net.sf.ehcache.store
Class MemoryStore

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

All Implemented Interfaces:

CacheConfigurationListener, Store

public class MemoryStore
extends AbstractStore
implements CacheConfigurationListener, Store

A Store implementation suitable for fast, concurrent in memory stores. The policy is determined by that configured in the cache.

Version:

$Id: MemoryStore.java 7527 2013-05-13 15:05:43Z cdennis $

Author:

Surya Suravarapu

Nested Class Summary

protected static interface	MemoryStore.BackingFactory Factory interface to create a MemoryStore backing.
static class	MemoryStore.BruteForceSearchManager Brute force search implementation

Field Summary

protected org.terracotta.statistics.observer.OperationObserver<CacheOperationOutcomes.EvictionOutcome>

evictionObserver Eviction outcome observer

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

attributeExtractors

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

CLUSTER_COHERENT, NODE_COHERENT

Constructor Summary

protected

MemoryStore(Ehcache cache, Pool pool, MemoryStore.BackingFactory factory, SearchManager searchManager) Constructs things that all MemoryStores have in common.

Method Summary

boolean	bufferFull() Memory stores are never backed up and always return false
boolean	canPutWithoutEvicting(Element element) Check if adding an element won't provoke an eviction.
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 Store	create(Ehcache cache, Pool pool) A factory method to create a MemoryStore.
void	deregistered(CacheConfiguration config) Indicates that this listener was removed from the given configuration
void	diskCapacityChanged(int oldCapacity, int newCapacity) Indicates a change in the configurations disk store capacity
void	dispose() Prepares for shutdown.
Collection<Element>	elementSet() Get a collection of the elements in this store
protected boolean	evict(Element element) Evicts the element from the store
protected Element	expireElement(Object key) Evicts the element for the given key, if it exists and is expired
void	expireElements() Expire all elements.
void	flush() Flush to disk only if the cache is diskPersistent.
Element	get(Object key) Gets an item from the cache.
protected static int	getInitialCapacityForLoadFactor(int maximumSizeGoal, float loadFactor) Calculates the initialCapacity for a desired maximumSize goal and loadFactor.
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 memory cache.
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.
Element	getQuiet(Object key) Gets an item from the cache, without updating statistics.
int	getSize() Returns the current store size.
Status	getStatus() Gets the status of the MemoryStore.
int	getTerracottaClusteredSize() Returns nothing since a disk store isn't clustered
boolean	hasAbortedSizeOf() Checks if the cache may contain elements for which the SizeOf engine gave up and only partially calculated the size.
boolean	isFull() An algorithm to tell if the MemoryStore is at or beyond its carrying capacity.
protected Set<?>	keySet() Returns the keySet for this store
void	loggingChanged(boolean oldValue, boolean newValue) Indicates a change in the configuration for enable/disable logging
void	maxBytesLocalDiskChanged(long oldValue, long newValue) Indicates a change in the configuration for maxBytesLocalDisk setting
void	maxBytesLocalHeapChanged(long oldValue, long newValue) Indicates a change in the configuration for maxBytesLocalHeap setting
void	maxEntriesInCacheChanged(long oldValue, long newValue) Indicates a change in the configuration for maxEntriesInCache setting
void	memoryCapacityChanged(int oldCapacity, int newCapacity) Indicates a change in the configurations memory store capacity
protected void	notifyDirectEviction(Element element) Called when an element is evicted even before it could be installed inside the store
boolean	put(Element element) Puts an item in 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
void	registered(CacheConfiguration config) Indicates that this listener was registered with the given configuration
Element	remove(Object key) Removes an Element from the store.
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.
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	timeToIdleChanged(long oldTti, long newTti) Indicates a change in the configurations time to idle
void	timeToLiveChanged(long oldTtl, long newTtl) Indicates a change in the configurations time to live

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

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

Field Detail

evictionObserver

protected final org.terracotta.statistics.observer.OperationObserver<CacheOperationOutcomes.EvictionOutcome> evictionObserver

Eviction outcome observer

Constructor Detail

MemoryStore

protected MemoryStore(Ehcache cache,
                      Pool pool,
                      MemoryStore.BackingFactory factory,
                      SearchManager searchManager)

Constructs things that all MemoryStores have in common.

Parameters:

cache - the cache

pool - the pool tracking the on-heap usage

searchManager - the search manager

Method Detail

getInitialCapacityForLoadFactor

protected static int getInitialCapacityForLoadFactor(int maximumSizeGoal,
                                                     float loadFactor)

Calculates the initialCapacity for a desired maximumSize goal and loadFactor.

Parameters:

maximumSizeGoal - the desired maximum size goal

loadFactor - the load factor

Returns:

the calculated initialCapacity. Returns 0 if the parameter maximumSizeGoal is less than or equal to 0

create

public static Store create(Ehcache cache,
                           Pool pool)

A factory method to create a MemoryStore.

Parameters:

cache - the cache

pool - the pool tracking the on-heap usage

Returns:

an instance of a NotifyingMemoryStore, configured with the appropriate eviction policy

put

public boolean put(Element element)
            throws CacheException

Puts an item in the store. Note that this automatically results in an eviction if the store is full.

Specified by:

put in interface Store

Parameters:

element - the element to add

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 final Element get(Object key)

Gets an item from the cache.

The last access time in Element is updated.

Specified by:

get in interface Store

Parameters:

key - the key of the Element

Returns:

the element, or null if there was no match for the key

getQuiet

public final Element getQuiet(Object key)

Gets an item from the cache, without updating statistics.

Specified by:

getQuiet in interface Store

Parameters:

key - the cache key

Returns:

the element, or null if there was no match for the key

remove

public Element remove(Object key)

Removes an Element from the store.

Specified by:

remove in interface Store

Parameters:

key - the key of the Element, usually a String

Returns:

the Element if one was found, else null

removeWithWriter

public final 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

bufferFull

public final boolean bufferFull()

Memory stores are never backed up and always return false

Specified by:

bufferFull in interface Store

Returns:

true if the store write buffer is backed up.

expireElements

public void expireElements()

Expire all elements.

This is a default implementation which does nothing. Expiration on demand is only implemented for disk stores.

Specified by:

expireElements in interface Store

expireElement

protected Element expireElement(Object key)

Evicts the element for the given key, if it exists and is expired

Parameters:

key - the key

Returns:

the evicted element, if any. Otherwise null

removeAll

public final void removeAll()
                     throws CacheException

Remove all of the elements from the store.

Specified by:

removeAll in interface Store

Throws:

CacheException

dispose

public void dispose()

Prepares for shutdown.

Specified by:

dispose in interface Store

flush

public void flush()

Flush to disk only if the cache is diskPersistent.

Specified by:

flush in interface Store

getKeys

public final List<?> getKeys()

Gets an Array of the keys for all elements in the memory cache.

Does not check for expired entries

Specified by:

getKeys in interface Store

Returns:

An List

keySet

protected Set<?> keySet()

Returns the keySet for this store

Returns:

keySet

getSize

public final int getSize()

Returns the current store size.

Specified by:

getSize in interface Store

Returns:

The size value

getTerracottaClusteredSize

public final int getTerracottaClusteredSize()

Returns nothing since a disk store isn't clustered

Specified by:

getTerracottaClusteredSize in interface Store

Returns:

returns 0

containsKey

public final boolean containsKey(Object key)

A check to see if a key is in the Store. No check is made to see if the Element is expired.

Specified by:

containsKey in interface Store

Parameters:

key - The Element key

Returns:

true if found. If this method return false, it means that an Element with the given key is definitely not in the MemoryStore. If it returns true, there is an Element there. An attempt to get it may return null if the Element has expired.

notifyDirectEviction

protected void notifyDirectEviction(Element element)

Called when an element is evicted even before it could be installed inside the store

Parameters:

element - the evicted element

isFull

public final boolean isFull()

An algorithm to tell if the MemoryStore is at or beyond its carrying capacity.

Returns:

true if the store is full, false otherwise

canPutWithoutEvicting

public final boolean canPutWithoutEvicting(Element element)

Check if adding an element won't provoke an eviction.

Parameters:

element - the element

Returns:

true if the element can be added without provoking an eviction.

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)

getStatus

public final Status getStatus()

Gets the status of the MemoryStore.

Specified by:

getStatus in interface Store

timeToIdleChanged

public void timeToIdleChanged(long oldTti,
                              long newTti)

Indicates a change in the configurations time to idle

Specified by:

timeToIdleChanged in interface CacheConfigurationListener

Parameters:

oldTti - previous time to idle value

newTti - new time to idle value

timeToLiveChanged

public void timeToLiveChanged(long oldTtl,
                              long newTtl)

Indicates a change in the configurations time to live

Specified by:

timeToLiveChanged in interface CacheConfigurationListener

Parameters:

oldTtl - previous time to live value

newTtl - new time to live value

diskCapacityChanged

public void diskCapacityChanged(int oldCapacity,
                                int newCapacity)

Indicates a change in the configurations disk store capacity

Specified by:

diskCapacityChanged in interface CacheConfigurationListener

Parameters:

oldCapacity - previous capacity

newCapacity - new capacity

loggingChanged

public void loggingChanged(boolean oldValue,
                           boolean newValue)

Indicates a change in the configuration for enable/disable logging

Specified by:

loggingChanged in interface CacheConfigurationListener

Parameters:

oldValue - old value whether logging was enabled or not

newValue - new value whether logging was enabled or not

memoryCapacityChanged

public void memoryCapacityChanged(int oldCapacity,
                                  int newCapacity)

Indicates a change in the configurations memory store capacity

Specified by:

memoryCapacityChanged in interface CacheConfigurationListener

Parameters:

oldCapacity - previous capacity

newCapacity - new capacity

registered

public void registered(CacheConfiguration config)

Indicates that this listener was registered with the given configuration

Specified by:

registered in interface CacheConfigurationListener

deregistered

public void deregistered(CacheConfiguration config)

Indicates that this listener was removed from the given configuration

Specified by:

deregistered in interface CacheConfigurationListener

maxBytesLocalHeapChanged

public void maxBytesLocalHeapChanged(long oldValue,
                                     long newValue)

Indicates a change in the configuration for maxBytesLocalHeap setting

Specified by:

maxBytesLocalHeapChanged in interface CacheConfigurationListener

Parameters:

oldValue - old value in bytes

newValue - new value in bytes

maxBytesLocalDiskChanged

public void maxBytesLocalDiskChanged(long oldValue,
                                     long newValue)

Indicates a change in the configuration for maxBytesLocalDisk setting

Specified by:

maxBytesLocalDiskChanged in interface CacheConfigurationListener

Parameters:

oldValue - old value in bytes

newValue - new value in bytes

maxEntriesInCacheChanged

public void maxEntriesInCacheChanged(long oldValue,
                                     long newValue)

Indicates a change in the configuration for maxEntriesInCache setting

Specified by:

maxEntriesInCacheChanged in interface CacheConfigurationListener

Parameters:

oldValue - old value

newValue - new value

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.

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.

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.

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)

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

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

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

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

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

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

hasAbortedSizeOf

public boolean hasAbortedSizeOf()

Checks if the cache may contain elements for which the SizeOf engine gave up and only partially calculated the size.

Specified by:

hasAbortedSizeOf in interface Store

Overrides:

hasAbortedSizeOf in class AbstractStore

Returns:

true if at least one partially sized element may be in the cache

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

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

evict

protected boolean evict(Element element)

Evicts the element from the store

Parameters:

element - the element to be evicted

Returns:

true if succeeded, false otherwise

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

getMBean

public Object getMBean()

Optional implementation specific MBean exposed by the store.

Specified by:

getMBean in interface Store

Returns:

implementation specific management bean

elementSet

public Collection<Element> elementSet()

Get a collection of the elements in this store

Returns:

element collection

recalculateSize

public void recalculateSize(Object key)

Description copied from class: AbstractStore

Recalculate size of the element mapped to the key

Specified by:

recalculateSize in interface Store

Overrides:

recalculateSize in class AbstractStore

Parameters:

key - the key