Share cache manager with hibernate

[scesbron]

Is it possible to define an ehcache cache manager in my applicationContext and to use it in both hibernate and my caches.

It can't figure out how I can pass my cache manager to hibernate. Does this mean that if I use ehcache for my own purpose I will have two cache manager : one for hibernate and one for me ? Is it a problem ?

Thanx

Seb

[alesj]

EhCache uses only one CacheManager instance - singleton. So you will always get the same instance, no matter wher you use it.
But at the moment ehcache doesn't count instance requests, which is not a good thing when doing a manager shutdown - it closes it on first call, although other parts of app might still use it.

I fixed this part:

public void shutdown() {
if (isAlive()) {
released();
return;
} else if (status == STATUS_SHUTDOWN) {

/**
* Counting the number of times the instance has been requested.
* So when different libraries or parts of app use getInstance method
* it get incremented and when that same code calls (it should!) shutdown it gets decremented.
* So that we don't get warning log output on shut down.
*/

private void requested() {
instanceRequestCount++;
}

private void released() {
instanceRequestCount--;
}

public boolean isAlive() {
return (status == STATUS_ALIVE && instanceRequestCount > 0);
}

public static CacheManager create() throws CacheException {
synchronized (CacheManager.class) {
if (instance == null) {
if (LOG.isDebugEnabled()) {
LOG.debug("Creating new CacheManager with default config");
}
instance = new CacheManager();
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("Attempting to create an existing instance. Existing instance returned.");
}
}
instance.requested();
return instance;
}
}

[Costin Leau]

One other solution (but I depends on your requirements) is to use a different cache provider like OSCache. Take a look at it - it's well supported and has plenty of nifty features.

[jfrank]

Now that EhCache supports multiple CacheManagers, I am wondering how to ensure that I use the same one for Hibernate as for my other caching needs.

I am using "declarative caching" via Spring Modules 0.7, and I thought it would be smart to use EhCache as the backing cache considering that I'm already using it for Hibernate. I configured a cache provider in one of my xml files as follows:

<bean id="cacheManager"
  class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
</bean>

<bean id="cacheProviderFacade"
  class="org.springmodules.cache.provider.ehcache.EhCacheFacade">
  <property name="cacheManager" ref="cacheManager" />
</bean>

I have omitted the part where I configure the target bean and the method names to cache.

For hibernate, I have my hibernate.cacheProvider property set to org.hibernate.cache.EhCacheProvider.

Everything works fine, in the sense that things get cached as expected.

However, when I start up my web app, I get a warning message that indicates I am using two separate CacheManagers:

CacheManager.detectAndFixDiskStorePathConflict(271 ) | Creating a new instance of CacheManager using the diskStorePath "C:\Tools\tomcat-5.5.16\temp" which is already used by an existing CacheManager.
The source of the configuration was classpath.
The diskStore path for this CacheManager will be set to C:\Tools\tomcat-5.5.16\temp\ehcache_auto_created_1170880092968.
To avoid this warning consider using the CacheManager factory methods to create a singleton CacheManager or specifying a separate ehcache configuration (ehcache.xml) for each CacheManager instance.

So it seems that Hibernate is instantiating a CacheManager, and then my declarative caching is instantiating a different one using the same ehcache.xml config file and thus colliding on the disk store path.

I could pretty easily create a second ehcache.xml and then use two CacheManagers, but I'd prefer to use just one. I tried setting the property "shared" to "true" on my cacheManager bean, but that didn't cause the warning message to go away like I had hoped.

How can I get Hibernate and the declarative caching to use the same CacheManager?

[karldmoore]

I'm pretty sure there is already a defect in JIRA regarding this. When I was looking into sharing the cache between Hibernate and Acegi, I wondered if this was possible. I'm not sure about the current state as I didn't set a watch on it.

[karldmoore]

Ok, I think this might have been it..........
http://opensource.atlassian.com/proj...rowse/SPR-1966

[F.Degenaar]

Solved the problem with our own EhCacheProvider, that uses the global instance instead of creating is own:

package dummy;

import java.net.URL;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;
import net.sf.ehcache.CacheManager;
import org.hibernate.cache.Cache;
import org.hibernate.cache.CacheException;
import org.hibernate.cache.CacheProvider;
import org.hibernate.cache.Timestamper;
import org.hibernate.cfg.Environment;
import org.hibernate.util.ConfigHelper;

import org.hibernate.util.StringHelper;

public class EhCacheProvider implements CacheProvider
{
  private static Logger logger = Logger.getLogger(EhCacheProvider.class.getName());

  private CacheManager cacheManager;

  public Cache buildCache(String name, Properties properties) throws CacheException
  {
    try
    {
      net.sf.ehcache.Cache cache = cacheManager.getCache(name);
      if (cache == null)
      {
        logger.warning("Could not find configuration [" + name + "]; using defaults.");
        cacheManager.addCache(name);
        cache = cacheManager.getCache(name);
        logger.config("started EHCache region: " + name);
      }
      else
      {
        logger.config("found EHCache region: " + name);
      }
      return new EhCache(cache);
    }
    catch (net.sf.ehcache.CacheException e)
    {
      throw new CacheException(e);
    }
  }

  public long nextTimestamp()
  {
    return Timestamper.next();
  }

  public void start(Properties properties) throws CacheException
  {
    cacheManager=CacheManager.getInstance();
  }

  public void stop()
  {
    // Spring will do this already
  }

  public boolean isMinimalPutsEnabledByDefault()
  {
    return false;
  }

  public CacheManager getCacheManager()
  {
    return cacheManager;
  }

  public void setCacheManager(CacheManager manager)
  {
    cacheManager = manager;
  }
  
  private class EhCache extends org.hibernate.cache.EhCache
  {
    public EhCache(net.sf.ehcache.Cache cache) {
      super(cache);
    }

    public void destroy() throws CacheException
    {
      // Spring will do this already
    }

  }

}

XML configuration as follows (Important: use depends-on, to make sure, the cache regions already exist):

	<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean" depends-on="lastCacheRegion">
		<property name="hibernateProperties">
			<props>
				<prop key="hibernate.cache.provider_class">dummy.EhCacheProvider</prop>
				...
			</props>
		</property>
		...
	</bean>

Hope, that helps.

[karldmoore]

I would be nice if the JIRA issue was fixed though . Have to get voting.

[cheesus]

No need to patch this yourself, at least not anymore with ehcache1.2.3, it
comes with a SingletonEhCacheProvider, as in

hibernate.cache.provider_class=net.sf.ehcache.hibernate.SingletonEhCacheProvider

[kenstershiro]

I've tried replacing EhCacheProvider with SingletonEhCacheProvider, but it doesn't seem to make any difference. I still get the Warning
"Creating a new instance of CacheManager using the diskStorePath "C:\xxx\Temp\" which is already used by an existing CacheManager. ...."

I'm using ehcache-1.2.4.

In my LocalSessionFactoryBean I've set the hibernate.cache.provider_class as a property of hibernateProperties, which is getting picked up correctly.
But in another part of my config I've already got a org.springframework.cache.ehcache.EhCacheManagerFa ctoryBean set up as a cacheManager for a CasAuthenticationProvider.

Anything else I can try to get them to point to the same instance?