SpringCloud学习之(二十)SpringCloud Alibaba Seata处理分布式事务

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(二十)SpringCloud Alibaba Seata处理分布式事务

1、分布式问题

分布式前:

  • 单机单库没这个问题
  • 从1:1 -> 1:N -> N: N

分布式之后:

image-20200831104711048

image-20200831104730501

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

2、Seata简介

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:seata.io/zh-cn/

2.2 能干嘛

一个典型的分布式事务过程

分布式事务处理过程的——ID+三组件模型

Transaction ID XID:全局唯一的事务ID

3组件概念:

  • 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(TM) :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;

2.3 去那下

发布说明:github.com/seata/seata…

2.4 怎么玩

Spring 本地@Transactional

全局@GlobalTransactional:SEATA的分布式交易解决方案

image-20200831105509045

3、Seata-Server安装

3.1 官网地址

seata.io/zh-cn/blog/…

3.2 下载版本

seata-server-0.9.0

3.3 解压

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修改:

    • service模块:vgroup_mapping.my_test_tx_group = "fsp_tx_group"

    • store模块:

      mode = "db"

      url = "jdbc:mysql://127.0.0.1:3306/seata" user = "root" password = "你自己的密码"

3.4 mysql5.7数据库新建库seata

3.5 在seata库里建表

建表db_store.sql在\seata-server-0.9.0\seata\conf目录里面

赋值db_store.sql里的内容,粘贴到SQLYog中执行

image-20200831164856266

3.6 修改 registry.conf配置文件

修改seata-server-0.9.0\seata\conf目录下的registry.conf配置文件

image-20200831163811395

registry {
#file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"
  nacos {
    serverAddr = "localhost:8848"
    namespace = ""
    cluster = "default"
  }

3.7 先启动Nacos端口号8848

3.8 再启动seata-server

找到目录softs\seata-server-0.9.0\seata\bin下,执行cmd,输入seata-server.bat

4、订单/库存/账户业务数据库准备

4.1 说明

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

4.2 分布式事务业务说明

image-20200831223727224

下订单-->扣库存-->减账户(余额)

4.3 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

4.3 按照上述3库分别建对应业务表

  • seata_order库下建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=7 DEFAULT CHARSET=utf8;
     
    SELECT * FROM t_order;
    
  • seata_storage库下建t_storage表

    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;
    
  • seata_account库下建t_account表

    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;
    

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

粘贴该目录:\seata-server-0.9.0\seata\conf目录下的db_undo_log.sql

然后在每个数据库中就新建该表

4.5 最终效果

image-20200831223454083

image-20200831223515695

5、订单/库存/账户业务微服务准备

5.1 业务需求

下订单->减库存->扣余额->改(订单)状态

5.2 新建订单Order-Module

5.2.1 新建model

seata-order-service2001

5.2.2 POM

 <dependencies>
        <!--nacos-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--seata 因为兼容版本问题,所以需要剔除它自带的seata的包 -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
            <exclusions>
                <exclusion>
                    <artifactId>seata-all</artifactId>
                    <groupId>io.seata</groupId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>io.seata</groupId>
            <artifactId>seata-all</artifactId>
            <version>0.9.0</version>
        </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>
        <!--spring cloud alibaba nacos-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--SpringCloud alibaba sentinel-datasource-nacos:后续做持久化用到-->
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-datasource-nacos</artifactId>
        </dependency>
        <!--SpringCloud alibaba Sentinel-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</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>
        <!--Mybatis和SpringBoot整合-->
        <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>

5.2.3 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: localhost:8848
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/seata_order?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=GMT
    username: root
    password: root

feign:
  hystrix:
    enabled: false

logging:
  level:
    io:
      seata: info

mybatis:
  mapperLocations: classpath:mapper/*.xml

5.2.4 file.conf

transport {
  # tcp udt unix-domain-socket
  type = "TCP"
  #NIO NATIVE
  server = "NIO"
  #enable heartbeat
  heartbeat = true
  #thread factory for netty
  thread-factory {
    boss-thread-prefix = "NettyBoss"
    worker-thread-prefix = "NettyServerNIOWorker"
    server-executor-thread-prefix = "NettyServerBizHandler"
    share-boss-worker = false
    client-selector-thread-prefix = "NettyClientSelector"
    client-selector-thread-size = 1
    client-worker-thread-prefix = "NettyClientWorkerThread"
    # netty boss thread size,will not be used for UDT
    boss-thread-size = 1
    #auto default pin or 8
    worker-thread-size = 8
  }
  shutdown {
    # when destroy server, wait seconds
    wait = 3
  }
  serialization = "seata"
  compressor = "none"
}

service {

  vgroup_mapping.fsp_tx_group = "default"

  default.grouplist = "127.0.0.1:8091"
  enableDegrade = false
  disable = false
  max.commit.retry.timeout = "-1"
  max.rollback.retry.timeout = "-1"
  disableGlobalTransaction = false
}


client {
  async.commit.buffer.limit = 10000
  lock {
    retry.internal = 10
    retry.times = 30
  }
  report.retry.count = 5
  tm.commit.retry.count = 1
  tm.rollback.retry.count = 1
}

## transaction log store
store {
  ## store mode: file、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"
    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
  }
}
lock {
  ## the lock store mode: local、remote
  mode = "remote"

  local {
    ## store locks in user's database
  }

  remote {
    ## store locks in the seata's server
  }
}
recovery {
  #schedule committing retry period in milliseconds
  committing-retry-period = 1000
  #schedule asyn committing retry period in milliseconds
  asyn-committing-retry-period = 1000
  #schedule rollbacking retry period in milliseconds
  rollbacking-retry-period = 1000
  #schedule timeout retry period in milliseconds
  timeout-retry-period = 1000
}

transaction {
  undo.data.validation = true
  undo.log.serialization = "jackson"
  undo.log.save.days = 7
  #schedule delete expired undo_log in milliseconds
  undo.log.delete.period = 86400000
  undo.log.table = "undo_log"
}

## metrics settings
metrics {
  enabled = false
  registry-type = "compact"
  # multi exporters use comma divided
  exporter-list = "prometheus"
  exporter-prometheus-port = 9898
}

support {
  ## spring
  spring {
    # auto proxy the DataSource bean
    datasource.autoproxy = false
  }
}

5.2.5 registry.conf

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"

  nacos {
    serverAddr = "localhost:8848"
    namespace = ""
    cluster = "default"
  }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    application = "default"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = "0"
  }
  zk {
    cluster = "default"
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  consul {
    cluster = "default"
    serverAddr = "127.0.0.1:8500"
  }
  etcd3 {
    cluster = "default"
    serverAddr = "http://localhost:2379"
  }
  sofa {
    serverAddr = "127.0.0.1:9603"
    application = "default"
    region = "DEFAULT_ZONE"
    datacenter = "DefaultDataCenter"
    cluster = "default"
    group = "SEATA_GROUP"
    addressWaitTime = "3000"
  }
  file {
    name = "file.conf"
  }
}

config {
  # file、nacos 、apollo、zk、consul、etcd3
  type = "file"

  nacos {
    serverAddr = "localhost"
    namespace = ""
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    app.id = "seata-server"
    apollo.meta = "http://192.168.1.204:8801"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
    name = "file.conf"
  }
}

5.2.6 domain

Order类:

package com.atguigu.springcloud.alibaba.domain;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.math.BigDecimal;
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Order
{
    private Long id;

    private Long userId;

    private Long productId;

    private Integer count;

    private BigDecimal money;

    private Integer status; //订单状态:0:创建中;1:已完结
}

CommonResult类:

package com.atguigu.springcloud.alibaba.domain;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;


@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);
    }
}

5.2.7 Dao接口与实现

package com.atguigu.springcloud.alibaba.dao;

import com.atguigu.springcloud.alibaba.domain.Order;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;

@Mapper
public interface OrderDao {

    //新建订单
    void create(Order order);

    //修改订单的状态  从零改为1
    void update(@Param("userId") Long userId, @Param("status") Integer status);
}

resources文件夹下新建mapper文件夹后添加:OrderMapper.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.atguigu.springcloud.alibaba.dao.OrderDao">

    <resultMap id="BaseResultMap" type="com.atguigu.springcloud.alibaba.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,#{userId},#{productId},#{count},#{money},0);
    </insert>

    <update id="update">
        update t_order set status = 1 where user_id = #{userId} and status = #{status}
    </update>

</mapper>

5.2.8 Service接口与实现

OrderService:

package com.atguigu.springcloud.alibaba.service;

import com.atguigu.springcloud.alibaba.domain.Order;

public interface OrderService {
    //新建订单
    void create(Order order);
}

AccountService:

package com.atguigu.springcloud.alibaba.service;

import com.atguigu.springcloud.alibaba.domain.CommonResult;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;

import java.math.BigDecimal;

@FeignClient(value = "seata-account-service")
public interface AccountService {
    @PostMapping(value = "/account/decrease")
    CommonResult decrease(@RequestParam("userId")Long userId,
                          @RequestParam("money")BigDecimal money);
}

StorageService:

package com.atguigu.springcloud.alibaba.service;

import com.atguigu.springcloud.alibaba.domain.CommonResult;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(value = "seata-storage-service")//调用库存微服务
public interface StorageService {

    @PostMapping(value = "/storage/decrease")
    CommonResult decrease(@RequestParam("productId") Long productId,@RequestParam("count") Integer count);
}

OrderServiceImpl:

package com.atguigu.springcloud.alibaba.service.impl;

import com.atguigu.springcloud.alibaba.dao.OrderDao;
import com.atguigu.springcloud.alibaba.domain.Order;
import com.atguigu.springcloud.alibaba.service.AccountService;
import com.atguigu.springcloud.alibaba.service.OrderService;
import com.atguigu.springcloud.alibaba.service.StorageService;
import io.seata.spring.annotation.GlobalTransactional;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
@Service
@Slf4j
public class OrderServiceImpl implements OrderService {

    @Resource
    private OrderDao orderDao;
    @Resource
    private StorageService storageService;
    @Resource
    private AccountService accountService;

    /**
     * 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
     */

    @GlobalTransactional
    @Override
    public void create(Order order) {
        System.out.println("-------->开始新建订单");
        //新建订单
        orderDao.create(order);

        //扣减库存
        System.out.println("---->订单微服务开始调用库存,做扣减Count");
        storageService.decrease(order.getProductId(),order.getCount());
        System.out.println("---->订单微服务开始调用库存,做扣减end");

        //做扣减账户
        System.out.println("--->订单微服务开始调用账户,做扣减Money");
        accountService.decrease(order.getUserId(),order.getMoney());
        System.out.println("--->订单微服务调用账户,做扣减end");

        //修改订单状态,从0到1代表已经完成
        System.out.println("--->修改订单状态开始");
        orderDao.update(order.getUserId(),0);
        System.out.println("--->修改订单状态结束(#^.^#)");


    }
}

5.2.9 Controller

package com.atguigu.springcloud.alibaba.controller;

import com.atguigu.springcloud.alibaba.domain.CommonResult;
import com.atguigu.springcloud.alibaba.domain.Order;
import com.atguigu.springcloud.alibaba.service.OrderService;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import javax.smartcardio.CommandAPDU;

@RestController
public class OrderController {

    @Resource
    private OrderService orderService;

    @GetMapping("/order/create")
    public CommonResult create(Order order){
        orderService.create(order);
        return new CommonResult(200,"订单创建成功");
    }
    @RequestMapping("/order/test")
    public String test(){
        System.out.println("test 2001");
        return "test 2001";
    }
}

5.2.10 Config配置

MyBatisConfig:

package com.atguigu.springcloud.alibaba.config;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Configuration;


@Configuration
@MapperScan({"com.atguigu.springcloud.alibaba.dao"})
public class MyBatisConfig {

}

DataSourceProxyConfig:

package com.atguigu.springcloud.alibaba.config;

import com.alibaba.druid.pool.DruidDataSource;
import io.seata.rm.datasource.DataSourceProxy;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.transaction.SpringManagedTransactionFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import javax.sql.DataSource;

/**
 * 使用Seata对数据源进行代理
 */
@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();
    }

}

5.2.11 主启动类

package com.atguigu.springcloud.alibaba;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@EnableDiscoveryClient
@EnableFeignClients
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)//取消数据源的自动配置,使用Seata对数据源进行代理
public class SeataOrderMainApp2001 {
    public static void main(String[] args) {
        SpringApplication.run(SeataOrderMainApp2001.class,args);
    }
}

www.freesion.com/article/755…

no available server to connect.

image-20200901111956757

5.3 新建库存Storage-Module

5.4 新建账户Account-Module

6、Test

6.1 测试之前数据库情况:

image-20200901150759033

6.2 访问:

http://localhost:2001/order/create?userId=1&productId=1&count=10&money=100

image-20200901151452281

6.3 访问之后数据库情况:

image-20200901151109607

6.4 后台情况:

2001

image-20200901151239716

2002:

image-20200901151315657

2003:

image-20200901151347090

6.4 超时异常,没加@GlobalTransactional:

  • AccountServiceImpl添加超时

    public void decrease(Long userId, BigDecimal  money) {
    
        System.out.println(("------->account-service中扣减账户余额开始"));
        //模拟超时异常,全局事务回滚
        try {
            TimeUnit.SECONDS.sleep(20);
        }catch (InterruptedException e) {
            e.printStackTrace();
        }
        accountDao.decrease(userId,money);
        System.out.println("------->account-service中扣减账户余额结束");
    }
    
  • 重启2003,再次访问

    image-20200901181252426

  • 数据库情况

    image-20200901181538695

  • 故障情况

    • 当库存和账户余额扣减后,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

6.5 超时异常,添加@GlobalTransactional

  • AccountServiceImpl添加超时

  • OrderServiceImpl@GlobalTransactional

  • 再次测试:

    image-20200901182055441

  • 查看数据库:

    • 下单后数据库数据并没有任何改变,记录都添加不进来

7、Seata之原理简介

7.1 Seata

Simple Extensible Autonomous Transaction Architecture:简单可扩展自治事务框架

2020起初,参加工作后用1.0以后的版本

image-20200901204824608

7.2 再看TC/TM/RM三大组件

TC:seata的服务器

TM:事物的发起者,业务的入口。 @GlobalTransactional(name = "txl-create-order", rollbackFor = Exception.class)

RM:事务的参与者,一个数据库就是一个RM。

image-20200901205007911

分布式事务的执行流程:

  • TM开启分布式事务(TM向TC注册全局事务记录)
  • 换业务场景,编排数据库,服务等事务内资源(RM向TC汇报资源准备状态)
  • TM结束分布式事务,事务一阶段结束(TM通知TC提交/回滚分布式事务)
  • TC汇总事务信息,决定分布式事务是提交还是回滚
  • TC通知所有RM提交/回滚资源,事务二阶段结束。

7.3 AT模式如何做到对业务的无侵入

1)是什么

image-20200901205327909

image-20200901205336720

2)一阶段加载

image-20200901205416355

3)二阶段提交

image-20200901205441964

4)二阶段回滚

image-20200901205456947

image-20200901205512587