Task Scheduler in spring boot

Question

I asked this question before but unfortunately did not receive an answer.

I am writing a Spring Boot application. We send out over 1000 emails per day to our employees.

Since there is a limit on the number of emails I can send per hour, I want to send 99 emails per hour to the email addresses on my list.

I have the code that you see on your screens, how could I rewrite it with TASK SCHEDULER?

The mailing starts AFTER the send button is pressed on the front (I have an endpoint with a POST method for this) mailing so I don't use a normal SCHEDULER with cron that runs at a specific time regardless of whether my controller method was called from the front.

        Runnable task = () -> {

            int counter = 0;
            long startTime = System.currentTimeMillis();
            for (String emailAddress : usersEmailAddresses) {
                counter++;
                bulkEmailService.send(BulkEmailMessage.builder()
                        .from(bulkEmailMessage.getFrom())
                        .subject(bulkEmailMessage.getSubject())
                        .content(bulkEmailMessage.getContent())
                        .toAddresses(emailAddress)
                        .build());

                if (counter % 99 == 0) {
                    long endTime = System.currentTimeMillis() - startTime;
                    try {
                        Thread.sleep(6000 * 60 * 60 - endTime);
                    } catch (InterruptedException e) {
                        throw new RuntimeException(e);
                    }
                    startTime = System.currentTimeMillis();
                }
            }

        };
        taskExecutor.execute(task);

Answer 1

You could create a database table that saves the task you want to execute when a user calls your endpoint. Then you can use a scheduler using the data saved in the database.

Task	Cron	Execs
Email	0 0 */1 * * *	10