Package org.apache.openjpa.lib.util

Class ReferenceHashMap

java.lang.Object

java.util.AbstractMap<K,V>

org.apache.openjpa.lib.util.collections.AbstractHashedMap<K,V>

org.apache.openjpa.lib.util.collections.AbstractReferenceMap<K,V>

org.apache.openjpa.lib.util.collections.ReferenceMap

org.apache.openjpa.lib.util.ReferenceHashMap

All Implemented Interfaces:

java.io.Serializable, java.util.Map, IterableMap, ReferenceMap, SizedMap

public class ReferenceHashMap
extends ReferenceMap
implements ReferenceMap, SizedMap

Map in which the key, value, or both may be weak/soft references.

Since:

0.4.0

Author:

Abe White

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.openjpa.lib.util.collections.AbstractReferenceMap

AbstractReferenceMap.ReferenceEntry<K,V>, AbstractReferenceMap.ReferenceStrength

Nested classes/interfaces inherited from class org.apache.openjpa.lib.util.collections.AbstractHashedMap

AbstractHashedMap.EntrySet<K,V>, AbstractHashedMap.EntrySetIterator<K,V>, AbstractHashedMap.HashEntry<K,V>, AbstractHashedMap.HashIterator<K,V>, AbstractHashedMap.HashMapIterator<K,V>, AbstractHashedMap.KeySet<K>, AbstractHashedMap.KeySetIterator<K>, AbstractHashedMap.Values<V>, AbstractHashedMap.ValuesIterator<V>

Nested classes/interfaces inherited from class java.util.AbstractMap

java.util.AbstractMap.SimpleEntry<K extends java.lang.Object,V extends java.lang.Object>, java.util.AbstractMap.SimpleImmutableEntry<K extends java.lang.Object,V extends java.lang.Object>

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

java.util.Map.Entry<K extends java.lang.Object,V extends java.lang.Object>

Field Summary

Fields inherited from class org.apache.openjpa.lib.util.collections.AbstractHashedMap

DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD, GETKEY_INVALID, GETVALUE_INVALID, MAXIMUM_CAPACITY, NO_NEXT_ENTRY, NO_PREVIOUS_ENTRY, NULL, REMOVE_INVALID, SETVALUE_INVALID

Constructor Summary

Constructors

Constructor	Description
ReferenceHashMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType)
ReferenceHashMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, int capacity, float loadFactor)

Method Summary

Modifier and Type	Method	Description
protected void	addMapping(int hashIndex, int hashCode, java.lang.Object key, java.lang.Object value)	Adds a new key-value mapping into this map.
protected AbstractReferenceMap.ReferenceEntry	createEntry(AbstractHashedMap.HashEntry next, int hashCode, java.lang.Object key, java.lang.Object value)	Creates a ReferenceEntry instead of a HashEntry.
protected void	doReadObject(java.io.ObjectInputStream in)	Replaces the superclass method to read the state of this class.
protected void	doWriteObject(java.io.ObjectOutputStream out)	Replaces the superclass method to store the state of this class.
int	getMaxSize()	The maximum number of entries, or Integer.MAX_VALUE for no limit.
boolean	isFull()	Whether the map is full.
void	keyExpired(java.lang.Object value)	Overridable callback for when a key reference expires.
void	overflowRemoved(java.lang.Object key, java.lang.Object value)	Overridable callback for when an overflow entry is automatically removed.
void	removeExpired()	Purge stale entries.
void	setMaxSize(int maxSize)	The maximum number of entries, or Integer.MAX_VALUE for no limit.
void	valueExpired(java.lang.Object key)	Overridable callback for when a value reference expires.

Methods inherited from class org.apache.openjpa.lib.util.collections.AbstractReferenceMap

clear, containsKey, containsValue, createEntrySetIterator, createKeySetIterator, createValuesIterator, entrySet, get, getEntry, hashEntry, init, isEmpty, isEqualKey, isKeyType, isValueType, keySet, mapIterator, purge, purge, purgeBeforeRead, purgeBeforeWrite, put, remove, size, values

Methods inherited from class org.apache.openjpa.lib.util.collections.AbstractHashedMap

addEntry, calculateNewCapacity, calculateThreshold, checkCapacity, clone, convertKey, destroyEntry, ensureCapacity, entryHashCode, entryKey, entryNext, entryValue, equals, hash, hashCode, hashIndex, isEqualValue, putAll, removeEntry, removeMapping, reuseEntry, toString, updateEntry

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, containsKey, containsValue, entrySet, equals, forEach, get, getOrDefault, hashCode, isEmpty, keySet, merge, putIfAbsent, remove, remove, replace, replace, replaceAll, size, values

Constructor Detail

ReferenceHashMap

public ReferenceHashMap(AbstractReferenceMap.ReferenceStrength keyType,
                        AbstractReferenceMap.ReferenceStrength valueType)

ReferenceHashMap

public ReferenceHashMap(AbstractReferenceMap.ReferenceStrength keyType,
                        AbstractReferenceMap.ReferenceStrength valueType,
                        int capacity,
                        float loadFactor)

Method Detail

getMaxSize

public int getMaxSize()

Description copied from interface: SizedMap

The maximum number of entries, or Integer.MAX_VALUE for no limit.

Specified by:

getMaxSize in interface SizedMap

setMaxSize

public void setMaxSize(int maxSize)

Description copied from interface: SizedMap

The maximum number of entries, or Integer.MAX_VALUE for no limit.

Specified by:

setMaxSize in interface SizedMap

isFull

public boolean isFull()

Description copied from interface: SizedMap

Whether the map is full.

Specified by:

isFull in interface SizedMap

overflowRemoved

public void overflowRemoved(java.lang.Object key,
                            java.lang.Object value)

Description copied from interface: SizedMap

Overridable callback for when an overflow entry is automatically removed.

Specified by:

overflowRemoved in interface SizedMap

valueExpired

public void valueExpired(java.lang.Object key)

Description copied from interface: ReferenceMap

Overridable callback for when a value reference expires.

Specified by:

valueExpired in interface ReferenceMap

Parameters:

key - the key for the expired value

keyExpired

public void keyExpired(java.lang.Object value)

Description copied from interface: ReferenceMap

Overridable callback for when a key reference expires.

Specified by:

keyExpired in interface ReferenceMap

Parameters:

value - the value for the expired key

removeExpired

public void removeExpired()

Description copied from interface: ReferenceMap

Purge stale entries.

Specified by:

removeExpired in interface ReferenceMap

addMapping

protected void addMapping(int hashIndex,
                          int hashCode,
                          java.lang.Object key,
                          java.lang.Object value)

Description copied from class: AbstractHashedMap

Adds a new key-value mapping into this map.

This implementation calls createEntry(), addEntry() and checkCapacity(). It also handles changes to modCount and size. Subclasses could override to fully control adds to the map.

Overrides:

addMapping in class AbstractHashedMap

Parameters:

hashIndex - the index into the data array to store at

hashCode - the hash code of the key to add

key - the key to add

value - the value to add

createEntry

protected AbstractReferenceMap.ReferenceEntry createEntry(AbstractHashedMap.HashEntry next,
                                                          int hashCode,
                                                          java.lang.Object key,
                                                          java.lang.Object value)

Description copied from class: AbstractReferenceMap

Creates a ReferenceEntry instead of a HashEntry.

Overrides:

createEntry in class AbstractReferenceMap

Parameters:

next - the next entry in sequence

hashCode - the hash code to use

key - the key to store

value - the value to store

Returns:

the newly created entry

doWriteObject

protected void doWriteObject(java.io.ObjectOutputStream out)
                      throws java.io.IOException

Description copied from class: AbstractReferenceMap

Replaces the superclass method to store the state of this class.

Serialization is not one of the JDK's nicest topics. Normal serialization will initialise the superclass before the subclass. Sometimes however, this isn't what you want, as in this case the put() method on read can be affected by subclass state.

The solution adopted here is to serialize the state data of this class in this protected method. This method must be called by the writeObject() of the first serializable subclass.

Subclasses may override if they have a specific field that must be present on read before this implementation will work. Generally, the read determines what must be serialized here, if anything.

Overrides:

doWriteObject in class AbstractReferenceMap

Parameters:

out - the output stream

Throws:

java.io.IOException - if an error occurs while writing to the stream

doReadObject

protected void doReadObject(java.io.ObjectInputStream in)
                     throws java.lang.ClassNotFoundException,
                            java.io.IOException

Description copied from class: AbstractReferenceMap

Replaces the superclass method to read the state of this class.

Serialization is not one of the JDK's nicest topics. Normal serialization will initialise the superclass before the subclass. Sometimes however, this isn't what you want, as in this case the put() method on read can be affected by subclass state.

The solution adopted here is to deserialize the state data of this class in this protected method. This method must be called by the readObject() of the first serializable subclass.

Subclasses may override if the subclass has a specific field that must be present before put() or calculateThreshold() will work correctly.

Overrides:

doReadObject in class AbstractReferenceMap

Parameters:

in - the input stream

Throws:

java.lang.ClassNotFoundException - if an object read from the stream can not be loaded

java.io.IOException - if an error occurs while reading from the stream