I am new to spring boot and I have a requirement in which I have to run scheduler only if new data is inserted into table. Thanks for any help

CodePudding user response：

Hibernate has an interceptor mecanism that allows you to get notified, at specific times, when database events occurs.

Such events are creation/deletion/flush of the session. As you get access to the objects being subject to the given event, you have a mean to fire a process when a given object of a given class (which you can easily map to a table in your schema) is modified.

The javadoc can be found here : https://docs.jboss.org/hibernate/orm/4.0/manual/en-US/html/events.html

You can use the interceptor mecanism along with Java's ScheduledExecutorService to schedule a task when hibernate intercepts the save operation. You can create your business logic under that interceptor.

CodePudding user response：

Scheduling is not enabled by default. Before adding any scheduled jobs we need to enable scheduling explicitly by adding the @enableScheduling annotation.

Now with the help of the ScheduledTaskRegistrar#addTriggerTask method, we can add a Runnable task and a Trigger implementation to recalculate the next execution time after the end of each execution.

@EnableScheduling
public class DynamicSchedulingConfig implements SchedulingConfigurer {

    @Autowired
    private TickService tickService;

    @Bean
    public Executor taskExecutor() {
        return Executors.newSingleThreadScheduledExecutor();
    }

    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        taskRegistrar.setScheduler(taskExecutor());
        taskRegistrar.addTriggerTask(
          new Runnable() {
              @Override
              public void run() {
                  tickService.tick();
              }
          },
          new Trigger() {
              @Override
              public Date nextExecutionTime(TriggerContext context) {
                  Optional<Date> lastCompletionTime =
                    Optional.ofNullable(context.lastCompletionTime());
                  Instant nextExecutionTime =
                    lastCompletionTime.orElseGet(Date::new).toInstant()
                      .plusMillis(tickService.getDelay());
                  return Date.from(nextExecutionTime);
              }
          }
        )
    }

}