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分布式事务-Seata

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seata

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。

server端

点击下载

mysql-sql

全局事务会话信息由3块内容构成，全局事务–>分支事务–>全局锁，对应表global_table、branch_table、lock_table

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-- -------------------------------- The script used when storeMode is 'db' --------------------------------
-- the table to store GlobalSession data
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(128),
    `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;

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);

实际操作中遇见io.seata.core.exception.TmTransactionException: TransactionException[begin global request failed. xid=null, msg=Data truncation: Data too long for column 'transaction_service_group' at row 1]错误

global_table表的transaction_service_group字段在存放事务组名称“tx-seata-user-seata-service-group”时超过长度，手动调长了该字段长度

注册中心

记录了服务和服务地址的映射关系。在分布式架构中，服务会注册到这里，当服务需要调用其它服务时，就到这里找到服务的地址，进行调用.比如Seata Client端(TM,RM),发现Seata Server(TC)集群的地址,彼此通信.

启动包: seata–>conf–>registry.conf

file：

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#注册中心
registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "file"
....
 file {
    name = "file.conf"
  }
}
#配置中心
config {
  # file、nacos 、apollo、zk、consul、etcd3
  type = "file"
file {
    name = "file.conf"
  }
}

eureka

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registry {
  type = "eureka"
 
  eureka {
    #eureka地址
    serviceUrl = "http://localhost:8081/eureka"
    #当前seata-server服务名
    application = "seata-server"
    weight = "1"
  }
}

配置中心

放置着各种配置文件,你可以通过自己所需进行获取配置加载到对应的客户端.比如Seata Client端(TM,RM),Seata Server(TC),会去读取全局事务开关,事务会话存储模式等信息.

conf–>file.conf，根据store.mode=”db或者redis”去加载存储于不同渠道的配置

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## transaction log store, only used in seata-server
store {
  ## store mode: file、db、redis
  #mode = "file"
  mode = "db"
  ## rsa decryption public key
  publicKey = ""
  ## 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)/HikariDataSource(hikari) etc.
    datasource = "druid"
    ## mysql/oracle/postgresql/h2/oceanbase etc.
    dbType = "mysql"
    driverClassName = "com.mysql.jdbc.Driver"
    ## if using mysql to store the data, recommend add rewriteBatchedStatements=true in jdbc connection param
    url = "jdbc:mysql://127.0.0.1:3306/seata?rewriteBatchedStatements=true"
    user = "root"
    password = "123"
    minConn = 5
    maxConn = 100
    globalTable = "global_table"
    branchTable = "branch_table"
    lockTable = "lock_table"
    queryLimit = 100
    maxWait = 5000
  }

  ## redis store property
  redis {
    ## redis mode: single、sentinel
    mode = "single"
    ## single mode property
    single {
      host = "127.0.0.1"
      port = "6379"
    }
    ## sentinel mode property
    sentinel {
      masterName = ""
      ## such as "10.28.235.65:26379,10.28.235.65:26380,10.28.235.65:26381"
      sentinelHosts = ""
    }
    password = ""
    database = "0"
    minConn = 1
    maxConn = 10
    maxTotal = 100
    queryLimit = 100
  }
}

启动命令

  • 源码启动: 执行Server.java的main方法

  • 命令启动: seata-server.sh -h 127.0.0.1 -p 8091 -m db -n 1 -e test

    -h: 注册到注册中心的ip
    -p: Server rpc 监听端口
    -m: 全局事务会话信息存储模式，file、db、redis，优先读取启动参数 (Seata-Server 1.3及以上版本支持redis)
    -n: Server node，多个Server时，需区分各自节点，用于生成不同区间的transactionId，以免冲突
    -e: 多环境配置参考 http://seata.io/en-us/docs/ops/multi-configuration-isolation.html

高可用部署参考http://seata.io/zh-cn/docs/ops/deploy-ha.html

环境隔离

Seata从0.6.1开始支持多配置隔离，假设我们现在有一个测试环境，在这个测试环境中，我们希望只读取与测试环境相对应的配置项。

1、环境配置

Seata提供了两种方法来设置不同的环境:
-e test，其中test是环境的名称。(这只能用于服务器端)
例如(Linux)
Sh seata-server.sh -e test
使用SEATA_ENV作为环境变量的键，它的值将是环境的名称。(这只能用于客户端)[推荐]
例如(Linux)

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vi /etc/profile 
export SEATA_ENV=test

source /etc/profile

使用seataEnv作为jvm选项的键，它的值将是环境的名称。(这只能用于客户端)[推荐]
-DseataEnv=test

2、为新配置文件命名

将file.conf复制并重命名为file-env.conf，其中env是环境的名称。例如file-test.conf
复制并重命名registry.conf到registry-env.conf，其中env是环境的名称。例如registry-test.conf
在“registry-test.conf”文件中修改如下内容:

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registry {
...
file {
    name = "file-test.conf"
  }

config {
...
file {
    name = "file-test.conf"
  }

设置完所有步骤后，就可以开始使用Seata配置隔离了。

client端

AT模式

两阶段提交协议的演变：

  • 一阶段：业务数据和回滚日志记录在同一个本地事务中提交，释放本地锁和连接资源（与传统的2PC区别，一阶段不占用资源）。
  • 二阶段：
    • 提交异步化，非常快速地完成。
    • 回滚通过一阶段的回滚日志进行反向补偿。

mysql-sql

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-- for AT mode you must to init this sql for you business database. the seata server not need it.
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 = utf8 COMMENT ='AT transaction mode undo table';

pom

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<!-- seata -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-alibaba-seata</artifactId>
    <version>2.2.0.RELEASE</version>
</dependency>

注册中心

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

  nacos {
    application = "seata-server"
    serverAddr = "127.0.0.1:8848"
    group = "SEATA_GROUP"
    namespace = ""
    cluster = "default"
    username = ""
    password = ""
  }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    application = "default"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = 0
    password = ""
    cluster = "default"
    timeout = 0
  }
  zk {
    cluster = "default"
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
  }
  consul {
    cluster = "default"
    serverAddr = "127.0.0.1:8500"
    aclToken = ""
  }
  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"
  }
}
file模式（默认）

file加载模式：在在每个客户端的resource下增加registry.conf和file.conf文件

eureka模式
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#客户端yml配置
seata:
  tx-service-group: my_test_tx_group
  service:
    vgroup-mapping:
      my_test_tx_group: seata-server # 此处配置对应Server端配置registry.eureka.application的值
  registry:
    type: eureka
    eureka:
      service-url: http://localhost:8081/eureka
      weight: 1

nacos模式

配置中心

registry.conf

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

  nacos {
    serverAddr = "127.0.0.1:8848"
    namespace = ""
    group = "SEATA_GROUP"
    username = ""
    password = ""
    dataId = "seataServer.properties"
  }
  consul {
    serverAddr = "127.0.0.1:8500"
    aclToken = ""
  }
  apollo {
    appId = "seata-server"
    ## apolloConfigService will cover apolloMeta
    apolloMeta = "http://192.168.1.204:8801"
    apolloConfigService = "http://192.168.1.204:8080"
    namespace = "application"
    apolloAccesskeySecret = ""
    cluster = "seata"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
    nodePath = "/seata/seata.properties"
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
    name = "file.conf"
  }
}

file.conf

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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 {
  #transaction service group mapping
  vgroupMapping.my_test_tx_group = "default"
  #only support when registry.type=file, please don't set multiple addresses
  default.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
  }
}
file模式（默认）

file加载模式：在在每个客户端的resource下增加registry.conf和file.conf文件

注解

加载需要控制的业务方法上

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@GlobalTransactional(rollbackFor = Exception.class)

TCC模式

相关配置参照AT模式，TCC模式不依赖于底层数据资源的事务支持。

  • 一阶段 prepare 行为：调用 自定义 的 prepare 逻辑。
  • 二阶段 commit 行为：调用 自定义 的 commit 逻辑。
  • 二阶段 rollback 行为：调用 自定义 的 rollback 逻辑。

所谓 TCC 模式，是指支持把 自定义 的分支事务纳入到全局事务的管理中。

java

业务入口,添加@GlobalTransactional注解

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@GlobalTransactional(rollbackFor = Exception.class)
@GetMapping("/add")
public String atUser() {
    userService.rmUser(null);

    return "tcc新增用户成功";
}

业务接口层，维护tcc各阶段逻辑

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@LocalTCC
public interface RmUserInterface {
    @TwoPhaseBusinessAction(name = "rmUserInterface" , commitMethod = "rmUserCommit" ,rollbackMethod = "rmUserRollback")
    public boolean rmUser(BusinessActionContext businessActionContext);

    public boolean rmUserCommit(BusinessActionContext businessActionContext);

    public boolean rmUserRollback(BusinessActionContext businessActionContext);
}

跨服务之间调用的事务保证实现方式一致。