Seata源码—2.seata-samples项目介绍

Seata源码—2.seata-samples项目介绍

大纲

1.seata-samples的配置文件和启动类

2.seata-samples业务服务启动时的核心工作

3.seata-samples库存服务的连接池配置

4.Seata对数据库连接池代理配置的分析

5.Dubbo RPC通信过程中传递全局事务XID

6.Seata跟Dubbo整合的Filter(基于SPI机制)

7.seata-samples的AT事务例子原理流程

8.Seata核心配置文件file.conf的内容介绍

 

1.seata-samples的配置文件和启动类

(1)seata-samples的测试步骤

(2)seata-samples用户服务的配置和启动类

(3)seata-samples库存服务的配置和启动类

(4)seata-samples订单服务的配置和启动类

(5)seata-samples业务服务的配置和启动类

 

示例仓库：

https://github.com/seata/seata-samples

示例代码的模块ID：seata-samples-dubbo

 

(1)seata-samples的测试步骤

步骤一：启动DubboAccountServiceStarter

步骤二：启动DubboStorageServiceStarter

步骤三：启动DubboOrderServiceStarter

步骤四：运行DubboBusinessTester

 

(2)seata-samples用户服务的配置和启动类

dubbo-account-service.xml配置文件：

<?xml version=”1.0″ encoding=”UTF-8″?>

<beans xmlns=”http://www.springframework.org/schema/beans”

     xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”

     xmlns:dubbo=”http://dubbo.apache.org/schema/dubbo”

     xsi:schemaLocation=”http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd”>

    

    <!– 把jdbc.properties文件里的配置加载进来 –>

    <bean class=”org.springframework.beans.factory.config.PropertyPlaceholderConfigurer”>

        <property name=”locations” value=”classpath:jdbc.properties”/>

    </bean>

    

    <!– 将配置文件里的值注入到库存服务的数据库连接池accountDataSource中 –>

    <bean name=”accountDataSource” class=”com.alibaba.druid.pool.DruidDataSource” init-method=”init” destroy-method=”close”>

        <property name=”url” value=”${jdbc.account.url}”/>

        <property name=”username” value=”${jdbc.account.username}”/>

        <property name=”password” value=”${jdbc.account.password}”/>

        <property name=”driverClassName” value=”${jdbc.account.driver}”/>

        <property name=”initialSize” value=”0″/>

        <property name=”maxActive” value=”180″/>

        <property name=”minIdle” value=”0″/>

        <property name=”maxWait” value=”60000″/>

        <property name=”validationQuery” value=”Select 'x' from DUAL”/>

        <property name=”testOnBorrow” value=”false”/>

        <property name=”testOnReturn” value=”false”/>

        <property name=”testWhileIdle” value=”true”/>

        <property name=”timeBetweenEvictionRunsMillis” value=”60000″/>

        <property name=”minEvictableIdleTimeMillis” value=”25200000″/>

        <property name=”removeAbandoned” value=”true”/>

        <property name=”removeAbandonedTimeout” value=”1800″/>

        <property name=”logAbandoned” value=”true”/>

        <property name=”filters” value=”mergeStat”/>

    </bean>

    

    <!– 创建数据库连接池代理，通过DataSourceProxy代理accountDataSourceProxy数据库连接池 –>

    <bean class=”io.seata.rm.datasource.DataSourceProxy”>

        <constructor-arg ref=”accountDataSource”/>

    </bean>

    

    <!– 将数据库连接池代理accountDataSourceProxy注入到JdbcTemplate数据库操作组件中–>

    <bean class=”org.springframework.jdbc.core.JdbcTemplate”>

        <property name=”dataSource” ref=”accountDataSourceProxy”/>

    </bean>

    <dubbo:application name=”dubbo-demo-account-service”>

        <dubbo:parameter key=”qos.enable” value=”false”/>

    </dubbo:application>

    <dubbo:registry address=”zookeeper://localhost:2181″ />

    <dubbo:protocol name=”dubbo” port=”20881″/>

    <dubbo:service interface=”io.seata.samples.dubbo.service.AccountService” ref=”service” timeout=”10000″/>

    

    <!– 将JdbcTemplate数据库操作组件注入到AccountServiceImpl中 –>

    <bean class=”io.seata.samples.dubbo.service.impl.AccountServiceImpl”>

        <property name=”jdbcTemplate” ref=”jdbcTemplate”/>

    </bean>

    

    <!– 全局事务注解扫描组件 –>

    <bean class=”io.seata.spring.annotation.GlobalTransactionScanner”>

        <constructor-arg value=”dubbo-demo-account-service”/>

        <constructor-arg value=”my_test_tx_group”/>

    </bean>

</beans>

启动类：

public class DubboAccountServiceStarter {

    //Account service is ready. A buyer register an account: U100001 on my e-commerce platform

    public static void main(String[] args) {

        ClassPathXmlApplicationContext accountContext = new ClassPathXmlApplicationContext(

            new String[] {“spring/dubbo-account-service.xml”}

        );

        accountContext.getBean(“service”);

        JdbcTemplate accountJdbcTemplate = (JdbcTemplate)accountContext.getBean(“jdbcTemplate”);

        accountJdbcTemplate.update(“delete from account_tbl where user_id = 'U100001'”);

        accountJdbcTemplate.update(“insert into account_tbl(user_id, money) values ('U100001', 999)”);

        new ApplicationKeeper(accountContext).keep();

    }

}

//The type Application keeper.

public class ApplicationKeeper {

    private static final Logger LOGGER = LoggerFactory.getLogger(ApplicationKeeper.class);

    private final ReentrantLock LOCK = new ReentrantLock();

    private final Condition STOP = LOCK.newCondition();

    //Instantiates a new Application keeper.

    public ApplicationKeeper(AbstractApplicationContext applicationContext) {

        addShutdownHook(applicationContext);

    }

    

    private void addShutdownHook(final AbstractApplicationContext applicationContext) {

        Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {

            @Override

            public void run() {

                try {

                    applicationContext.close();

                    LOGGER.info(“ApplicationContext ” + applicationContext + ” is closed.”);

                } catch (Exception e) {

                    LOGGER.error(“Failed to close ApplicationContext”, e);

                }

                LOCK.lock();

                try {

                    STOP.signal();

                } finally {

                    LOCK.unlock();

                }

            }

        }));

    }

    

    public void keep() {

        LOCK.lock();

        try {

            LOGGER.info(“Application is keep running … “);

            STOP.await();

        } catch (InterruptedException e) {

            LOGGER.error(“ApplicationKeeper.keep() is interrupted by InterruptedException!”, e);

        } finally {

            LOCK.unlock();

        }

    }

}

(3)seata-samples库存服务的配置和启动类

dubbo-stock-service.xml配置文件：

<?xml version=”1.0″ encoding=”UTF-8″?>

<beans xmlns=”http://www.springframework.org/schema/beans”

     xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”

     xmlns:dubbo=”http://dubbo.apache.org/schema/dubbo”

     xsi:schemaLocation=”http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd”>

    

    <!– 把jdbc.properties文件里的配置加载进来 –>

    <bean class=”org.springframework.beans.factory.config.PropertyPlaceholderConfigurer”>

        <property name=”locations” value=”classpath:jdbc.properties”/>

    </bean>

    

    <!– 将配置文件里的值注入到库存服务的数据库连接池stockDataSource中 –>

    <bean name=”stockDataSource” class=”com.alibaba.druid.pool.DruidDataSource” init-method=”init” destroy-method=”close”>

        <property name=”url” value=”${jdbc.stock.url}”/>

        <property name=”username” value=”${jdbc.stock.username}”/>

        <property name=”password” value=”${jdbc.stock.password}”/>

        <property name=”driverClassName” value=”${jdbc.stock.driver}”/>

        <property name=”initialSize” value=”0″/>

        <property name=”maxActive” value=”180″/>

        <property name=”minIdle” value=”0″/>

        <property name=”maxWait” value=”60000″/>

        <property name=”validationQuery” value=”Select 'x' from DUAL”/>

        <property name=”testOnBorrow” value=”false”/>

        <property name=”testOnReturn” value=”false”/>

        <property name=”testWhileIdle” value=”true”/>

        <property name=”timeBetweenEvictionRunsMillis” value=”60000″/>

        <property name=”minEvictableIdleTimeMillis” value=”25200000″/>

        <property name=”removeAbandoned” value=”true”/>

        <property name=”removeAbandonedTimeout” value=”1800″/>

        <property name=”logAbandoned” value=”true”/>

        <property name=”filters” value=”mergeStat”/>

    </bean>

    

    <!– 创建数据库连接池代理，通过DataSourceProxy代理stockDataSource数据库连接池 –>

    <bean class=”io.seata.rm.datasource.DataSourceProxy”>

        <constructor-arg ref=”stockDataSource”/>

    </bean>

    <!– 将数据库连接池代理stockDataSourceProxy注入到JdbcTemplate数据库操作组件中–>

    <bean class=”org.springframework.jdbc.core.JdbcTemplate”>

        <property name=”dataSource” ref=”stockDataSourceProxy”/>

    </bean>

    <dubbo:application name=”dubbo-demo-stock-service”>

        <dubbo:parameter key=”qos.enable” value=”false”/>

    </dubbo:application>

    <dubbo:registry address=”zookeeper://localhost:2181″ />

    <dubbo:protocol name=”dubbo” port=”20882″/>

    <dubbo:service interface=”io.seata.samples.dubbo.service.StockService” ref=”service” timeout=”10000″/>

    

    <!– 将JdbcTemplate数据库操作组件注入到StockServiceImpl中 –>

    <bean class=”io.seata.samples.dubbo.service.impl.StockServiceImpl”>

        <property name=”jdbcTemplate” ref=”jdbcTemplate”/>

    </bean>

    

    <!– 全局事务注解扫描组件 –>

    <bean class=”io.seata.spring.annotation.GlobalTransactionScanner”>

        <constructor-arg value=”dubbo-demo-stock-service”/>

        <constructor-arg value=”my_test_tx_group”/>

    </bean>

</beans>

启动类：

//The type Dubbo stock service starter.

public class DubboStockServiceStarter {

    //Stock service is ready. A seller add 100 stock to a sku: C00321

    public static void main(String[] args) {

        ClassPathXmlApplicationContext stockContext = new ClassPathXmlApplicationContext(

            new String[] {“spring/dubbo-stock-service.xml”}

        );

        stockContext.getBean(“service”);

        JdbcTemplate stockJdbcTemplate = (JdbcTemplate)stockContext.getBean(“jdbcTemplate”);

        stockJdbcTemplate.update(“delete from stock_tbl where commodity_code = 'C00321'”);

        stockJdbcTemplate.update(“insert into stock_tbl(commodity_code, count) values ('C00321', 100)”);

        new ApplicationKeeper(stockContext).keep();

    }

}

(4)seata-samples订单服务的配置和启动类

dubbo-order-service.xml配置文件：

<?xml version=”1.0″ encoding=”UTF-8″?>

<beans xmlns=”http://www.springframework.org/schema/beans”

     xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”

     xmlns:dubbo=”http://dubbo.apache.org/schema/dubbo”

     xsi:schemaLocation=”http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd”>

    

    <!– 把jdbc.properties文件里的配置加载进来 –>

    <bean class=”org.springframework.beans.factory.config.PropertyPlaceholderConfigurer”>

        <property name=”locations” value=”classpath:jdbc.properties”/>

    </bean>

    

    <!– 将配置文件里的值注入到库存服务的数据库连接池orderDataSource中 –>

    <bean name=”orderDataSource” class=”com.alibaba.druid.pool.DruidDataSource” init-method=”init” destroy-method=”close”>

        <property name=”url” value=”${jdbc.order.url}”/>

        <property name=”username” value=”${jdbc.order.username}”/>

        <property name=”password” value=”${jdbc.order.password}”/>

        <property name=”driverClassName” value=”${jdbc.order.driver}”/>

        <property name=”initialSize” value=”0″/>

        <property name=”maxActive” value=”180″/>

        <property name=”minIdle” value=”0″/>

        <property name=”maxWait” value=”60000″/>

        <property name=”validationQuery” value=”Select 'x' from DUAL”/>

        <property name=”testOnBorrow” value=”false”/>

        <property name=”testOnReturn” value=”false”/>

        <property name=”testWhileIdle” value=”true”/>

        <property name=”timeBetweenEvictionRunsMillis” value=”60000″/>

        <property name=”minEvictableIdleTimeMillis” value=”25200000″/>

        <property name=”removeAbandoned” value=”true”/>

        <property name=”removeAbandonedTimeout” value=”1800″/>

        <property name=”logAbandoned” value=”true”/>

        <property name=”filters” value=”mergeStat”/>

    </bean>

    

    <!– 创建数据库连接池代理，通过DataSourceProxy代理stockDataSource数据库连接池 –>

    <bean class=”io.seata.rm.datasource.DataSourceProxy”>

        <constructor-arg ref=”orderDataSource”/>

    </bean>

    

    <!– 将数据库连接池代理orderDataSourceProxy注入到JdbcTemplate数据库操作组件中–>

    <bean class=”org.springframework.jdbc.core.JdbcTemplate”>

        <property name=”dataSource” ref=”orderDataSourceProxy”/>

    </bean>

    <dubbo:application name=”dubbo-demo-order-service”>

        <dubbo:parameter key=”qos.enable” value=”false”/>

    </dubbo:application>

    <dubbo:registry address=”zookeeper://localhost:2181″ />

    <dubbo:protocol name=”dubbo” port=”20883″/>

    <dubbo:service interface=”io.seata.samples.dubbo.service.OrderService” ref=”service” timeout=”10000″/>

    <dubbo:reference check=”false” interface=”io.seata.samples.dubbo.service.AccountService”/>

    

    <!– 将JdbcTemplate数据库操作组件注入到OrderServiceImpl中 –>

    <bean class=”io.seata.samples.dubbo.service.impl.OrderServiceImpl”>

        <property name=”jdbcTemplate” ref=”jdbcTemplate”/>

        <property name=”accountService” ref=”accountService”/>

    </bean>

    

    <!– 全局事务注解扫描组件 –>

    <bean class=”io.seata.spring.annotation.GlobalTransactionScanner”>

        <constructor-arg value=”dubbo-demo-order-service”/>

        <constructor-arg value=”my_test_tx_group”/>

    </bean>

</beans>

启动类：

//The type Dubbo order service starter.

public class DubboOrderServiceStarter {

    //The entry point of application.

    public static void main(String[] args) {

        //Order service is ready . Waiting for buyers to order

        ClassPathXmlApplicationContext orderContext = new ClassPathXmlApplicationContext(

            new String[] {“spring/dubbo-order-service.xml”}

        );

        orderContext.getBean(“service”);

        new ApplicationKeeper(orderContext).keep();

    }

}

(5)seata-samples业务服务的配置和启动类

dubbo-business.xml配置文件：

<?xml version=”1.0″ encoding=”UTF-8″?>

<beans xmlns=”http://www.springframework.org/schema/beans”

     xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”

     xmlns:dubbo=”http://dubbo.apache.org/schema/dubbo”

     xsi:schemaLocation=”http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd”>

    <dubbo:application name=”dubbo-demo-app”>

        <dubbo:parameter key=”qos.enable” value=”false”/>

        <dubbo:parameter key=”qos.accept.foreign.ip” value=”false”/>

        <dubbo:parameter key=”qos.port” value=”33333″/>

    </dubbo:application>

    <dubbo:registry address=”zookeeper://localhost:2181″ />

    <dubbo:reference check=”false” interface=”io.seata.samples.dubbo.service.OrderService”/>

    <dubbo:reference check=”false” interface=”io.seata.samples.dubbo.service.StockService”/>

    <bean class=”io.seata.samples.dubbo.service.impl.BusinessServiceImpl”>

        <property name=”orderService” ref=”orderService”/>

        <property name=”stockService” ref=”stockService”/>

    </bean>

    

    <!– 全局事务注解扫描组件 –>

    <bean class=”io.seata.spring.annotation.GlobalTransactionScanner”>

        <constructor-arg value=”dubbo-demo-app”/>

        <constructor-arg value=”my_test_tx_group”/>

    </bean>

</beans>

启动类：

//The type Dubbo business tester.

public class DubboBusinessTester {

    //The entry point of application.

    public static void main(String[] args) {

        //The whole e-commerce platform is ready, The buyer(U100001) create an order on the sku(C00321) , the count is 2

        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(

            new String[] {“spring/dubbo-business.xml”}

        );

        //模拟调用下单接口

        final BusinessService business = (BusinessService)context.getBean(“business”);

        business.purchase(“U100001”, “C00321”, 2);

    }

}

 

2.seata-samples业务服务启动时的核心工作

BusinessService业务服务启动时，会创建两个服务接口的动态代理。一个是OrderService订单服务接口的Dubbo动态代理，另一个是StockService库存服务接口的Dubbo动态代理。BusinessService业务服务的下单接口会添加@GlobalTransaction注解，通过@GlobalTransaction注解开启一个分布式事务，Seata的内核组件GlobalTransactionScanner就会扫描到这个注解。

//The type Dubbo business tester.

public class DubboBusinessTester {

    //The entry point of application.

    public static void main(String[] args) {

        //The whole e-commerce platform is ready , The buyer(U100001) create an order on the sku(C00321) , the count is 2

        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(

            new String[] {“spring/dubbo-business.xml”}

        );

        //模拟调用下单接口

        final BusinessService business = (BusinessService)context.getBean(“business”);

        business.purchase(“U100001”, “C00321”, 2);

    }

}

public class BusinessServiceImpl implements BusinessService {

    private static final Logger LOGGER = LoggerFactory.getLogger(BusinessService.class);

    private StockService stockService;

    private OrderService orderService;

    private Random random = new Random();

    @Override

    @GlobalTransactional(timeoutMills = 300000, name = “dubbo-demo-tx”)//分布式事务如果5分钟还没跑完，就是超时

    public void purchase(String userId, String commodityCode, int orderCount) {

        LOGGER.info(“purchase begin … xid: ” + RootContext.getXID());

        stockService.deduct(commodityCode, orderCount);

        orderService.create(userId, commodityCode, orderCount);

        if (random.nextBoolean()) {

            throw new RuntimeException(“random exception mock!”);

        }

    }

    

    //Sets stock service.

    public void setStockService(StockService stockService) {

        this.stockService = stockService;

    }

    

    //Sets order service.

    public void setOrderService(OrderService orderService) {

        this.orderService = orderService;

    }

}

 

3.seata-samples库存服务的连接池配置

首先会把jdbc.properties文件里的配置加载进来，然后将配置配置的值注入到库存服务的数据库连接池，接着通过Seata的DataSourceProxy对数据库连接池进行代理。

 

一.启动类

//The type Dubbo stock service starter.

public class DubboStockServiceStarter {

    //Stock service is ready. A seller add 100 stock to a sku: C00321

    public static void main(String[] args) {

        ClassPathXmlApplicationContext stockContext = new ClassPathXmlApplicationContext(

            new String[] {“spring/dubbo-stock-service.xml”}

        );

        stockContext.getBean(“service”);

        JdbcTemplate stockJdbcTemplate = (JdbcTemplate)stockContext.getBean(“jdbcTemplate”);

        stockJdbcTemplate.update(“delete from stock_tbl where commodity_code = 'C00321'”);

        stockJdbcTemplate.update(“insert into stock_tbl(commodity_code, count) values ('C00321', 100)”);

        new ApplicationKeeper(stockContext).keep();

    }

}

二.dubbo-stock-service.xml文件

<?xml version=”1.0″ encoding=”UTF-8″?>

<beans xmlns=”http://www.springframework.org/schema/beans”

       xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”

       xmlns:dubbo=”http://dubbo.apache.org/schema/dubbo”

       xsi:schemaLocation=”http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd”>

    

    <!– 把jdbc.properties文件里的配置加载进来 –>

    <bean class=”org.springframework.beans.factory.config.PropertyPlaceholderConfigurer”>

        <property name=”locations” value=”classpath:jdbc.properties”/>

    </bean>

    

    <!– 将配置文件里的值注入到库存服务的数据库连接池stockDataSource中 –>

    <bean name=”stockDataSource” class=”com.alibaba.druid.pool.DruidDataSource” init-method=”init” destroy-method=”close”>

        <property name=”url” value=”${jdbc.stock.url}”/>

        <property name=”username” value=”${jdbc.stock.username}”/>

        <property name=”password” value=”${jdbc.stock.password}”/>

        <property name=”driverClassName” value=”${jdbc.stock.driver}”/>

        <property name=”initialSize” value=”0″/>

        <property name=”maxActive” value=”180″/>

        <property name=”minIdle” value=”0″/>

        <property name=”maxWait” value=”60000″/>

        <property name=”validationQuery” value=”Select 'x' from DUAL”/>

        <property name=”testOnBorrow” value=”false”/>

        <property name=”testOnReturn” value=”false”/>

        <property name=”testWhileIdle” value=”true”/>

        <property name=”timeBetweenEvictionRunsMillis” value=”60000″/>

        <property name=”minEvictableIdleTimeMillis” value=”25200000″/>

        <property name=”removeAbandoned” value=”true”/>

        <property name=”removeAbandonedTimeout” value=”1800″/>

        <property name=”logAbandoned” value=”true”/>

        <property name=”filters” value=”mergeStat”/>

    </bean>

    

    <!– 创建数据库连接池代理，通过DataSourceProxy代理stockDataSource数据库连接池 –>

    <bean class=”io.seata.rm.datasource.DataSourceProxy”>

        <constructor-arg ref=”stockDataSource”/>

    </bean>

    

    <!– 将数据库连接池代理stockDataSourceProxy注入到JdbcTemplate数据库操作组件中–>

    <bean class=”org.springframework.jdbc.core.JdbcTemplate”>

        <property name=”dataSource” ref=”stockDataSourceProxy”/>

    </bean>

    <dubbo:application name=”dubbo-demo-stock-service”>

        <dubbo:parameter key=”qos.enable” value=”false”/>

    </dubbo:application>

    <dubbo:registry address=”zookeeper://localhost:2181″ />

    <dubbo:protocol name=”dubbo” port=”20882″/>

    <dubbo:service interface=”io.seata.samples.dubbo.service.StockService” ref=”service” timeout=”10000″/>

    

    <!– 将JdbcTemplate数据库操作组件注入到StockServiceImpl中 –>

    <bean class=”io.seata.samples.dubbo.service.impl.StockServiceImpl”>

        <property name=”jdbcTemplate” ref=”jdbcTemplate”/>

    </bean>

    

    <!– 全局事务注解扫描组件 –>

    <bean class=”io.seata.spring.annotation.GlobalTransactionScanner”>

        <constructor-arg value=”dubbo-demo-stock-service”/>

        <constructor-arg value=”my_test_tx_group”/>

    </bean>

</beans>

三.jdbc.properties文件文件

jdbc.account.url=jdbc:mysql://localhost:3306/seata

jdbc.account.username=root

jdbc.account.password=123456

jdbc.account.driver=com.mysql.jdbc.Driver

# stock db config

jdbc.stock.url=jdbc:mysql://localhost:3306/seata

jdbc.stock.username=root

jdbc.stock.password=123456

jdbc.stock.driver=com.mysql.jdbc.Driver

# order db config

jdbc.order.url=jdbc:mysql://localhost:3306/seata

jdbc.order.username=root

jdbc.order.password=123456

jdbc.order.driver=com.mysql.jdbc.Driver

 

4.Seata对数据库连接池代理配置的分析

数据库连接池代理DataSourceProxy，会注入到JdbcTemplate数据库操作组件中。这样库存或者订单服务就可以通过Spring数据库操作组件JdbcTemplate，向Seata数据库连接池代理DataSourceProxy获取一个数据库连接。然后通过数据库连接，把SQL请求发送给MySQL进行处理。

 

5.Dubbo RPC通信过程中传递全局事务XID

BusinessService对StockService进行RPC调用时，会传递全局事务XID。StockService便可以根据RootContext.getXID()获取到全局事务XID。

public class BusinessServiceImpl implements BusinessService {

    private static final Logger LOGGER = LoggerFactory.getLogger(BusinessService.class);

    private StockService stockService;

    private OrderService orderService;

    private Random random = new Random();

    @Override

    @GlobalTransactional(timeoutMills = 300000, name = “dubbo-demo-tx”)//分布式事务如果5分钟还没跑完，就是超时

    public void purchase(String userId, String commodityCode, int orderCount) {

        LOGGER.info(“purchase begin … xid: ” + RootContext.getXID());

        stockService.deduct(commodityCode, orderCount);

        orderService.create(userId, commodityCode, orderCount);

        if (random.nextBoolean()) {

            throw new RuntimeException(“random exception mock!”);

        }

    }

    …

}

public class StockServiceImpl implements StockService {

    private static final Logger LOGGER = LoggerFactory.getLogger(StockService.class);

    private JdbcTemplate jdbcTemplate;

    @Override

    public void deduct(String commodityCode, int count) {

        LOGGER.info(“Stock Service Begin … xid: ” + RootContext.getXID());

        LOGGER.info(“Deducting inventory SQL: update stock_tbl set count = count – {} where commodity_code = {}”, count, commodityCode);

        jdbcTemplate.update(“update stock_tbl set count = count – ? where commodity_code = ?”, new Object[] {count, commodityCode});

        LOGGER.info(“Stock Service End … “);

    }

    …

}

 

6.Seata跟Dubbo整合的Filter(基于SPI机制)

Seata与Dubbo整合的Filter过滤器ApacheDubboTransactionPropagationFilter会将向SeataServer注册的全局事务xid，设置到RootContext中。

 

7.seata-samples的AT事务例子原理流程

 

8.Seata核心配置文件file.conf的内容介绍

# Seata网络通信相关的配置

transport {

    # 网络通信的类型是TCP

    type = “TCP”

    # 网络服务端使用NIO模式

    server = “NIO”

    # 是否开启心跳

    heartbeat = true

    # 是否允许Seata的客户端批量发送请求

    enableClientBatchSendRequest = true

    # 使用Netty进行网络通信时的线程配置

    threadFactory {

        bossThreadPrefix = “NettyBoss”

        workerThreadPrefix = “NettyServerNIOWorker”

        serverExecutorThread-prefix = “NettyServerBizHandler”

        shareBossWorker = false

        clientSelectorThreadPrefix = “NettyClientSelector”

        clientSelectorThreadSize = 1

        clientWorkerThreadPrefix = “NettyClientWorkerThread”

        # 用来监听和建立网络连接的Boss线程的数量

        bossThreadSize = 1

        # 默认的Worker线程数量是8

        workerThreadSize = “default”

    }

    shutdown {

        # 销毁服务端的时候的等待时间是多少秒

        wait = 3

    }

    # 序列化类型是Seata

    serialization = “seata”

    # 是否开启压缩

    compressor = “none”

}

# Seata服务端相关的配置

service {

    # 分布式事务的分组

    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”

    # 是否开启降级

    enableDegrade = false

    # 是否禁用全局事务

 

   disableGlobalTransaction = false

}

# Seata客户端相关的配置

client {

    # 数据源管理组件的配置

    rm {

        # 异步提交缓冲区的大小

        asyncCommitBufferLimit = 10000

        # 锁相关的配置：重试间隔、重试次数、回滚冲突处理

        lock {

            retryInterval = 10

            retryTimes = 30

            retryPolicyBranchRollbackOnConflict = true

        }

        reportRetryCount = 5

        tableMetaCheckEnable = false

        reportSuccessEnable = false

    }

    # 事务管理组件的配置

    tm {

        commitRetryCount = 5

        rollbackRetryCount = 5

    }

    # 回滚日志的配置

    undo {

        dataValidation = true