分布式事务
seata安装与使用
- 我们先从官网下载seata-server,这里下载的是seata-server-0.9.0.zip,下载地址:https://github.com/seata/seata/releases
- 这里我们使用Nacos作为注册中心,Nacos的安装及使用可以参考nacos详解
- 解压seata-server安装包到指定目录,修改conf目录下的file.conf配置文件,主要修改自定义事务组名称,事务日志存储模式为db及数据库连接信息;
service {
#vgroup->rgroup
vgroup_mapping.fsp_tx_group = "default" #修改事务组名称为:fsp_tx_group,和客户端自定义的名称对应
#only support single node
default.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"
}
## transaction log store
store {
## store mode: file、db
mode = "db" #修改此处将事务信息存储到数据库中
## 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://localhost:3306/seat-server" #修改数据库连接地址
user = "root" #修改数据库用户名
password = "123456" #修改数据库密码
min-conn = 1
max-conn = 3
global.table = "global_table"
branch.table = "branch_table"
lock-table = "lock_table"
query-limit = 100
}
}
- 由于我们使用了db模式存储事务日志,所以我们需要创建一个seat-server数据库,建表sql在seata-server的/conf/db_store.sql中;
- 修改conf目录下的registry.conf配置文件,指明注册中心为nacos,及修改nacos连接信息即可;
registry {
# file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
type = "nacos" #改为nacos
nacos {
serverAddr = "localhost:8848" #改为nacos的连接地址
namespace = ""
cluster = "default"
}
}
- 先启动Nacos,再使用seata-server中/bin/seata-server.bat文件启动seata-server。
数据库准备
- 创建业务数据库
- seat-order:存储订单的数据库;
- seat-storage:存储库存的数据库;
- seat-account:存储账户信息的数据库。
- 初始化业务表
- order表
CREATE TABLE `order` (
`id` bigint(11) NOT NULL AUTO_INCREMENT,
`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',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;
ALTER TABLE `order` ADD COLUMN `status` int(1) DEFAULT NULL COMMENT '订单状态:0:创建中;1:已完结' AFTER `money` ;
CREATE TABLE `storage` (
`id` bigint(11) NOT NULL AUTO_INCREMENT,
`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',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
INSERT INTO `seat-storage`.`storage` (`id`, `product_id`, `total`, `used`, `residue`) VALUES ('1', '1', '100', '0', '100');
CREATE TABLE `account` (
`id` bigint(11) NOT NULL AUTO_INCREMENT COMMENT 'id',
`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 '已用余额',
`residue` decimal(10,0) DEFAULT '0' COMMENT '剩余可用额度',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
INSERT INTO `seat-account`.`account` (`id`, `user_id`, `total`, `used`, `residue`) VALUES ('1', '1', '1000', '0', '1000');
创建日志回滚表
制造一个分布式事务问题
- 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存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。
客户端配置
- 对seata-order-service、seata-storage-service和seata-account-service三个seata的客户端进行配置,它们配置大致相同,我们下面以seata-order-service的配置为例;
- 修改application.yml文件,自定义事务组的名称;
spring:
cloud:
alibaba:
seata:
tx-service-group: fsp_tx_group #自定义事务组名称需要与seata-server中的对应
- 添加并修改file.conf配置文件,主要是修改自定义事务组名称;
service {
#vgroup->rgroup
vgroup_mapping.fsp_tx_group = "default" #修改自定义事务组名称
#only support single node
default.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"
disableGlobalTransaction = false
}
- 添加并修改registry.conf配置文件,主要是将注册中心改为nacos;
registry {
# file 、nacos 、eureka、redis、zk
type = "nacos" #修改为nacos
nacos {
serverAddr = "localhost:8848" #修改为nacos的连接地址
namespace = ""
cluster = "default"
}
}
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
@EnableDiscoveryClient
@EnableFeignClients
public class SeataOrderServiceApplication {
public static void main(String[] args) {
SpringApplication.run(SeataOrderServiceApplication.class, args);
}
}
@Configuration
public class DataSourceProxyConfig {
@Value("${mybatis.mapperLocations}")
private String mapperLocations;
@Bean
@ConfigurationProperties(prefix = "spring.datasource")
public DataSource druidDataSource(){
return new DruidDataSource();
}
@Bean
public DataSourceProxy dataSourceProxy(DataSource dataSource) {
return new DataSourceProxy(dataSource);
}
@Bean
public SqlSessionFactory sqlSessionFactoryBean(DataSourceProxy dataSourceProxy) throws Exception {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSourceProxy);
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
.getResources(mapperLocations));
sqlSessionFactoryBean.setTransactionFactory(new SpringManagedTransactionFactory());
return sqlSessionFactoryBean.getObject();
}
}
- 使用@GlobalTransactional注解开启分布式事务:
import io.seata.spring.annotation.GlobalTransactional;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class OrderServiceImpl implements OrderService {
private static final Logger LOGGER = LoggerFactory.getLogger(OrderServiceImpl.class);
@Autowired
private OrderDao orderDao;
@Autowired
private StorageService storageService;
@Autowired
private AccountService accountService;
@Override
@GlobalTransactional(name = "fsp-create-order",rollbackFor = Exception.class)
public void create(Order order) {
LOGGER.info("------->下单开始");
orderDao.create(order);
LOGGER.info("------->order-service中扣减库存开始");
storageService.decrease(order.getProductId(),order.getCount());
LOGGER.info("------->order-service中扣减库存结束:{}",order.getId());
LOGGER.info("------->order-service中扣减余额开始");
accountService.decrease(order.getUserId(),order.getMoney());
LOGGER.info("------->order-service中扣减余额结束");
LOGGER.info("------->order-service中修改订单状态开始");
orderDao.update(order.getUserId(),0);
LOGGER.info("------->order-service中修改订单状态结束");
LOGGER.info("------->下单结束");
}
}
分布式事务功能演示
- 运行seata-order-service、seata-storage-service和seata-account-service三个服务;
- 数据库初始信息状态:
![springcloud基于seata的分布式事务快速实践_第2张图片](http://img.e-com-net.com/image/info8/b598cfbb20c741f3b44fabe8a6ad1bf0.jpg)
- 调用接口进行下单操作后查看数据库:http://localhost:8180/order/create?userId=1&productId=1&count=10&money=100
![springcloud基于seata的分布式事务快速实践_第3张图片](http://img.e-com-net.com/image/info8/247998449dd0467fb82f527301cdd2f1.jpg)
- 我们在seata-account-service中制造一个超时异常后,调用下单接口:
@Service
public class AccountServiceImpl implements AccountService {
private static final Logger LOGGER = LoggerFactory.getLogger(AccountServiceImpl.class);
@Autowired
private AccountDao accountDao;
@Override
public void decrease(Long userId, BigDecimal money) {
LOGGER.info("------->account-service中扣减账户余额开始");
try {
Thread.sleep(30*1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
accountDao.decrease(userId,money);
LOGGER.info("------->account-service中扣减账户余额结束");
}
}
- 此时我们可以发现下单后数据库数据并没有任何改变;
![springcloud基于seata的分布式事务快速实践_第4张图片](http://img.e-com-net.com/image/info8/e76e1c59e14141baa00477b308b526dc.jpg)
- 我们可以在seata-order-service中注释掉@GlobalTransactional来看看没有Seata的分布式事务管理会发生什么情况:
@Service
public class OrderServiceImpl implements OrderService {
@Override
public void create(Order order) {
LOGGER.info("------->下单开始");
LOGGER.info("------->下单结束");
}
}
- 由于seata-account-service的超时会导致当库存和账户金额扣减后订单状态并没有设置为已经完成,而且由于远程调用的重试机制,账户余额还会被多次扣减。
![springcloud基于seata的分布式事务快速实践_第5张图片](http://img.e-com-net.com/image/info8/df4eace573574d4eb0e64e09c5f5914e.jpg)