How to commit the current guice-persist UnitOfWork?

Question

I'm using a UnitOfWork in a background task method (operated by Quartz) with Guice-persist on top of hibernate. The background task call a service, which need to commit the current transaction in the middle of it's task - and continue on another transaction. How can I commit the current UnitOfWork and create a new one?

class BackgroundJob {
    @Inject UnitOfWork unitOfWork;
    @Inject MyService myService;
    public void run() {
        try {
            unitOfWork.begin();
            myService.foo();
        } finally {
            unitOfWork.end();
}   }   }

class MyServiceImpl implements MyService {
    @Override public void foo() {
        foo1();
        // I would like to commit here and start a new transaction
        foo2();
}   }

The service is also managed by Guice, but is a singleton, and do not have access to the caller UnitOfWork as is.

Ideally I do not want to change service signature. A workaround is for the caller to give two UnitOfWork as parameters to foo(), but this seems a bit hacked.

EDIT: For ease of use of future fellow reader, here is my implementation of the solution given by ColinD, which fits the bill nicely:

class BackgroundJob {
    @Inject UnitOfWork unitOfWork;
    @Inject MyService myService;
    public void run() {
        try {
            unitOfWork.begin();
            myService.foo();
        } finally {
            unitOfWork.end();
}   }   }

class MyServiceImpl implements MyService {
    @Override public void foo() {
        foo1();
        foo2();
    }
    @Transactional private void foo1() { ... }
    @Transactional private void foo2() { ... }
}

Just an observation, don't you want to rollback the transaction in case of exception ?. — Sajan Chandran, Feb 08 '12 at 18:05
Well, I want to rollback the first if the first transaction has an exception, but once committed I do not care. If the second fails, I want to rollback the second transaction but not the first. Thus my need to have *two* transaction. — Laurent Grégoire, Feb 08 '12 at 19:43

score 4 · Accepted Answer · answered Feb 09 '12 at 14:59

If I recall correctly, a unit of work in Guice Persist is not a single transaction. Rather, it represents a single unit of work such as a single web request or, in your case, a single background job. I believe that a single database connection is used for a whole unit of work, but that unit of work may have multiple distinct transactions. In fact, I think that just starting and ending a unit of work will not cause any transactions to be started or ended.

I think what you want to do is to annotate both foo1() and foo2() (but not foo()) with @Transactional. As long as there's no outer transaction wrapping both calls, they'll each run in a separate transaction.

score 0 · Answer 2 · edited Mar 04 '17 at 14:49

0

This may fit the bill.

class BackgroundJob {
    @Inject UnitOfWork unitOfWork;
    @Inject MyService myService;

    public void run() {
        try {
            unitOfWork.begin();
            myService.foo1();
            unitOfWork.end();
           unitOfWork.begin();
            myService.foo2();
            unitOfWork.end();
        } finally {
            unitOfWork.end();
        }
    }
}

edited Mar 04 '17 at 14:49

Sergey Vyacheslavovich Brunov

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answered Feb 08 '12 at 18:08

Sajan Chandran

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How to commit the current guice-persist UnitOfWork?

2 Answers2