CODEWITHSUNDEEP
javaspring-bootschedulerspring-scheduled
noobCoder
noobCoder

Reputation: 322

How to schedule a task in spring boot with increasing delay?

I need to schedule a task which will execute first after 10 mins then 100, then 1000 and so on (basically exponentially 10^n). I have found that @Scheduled takes only constant as parameter. How can achieve increment in delay?

Upvotes: 2

Views: 2075

Answers (1)

František Hartman
František Hartman

Reputation: 15076

You can use SchedulingConfigurer with custom Trigger:

@Configuration
@EnableScheduling
public class Schedule implements SchedulingConfigurer {

@Override
public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
    taskRegistrar.setScheduler(taskScheduler());
    taskRegistrar.addTriggerTask(
            myTask(), new ExponentialTrigger()
    );
}

static class ExponentialTrigger implements Trigger {

    long n = 0;

    @Override
    public Date nextExecutionTime(TriggerContext triggerContext) {
        // delay from last scheduled time or completion time? pick yours 
        Date lastDate = triggerContext.lastScheduledExecutionTime(); 
        long last;
        if (lastDate == null) {
            last = System.currentTimeMillis();
        } else {
            last = lastDate.getTime();
        }

        return new Date(last + ((int) Math.pow(10, n++)) * 60_000); // * 60_000 millis to minutes
    }
}


@Bean(destroyMethod = "shutdown")
public ExecutorService taskScheduler() {
    return Executors.newScheduledThreadPool(42); // if you have single task, which is faster than delay then this can be 1
}

@Bean
public Runnable myTask() {
    return new Runnable() {
        @Override
        public void run() {
            System.out.println(System.currentTimeMillis());
        }
    };
}

}

Upvotes: 3

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