Seata的簡單使用

本文只介紹Seata的簡單使用,沒有涉及其原理.

 

1.在本地搭建一個TC服務(事務協調者).

1.1 下載seata的安裝包

官網(https://github.com/seata/seata/releases)

　　往下滑滑,找到你想要的版本和格式下載即可.我這里使用的是seata-server-1.1.0.zip,解壓即可使用.

 

1.2 配置

打開解壓目錄下的conf/registry.conf文件如下

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  # 可以把seata-server理解為一個服務,它需要把自己注冊到某個注冊中心上去,方便使用seata的服務來找到自己
    #在這里就是指定注冊中心的類型,由於我們項目用的是eureka,所以這里我選擇eureka,即這一堆配置就下面一個eureka生效了
    #這里默認的是file,即文件,選了文件就可以不用搭注冊中心,直接從文件里讀取服務列表
    #復制之后一定要改一改
  type = "eureka"  

  nacos {
    serverAddr = "localhost"
    namespace = ""
    cluster = "default"
  }
  eureka { #"只有我生效啦"
    serviceUrl = "http://localhost:10086/eureka"  #eureka地址
    application = "seata_tc_server"		#在eureka里顯示的名字
    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 {
    #在這里選擇配置中心,這里我們選擇file
  # file、nacos 、apollo、zk、consul、etcd3
  type = "file"

  nacos {
    serverAddr = "localhost"
    namespace = ""
    group = "SEATA_GROUP"
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    app.id = "seata-server"
    apollo.meta = "http://192.168.1.204:8801"
    namespace = "application"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
      #由於選擇了file,所以這里生效了
    name = "file.conf"
  }
}

所以接下來看一下file.conf文件

## transaction log store, only used in seata-server
store {
  ## store mode: file、db
    #選擇配置中心的存儲模式,由於選擇file存到文件里(性能高)會變為二進制流不好觀察,所以選擇數據庫
     #復制之后一定要改一改
  mode = "db"

  ## file store property
  file {
    ## store location dir
    dir = "sessionStore"
    # branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
    maxBranchSessionSize = 16384
    # globe session size , if exceeded throws exceptions
    maxGlobalSessionSize = 512
    # file buffer size , if exceeded allocate new buffer
    fileWriteBufferCacheSize = 16384
    # when recover batch read size
    sessionReloadReadSize = 100
    # async, sync
    flushDiskMode = async
  }

  ## database store property
  db {
      #選擇了數據庫必定要做出一些配置,數據庫里一定要有這3張表
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
    datasource = "dbcp"
    ## mysql/oracle/h2/oceanbase etc.
    dbType = "mysql"
    driverClassName = "com.mysql.jdbc.Driver"
    url = "jdbc:mysql://192.168.206.99:3306/seata"
    user = "root"
    password = "root"
    minConn = 1
    maxConn = 10
    globalTable = "global_table"
    branchTable = "branch_table"
    lockTable = "lock_table"
    queryLimit = 100
  }
}

建表SQL如下:

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_gmt_modified_status` (`gmt_modified`, `status`),
    KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

-- 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,
    `gmt_modified`      DATETIME,
    PRIMARY KEY (`branch_id`),
    KEY `idx_xid` (`xid`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

-- the table to store lock data
CREATE TABLE IF NOT EXISTS `lock_table`
(
    `row_key`        VARCHAR(128) NOT NULL,
    `xid`            VARCHAR(96),
    `transaction_id` BIGINT,
    `branch_id`      BIGINT       NOT NULL,
    `resource_id`    VARCHAR(256),
    `table_name`     VARCHAR(32),
    `pk`             VARCHAR(36),
    `gmt_create`     DATETIME,
    `gmt_modified`   DATETIME,
    PRIMARY KEY (`row_key`),
    KEY `idx_branch_id` (`branch_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

1.3 啟動

如果是linux環境（要有JRE），執行seata-server.sh

如果是windows環境，執行seata-server.bat

 

 

2 改造微服務

只要是需要用到seata(分布式事務)的服務,都要做類似的配置.

 

2.1 引入依賴

我這里是springboot項目,所以我先在父pom中聲明了.如下

    <properties>    
        <alibaba.seata.version>2.1.0.RELEASE</alibaba.seata.version>
        <seata.version>1.1.0</seata.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <!--seata-->
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-seata</artifactId>
                <version>${alibaba.seata.version}</version>
                <exclusions>
                    <exclusion>
                        <artifactId>seata-all</artifactId>
                        <groupId>io.seata</groupId>
                    </exclusion>
                </exclusions>
            </dependency>
            <dependency>
                <artifactId>seata-all</artifactId>
                <groupId>io.seata</groupId>
                <version>${seata.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>

接下來只要在需要seata的微服務里添加依賴就好了.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-alibaba-seata</artifactId>
</dependency>
<dependency>
    <groupId>io.seata</groupId>
    <artifactId>seata-all</artifactId>
</dependency>

 

2.2 添加配置

spring:
  cloud:
    alibaba:
      seata:
        tx-service-group: test_tx_group # 定義事務組的名稱

 

2.3 在resources目錄下添加2個文件file.conf和registry.conf

registry.conf和前面的一樣,直接復制過來就好.

file.conf里的內容不同了,新的內容如下:

transport {
  # tcp udt unix-domain-socket
  type = "TCP"
  #NIO NATIVE
  server = "NIO"
  #enable heartbeat
  heartbeat = true
  # the client batch send request enable
  enableClientBatchSendRequest = true
  #thread factory for netty
  threadFactory {
    bossThreadPrefix = "NettyBoss"
    workerThreadPrefix = "NettyServerNIOWorker"
    serverExecutorThread-prefix = "NettyServerBizHandler"
    shareBossWorker = false
    clientSelectorThreadPrefix = "NettyClientSelector"
    clientSelectorThreadSize = 1
    clientWorkerThreadPrefix = "NettyClientWorkerThread"
    # netty boss thread size,will not be used for UDT
    bossThreadSize = 1
    #auto default pin or 8
    workerThreadSize = "default"
  }
  shutdown {
    # when destroy server, wait seconds
    wait = 3
  }
  serialization = "seata"
  compressor = "none"
}
service {
#這里注意,等號前后都是配置,前面是yml里配置的事務組,后面是register.conf里定義的seata-server
  vgroupMapping.test_tx_group = "seata_tc_server"
  #only support when registry.type=file, please don't set multiple addresses
  seata_tc_server.grouplist = "127.0.0.1:8091"
  #degrade, current not support
  enableDegrade = false
  #disable seata
  disableGlobalTransaction = false
}

client {
  rm {
    asyncCommitBufferLimit = 10000
    lock {
      retryInterval = 10
      retryTimes = 30
      retryPolicyBranchRollbackOnConflict = true
    }
    reportRetryCount = 5
    tableMetaCheckEnable = false
    reportSuccessEnable = false
  }
  tm {
    commitRetryCount = 5
    rollbackRetryCount = 5
  }
  undo {
    dataValidation = true
    logSerialization = "jackson"
    logTable = "undo_log"
  }
  log {
    exceptionRate = 100
  }
}

配置解讀：

• transport：與TC交互的一些配置

  • heartbeat：client和server通信心跳檢測開關

  • enableClientBatchSendRequest：客戶端事務消息請求是否批量合並發送

• service：TC的地址配置，用於獲取TC的地址

  • vgroupMapping.test_tx_group = "seata_tc_server"：

    • test_tx_group：是事務組名稱，要與application.yml中配置一致，

    • seata_tc_server：是TC服務端集群的名稱，將來通過注冊中心獲取TC地址

    • enableDegrade：服務降級開關，默認關閉。如果開啟，當業務重試多次失敗后會放棄全局事務

    • disableGlobalTransaction：全局事務開關，默認false。false為開啟，true為關閉

  • default.grouplist：這個當注冊中心為file的時候，才用到

• client：客戶端配置

  • rm：資源管理器配

    • asynCommitBufferLimit：二階段提交默認是異步執行，這里指定異步隊列的大小

    • lock：全局鎖配置

      • retryInterval：校驗或占用全局鎖重試間隔，默認10，單位毫秒

      • retryTimes：校驗或占用全局鎖重試次數，默認30次

      • retryPolicyBranchRollbackOnConflict：分支事務與其它全局回滾事務沖突時鎖策略，默認true，優先釋放本地鎖讓回滾成功

    • reportRetryCount：一階段結果上報TC失敗后重試次數，默認5次

  • tm：事務管理器配置

    • commitRetryCount：一階段全局提交結果上報TC重試次數，默認1

    • rollbackRetryCount：一階段全局回滾結果上報TC重試次數，默認1

  • undo：undo_log的配置

    • dataValidation：是否開啟二階段回滾鏡像校驗，默認true

    • logSerialization：undo序列化方式，默認Jackson

    • logTable：自定義undo表名，默認是undo_log

  • log：日志配置

    • exceptionRate：出現回滾異常時的日志記錄頻率，默認100，百分之一概率。回滾失敗基本是臟數據，無需輸出堆棧占用硬盤空間

 

 

2.4 代理DataSource

由於在一階段是通過攔截sql分析語義來生成回滾策略,原來的數據源已經不夠用了,得換個牛逼的.在服務里新建一個配置類.

• 如果是使用的是mybatis

import io.seata.rm.datasource.DataSourceProxy;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
public class DataSourceProxyConfig {

    @Bean
    public SqlSessionFactory sqlSessionFactoryBean(DataSource dataSource) throws Exception {
        // 因為使用的是mybatis，這里定義SqlSessionFactoryBean
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        // 配置數據源代理
        sqlSessionFactoryBean.setDataSource(new DataSourceProxy(dataSource));
        return sqlSessionFactoryBean.getObject();
    }
}

　　

如果使用的是mybatis-plus

 

import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import io.seata.rm.datasource.DataSourceProxy;
import org.apache.ibatis.session.SqlSessionFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
public class DataSourceProxyConfig {

    @Bean
    public SqlSessionFactory sqlSessionFactoryBean(DataSource dataSource) throws Exception {
        // 訂單服務中引入了mybatis-plus，所以要使用特殊的SqlSessionFactoryBean
        MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
        // 代理數據源
        sqlSessionFactoryBean.setDataSource(new DataSourceProxy(dataSource));
        // 生成SqlSessionFactory
        return sqlSessionFactoryBean.getObject();
    }
}

 

2.5 加上注解

給事務發起者的方法上加上@GlobalTransactional即可,其它的參與者只要加@Transactional就好了.

 

 

3.踩坑記錄

1.由於更換了數據源,不知道為什么我在yml里給mybatis配置的駝峰映射失效了,導致我查到的數據缺少了某些字段.不知道這個問題在mybatis-plus中會不會出現.

解決辦法:單獨給數據源配置映射規則就好了.所以我把上面的配置類加了一個設置,修改后的代碼如下.

import io.seata.rm.datasource.DataSourceProxy;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
public class DataSourceProxyConfig {

    @Bean
    public SqlSessionFactory sqlSessionFactoryBean(DataSource dataSource) throws Exception {
        // 因為使用的是mybatis，這里定義SqlSessionFactoryBean
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        // 配置數據源代理
        sqlSessionFactoryBean.setDataSource(new DataSourceProxy(dataSource));
        SqlSessionFactory object = sqlSessionFactoryBean.getObject();
        assert object != null;
　　　　　// 單獨給數據源設置駝峰映射
        object.getConfiguration().setMapUnderscoreToCamelCase(true);
        return object;
    }
}