Java:多线程内的 XA 事务传播 [英] Java: XA Transaction propagation within many threads

问题描述

如何使用事务管理器(例如 Bitronix、JBoss TS 或 Atomikos) 在 Java SE(不是 Java EE 或 Spring)中支持以下用例:

How can I use a transaction manager (such as Bitronix, JBoss TS or Atomikos) in a Java SE (not Java EE or Spring) to support the following use case:

假设我们有以下类:

public class Dao {

    public void updateDatabase(DB db) {
        connet to db
        run a sql
    }

}

然后我们从中创建一个 Java Runnable，如下所示:

and we create a Java Runnable from that, like the following:

public class MyRunnable extends Runnable {

    Dao dao;
    DB db;

    public MyRunnable(Dao dao, DB db) {
        this.dao=dao;
        this.db = db;
    }           

    public run() throws Exception {
        return dao.updateDatabase(db);
    }
}

现在在我们的服务层，我们有另一个类:

Now in our Service layer, we have another class:

public class Service {

    public void updateDatabases() {

        BEGIN TRANSACTION;

        ExecutorService es = Executors.newFixedThreadPool(10);

        ExecutorCompletionService ecs = new ExecutorCompletionService(es);

        List<Future<T>> futures = new ArrayList<Future<T>>(n);

        Dao dao = new Dao();

        futures.add(ecs.submit(new MyRunnable(dao, new DB("db1")));
        futures.add(ecs.submit(new MyRunnable(dao, new DB("db2")));
        futures.add(ecs.submit(new MyRunnable(dao, new DB("db3")));

        for (int i = 0; i < n; ++i) {
            completionService.take().get();
        }

       END TRANSACTION;
    }

}

并且客户端可以是 Servlet 或任何其他多线程环境:

And the client can be a Servlet or any other multi-threaded environment:

public MyServlet extend HttpServlet {

    protected void service(final HttpServletRequest request, final HttpServletResponse response) throws IOException {

        Service service = new Service();

        service.updateDatabases();

    }

}

BEGIN TRANSACTION 和 END TRANSACTION 部分的正确代码是什么?这甚至可行吗?如果不是，需要改变什么?要求是使 updateDatabases() 方法保持并发(因为它将同时访问多个数据库)和事务性.

What would be the correct code for BEGIN TRANSACTION and END TRANSACTION parts? Is this even feasible? If not, what needs to be changed? The requirements is to keep the updateDatabases() method concurrent (since it will be accessing multiple databases at the same time) and transactional.

推荐答案

使用 Atomikos 使用 SubTxThread

//first start a tx
TransactionManager tm = ...
tm.begin();

Waiter waiter = new Waiter();

//the code that calls the first EIS; defined by you
SubTxCode code1 = ...

//the associated thread
SubTxThread thread1 = new SubTxThread ( waiter , code1 );

//the code that calls the second EIS; defined by you
SubTxCode code2 = ...

//the associated thread
SubTxThread thread2 = new SubTxThread ( waiter , code2 );

//start each thread
thread1.start();

thread2.start();

//wait for completion of all calls
waiter.waitForAll();

//check result
if ( waiter.getAbortCount() == 0 ) {
    //no failures -> commit tx
    tm.commit();
} else {
    tm.rollback();
}

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