net.sf.ehcache.store
Class NullStore

java.lang.Object
  net.sf.ehcache.store.AbstractStore
      net.sf.ehcache.store.NullStore

All Implemented Interfaces:

Store, TierableStore

public final class NullStore
extends AbstractStore
implements TierableStore

A store implementation which does not store anything.

Author:

Ludovic Orban

Field Summary

Fields inherited from class net.sf.ehcache.store.AbstractStore

attributeExtractors

Fields inherited from interface net.sf.ehcache.store.Store

CLUSTER_COHERENT, NODE_COHERENT

Method Summary

boolean	bufferFull() Some store types, such as the disk stores can fill their write buffers if puts come in too fast.
boolean	containsKey(Object key) A check to see if a key is in the Store.
boolean	containsKeyInMemory(Object key) A check to see if a key is in the Store and is currently held in memory.
boolean	containsKeyOffHeap(Object key) A check to see if a key is in the Store and is currently held off-heap.
boolean	containsKeyOnDisk(Object key) A check to see if a key is in the Store and is currently held on disk.
static NullStore	create() Create a new NullStore instance.
void	dispose() Prepares for shutdown.
void	expireElements() Expire all elements.
void	fill(Element e) Add this element to the cache if the key is already present or the add can succeed without resorting to eviction.
void	flush() Flush elements to persistent store.
Element	get(Object key) Gets an item from the cache.
Policy	getInMemoryEvictionPolicy()
int	getInMemorySize() Returns the current local in-memory store size
long	getInMemorySizeInBytes() Gets the size of the in-memory portion of the store, in bytes.
Object	getInternalContext() This should not be used, and will generally return null
List	getKeys() Gets an Array of the keys for all elements in the disk store.
Object	getMBean() Optional implementation specific MBean exposed by the store.
int	getOffHeapSize() Returns the current local off-heap store size
long	getOffHeapSizeInBytes() Gets the size of the off-heap portion of the store, in bytes.
int	getOnDiskSize() Returns the current local on-disk store size
long	getOnDiskSizeInBytes() Gets the size of the on-disk portion of the store, in bytes.
Set	getPresentPinnedKeys() Returns all the keys that are pinned, for which there is a mapping present
Element	getQuiet(Object key) Gets an Element from the Store, without updating statistics
int	getSize() Returns the current local store size
Status	getStatus() Returns the cache status.
int	getTerracottaClusteredSize() Returns the current Terracotta clustered store size
boolean	isPersistent() Is this store persistent (data survives a JVM restart)
boolean	isPinned(Object key) Check if the key is pinned
boolean	isTierPinned() Is this TierableStore pinned ?
boolean	put(Element element) Puts an item into the store.
Element	putIfAbsent(Element element) Put an element in the store if no element is currently mapped to the elements key.
boolean	putWithWriter(Element element, CacheWriterManager writerManager) Puts an item into the store and the cache writer manager in an atomic operation
void	recalculateSize(Object key) Recalculate size of the element mapped to the key
Element	remove(Object key) Removes an item from the cache.
void	removeAll() Remove all of the elements from the store.
Element	removeElement(Element element, ElementValueComparator comparator) Remove the Element mapped to the key for the supplied element if the value of the supplied Element is equal to the value of the cached Element.
boolean	removeIfNotPinned(Object key) This method will only remove if the element or the store is not pinned and the key is present in the store
void	removeNoReturn(Object key) Removes an item from the cache.
Element	removeWithWriter(Object key, CacheWriterManager writerManager) Removes an item from the store and the cache writer manager in an atomic operation.
Element	replace(Element element) Replace the cached element only if an Element is currently cached for this key
boolean	replace(Element old, Element element, ElementValueComparator comparator) Replace the cached element only if the value of the current Element is equal to the value of the supplied old Element.
void	setInMemoryEvictionPolicy(Policy policy) Sets the eviction policy strategy.
void	setPinned(Object key, boolean pinned) Mark the key as pinned or not
void	unpinAll() unpin all pinned keys

Methods inherited from class net.sf.ehcache.store.AbstractStore

addStoreListener, executeQuery, getAll, getAllQuiet, getEventListenerList, getSearchAttribute, hasAbortedSizeOf, isCacheCoherent, isClusterCoherent, isNodeCoherent, putAll, removeAll, removeStoreListener, setAttributeExtractors, setNodeCoherent, waitUntilClusterCoherent

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.ehcache.store.Store

addStoreListener, executeQuery, getAll, getAllQuiet, getSearchAttribute, hasAbortedSizeOf, isCacheCoherent, isClusterCoherent, isNodeCoherent, putAll, removeAll, removeStoreListener, setAttributeExtractors, setNodeCoherent, waitUntilClusterCoherent

Method Detail

create

public static NullStore create()

Create a new NullStore instance.

Returns:

a NullStore instance

unpinAll

public void unpinAll()

unpin all pinned keys

Specified by:

unpinAll in interface Store

isPinned

public boolean isPinned(Object key)

Check if the key is pinned

Specified by:

isPinned in interface Store

Parameters:

key - the key to be checked

Returns:

true if the element is pinned

setPinned

public void setPinned(Object key,
                      boolean pinned)

Mark the key as pinned or not

Specified by:

setPinned in interface Store

Parameters:

key - the key to be pinned or not

pinned - true if the key should be pinned, false otherwise

put

public boolean put(Element element)
            throws CacheException

Puts an item into the store.

Specified by:

put in interface Store

Returns:

true if this is a new put for the key or element is null. Returns false if it was an update.

Throws:

CacheException

putWithWriter

public boolean putWithWriter(Element element,
                             CacheWriterManager writerManager)
                      throws CacheException

Puts an item into the store and the cache writer manager in an atomic operation

Specified by:

putWithWriter in interface Store

Returns:

true if this is a new put for the key or element is null. Returns false if it was an update.

Throws:

CacheException

get

public Element get(Object key)

Gets an item from the cache.

Specified by:

get in interface Store

getQuiet

public Element getQuiet(Object key)

Gets an Element from the Store, without updating statistics

Specified by:

getQuiet in interface Store

Returns:

The element

getKeys

public List getKeys()

Gets an Array of the keys for all elements in the disk store.

Specified by:

getKeys in interface Store

Returns:

An List of Serializable keys

remove

public Element remove(Object key)

Removes an item from the cache.

Specified by:

remove in interface Store

removeNoReturn

public void removeNoReturn(Object key)

Removes an item from the cache.

Specified by:

removeNoReturn in interface TierableStore

isTierPinned

public boolean isTierPinned()

Is this TierableStore pinned ?

Specified by:

isTierPinned in interface TierableStore

Returns:

true if pinned

getPresentPinnedKeys

public Set getPresentPinnedKeys()

Returns all the keys that are pinned, for which there is a mapping present

Specified by:

getPresentPinnedKeys in interface TierableStore

Returns:

the set of keys with values that are currently pinned

isPersistent

public boolean isPersistent()

Is this store persistent (data survives a JVM restart)

Specified by:

isPersistent in interface TierableStore

Returns:

true if persistent

removeWithWriter

public Element removeWithWriter(Object key,
                                CacheWriterManager writerManager)
                         throws CacheException

Removes an item from the store and the cache writer manager in an atomic operation.

Specified by:

removeWithWriter in interface Store

Throws:

CacheException

removeAll

public void removeAll()
               throws CacheException

Remove all of the elements from the store.

If there are registered CacheEventListeners they are notified of the expiry or removal of the Element as each is removed.

Specified by:

removeAll in interface Store

Throws:

CacheException

putIfAbsent

public Element putIfAbsent(Element element)
                    throws NullPointerException

Put an element in the store if no element is currently mapped to the elements key.

Specified by:

putIfAbsent in interface Store

Parameters:

element - element to be added

Returns:

the element previously cached for this key, or null if none.

Throws:

NullPointerException - if the element is null, or has a null key

removeElement

public Element removeElement(Element element,
                             ElementValueComparator comparator)
                      throws NullPointerException

Remove the Element mapped to the key for the supplied element if the value of the supplied Element is equal to the value of the cached Element. This is a CAS operation. It is consistent even against a distributed cache that is not coherent. If the old value is stale when this operation is attempted the remove does not take place.

Specified by:

removeElement in interface Store

Parameters:

element - Element to be removed

comparator - ElementValueComparator to use to compare elements

Returns:

the Element removed or null if no Element was removed

Throws:

NullPointerException - if the element is null, or has a null key

replace

public boolean replace(Element old,
                       Element element,
                       ElementValueComparator comparator)
                throws NullPointerException,
                       IllegalArgumentException

Replace the cached element only if the value of the current Element is equal to the value of the supplied old Element.

Specified by:

replace in interface Store

Parameters:

old - Element to be test against

element - Element to be cached

comparator - ElementValueComparator to use to compare elements

Returns:

true is the Element was replaced

Throws:

NullPointerException - if the either Element is null or has a null key

IllegalArgumentException - if the two Element keys are non-null but not equal

replace

public Element replace(Element element)
                throws NullPointerException

Replace the cached element only if an Element is currently cached for this key

Specified by:

replace in interface Store

Parameters:

element - Element to be cached

Returns:

the Element previously cached for this key, or null if no Element was cached

Throws:

NullPointerException - if the Element is null or has a null key

dispose

public void dispose()

Prepares for shutdown.

Specified by:

dispose in interface Store

getSize

public int getSize()

Returns the current local store size

Specified by:

getSize in interface Store

Returns:

the count of the Elements in the Store on the local machine

getInMemorySize

public int getInMemorySize()

Returns the current local in-memory store size

Specified by:

getInMemorySize in interface Store

Returns:

the count of the Elements in the Store and in-memory on the local machine

getOffHeapSize

public int getOffHeapSize()

Returns the current local off-heap store size

Specified by:

getOffHeapSize in interface Store

Returns:

the count of the Elements in the Store and off-heap on the local machine

getOnDiskSize

public int getOnDiskSize()

Returns the current local on-disk store size

Specified by:

getOnDiskSize in interface Store

Returns:

the count of the Elements in the Store and on-disk on the local machine

getTerracottaClusteredSize

public int getTerracottaClusteredSize()

Returns the current Terracotta clustered store size

Specified by:

getTerracottaClusteredSize in interface Store

Returns:

the count of the Elements in the Store across the cluster

getInMemorySizeInBytes

public long getInMemorySizeInBytes()

Gets the size of the in-memory portion of the store, in bytes.

This method may be expensive to run, depending on implementation. Implementers may choose to return an approximate size.

Specified by:

getInMemorySizeInBytes in interface Store

Returns:

the approximate in-memory size of the store in bytes

getOffHeapSizeInBytes

public long getOffHeapSizeInBytes()

Gets the size of the off-heap portion of the store, in bytes.

Specified by:

getOffHeapSizeInBytes in interface Store

Returns:

the approximate off-heap size of the store in bytes

getOnDiskSizeInBytes

public long getOnDiskSizeInBytes()

Gets the size of the on-disk portion of the store, in bytes.

Specified by:

getOnDiskSizeInBytes in interface Store

Returns:

the on-disk size of the store in bytes

getStatus

public Status getStatus()

Returns the cache status.

Specified by:

getStatus in interface Store

containsKey

public boolean containsKey(Object key)

A check to see if a key is in the Store.

Specified by:

containsKey in interface Store

Parameters:

key - The Element key

Returns:

true if found. No check is made to see if the Element is expired. 1.2

containsKeyOnDisk

public boolean containsKeyOnDisk(Object key)

A check to see if a key is in the Store and is currently held on disk.

Specified by:

containsKeyOnDisk in interface Store

Parameters:

key - The Element key

Returns:

true if found. No check is made to see if the Element is expired.

containsKeyOffHeap

public boolean containsKeyOffHeap(Object key)

A check to see if a key is in the Store and is currently held off-heap.

Specified by:

containsKeyOffHeap in interface Store

Parameters:

key - The Element key

Returns:

true if found. No check is made to see if the Element is expired.

containsKeyInMemory

public boolean containsKeyInMemory(Object key)

A check to see if a key is in the Store and is currently held in memory.

Specified by:

containsKeyInMemory in interface Store

Parameters:

key - The Element key

Returns:

true if found. No check is made to see if the Element is expired.

expireElements

public void expireElements()

Expire all elements.

Specified by:

expireElements in interface Store

flush

public void flush()
           throws IOException

Flush elements to persistent store.

Specified by:

flush in interface Store

Throws:

IOException - if any IO error occurs

bufferFull

public boolean bufferFull()

Some store types, such as the disk stores can fill their write buffers if puts come in too fast. The thread will wait for a short time before checking again.

Specified by:

bufferFull in interface Store

Returns:

true if the store write buffer is backed up.

getInMemoryEvictionPolicy

public Policy getInMemoryEvictionPolicy()

Specified by:

getInMemoryEvictionPolicy in interface Store

Returns:

the current eviction policy. This may not be the configured policy, if it has been dynamically set.

See Also:

Store.setInMemoryEvictionPolicy(Policy)

setInMemoryEvictionPolicy

public void setInMemoryEvictionPolicy(Policy policy)

Sets the eviction policy strategy. The Store will use a policy at startup. The store may allow changing the eviction policy strategy dynamically. Otherwise implementations will throw an exception if this method is called.

Specified by:

setInMemoryEvictionPolicy in interface Store

Parameters:

policy - the new policy

getInternalContext

public Object getInternalContext()

This should not be used, and will generally return null

Specified by:

getInternalContext in interface Store

Returns:

some internal context (probably null)

getMBean

public Object getMBean()

Optional implementation specific MBean exposed by the store.

Specified by:

getMBean in interface Store

Returns:

implementation specific management bean

fill

public void fill(Element e)

Add this element to the cache if the key is already present or the add can succeed without resorting to eviction.

Specified by:

fill in interface TierableStore

Parameters:

e - element to be added

removeIfNotPinned

public boolean removeIfNotPinned(Object key)

This method will only remove if the element or the store is not pinned and the key is present in the store

Specified by:

removeIfNotPinned in interface TierableStore

Parameters:

key - the key to the element

Returns:

true if an element was removed

See Also:

Store.remove(Object)

recalculateSize

public void recalculateSize(Object key)

Recalculate size of the element mapped to the key

Specified by:

recalculateSize in interface Store

Overrides:

recalculateSize in class AbstractStore

Parameters:

key - the key