As explained in {@link org.exolab.castor.persist}, {@link org.exolab.castor.persist.LockEngine} implements a persistence engine that caches objects in memory for performance reasons and thus eliminates the number of operations against the persistence storage.

Author:
Werner Guttmann

The main component of this package is the interface {@link org.castor.cache.Cache}, which declares the external functionality of a performance cache. Existing (and future) cache engines have to implement this interface, which extends {@link java.util.Map}. To obtain an instance of a particular cache engine, use {@link org.castor.cache.CacheFactoryRegistry} and its factory methods.

The remainder of this package are exceptions associated with cache interaction, an enumeration of all (currently) available cache types and a prototype for an (abstract) base class to assist future cache engine additions.

Configuration

Castor (as of release 0.9.6) allows for addition of user-defined cache implementations.

By default, the file castor.properties includes a section as follows:

#
# Cache implementations
#
org.castor.cache.Factories=\
  org.castor.cache.simple.NoCacheFactory,\
  org.castor.cache.simple.TimeLimitedFactory,\
  org.castor.cache.simple.CountLimitedFactory,\
  org.castor.cache.simple.UnlimitedFactory,\
  org.castor.cache.distributed.FKCacheFactory,\
  org.castor.cache.distributed.JcsCacheFactory,\
  org.castor.cache.distributed.JCacheFactory,\
  org.castor.cache.distributed.CoherenceCacheFactory,\
  org.castor.cache.distributed.OsCacheFactory,\
  org.castor.cache.hashbelt.FIFOHashbeltFactory,\
  org.castor.cache.hashbelt.LRUHashbeltFactory

To add your own performance cache implementation, please append the fully-qualified class name to this list as shown here:

#
# Cache implementations
#
org.castor.cache.Factories=\
  org.castor.cache.simple.NoCacheFactory,\
  org.castor.cache.simple.TimeLimitedFactory,\
  org.castor.cache.simple.CountLimitedFactory,\
  org.castor.cache.simple.UnlimitedFactory,\
  org.castor.cache.distributed.FKCacheFactory,\
  org.castor.cache.distributed.JcsCacheFactory,\
  org.castor.cache.distributed.JCacheFactory,\
  org.castor.cache.distributed.CoherenceCacheFactory,\
  org.castor.cache.distributed.OsCacheFactory,\
  org.castor.cache.hashbelt.FIFOHashbeltFactory,\
  org.castor.cache.hashbelt.LRUHashbeltFactory,\
  org.whatever.somewhere.nevermind.CustomCache

In addition, you will have to provide the cache implementation and a CacheFactory implementation for your new cache instance. For this, please add an implementation of {@link org.castor.cache.CacheFactory} and make sure that you provide valid values for the two properties name and className.

To assist users in this task, a {@link org.castor.cache.AbstractCacheFactory} class has been supplied, which users should derive their custom {@link org.castor.cache.CacheFactory} instances from, if they wish so. Please consult existing {@link org.castor.cache.CacheFactory} implementations such as {@link org.castor.cache.simple.TimeLimitedFactory} or {@link org.castor.cache.simple.CountLimitedFactory} for code samples.

/**
 * My own cache implementation
 */
 public class CustomCache extends AbstractBaseCache {

    ...

 }
/**
 * My own cache factory implementation
 */
 public class CustomCacheFactory extends AbstractCacheFactory {

    /**
     * The name of the factory
     */
    private static final String NAME = "custom";

    /**
     * Full class name of the underlying cache implementation.
     */
    private static final String CLASS_NAME = "my.company.project.CustomCache";

    /**
     * Returns the short alias for this factory instance.
     * @return The short alias name.
     */
    public String getName() {
        return NAME;
    }

    /**
     * Returns the full class name of the underlying cache implementation.
     * @return The full cache class name.
     */
    public String getCacheClassName() {
        return CLASS_NAME;
    }

 }