参考文档
相关术语:
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: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,并驱动分支事务的提交和回滚。
创建undo_log表,每一个微服务对应的数据库都需要创建该表
-- 注意此处0.3.0+ 增加唯一索引 ux_undo_log
CREATE TABLE `undo_log` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`branch_id` bigint(20) NOT NULL,
`xid` varchar(100) NOT NULL,
`context` varchar(128) NOT NULL,
`rollback_info` longblob NOT NULL,
`log_status` int(11) NOT NULL,
`log_created` datetime NOT NULL,
`log_modified` datetime NOT NULL,
`ext` varchar(100) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `ux_undo_log` (`xid`,`branch_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
下载 seata-server-1.3.0.tar.gz ,解压 seata 后进入 seata/conf 目录,修改配置文件 registry.conf,让 seata 启动后,注册到注册中心 nacos。
registry {
# file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
type = "nacos"
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"
}
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 = "127.0.0.1:8848"
namespace = ""
group = "SEATA_GROUP"
username = ""
password = ""
}
consul {
serverAddr = "127.0.0.1:8500"
}
apollo {
appId = "seata-server"
apolloMeta = "http://192.168.1.204:8801"
namespace = "application"
}
zk {
serverAddr = "127.0.0.1:2181"
sessionTimeout = 6000
connectTimeout = 2000
username = ""
password = ""
}
etcd3 {
serverAddr = "http://localhost:2379"
}
file {
name = "file.conf"
}
}
file.conf 配置文件
## transaction log store, only used in seata-server
store {
## store mode: file、db、redis
mode = "file"
## 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"
url = "jdbc:mysql://127.0.0.1:3306/seata"
user = "mysql"
password = "mysql"
minConn = 5
maxConn = 30
globalTable = "global_table"
branchTable = "branch_table"
lockTable = "lock_table"
queryLimit = 100
maxWait = 5000
}
## redis store property
redis {
host = "127.0.0.1"
port = "6379"
password = ""
database = "0"
minConn = 1
maxConn = 10
queryLimit = 100
}
}
导入 seata 依赖
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-seata</artifactId>
<version>2021.1</version>
</dependency>
大事务方法上,标注 @GlobalTransactional 注解
所有想要用到分布式事务的微服务,都应该使用 seata 代理数据源。
5.1 Spring的容器中,自动配置了数据源, 查看 DataSourceAutoConfiguration 类的源码
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })
@ConditionalOnMissingBean(type = "io.r2dbc.spi.ConnectionFactory")
@EnableConfigurationProperties(DataSourceProperties.class)
@Import({ DataSourcePoolMetadataProvidersConfiguration.class,
DataSourceInitializationConfiguration.InitializationSpecificCredentialsDataSourceInitializationConfiguration.class,
DataSourceInitializationConfiguration.SharedCredentialsDataSourceInitializationConfiguration.class })
public class DataSourceAutoConfiguration {
@Configuration(proxyBeanMethods = false)
@Conditional(PooledDataSourceCondition.class)
@ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
@Import({ DataSourceConfiguration.Hikari.class, DataSourceConfiguration.Tomcat.class,
DataSourceConfiguration.Dbcp2.class, DataSourceConfiguration.OracleUcp.class,
DataSourceConfiguration.Generic.class, DataSourceJmxConfiguration.class })
protected static class PooledDataSourceConfiguration {
}
}
初始化数据源的时候,首先确保 Spring 的容器中已经存在了 DataSourceProperties 配置信息。
@Import({ DataSourceConfiguration.Hikari.class, DataSourceConfiguration.Tomcat.class,
DataSourceConfiguration.Dbcp2.class, DataSourceConfiguration.OracleUcp.class,
DataSourceConfiguration.Generic.class, DataSourceJmxConfiguration.class })
如下代码,导入了各种数据源。而Spring Boot项目中现在默认的数据源是 Hikari。查看Hikari数据导入的过程:
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(HikariDataSource.class)
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "com.zaxxer.hikari.HikariDataSource",
matchIfMissing = true)
static class Hikari {
@Bean
@ConfigurationProperties(prefix = "spring.datasource.hikari")
HikariDataSource dataSource(DataSourceProperties properties) {
HikariDataSource dataSource = createDataSource(properties, HikariDataSource.class);
if (StringUtils.hasText(properties.getName())) {
dataSource.setPoolName(properties.getName());
}
return dataSource;
}
}
从代码中,我们看到,向Spring容器中添加了 HikariDataSource 数据源。但是 @ConditionalOnMissingBean(DataSource.class)
这行代码表明,向容器中,添加该数据源是有条件,也就是,容器中不存在 DataSource 数据源的时候,才向容器中添加数据源。因此,Seata要想代理我们的数据源,需要我们自己先创建数据源,而不是让Spring Boot自动创建。
5.2. 创建自己数据源,并让Seata代理
@Configuration
public class MySeataConfig {
@Autowired
DataSourceProperties dataSourceProperties;
@Bean
DataSource dataSource(DataSourceProperties dataSourceProperties) {
// 下面代码,仿照 HikariDataSource 数据源创建过程,添加如下
HikariDataSource dataSource = dataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
if (StringUtils.hasText(dataSourceProperties.getName())) {
dataSource.setPoolName(dataSourceProperties.getName());
}
return new DataSourceProxy(dataSource);
}
}
每个微服务的classpath路径下,都需要放入 registry.conf 和 file.conf配置文件, 参考。
file.conf 的 service.vgroup_mapping 配置必须和spring.application.name一致
在 org.springframework.cloud:spring-cloud-starter-alibaba-seata的org.springframework.cloud.alibaba.seata.GlobalTransactionAutoConfiguration类中,默认会使用 ${spring.application.name}-fescar-service-group作为服务名注册到 Seata Server上,如果和file.conf中的配置不一致,会提示 no available server to connect错误
也可以通过配置 spring.cloud.alibaba.seata.tx-service-group修改后缀,但是必须和file.conf中的配置保持一致
每个远程调用的小的事务方法上,标注@Transactional 注解