com.solarmetric.kodo.runtime.datacache.plugins
Class LocalCache

java.lang.Object
  |
  +--com.solarmetric.kodo.runtime.datacache.plugins.LocalCache

All Implemented Interfaces:

DataCache

Direct Known Subclasses:

DistributedCache

public class LocalCache

extends Object

implements DataCache

A single-PersistenceManagerFactory cache. This cache can be used to share data among PersistenceManagers created from a single PersistenceManagerFactory. Batch updates are performed atomically.

Field Summary

protected CacheMap

cache

Constructor Summary

LocalCache()

Method Summary

void	batchUpdate(Map additions, Map updates, Collection deletes, Object origin) Perform a batch update of the cache.
void	clear() Remove all data from this cache.
void	close() Close this cache, dropping all hard references and releasing any resources that this cache maintains.
Object	get(Object key) Return the cached object for the given key.
int	getCacheSize() Returns the maximum number of unpinned objects to keep hard references to.
CacheMap	newCacheMap() Returns a new CacheMap for use as the underlying data cache.
boolean	pin(Object key) Pin the value stored under key into the cache.
Object	put(Object key, Object value) Set the cached value for the given key.
Object	remove(Object key) Remove the value stored under the given key.
void	removeAll(Collection keys)
void	setCacheSize(int size) Sets the maximum number of unpinned objects to keep hard references to.
boolean	unpin(Object key) Unpin the value stored under key into the cache.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

cache

protected CacheMap cache

Constructor Detail

LocalCache

public LocalCache()

Method Detail

setCacheSize

public void setCacheSize(int size)

Sets the maximum number of unpinned objects to keep hard references to. If the map contains more unpinned objects than size, then this method will result in the cache flushing old values.

getCacheSize

public int getCacheSize()

Returns the maximum number of unpinned objects to keep hard references to.

newCacheMap

public CacheMap newCacheMap()

Returns a new CacheMap for use as the underlying data cache. This implementation returns a CacheMap. To implement a more sophisticated caching strategy, override this method to return a subclass of CacheMap.

batchUpdate

public void batchUpdate(Map additions,
                        Map updates,
                        Collection deletes,
                        Object origin)

Description copied from interface: DataCache

Perform a batch update of the cache. Add all key-value pairs in additions, make the appropriate modifications to all key-value pairs in updates, and delete all keys in deletes. Processing the updates map might involve adding or removing objects to the cache or modifying data already in the cache.

All changes made to cached data must be cached via this method. It is this method that is responsible for performing any side-effects that should happen on meaningful cache changes.

Implementations should bear in mind that the deletes collection may contain oids that are also in the additions map. This is possible because it is valid for a user to delete an object with a particular oid and then add that object in the same batch.

Specified by:

batchUpdate in interface DataCache

Following copied from interface: com.solarmetric.kodo.runtime.datacache.DataCache

Parameters:

origin - the object that initiated this cache update. This can be useful for implementations in which many sources share a single cache, which in turn communicates back to the sources on cache updates.

get

public Object get(Object key)

Description copied from interface: DataCache

Return the cached object for the given key. Modifying the returned object may or may not change the cached value; the DataCache.put(java.lang.Object, java.lang.Object) method should be used to re-cache any changed objects.

Specified by:

get in interface DataCache

Following copied from interface: com.solarmetric.kodo.runtime.datacache.DataCache

Returns:

the object matching the given key, or null if none

put

public Object put(Object key,
                  Object value)

Description copied from interface: DataCache

Set the cached value for the given key. This does not result in an update of other caches. Rather, it should only be used for loading clean data into the cache. Meaningful changes to the state of the cache should be made via the DataCache.batchUpdate(java.util.Map, java.util.Map, java.util.Collection, java.lang.Object) method.

Specified by:

put in interface DataCache

Following copied from interface: com.solarmetric.kodo.runtime.datacache.DataCache

Returns:

The previously cached value, or null if the key was not previously cached. See Map.put(java.lang.Object, java.lang.Object) for more information.

remove

public Object remove(Object key)

Description copied from interface: DataCache

Remove the value stored under the given key. This does not result in an update of other caches. Rather, it should only be used for removing data into the cache. Meaningful changes to the state of the cache should be made via the batchUpdate method.

Specified by:

remove in interface DataCache

Following copied from interface: com.solarmetric.kodo.runtime.datacache.DataCache

Returns:

The previously cached value, or null if the key was not previously cached. See Map.remove(java.lang.Object) for more information.

removeAll

public void removeAll(Collection keys)

clear

public void clear()

Description copied from interface: DataCache

Remove all data from this cache. This does not result in an update of other caches. Rather, it should only be used for clearing the cache. Meaningful changes to the state of the cache should be made via the batchUpdate method.

Specified by:

clear in interface DataCache

pin

public boolean pin(Object key)

Description copied from interface: DataCache

Pin the value stored under key into the cache. This method guarantees that key's value will not be dropped by the caching algorithm. This method does not affect the behavior of remove.

Specified by:

pin in interface DataCache

Following copied from interface: com.solarmetric.kodo.runtime.datacache.DataCache

Returns:

true if key's value was pinned into the cache; false if the key is not in the cache.

unpin

public boolean unpin(Object key)

Description copied from interface: DataCache

Unpin the value stored under key into the cache. This method reverses a previous invocation of DataCache.pin(java.lang.Object). This method does not remove anything from the cache; it merely makes key's value a candidate for flushing from the cache.

Specified by:

unpin in interface DataCache

Following copied from interface: com.solarmetric.kodo.runtime.datacache.DataCache

Returns:

true if key's value was unpinned from the cache; false if the key is not in the cache.

close

public void close()

Description copied from interface: DataCache

Close this cache, dropping all hard references and releasing any resources that this cache maintains.

Specified by:

close in interface DataCache