SpringCloud Alibaba Seata (收藏版)

SpringCloud Alibaba Seata (收藏版)

一、简介

官网地址: http://seata.io/zh-cn/

1，概念

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在提供高性能和简单一样的分布式事务服务。

2，处理过程

Transaction ID XID:全局唯一的事务ID

Transaction Coordinator(TC) :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™ :定义全局事务的范围：开始全局事务、提交或回滚全局事务。

Resource Manager(RM) :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。

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

XID在微服务调用链路的上下文中传播

RM向TC注册分支事务，将其纳入XID对应全局事务的管辖

TM向TC发起针对XID的全局提交或回滚决议

TC调度XID下管辖的全部分支事务完成提交或回滚请求

二、Seata-Server的安装

1，下载

http://seata.io/zh-cn/blog/download.html 选择指定版本下载(我这里用的是0.9.0)

2，修改配置文件

修改seata/conf/file.conf

#将service中修改group

vgroup_mapping.my_test_tx_group = "my_group"

#将store模块修改为db并修改数据连接，将conf目录下的db_store.sql文件导入到数据库中

mode = "db"

db {

datasource = "dbcp"

db-type = "mysql"

driver-class-name = "com.mysql.jdbc.Driver"

url = "jdbc:mysql://127.0.0.1:3306/seata"

user = "root"

password = "123456"

}

修改seata/conf/registry.conf

registry {

type = "nacos"

nacos {

serverAddr = "localhost:8848"

namespace = ""

cluster = "default"

}

三、Seata的应用

1，订单服务

源码: seata-order-service2001

a，配置pom

com.alibaba.cloud

spring-cloud-starter-alibaba-nacos-discovery

com.alibaba.cloud

spring-cloud-starter-alibaba-seata

seata-all

io.seata

io.seata

seata-all

0.9.0

org.springframework.cloud

spring-cloud-starter-openfeign

org.springframework.boot

spring-boot-starter-web

org.springframework.boot

spring-boot-starter-actuator

mysql

mysql-connector-java

5.1.37

com.alibaba

druid-spring-boot-starter

1.1.10

org.mybatis.spring.boot

mybatis-spring-boot-starter

2.0.0

b，配置yaml

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: my_group

nacos:

discovery:

server-addr: localhost:8848

datasource:

driver-class-name: com.mysql.jdbc.Driver

url: jdbc:mysql://localhost:3306/seata_order

username: root

password: 123456

feign:

hystrix:

enabled: false

logging:

level:

io:

seata: info

mybatis:

mapperLocations: classpath:mapper/*.xml

c，添加file.conf(与seata-server配置相同)

transport {

# tcp udt unix-domain-socket

type = "TCP"

#NIO NATIVE

server = vGSSfOEQD"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.my_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 = "123456"

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

#schevGSSfOEQDdule 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

}

}

d，添加registry.conf(与seata-server的配置相同)

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"

}

}

e，fegin调用(这里以其中一个account为例)

@FeignClient(value = "seata-account-service")

public interface AccountService {

@RequestMapping("/account/decrease")

public CommonResult decrease(@RequestParam("userId") Long userId, @RequestParam("money") BigDecimal money);

}

f，事务service

@Slf4j

@Service

public class OrderServiceImpl implements OrderService {

@Autowired

OrderDao orderDao;

@Autowired

AccountService accountService;

@Autowired

StorageService storageService;

@Override

@GlobalTransactional(name = "my-order-test",rollbackFor = Exception.class) //加注解使用全局的事务，name 为事务名称不重复就行

public Long create(Order order) {

log.info("=========================下订单，开始");

orderDao.create(order);

log.info("=========================下订单，完成");

log.info("=========================减库存，开始");

storageService.decrease(order.getProductId(), order.getCount());

log.info("=========================减库存，完成");

log.info("=========================减积分，开始");

accountService.decrease(order.getUserId(), order.getMoney());

log.info("=========================减积分，完成");

log.info("=========================订单状态修改，开始");

orderDao.update(order.getId(),1);

log.info("=========================订单状态修改，完成");

return order.getId();

}

}

g，启动类

2，库存服务

源码： seata-storage-service2002

与订单服务中的a，b，c，d，g配置步骤相同

3，账户服务

源码: seata-account-service2003

与库存服务的配置步骤相同

四、Seata的原理解析

参考文档： http://seata.io/zh-cn/docs/overview/what-is-seata.html

1，AT模式 一阶段

1，解析SQL语义，找到"业务SQL"要更新的业务数据，在业务数据被更新前，将其保存成"before image"

2，执行"业务SQL"更新业务数据，在业务数更新之后

3，将其保存成"after image"，最后生成行锁。

以上操作全部在一个数据库事务内完成，这样保证了一阶段操作的原子性。

二阶段提交

因为"业务SQL"在一阶段已经提交至数据库，所以seata框架只需 将一阶段保存的快照数据和行锁删掉 ，完成数据清理即可。

二阶段回滚

二阶段如果是回滚的话，seata就需要回滚一阶段已经执行的"业务SQL"，还原业务数据。

回滚的方式便是用"before image"还原业务数据；但在还原前要首先校验脏写，对比"数据库当前业务数据"和"after image"

如果两份数据完全一致就说明没有脏写，可以还原业务数据，如果不一致就说明有脏写，出现脏写就需要转人工处理。

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。