Pluggable Disk Stores

[Tim Langford-2]

Hello All,

I would like to use EHCache, but, also want it to back to a database instead of disk when the in-memory cache overflows.

I saw a feature on the road map for 'Pluggable Disk Stores'. Has this been implemented yet? Anyone else looked into such functionality?

Thanks

Tim


-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
ehcache-list mailing list
ehcache-list@...
https://lists.sourceforge.net/lists/listinfo/ehcache-list

[gregluck]

Tim 

The diskStore is reference as a Store in the main ehcache. I did this to move towards pluggability for the DiskStore, but never had a second implementation so never made it pluggable in configuration.  You should however be able to subclass cache and override:

/**
    * Creates a disk store when either:
    * <ol>
    * <li>overflowToDisk is enabled
    * <li>diskPersistent is enabled
    * </ol>
    */
   protected Store createDiskStore() {
       if (isDiskStore()) {
           return new DiskStore(this, diskStorePath);
       } else {
           return null;
       }
   }

Then you can put your DatabaseDiskStore cache back in CacheManager with:


   /**
    * Replaces in the map of Caches managed by this CacheManager an Ehcache with a decorated version of the same
    * Ehcache. CacheManager can operate fully with a decorated Ehcache.
    * <p/>
    * Ehcache Decorators can be used to obtain different behaviour from an Ehcache in a very flexible way. Some examples in
    * ehcache are:
    * <ol>
    * <li>{@link net.sf.ehcache.constructs.blocking.BlockingCache} - A cache that blocks other threads from getting a null element until the first thread
    * has placed a value in it.
    * <li>{@link net.sf.ehcache.constructs.blocking.SelfPopulatingCache} - A BlockingCache that has the additional
    * property of knowing how to load its own entries.
    * </ol>
    * Many other kinds are possible.
    * <p/>
    * It is generally required that a decorated cache, once constructed, is made available to other execution threads.
    * The simplest way of doing this is to substitute the original cache for the decorated one here.
    * <p/>
    * Note that any overwritten Ehcache methods will take on new behaviours without casting. Casting is only required
    * for new methods that the decorator introduces.
    * For more information see the well known Gang of Four Decorator pattern.
    *
    * @param ehcache
    * @param decoratedCache An implementation of Ehcache that wraps the original cache.
    * @throws CacheException if the two caches do not equal each other.
    */
   public synchronized void replaceCacheWithDecoratedCache(Ehcache ehcache, Ehcache decoratedCache) throws CacheException {
       if (!ehcache.equals(decoratedCache)) {
           throw new CacheException("Cannot replace " + decoratedCache.getName()
                   + " It does not equal the incumbent cache.");
       } else {
           String cacheName = ehcache.getName();
           ehcaches.remove(cacheName);
           caches.remove(cacheName);
           ehcaches.put(decoratedCache.getName(), decoratedCache);
           if (decoratedCache instanceof Cache) {
               caches.put(decoratedCache.getName(), decoratedCache);
           }
       }

   }

There is a patch that does this for Derby. See http://sourceforge.net/tracker/index.php?func=detail&aid=1727946&group_id=93232&atid=603561

On 29/05/2008, at 11:39 PM, Tim Langford wrote:

Hello All,

I would like to use EHCache, but, also want it to back to a database instead of disk when the in-memory cache overflows.

I saw a feature on the road map for 'Pluggable Disk Stores'. Has this been implemented yet? Anyone else looked into such functionality?

Thanks

Tim

-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/_______________________________________________
ehcache-list mailing list
ehcache-list@...
https://lists.sourceforge.net/lists/listinfo/ehcache-list

Regards

Greg Luck

web: http://gregluck.com

skype: gregrluck

yahoo: gregrluck

mobile: [phone]

-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
ehcache-list mailing list
ehcache-list@...
https://lists.sourceforge.net/lists/listinfo/ehcache-list