Invalidate @Cachable entries by annotation on interface?

Question

I'm using spring and @Cacheable annotation to cache some database entries. I want to invalidate the full cache periodically.

Therefore: is it valid to just put these annotations on an interface method? Or do these annotations have to be placed on class methods (even if they have an empty method body)?

public interface MyRepository extends CrudRepository<MyEntity, Long> {
    @Override
    @Cacheable("cache")
    Airline findOne(long id);

    @CacheEvict(value = "cache", allEntries = true)
    @Scheduled(cron = "0 0 1 * * *")
    void removeAll();
}

The application starts up successfully if I have the @Cacheable on the interface method and the @CacheEvict in a service. It does not work if I use the code above. But maybe I'm also doing things wrong?

Answer 1

It would probably work, but I'd suggest to put these annotations on the implementation.

It's more of a theoretical question, but think of it this way: an interface is a common contract, but caching is an implementation detail.

Your interface could be implemented in a number of ways for example, one day you could have a HsqlDBRepository, for which caching doesn't make sense at all as it's already in memory.

On a side-note, I'd think carefully about why you need to 'evict all'... depending on how often it happens, it could render your caching useless - also it's often a sign of a deeper problem with the design. If you want to evict entities after some time, consider configuring timeToLive/timeToIdle - most cache backends support this nicely.