Package org.apache.openjpa.util

Class CacheMap

java.lang.Object

org.apache.openjpa.util.CacheMap

All Implemented Interfaces:

Map

public class CacheMap
extends Object
implements Map

Fixed-size map that has ability to pin/unpin entries and move overflow to a backing soft map.

Author:

Patrick Linskey, Abe White

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K extends Object,V extends Object>

Field Summary

Fields

Modifier and Type	Field	Description
protected SizedMap	cacheMap	The map for non-expired and non-pinned references.
protected Map	pinnedMap	The set of objects pinned into the cache.
protected SizedMap	softMap	The map for expired references.

Constructor Summary

Constructors

Constructor	Description
CacheMap()	Create a non-LRU (and therefore highly concurrent) cache map with a size of 1000.
CacheMap(boolean lru)	Create a cache map with a size of 1000.
CacheMap(boolean lru, int max)	Create a cache map with the given properties.
CacheMap(boolean lru, int max, int size, float load)	Deprecated. use CacheMap(boolean, int, int, float, int) instead.
CacheMap(boolean lru, int max, int size, float load, int concurrencyLevel)	Create a cache map with the given properties.

Method Summary

Modifier and Type	Method	Description
protected void	cacheMapOverflowRemoved(Object key, Object value)	Called from SizedMap.overflowRemoved(java.lang.Object, java.lang.Object) in the cache map.
void	clear()	Removes pinned objects as well as unpinned ones.
boolean	containsKey(Object key)
boolean	containsValue(Object val)
protected void	entryAdded(Object key, Object value)	Invoked when an entry is added to the cache.
protected void	entryRemoved(Object key, Object value, boolean expired)	Invoked when a key-value pair is evicted from this data structure.
Set	entrySet()
Object	get(Object key)
int	getCacheSize()	The maximum number of hard references to maintain, or -1 for no limit.
Set	getPinnedKeys()	The keys pinned into the map.
int	getSoftReferenceSize()	The maximum number of soft references to maintain, or -1 for no limit.
boolean	isEmpty()
boolean	isLRU()	Whether this cache map uses LRU eviction.
Set	keySet()
boolean	pin(Object key)	Locks the given key and its value into the map.
Object	put(Object key, Object value)
protected Object	put(Map map, Object key, Object value)	Put the given entry into the given map.
void	putAll(Map map)
void	putAll(Map map, boolean replaceExisting)
void	readLock()	Acquire read lock.
void	readUnlock()	Release read lock.
Object	remove(Object key)	If key is pinned into the cache, the pin is cleared and the object is removed.
protected Object	remove(Map map, Object key)	Remove the given key from the given map.
void	setCacheSize(int size)	The maximum number of hard references to maintain, or -1 for no limit.
void	setSoftReferenceSize(int size)	The maximum number of soft references to maintain, or -1 for no limit.
int	size()
protected void	softMapOverflowRemoved(Object key, Object value)	Called from SizedMap.overflowRemoved(java.lang.Object, java.lang.Object) in the soft map.
protected void	softMapValueExpired(Object key)	Called when a value expires from the soft map.
String	toString()
boolean	unpin(Object key)	Undo a pinning.
Collection	values()
void	writeLock()	Acquire write lock.
void	writeUnlock()	Release write lock.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll

Field Detail

cacheMap

protected final SizedMap cacheMap

The map for non-expired and non-pinned references.

softMap

protected final SizedMap softMap

The map for expired references.

pinnedMap

protected final Map pinnedMap

The set of objects pinned into the cache.

Constructor Detail

CacheMap

public CacheMap()

Create a non-LRU (and therefore highly concurrent) cache map with a size of 1000.

CacheMap

public CacheMap(boolean lru)

Create a cache map with a size of 1000.

Parameters:

lru - if true, create a LRU cache map otherwise a non-LRU map will be created.

CacheMap

public CacheMap(boolean lru,
                int max)

Create a cache map with the given properties.

CacheMap

@Deprecated
public CacheMap(boolean lru,
                int max,
                int size,
                float load)

Deprecated.

use CacheMap(boolean, int, int, float, int) instead.

CacheMap

public CacheMap(boolean lru,
                int max,
                int size,
                float load,
                int concurrencyLevel)

Create a cache map with the given properties.

Since:

1.1.0

Method Detail

cacheMapOverflowRemoved

protected void cacheMapOverflowRemoved(Object key,
                                       Object value)

Called from SizedMap.overflowRemoved(java.lang.Object, java.lang.Object) in the cache map.

softMapOverflowRemoved

protected void softMapOverflowRemoved(Object key,
                                      Object value)

Called from SizedMap.overflowRemoved(java.lang.Object, java.lang.Object) in the soft map.

softMapValueExpired

protected void softMapValueExpired(Object key)

Called when a value expires from the soft map.

put

protected Object put(Map map,
                     Object key,
                     Object value)

Put the given entry into the given map. Allows subclasses to take additional actions.

remove

protected Object remove(Map map,
                        Object key)

Remove the given key from the given map. Allows subclasses to take additional actions.

readLock

public void readLock()

Acquire read lock.

readUnlock

public void readUnlock()

Release read lock.

writeLock

public void writeLock()

Acquire write lock.

writeUnlock

public void writeUnlock()

Release write lock.

isLRU

public boolean isLRU()

Whether this cache map uses LRU eviction.

setCacheSize

public void setCacheSize(int size)

The maximum number of hard references to maintain, or -1 for no limit.

getCacheSize

public int getCacheSize()

The maximum number of hard references to maintain, or -1 for no limit.

setSoftReferenceSize

public void setSoftReferenceSize(int size)

The maximum number of soft references to maintain, or -1 for no limit.

getSoftReferenceSize

public int getSoftReferenceSize()

The maximum number of soft references to maintain, or -1 for no limit.

getPinnedKeys

public Set getPinnedKeys()

The keys pinned into the map.

pin

public boolean pin(Object key)

Locks the given key and its value into the map. Objects pinned into the map are not counted towards the maximum cache size, and are never evicted implicitly. You may pin keys for which no value is in the map.

Returns:

true if the givne key's value was pinned; false if no value for the given key is cached

unpin

public boolean unpin(Object key)

Undo a pinning.

entryRemoved

protected void entryRemoved(Object key,
                            Object value,
                            boolean expired)

Invoked when a key-value pair is evicted from this data structure. This is invoked with expired set to true when an object is dropped because of space requirements or through garbage collection of soft references. It is invoked with expired set to false when an object is explicitly removed via the remove(java.util.Map, java.lang.Object) or clear() methods. This may be invoked more than once for a given entry.

Parameters:

value - may be null if the value was a soft reference that has been GCd

Since:

0.2.5.0

entryAdded

protected void entryAdded(Object key,
                          Object value)

Invoked when an entry is added to the cache. This may be invoked more than once for an entry.

get

public Object get(Object key)

Specified by:

get in interface Map

put

public Object put(Object key,
                  Object value)

Specified by:

put in interface Map

putAll

public void putAll(Map map)

Specified by:

putAll in interface Map

putAll

public void putAll(Map map,
                   boolean replaceExisting)

remove

public Object remove(Object key)

If key is pinned into the cache, the pin is cleared and the object is removed.

Specified by:

remove in interface Map

clear

public void clear()

Removes pinned objects as well as unpinned ones.

Specified by:

clear in interface Map

size

public int size()

Specified by:

size in interface Map

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map

containsValue

public boolean containsValue(Object val)

Specified by:

containsValue in interface Map

keySet

public Set keySet()

Specified by:

keySet in interface Map

values

public Collection values()

Specified by:

values in interface Map

entrySet

public Set entrySet()

Specified by:

entrySet in interface Map

toString

public String toString()

Overrides:

toString in class Object