud: nacos: discovery: server-addr: localhost:8848 #Nacos服务注册中心地址 # ==========applicationName + druid-mysql8 driver=================== datasource: type: com.alibaba.druid.pool.DruidDataSource driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/seata_account?characterEncoding=utf8&useSSL=false&serverTimezone=GMT%2B8&rewriteBatchedStatements=true&allowPublicKeyRetrieval=true username: root password: '020708' # ========================mybatis=================== mybatis: mapper-locations: classpath:mapper/*.xml type-aliases-package: org.cloud.entity configuration: map-underscore-to-camel-case: true # ========================seata=================== seata: registry: type: nacos nacos: server-addr: 127.0.0.1:8848 namespace: "" group: SEATA_GROUP application: seata-server tx-service-group: default_tx_group # 事务组，由它获得TC服务的集群名称 service: vgroup-mapping: default_tx_group: default # 事务组与TC服务集群的映射关系 data-source-proxy-mode: AT logging: level: io: seata: info启动类
@SpringBootApplication @MapperScan("org.cloud.mapper") @EnableDiscoveryClient @EnableFeignClients public class SeataAccountServiceApp { public static void main( String[] args ) { SpringApplication.run(SeataAccountServiceApp.class,args); } }业务类
AccountController
@RestController
@RequestMapping("/account")
public class AccountController {
@Resource
private IAccountService accountService;
/**
* 扣减账户余额
*/
@RequestMapping("/decrease")
public ResultData decrease(@RequestParam("userId") Long userId, @RequestParam("money") Long money){
accountService.decrease(userId,money);
return ResultData.success("扣减账户余额成功！");
}
}
AccountServiceImpl
@Slf4j
@Service
public class AccountServiceImpl extends ServiceImpl<AccountMapper, Account> implements IAccountService {
@Resource
AccountMapper accountMapper;
/**
* 扣减账户余额
*/
@Override
public void decrease(Long userId, Long money) {
log.info("------->account-service中扣减账户余额开始");
accountMapper.decrease(userId,money);
//myTimeOut();
//int age = 10/0;
log.info("------->account-service中扣减账户余额结束");
}
/**
* 模拟超时异常，全局事务回滚
*/
private static void myTimeOut()
{
try { TimeUnit.SECONDS.sleep(65); } catch (InterruptedException e) { e.printStackTrace(); }
}
}
AccountMapper
<?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="org.cloud.mapper.AccountMapper">
<resultMap id="BaseResultMap" type="org.cloud.model.entity.Account">
<id column="id" jdbcType="BIGINT" property="id" />
<result column="user_id" jdbcType="BIGINT" property="userId" />
<result column="total" jdbcType="DECIMAL" property="total" />
<result column="used" jdbcType="DECIMAL" property="used" />
<result column="residue" jdbcType="DECIMAL" property="residue" />
</resultMap>
<!--
money 本次消费金额
t_account数据库表
total总额度 = 累计已消费金额(used) + 剩余可用额度(residue)
-->
<update id="decrease">
UPDATE
t_account
SET
residue = residue - #{money},used = used + #{money}
WHERE user_id = #{userId};
</update>
</mapper>
案例实战测试
启动服务
- 启动Nacos
- 启动Seata
- 启动openfeign服务
- 启动订单微服务2001
- 启动库存微服务2002
- 启动账户微服务2003
数据库初始情况
正常下单
此时我们没有在订单模块添加==@GlobalTransactional==
结果：没有任何问题
超时异常出错
此时我们没有在订单模块添加==@GlobalTransactional==
故障情况：
当库存和账户全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
数据库情况
超时异常解决
此时我们在订单模块添加==@GlobalTransactional==
@Override
@GlobalTransactional(name = "swx-create-order",rollbackFor = Exception.class) //AT
public void create(Order order)
{
..........
}
此时，订单模块就是TM，也是其中一个RM
查看Seata后台
http://IocaIhost:7091/#/Iogin
全局事务ID
全局锁
下单后数据库并没有任何变化，被回滚了
- 业务中
按照正常逻辑，本该有新记录入库，等待最后完成提交。
回滚后
Order记录根本就插入不进来
5172cdaac923752a846fbe48f780eaf5.png
上一步准备新增的记录被彻底回滚了，保证的一致性。
全部回退
总结
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。
二阶段分2种情况
正常提交
二阶段如是顺利提交的话，
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。
异常回滚
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。
