com.jcorporate.expresso.core.cache
Interface CacheSystem

All Known Implementing Classes:

DefaultCacheManager

public interface CacheSystem

This is an interface for an underlying cache system. It allows clients of the itnerface to add items, retrieve items, and clear caches.

The CacheSystem is not data context aware. Classes that implement this interface are expected to be one instance per context. The Component System provides differentiation between caches.

Since:

Expresso 5.1

Author:

Michael Rimov

Method Summary

void	addItem(String cacheName, Cacheable newItem) Adds a Cacheable item into the cache
void	addItem(String cacheName, Cacheable newItem, long expiry) Adds an item to the cache named by parameter cacheName
void	addListener(String listener, String listenTo) Specify a relationship between caches.
void	adjustForMemory() Instructs the cache system to adjust it's usage profile based upon current memory information that the expresso system is telling us.
void	clear() Removes all cache items for a particular data context
void	clear(String cacheName) Clear's the named cache.
void	clearNoNotify() Clears all caches in this db context but doesn't notify any listeners
void	clearNoNotify(String cacheName) Clear the named cache, but don't send the remote system notifications.
Cache	createCache(String cacheName, boolean ordered) Creates a cache as specified by the parameters listed.
Cache	createCache(String cacheName, boolean ordered, int maxSize) Creates a cache defined by whether the cache is to be ordered, it's name and it's maximum size.
void	displayStatus() Displays the cache status.
boolean	existsCache(String cacheName) Checks to see if the cache already exists.
Set	getAllCacheNames() Return an iterator over a list of Strings that contain all the names of the caches stored in the system [For dbContext default]
Cache	getCache(String cacheName) Retrieve a given cache by name.
Cacheable	getItem(String cacheName, String valueKey) Get a particular item in the cache
int	getItemCount(String cacheName) Return a count of the number of items in a cache.
List	getItems(String cacheName) Return all of the items in a cache.
void	removeItem(String cacheName, Cacheable itemToRemove) Removes an item from the cache
void	removeItemNoNotify(String cacheName, Cacheable itemToRemove) Removes an item out of the cache without notifying the cache listeners
void	setItems(String cacheName, List itemList) Sets a cache to have the particular items specified in itemList.
void	setItems(String cacheName, List itemList, long expiration) Sets a cache to have the particular items specified in itemList.

Method Detail

adjustForMemory

public void adjustForMemory()

Instructs the cache system to adjust it's usage profile based upon current memory information that the expresso system is telling us.

getAllCacheNames

public Set getAllCacheNames()

Return an iterator over a list of Strings that contain all the names of the caches stored in the system [For dbContext default]

Returns:

java.util.Iterator

getItem

public Cacheable getItem(String cacheName,
                         String valueKey)

Get a particular item in the cache

Parameters:

cacheName - The name of the cache

valueKey - The particular item within the cache to get

Returns:

a Cacheable object or null if it doesn't exist in the cache

getCache

public Cache getCache(String cacheName)

Retrieve a given cache by name.

Parameters:

cacheName - the name of the cache to retrieve.

Returns:

a Cache instance or null if the Cache does not exist.

See Also:

Cache

getItemCount

public int getItemCount(String cacheName)

Return a count of the number of items in a cache. Return 0 if there is no such item

Parameters:

cacheName - The name of the cache

Returns:

an item count or zero if the cache doesn't exist or is empty;

setItems

public void setItems(String cacheName,
                     List itemList)
              throws CacheException

Sets a cache to have the particular items specified in itemList.

Parameters:

cacheName - The name of the cache

itemList - The items to set into the cache

Throws:

CacheException - if there's an error setting the items.

setItems

public void setItems(String cacheName,
                     List itemList,
                     long expiration)
              throws CacheException

Sets a cache to have the particular items specified in itemList.

Parameters:

cacheName - The name of the cache

itemList - The items to set into the cache

expiration - the expiration time in milliseconds for the items.

Throws:

CacheException - if there's an error setting the items.

getItems

public List getItems(String cacheName)

Return all of the items in a cache. If the cache was created as an ordered cache, the items will be in the order they were added. If not, they will be in no particular order. If there is no such cache or no items, null will be returned.

Parameters:

cacheName - The name of the cache to retrieve

Returns:

java.util.List of Cacheable items

addItem

public void addItem(String cacheName,
                    Cacheable newItem)
             throws CacheException

Adds a Cacheable item into the cache

Parameters:

cacheName - The name of the cache.

newItem - The new item to add to the cache

Throws:

CacheException - upon error inserting into the system

addItem

public void addItem(String cacheName,
                    Cacheable newItem,
                    long expiry)
             throws CacheException

Adds an item to the cache named by parameter cacheName

Parameters:

cacheName - The name of the cache to store the object in

newItem - The new item to add to the cache

expiry - The time in miliseconds that this cache item will expire

Throws:

CacheException - if there's an error inserting the item into the cache

addListener

public void addListener(String listener,
                        String listenTo)

Specify a relationship between caches. Whenever an add clear or remove event is sent to the specified cache, the listener is cleared as well. Adding a listener implies the relationship between the caches for the current db context.

Parameters:

listener - The classname of the listener

listenTo - The name of the cache to listen to.

clear

public void clear(String cacheName)
           throws CacheException

Clear's the named cache.

Parameters:

cacheName - The name of the cache to clear

Throws:

CacheException - if there's an error clearing the cache.

clear

public void clear()
           throws CacheException

Removes all cache items for a particular data context

Throws:

CacheException - CacheException if there's an error clearing the cache

clearNoNotify

public void clearNoNotify()

Clears all caches in this db context but doesn't notify any listeners

clearNoNotify

public void clearNoNotify(String cacheName)

Clear the named cache, but don't send the remote system notifications. This method actually removes the cache from the list of available caches

Parameters:

cacheName - The name of the cache

createCache

public Cache createCache(String cacheName,
                         boolean ordered)
                  throws CacheException

Creates a cache as specified by the parameters listed. Creation date: (9/7/00 2:18:09 PM)

Parameters:

cacheName - java.lang.String the name of the cache

ordered - boolean true if you want an ordered cache such as for ValidValues

Returns:

the newly instantiated Cache

Throws:

CacheException

createCache

public Cache createCache(String cacheName,
                         boolean ordered,
                         int maxSize)
                  throws CacheException

Creates a cache defined by whether the cache is to be ordered, it's name and it's maximum size. Creation date: (9/7/00 2:18:09 PM)

Parameters:

cacheName - java.lang.String The name of the cache

ordered - boolean True if you wish for an ordered cache.

maxSize - The maximum size of the cache

Returns:

the newly instantiated cache

Throws:

CacheException

existsCache

public boolean existsCache(String cacheName)

Checks to see if the cache already exists. One big note about this is that unless you already have a ReadLock, the cache may or may not exist once you go to put your data in the cache. Buyer beware.

Parameters:

cacheName - The name of the cache

Returns:

true if the named cache already exists in this data context

removeItem

public void removeItem(String cacheName,
                       Cacheable itemToRemove)
                throws CacheException

Removes an item from the cache

Parameters:

cacheName - The name of the cache

itemToRemove - the key of the item to remove

Throws:

CacheException

removeItemNoNotify

public void removeItemNoNotify(String cacheName,
                               Cacheable itemToRemove)
                        throws CacheException

Removes an item out of the cache without notifying the cache listeners

Parameters:

cacheName - The cache name

itemToRemove - the key in the cache that has been modified

Throws:

CacheException - Upon error removing the item from the cache

displayStatus

public void displayStatus()

Displays the cache status. Currently this is only really used for debugging purposes. Creation date: (9/7/00 2:44:05 PM)