send email after commit using spring transaction

Sometimes you want a little more control over transaction but at the same time you don't want to switch to programmatic transaction management. I'm talking about cases when you want to execute some activities only when transaction was completed successfully. For example: send an email with registration details, update a cache, send a message over network, etc. The tricky part here is that you want to perform these activities from a transactional method (a method marked with @Transactional which automatically will start and end the transaction).

@Component
public class AfterCommitExecutorImpl extends TransactionSynchronizationAdapter implements AfterCommitExecutor {
    private static final Logger LOGGER = LoggerFactory.getLogger(AfterCommitExecutorImpl.class);
    private static final ThreadLocal<List<Runnable>> RUNNABLES = new ThreadLocal<List<Runnable>>();

    @Override
    public void execute(Runnable runnable) {
        LOGGER.info("Submitting new runnable {} to run after commit", runnable);
        if (!TransactionSynchronizationManager.isSynchronizationActive()) {
            LOGGER.info("Transaction synchronization is NOT ACTIVE. Executing right now runnable {}", runnable);
            runnable.run();
            return;
        }
        List<Runnable> threadRunnables = RUNNABLES.get();
        if (threadRunnables == null) {
            threadRunnables = new ArrayList<Runnable>();
            RUNNABLES.set(threadRunnables);
            TransactionSynchronizationManager.registerSynchronization(this);
        }
        threadRunnables.add(runnable);
    }

    @Override
    public void afterCommit() {
        List<Runnable> threadRunnables = RUNNABLES.get();
        LOGGER.info("Transaction successfully committed, executing {} runnables", threadRunnables.size());
        for (int i = 0; i < threadRunnables.size(); i++) {
            Runnable runnable = threadRunnables.get(i);
            LOGGER.info("Executing runnable {}", runnable);
            try {
                runnable.run();
            } catch (RuntimeException e) {
                LOGGER.error("Failed to execute runnable " + runnable, e);
            }
        }
    }

    @Override
    public void afterCompletion(int status) {
        LOGGER.info("Transaction completed with status {}", status == STATUS_COMMITTED ? "COMMITTED" : "ROLLED_BACK");
        RUNNABLES.remove();
    }

}

example:

final String email = user.getEmail();
            afterCommitExecutor.execute(new Runnable() {
                @Override
                public void run() {
                    mailService.sendMail(email, "CreateUser", params, "templates/email/CreateUser.ftl");
                }
            });