org.apache.river.concurrent

Class ReferenceCollection<T>

java.lang.Object

java.util.AbstractCollection<T>

org.apache.river.concurrent.ReferenceCollection<T>

All Implemented Interfaces:

Serializable, Iterable<T>, Collection<T>

Direct Known Subclasses:

ReferencedQueue, ReferenceList, ReferenceSet

class ReferenceCollection<T>
extends AbstractCollection<T>
implements Collection<T>, Serializable

A Collection of Reference Objects, the developer may chose any Collection implementation to store the References, which is passed in a runtime. The underlying Collection implementation governs the specific behaviour of this Collection. Synchronisation must be implemented by the underlying Collection and cannot be performed externally to this class. The underlying Collection must also be mutable. Objects will be removed automatically from the underlying Collection when they are eligible for garbage collection. Weak, Weak Identity, Soft, Soft Identity or Strong references may be used. This Collection may be used as an Object pool cache or any other purpose that requires unique memory handling. For concurrent threads, it is recommended to encapsulate the underlying collection in a multi read, single write collection for scalability.

Author:

Peter Firmstone.

See Also:

Ref, ConcurrentCollections#multiReadCollection(java.util.Collection)

Field Summary

Fields

Modifier and Type	Field and Description
private Collection<Referrer<T>>	col
private ReferenceQueuingFactory<T,Referrer<T>>	rqf
private static long	serialVersionUID
private Ref	type

Constructor Summary

Constructors

Constructor and Description
ReferenceCollection(Collection<Referrer<T>> col, Ref type, boolean gcThread, long gcCycle)
ReferenceCollection(Collection<Referrer<T>> col, ReferenceQueuingFactory<T,Referrer<T>> rqf, Ref type)

Method Summary

Modifier and Type	Method and Description
boolean	add(T e)
boolean	addAll(Collection<? extends T> c)
void	clear()
boolean	contains(Object o)
boolean	containsAll(Collection<?> c)
boolean	equals(Object o) Because equals and hashCode are not defined for collections, we cannot guarantee consistent behaviour by implementing equals and hashCode.
(package private) Ref	getRef()
(package private) ReferenceQueuingFactory<T,Referrer<T>>	getRQF()
int	hashCode()
boolean	isEmpty()
Iterator<T>	iterator() This Iterator may return null values if garbage collection runs during iteration.
(package private) void	processQueue()
private void	readObject(ObjectInputStream stream)
boolean	remove(Object o)
int	size()
String	toString()
(package private) Referrer<T>	wrapObj(T t, boolean enqueue, boolean temporary)
(package private) Object	writeReplace()

Methods inherited from class java.util.AbstractCollection

removeAll, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

parallelStream, removeAll, removeIf, retainAll, spliterator, stream, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

col

private final Collection<Referrer<T>> col

rqf

private final ReferenceQueuingFactory<T,Referrer<T>> rqf

type

private final Ref type

Constructor Detail

ReferenceCollection

ReferenceCollection(Collection<Referrer<T>> col,
                    Ref type,
                    boolean gcThread,
                    long gcCycle)

ReferenceCollection

ReferenceCollection(Collection<Referrer<T>> col,
                    ReferenceQueuingFactory<T,Referrer<T>> rqf,
                    Ref type)

Method Detail

processQueue

void processQueue()

getRQF

ReferenceQueuingFactory<T,Referrer<T>> getRQF()

getRef

Ref getRef()

wrapObj

Referrer<T> wrapObj(T t,
                    boolean enqueue,
                    boolean temporary)

size

public int size()

Specified by:

size in interface Collection<T>

Specified by:

size in class AbstractCollection<T>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<T>

Overrides:

isEmpty in class AbstractCollection<T>

contains

public boolean contains(Object o)

Specified by:

contains in interface Collection<T>

Overrides:

contains in class AbstractCollection<T>

iterator

public Iterator<T> iterator()

This Iterator may return null values if garbage collection runs during iteration. Always check for null values.

Specified by:

iterator in interface Iterable<T>

Specified by:

iterator in interface Collection<T>

Specified by:

iterator in class AbstractCollection<T>

Returns:

T - possibly null.

add

public boolean add(T e)

Specified by:

add in interface Collection<T>

Overrides:

add in class AbstractCollection<T>

remove

public boolean remove(Object o)

Specified by:

remove in interface Collection<T>

Overrides:

remove in class AbstractCollection<T>

containsAll

public boolean containsAll(Collection<?> c)

Specified by:

containsAll in interface Collection<T>

Overrides:

containsAll in class AbstractCollection<T>

addAll

public boolean addAll(Collection<? extends T> c)

Specified by:

addAll in interface Collection<T>

Overrides:

addAll in class AbstractCollection<T>

clear

public void clear()

Specified by:

clear in interface Collection<T>

Overrides:

clear in class AbstractCollection<T>

toString

public String toString()

Overrides:

toString in class AbstractCollection<T>

hashCode

public int hashCode()

Specified by:

hashCode in interface Collection<T>

Overrides:

hashCode in class Object

equals

public boolean equals(Object o)

Because equals and hashCode are not defined for collections, we cannot guarantee consistent behaviour by implementing equals and hashCode. A collection could be a list, set, queue or deque. So a List != Queue and a Set != list. therefore equals for collections is not defined. However since two collections may both also be Lists, while abstracted from the client two lists may still be equal.

Specified by:

equals in interface Collection<T>

Overrides:

equals in class Object

See Also:

Collection.equals(java.lang.Object)

writeReplace

final Object writeReplace()
                   throws ObjectStreamException

Throws:

ObjectStreamException

readObject

private void readObject(ObjectInputStream stream)
                 throws InvalidObjectException

Throws:

InvalidObjectException