Setting hibernate second level cache

Question

I am new in hibernate and spring and I experiment with hibernate second level cache. But it seems doesn't work. I have a following test class:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:applicationContext.xml" })
@TransactionConfiguration
@Transactional
public class CacheTest extends AbstractTransactionalJUnit4SpringContextTests
{   
    @Test
        public void testCache1() 
        {
        System.out.println("Running testCache1");
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        MutableDAO<AppUser> appUserDAO = new MutableDAOImpl<AppUser>(AppUser.class, (SessionFactory) ctx.getBean("OnMediaSessionFactory"), 10);
        assertNotNull("AppUser DAO is null.", appUserDAO);

        SessionFactory sessionFactory = (SessionFactory)ctx.getBean("OnMediaSessionFactory");
        long numberOfUsers = appUserDAO.countAll();

        System.out.println("Number of rows :" + numberOfUsers);
        final String cacheRegion = AppUser.class.getCanonicalName();

        SecondLevelCacheStatistics settingsStatistics = sessionFactory.getStatistics().
            getSecondLevelCacheStatistics(cacheRegion);
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();
        appUserDAO.findAll();
        stopWatch.stop();
        System.out.println("Query time : " + stopWatch.getTotalTimeSeconds());
        System.out.println(settingsStatistics);
     }

    @Test
    public void testCache2() 
    {
        System.out.println("Running testCache2");
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        MutableDAO<AppUser> appUserDAO = new MutableDAOImpl<AppUser>(AppUser.class, (SessionFactory) ctx.getBean("OnMediaSessionFactory"), 10);
        assertNotNull("AppUser DAO is null.", appUserDAO);

        SessionFactory sessionFactory = (SessionFactory)ctx.getBean("OnMediaSessionFactory");
        long numberOfUsers = appUserDAO.countAll();

        System.out.println("Number of rows :" + numberOfUsers);
        final String cacheRegion = AppUser.class.getCanonicalName();

        SecondLevelCacheStatistics settingsStatistics = sessionFactory.getStatistics().
            getSecondLevelCacheStatistics(cacheRegion);
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();
        appUserDAO.findAll();
        stopWatch.stop();
        System.out.println("Query time : " + stopWatch.getTotalTimeSeconds());
        System.out.println(settingsStatistics);
     }
}

and i have

<prop key="hibernate.show_sql">false</prop>
<prop key="hibernate.format_sql">true</prop>
<prop key="hibernate.use_sql_comments">true</prop>
<prop key="hibernate.cache.use_query_cache">true</prop>
<prop key="hibernate.cache.use_second_level_cache">true</prop>
<prop key="hibernate.generate_statistics">true</prop>
<prop key="hibernate.cache.use_structured_entries">true</prop>

but i get output like this:

Running testCache1
Number of rows :81
Query time : 0.129
SecondLevelCacheStatistics[hitCount=0,missCount=0,putCount=81,elementCountInMemory=81,elementCountOnDisk=0,sizeInMemory=219634]
Running testCache2
Number of rows :81
Query time : 0.063
SecondLevelCacheStatistics[hitCount=0,missCount=0,putCount=81,elementCountInMemory=81,elementCountOnDisk=0,sizeInMemory=219634]

what i have to do to get it work ?

Answer 1

Your test looks very strange, you create a new application context for each test, therefore Hibernate SessionFactory doesn't survive between tests, as well as its second-level cache.

Correct test would look like this:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:applicationContext.xml" })
public class CacheTest extends AbstractTransactionalJUnit4SpringContextTests
{   
    @Autowired
    private MutableDAO<AppUser> appUserDAO;

    @Autowired
    private SessionFactory sessionFactory;

    private TransactionTemplate tx;

    @Autowired
    public void setPtm(PlatformTransactionManagement ptm) {
        tx = new TransactionTemplate(ptm);
    }

    @Test
    public void doTestCache() {
        // Using programmatic transaction management since we need 2 transactions
        // inside the same method

        // 1st attempt
        tx.execute(new TransactionCallbackWithoutResult() {
            public void doInTransactionWithoutResult(TransactionStatus status) {
                testCache();
            }
        });

        // 2nd attempt
        tx.execute(new TransactionCallbackWithoutResult() {
            public void doInTransactionWithoutResult(TransactionStatus status) {
                testCache();
            }
        });

    }

    public void testCache() {
        long numberOfUsers = appUserDAO.countAll();

        System.out.println("Number of rows :" + numberOfUsers);
        final String cacheRegion = AppUser.class.getCanonicalName();

        SecondLevelCacheStatistics settingsStatistics = sessionFactory.getStatistics().
            getSecondLevelCacheStatistics(cacheRegion);
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();
        appUserDAO.findAll();
        stopWatch.stop();
        System.out.println("Query time : " + stopWatch.getTotalTimeSeconds());
        System.out.println(settingsStatistics);
     }      
 }

Answer 2

First of all, remember that Hibernate doesn't uses any cache provider by default. So, you'll need an "external" cache provider for Hibernate's 2L cache. For my answer, I'll use ehcache and Hibernate 3.3. Note that the configuration was changed in more recent versions of Hibernate so, read the docs for the exact version you are using.

In your Hibernate configuration, you missed one part, which is to point Hibernate to the actual provider. The property hibernate.cache.provider_class does that for Hibernate 3.3. Set it's value to net.sf.ehcache.hibernate.SingletonEhCacheProvider

Now, you'll need also an ehcache.xml, like this:

<?xml version="1.0" encoding="UTF-8"?>
<ehcache>

    <diskStore path="./cache" />

    <defaultCache   maxElementsInMemory="10000" 
                    eternal="true"
                    overflowToDisk="true"
                    diskPersistent="true" 
                    diskExpiryThreadIntervalSeconds="120"
                    memoryStoreEvictionPolicy="FIFO" />

    <cache  name="com.mycompany.jpa.MyEntity" 
            maxElementsInMemory="50" 
            overflowToDisk="true" />

    <cache  name="org.hibernate.cache.StandardQueryCache" 
            maxElementsInMemory="50" 
            overflowToDisk="true" />

    <cache  name="org.hibernate.cache.UpdateTimestampsCache" 
            maxElementsInMemory="5000"
            overflowToDisk="true" />

</ehcache>

You didn't show your DAO, so, I'm not sure it's correct or not. Note that you always need to be explicit about cache, as it's meant to be used a solution for specific places, instead of generic solution for everything. That means, in your DAO, you'd add a query hint, stating that your query is cacheable (from your test, it seems you want query cache, not just entity caching).

If you are still unable to make it work, please see the attachment in the following JIRA. It contains a maven project with cache enabled, so, you may be able to compare it with your code:

https://issues.jboss.org/browse/JBPAPP-4224