seata学习

网络上的文章太多了，建议根据官网文档慢慢研究学习。

一.概述

1.Seata 是什么?

官网

Seata 是一款开源的分布式事务解决方案，致力于提供高性能和简单易用的分布式事务服务。Seata 将为用户提供了 AT、TCC、SAGA 和 XA 事务模式，为用户打造一站式的分布式解决方案。

简单的来说就是各个服务之间调用的事务要么一起成功要么一起失败，最基本的事务原子性。

这边主要研究学习AT模式

2.Seata术语

XID(Transaction ID XID)-全局唯一的事务ID

TC (Transaction Coordinator) - 事务协调者
维护全局和分支事务的状态，驱动全局事务提交或回滚。

TM (Transaction Manager) - 事务管理器
定义全局事务的范围：开始全局事务、提交或回滚全局事务。

RM (Resource Manager) - 资源管理器
管理分支事务处理的资源，与TC交谈以注册分支事务和报告分支事务的状态，并驱动分支事务提交或回滚。

3.各事务模式

Seata AT 模式
http://seata.io/zh-cn/docs/dev/mode/at-mode.html

Seata TCC 模式
http://seata.io/zh-cn/docs/dev/mode/tcc-mode.html

Seata Saga 模式
http://seata.io/zh-cn/docs/dev/mode/saga-mode.html

二.部署集群

1.前提部署了nacos

nacos.io

2.下载

https://github.com/seata/seata/releases/download/v1.3.0/seata-server-1.3.0.tar.gz

3.初始化数据库

https://github.com/seata/seata/blob/1.3.0/script/server/db/mysql.sql


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(6),
`gmt_modified` DATETIME(6),
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;

每个库都要添加undo_log表

https://github.com/seata/seata/blob/1.3.0/script/client/at/db/mysql.sql

DROP TABLE undo_log;

CREATE TABLE IF NOT EXISTS `undo_log`
(
    `branch_id`     BIGINT(20)   NOT NULL COMMENT 'branch transaction id',
    `xid`           VARCHAR(100) 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 = utf8 COMMENT ='AT transaction mode undo table';

4.配置

配置说明
http://seata.io/zh-cn/docs/user/configurations.html

https://github.com/seata/seata/blob/1.3.0/script/client/conf/file.conf

https://github.com/seata/seata/blob/1.3.0/script/client/conf/registry.conf

https://github.com/seata/seata/blob/1.3.0/script/client/spring/application.yml

vi file.conf

改

store {
  ## store mode: file、db
  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 {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
    datasource = "druid"
    ## mysql/oracle/postgresql/h2/oceanbase etc.
    dbType = "mysql"
    driverClassName = "com.mysql.jdbc.Driver"
    url = "jdbc:mysql://192.168.0.68:3306/seata"
    user = "root"
    password = "123456"
    minConn = 5
    maxConn = 30
    globalTable = "global_table"
    branchTable = "branch_table"
    lockTable = "lock_table"
    queryLimit = 100
    maxWait = 5000
  }
}

设置使用 Nacos 注册中心

cp registry.conf registry.conf.bak

vi registry.conf

改

  type = "nacos"
  nacos {
    application = "seata-server"
    serverAddr = "127.0.0.1:8848"
    namespace = ""
    cluster = "default"
    username = ""
    password = ""
  }

5.启动

nohup sh bin/seata-server.sh -p 18091 -n 1 &

nohup sh bin/seata-server.sh -p 28091 -n 1 &

支持的启动参数

三.实战

版本说明
https://github.com/alibaba/spring-cloud-alibaba/wiki/版本说明

项目源码

四.说明

通过jmeter高并发请求，seata能保证数据一致性。

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