风在路上
zdk
2022-11-22
目录

Seata

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# Seata

# 分布式事务问题

单体应用被拆分成微服务应用，原来的N个模块被拆分成N个独立的应用，分别使用N个独立的数据源, 业务操作需要调用N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

# Seata简介

官网：http://seata.io/zh-cn/

# 一个典型的分布式事务过程

# 一ID+三组件模型

一ID：

  • Transaction ID:XID，全局唯一的事务ID

三组件：

  • Transaction Coordinator(TC)：事务协调器，维护全局和分支事务的状态，驱动全局事务提交或回滚。
  • Transaction Manager(TM)：定义全局事务的范围：负责开始全局事务、并最终发起全局提交或回滚全局事务。
  • Resource Manager(RM)：管理分支事务处理的资源，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

# 处理过程

  1. 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;
  2. XID在微服务调用链路的上下文中传播;
  3. RM向TC注册分支事务，将其纳入XID对应全局事务的管辖;
  4. TM向TC发起针对XID的全局提交或回滚决议;
  5. TC调度XID下管辖的全部分支事务完成提交或回滚请求。

img

# Seata-Server安装

  • 在GitHub下载release版本，我这里是最新的v1.5.2版本

  • 修改application.yml配置文件

增加以下配置，将其配置中心、注册中心改为nacos，存储mode改为db-MySQL

seata:
  config:
    # support: nacos, consul, apollo, zk, etcd3
    type: nacos
  registry:
    # support: nacos, eureka, redis, zk, consul, etcd3, sofa
    type: nacos
  store:
    # support: file 、 db 、 redis
    mode: db
    db:
      driverClassName: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://localhost:3306/seata_temp?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT%2B8
      user: root
      password: root
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  • 在库中新建表，表的SQL文件在seata\script\server\db目录下，mysql.sql
  • 先运行nacos，再到seata的bin目录中运行seata-server.bat文件
  • 访问http://localhost:7091进入Seata控制台，账号密码均为seata

image-20221122173017446

# 订单/库存/账户业务数据库准备

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桧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。

即：下订单---扣库存---减余额

# 建库建表SQL

# seata_order
CREATE DATABASE seata_order;
USE seata_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 CHARSET=utf8;

# seata_storage
CREATE DATABASE seata_storage;
USE seata_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=7 CHARSET=utf8;
INSERT INTO t_storage(id, product_id, total, used, residue) VALUES(1,1,100,0,100);

# seata_account
CREATE DATABASE seata_account;
USE seata_account;
CREATE TABLE t_account(
    id BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY ,
    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 '已用额度',
    residue DECIMAL(10,0) DEFAULT 0 COMMENT '剩余可用额度'
)ENGINE=InnoDB AUTO_INCREMENT=7 CHARSET=utf8;
INSERT INTO t_account(id, user_id, total, used, residue) VALUES(1,1,1000,0,1000);
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# 按三个库都建立一个回滚日志表

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;
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# 订单/库存/账户业务微服务准备

业务需求很简单：下订单---扣库存---减余额----改(订单)状态

这里需要三个微服务

  • 订单：Order-Module-- seata-order-service2001
  • 库存：Storage-Module seata-storage-service2002
  • 账户：Account-Module seata-account-service2003

# Order

# pom

nacos、openfeign、seata、web、actuator、mysql、mybatis这些常规的

<dependencies>
        <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>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- nacos依赖 -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--  openfeign依赖 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!--  ribbon依赖 -->
        <!--  loadbalancer依赖 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <!--  seata依赖 -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
        </dependency>
    <!-- 下面是数据库相关依赖 -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>
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# yaml

server:
  port: 2001

spring:
  application:
    name: seata-order-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    alibaba:
      seata:
        tx-service-group: my_seata

  datasource:
    # 当前数据源类型
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/seata_order?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT%2B8
    username: root
    password: root

mybatis-plus:
  mapper-locations: classpath:/mapper/*.xml
  type-aliases-package: com.zdk.springcloud.alibaba.domain

logging:
  level:
    io:
      seata: info
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# file.conf

这个文件要注意这个部分的配置：

ervice { #vgroup->rgroup vgroupMapping.my_seata = "my_seata" #only support single node my_seata.grouplist = "127.0.0.1:8091"

vgroupMapping.my_seata的my_seata要与我们yaml中配置的tx-service-group值相同，然后引号中的值与my_seata.grouplist中的前一部分相同

否则会启动报错，找不到seata server

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->rgroup
  vgroupMapping.my_seata = "my_seata"
  #only support single node
  my_seata.grouplist = "127.0.0.1:8091"
  #degrade current not support
  enableDegrade = false
  #disable
  disable = false
  #unit ms,s,m,h,d represents milliseconds, seconds, minutes, hours, days, default permanent
  max.commit.retry.timeout = "-1"
  max.rollback.retry.timeout = "-1"
}

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

## transaction log store
store {
  ## store mode: file、db
  mode = "file"

  ## 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 = "druid"
    ## mysql/oracle/h2/oceanbase etc.
    db-type = "mysql"
    url = "jdbc:mysql://localhost:3306/seata_temp?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT%2B8"
    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 {
  committing-retry-delay = 30
  asyn-committing-retry-delay = 30
  rollbacking-retry-delay = 30
  timeout-retry-delay = 30
}

transaction {
  undo.data.validation = true
  undo.log.serialization = "jackson"
}

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

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

  nacos {
    serverAddr = "localhost"
    namespace = "public"
    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 = "nacos"

  nacos {
    serverAddr = "localhost"
    namespace = "public"
    cluster = "default"
  }
  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"
  }
}
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注意，以上两个conf文件都要放到resource目录下

余下的工程就不再写在笔记上了，参考GitHub仓库 (opens new window)或Gitee仓库 (opens new window)

# 测试

访问POST请求：http://localhost:2001/order/create

参数为：

{
    "userId":1,
    "productId":1,
    "count":10,
    "money":100,
    "status":0
}
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# 出异常，没加@GlobalTransactional

让AccountServiceImpl模拟超时异常

image-20221124161534037

此时db的情况是，order创建成功，storage也成功扣了，但account也扣了，但是订单状态并没有修改，因为在执行修改前出现了异常，而我们的期望是前面的三个库的操作都不执行，一起回滚

image-20221124161821578

# 出异常，添加@GlobalTransactional

我们添加上注解@GlobalTransactional(name = "my_seata", rollbackFor = Exception.class)

重启OrderService再次访问创建订单接口，发现所有数据均未发生变化，回滚已执行

在 GitHub 上编辑此页 (opens new window)
#Seata#SpringCloud Alibaba
最后更新: 2022/11/24, 17:11:00
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