Spring cache @Cacheable method ignored when called from within the same class

Question

I'm trying to call a @Cacheable method from within the same class:

@Cacheable(value = "defaultCache", key = "#id")
public Person findPerson(int id) {
   return getSession().getPerson(id);
} 

public List<Person> findPersons(int[] ids) {
   List<Person> list = new ArrayList<Person>();
   for (int id : ids) {
      list.add(findPerson(id));
   }
   return list;
}

and hoping that the results from findPersons are cached as well, but the @Cacheable annotation is ignored, and findPerson method got executed everytime.

Am I doing something wrong here, or this is intended?

Similar question: stackoverflow.com/questions/16899604/…. Here is another simple and good solution: stackoverflow.com/questions/16899604/… — Grigory Kislin
– Grigory Kislin, Commented Feb 16, 2016 at 17:06

uthark · Accepted Answer · 2013-09-11 21:08:51Z

65

This is because of the way proxies are created for handling caching, transaction related functionality in Spring. This is a very good reference of how Spring handles it - Transactions, Caching and AOP: understanding proxy usage in Spring

In short, a self call bypasses the dynamic proxy and any cross cutting concern like caching, transaction etc which is part of the dynamic proxies logic is also bypassed.

The fix is to use AspectJ compile time or load time weaving.

edited Sep 11, 2013 at 21:08

uthark

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answered Aug 24, 2012 at 20:22

Biju Kunjummen

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9 Comments

Gonzalo Over a year ago

We had the same problem with transactional annotations and did exactly as Biju posted. No problems since then.

David Zhao Over a year ago

@Gonzalo Just read the blog, could you elaborate on using AspectJ at compile time to solve this? thx!

Biju Kunjummen Over a year ago

I have one example of using caching annotations with compile time aspectj weaving at - github.com/bijukunjummen/cache-sample.git , the behavior is similar to yours, a method self calling an @Cacheable method

Biju Kunjummen Over a year ago

Also, one bad fix will be to get the proxy and make the call through that - ((PersonService)AopContext.currentProxy())).findPerson(id)

Gonzalo Over a year ago

@David We only had to include this in our applicationContext.xml: <aop:aspectj-autoproxy proxy-target-class="true" /> which worked with the same Transactional annotations. Didn't try with Cacheable methods though

|

Mario Eis · Accepted Answer · 2015-12-04 14:42:45Z

30

Here is what I do for small projects with only marginal usage of method calls within the same class. In-code documentation is strongly advidsed, as it may look strage to colleagues. But its easy to test, simple, quick to achieve and spares me the full blown AspectJ instrumentation. However, for more heavy usage I'd advice the AspectJ solution.

@Service
@Scope(proxyMode = ScopedProxyMode.TARGET_CLASS)
class PersonDao {

    private final PersonDao _personDao;

    @Autowired
    public PersonDao(PersonDao personDao) {
        _personDao = personDao;
    }

    @Cacheable(value = "defaultCache", key = "#id")
    public Person findPerson(int id) {
        return getSession().getPerson(id);
    }

    public List<Person> findPersons(int[] ids) {
        List<Person> list = new ArrayList<Person>();
        for (int id : ids) {
            list.add(_personDao.findPerson(id));
        }
        return list;
    }
}

answered Dec 4, 2015 at 14:42

Mario Eis

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5 Comments

jeffery.yuan Over a year ago

Could you please explain why it works after add @Scope(proxyMode = ScopedProxyMode.TARGET_CLASS)? What is used for?

Mario Eis Over a year ago

Because to inject PersonDao into PersonDao you need to have an instance of PersonDao before it gets instantiated :) To get around that, a stub proxy (see doc) is created, injected and later filled with the same PersonDao instance it got injected to. Sooo, PersonDao can hold an instance of itself, wrapped into a stub proxy. Easy as that :) Don't know if that was clear enough... :D

nkatsar Over a year ago

Thanks, it still works great! Note that I had to replace all lines before @Cacheable... find Person() by @Autowired private PersonDao _personDao;

JRA_TLL Over a year ago

The approach does not work if the class autowires some third class. In that case, the third class instances are not populated (remain null) in the _personDao instance.

JRA_TLL Over a year ago

Note that findPerson must be public! If it was private, all its field were null.

Dónal Boyle · Accepted Answer · 2013-05-31 19:13:39Z

2

For anyone using the Grails Spring Cache plugin, a workaround is described in the documentation. I had this issue on a grails app, but unfortunately the accepted answer seems to be unusable for Grails. The solution is ugly, IMHO, but it works.

The example code demonstrates it well:

class ExampleService {
    def grailsApplication

    def nonCachedMethod() {
        grailsApplication.mainContext.exampleService.cachedMethod()
    }

    @Cacheable('cachedMethodCache')
    def cachedMethod() {
        // do some expensive stuff
    }
}

Simply replace exampleService.cachedMethod() with your own service and method.

answered May 31, 2013 at 19:13

Dónal Boyle

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Comments

Tomas F. · Accepted Answer · 2023-11-20 15:52:51Z

0

If you're accessing cache from withing the same class, you probably don't need spring cache at all.

Take a look at different map implementations:

LoadingCache<Key, Graph> graphs = CacheBuilder.newBuilder()
.maximumSize(10000)
.expireAfterWrite(10, TimeUnit.MINUTES)
.build(
    new CacheLoader<Key, Graph>() {
      public Graph load(Key key) throws AnyException {
        return createExpensiveGraph(key);
      }
    });

Java time-based map/cache with expiring keys

answered Nov 20, 2023 at 15:52

Tomas F.

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