Re: ObjectCacheInternal and OSCache / JGroups issue

[Armin Waibel]

Hi,

Jacques Desmazieres wrote:

Based on all that I have been seeking a little bit deeper in the OSCache
documentation. Actually, OSCache sends notifications (Events) only on flush
events. The putInCache method do not flush the cache, so no event is sent.
The ObjectCacheOSCacheInternalImpl should force OSCache to flush the entry
in order to generate an events.

Based on that, there is a mistake in the sample code provided : you have to
add a call to remove(oid) just before calling putInCache (twice in the
code).

And now it works fine. Hope this could help anyone else.

Thanks much! I will patch the sample code.

regards
Armin

Jacques Desmazieres

Here is the code of my current implementation, based on your sample with
just some fixes

public class ObjectCacheOSCacheInternalImpl implements ObjectCacheInternal
{
        private static GeneralCacheAdministrator admin = new
GeneralCacheAdministrator();
        private static final int REFRESH_PERIOD =
com.opensymphony.oscache.base.CacheEntry.INDEFINITE_EXPIRY;
        private Logger log =
Logger.getLogger(ObjectCacheOSCacheInternalImpl.class);

        public ObjectCacheOSCacheInternalImpl(PersistenceBroker broker, 
Properties
prop)
        {
        }

        public void cache(Identity oid, Object obj)
        {
                try
                {
                        remove(oid);
                        admin.putInCache(oid.toString(), obj);
                }
                catch (Exception e)
                {
                        admin.cancelUpdate(oid.toString());
                        log.error("                Error while try to cache object: 
" + oid, e);
                }
        }

        public void doInternalCache(Identity oid, Object obj, int type)
        {
                cache(oid, obj);
        }

        public boolean cacheIfNew(Identity oid, Object obj)
        {
                boolean result = false;
                Cache cache = admin.getCache();
                try
                {
                        cache.getFromCache(oid.toString());
                }
                catch (NeedsRefreshException e)
                {
                        cache( oid, obj );
                        if (log.isDebugEnabled()) log.debug("              
retrieved from application
cache");
                }
                return result;
        }

        public Object lookup(Identity oid)
        {
                try
                {
                        return admin.getFromCache(oid.toString(), 
REFRESH_PERIOD);
                }
                catch (NeedsRefreshException e)
                {
                        // not found in cache
                        if (log.isDebugEnabled()) log.debug("Not found in cache: 
" + oid);
                        admin.cancelUpdate(oid.toString());
                        return null;
                }
                catch (Exception e)
                {
                        log.error("Unexpected error when lookup object from cache: 
" + oid, e);
                        admin.cancelUpdate(oid.toString());
                        return null;
                }
        }

        public void remove(Identity oid)
        {
                try
                {
                        admin.flushEntry(oid.toString());
                }
                catch (Exception e)
                {
                        throw new RuntimeCacheException("Unexpected error when 
remove object from
cache: " + oid, e);
                }
        }

        public void clear()
        {
                try
                {
                        if (log.isDebugEnabled()) log.debug("Clear cache");
                        admin.flushAll();
                }
                catch (Exception e)
                {
                        throw new RuntimeCacheException("Unexpected error while 
clear cache", e);
                }
        }
}

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