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.
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.
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;
}
}