seata(5):dubbo

golang算法架构leetcode技术php 2023-09-22

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接着看下dubbo模式的源码，它的实现和api其实很相似，只不过从单体服务变成了4个微服务，首先看下三个RM的实现，基本没有变化，比如Account

    public void debit(String userId, int money) {
        LOGGER.info("Account Service ... xid: " + RootContext.getXID());
        LOGGER.info("Deducting balance SQL: update account_tbl set money = money - {} where user_id = {}", money,
            userId);


        jdbcTemplate.update("update account_tbl set money = money - ? where user_id = ?", new Object[] {money, userId});
        LOGGER.info("Account Service End ... ");
    }
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order和stock也类似就不介绍了。TM抽象出了一个BusinessServiceImpl，它实现的区别是什么呢？去掉了申请全局事务id，然后通过try cache判断是否出错来决定提交事务还是回滚事务，多了一个 @GlobalTransactional注解

@Override
    @GlobalTransactional(timeoutMills = 300000, name = "dubbo-demo-tx")
    public void purchase(String userId, String commodityCode, int orderCount) {
        LOGGER.info("purchase begin ... xid: " + RootContext.getXID());
        stockService.deduct(commodityCode, orderCount);
        // just test batch update
        //stockService.batchDeduct(commodityCode, orderCount);
        orderService.create(userId, commodityCode, orderCount);
        if (random.nextBoolean()) {
            throw new RuntimeException("random exception mock!");
        }


    }
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相应的，我们到，src/main/resources/spring/dubbo-business.xml里面可以看到，它除了使用dubbo协议暴露服务外

    <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="multicast://224.5.6.7:1234?unicast=false"/>
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还加入了一个bean，通过这个bean完成注解的扫描，通过注解实现动态代理，添加事务执行和回滚对应的切片代码，降低了代码的复杂性。

    <bean class="io.seata.spring.annotation.GlobalTransactionScanner">
        <constructor-arg value="dubbo-demo-app"/>
        <constructor-arg value="my_test_tx_group"/>
    </bean>
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除了上述代码外，还实现了几个对应的starter，开启一个新的线程，等待退出之前来清理资源

    public static void main(String[] args) {
        /**
         *  3. 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();
    }
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在keeper里面注册了shutDown的hook方法

        Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
            @Override
            public void run() {
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然后在我们的testClient里面触发执行我们的业务。

    public static void main(String[] args) {
        /**
         *  4. 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"});
        final BusinessService business = (BusinessService)context.getBean("business");
        business.purchase("U100001", "C00321", 200);
    }
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seata(5):dubbo

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