com.simsilica.util

Class BufferedHashSet<E>

java.lang.Object

com.simsilica.util.BufferedHashSet<E>

All Implemented Interfaces:

java.lang.Iterable<E>, java.util.Collection<E>, java.util.Set<E>

public class BufferedHashSet<E>
extends java.lang.Object
implements java.util.Set<E>

A HashSet implementation that buffers modifications until a commit is performeed. The buffering can be done from one thread and the reads from another. So reads are safe from any thread but writes must be done from only one thread or properly synchronized externally. This is useful for efficiently buffering the output of one process for another. Note: this doubles the storage requirements over a typical HashSet is it internally keeps two sets, one for the writer and one for all readers. Also note: the semantics of the way reads and writes are decoupled mean that it is possible for add(element) to return false (indicating that the set already has the value) while contains(element) will also return false (because the element hasn't been committed yet). The writing thread should use getTransaction() if it wants to check transactional data integrity for some reason.

Constructor Summary

Constructors

Constructor and Description
BufferedHashSet()

Method Summary

Modifier and Type	Method and Description
boolean	add(E e) Updates the write buffer to reflect the addition of the specified element.
boolean	addAll(java.util.Collection<? extends E> c) Updates the write buffer to reflect the removal of the specified elements.
void	clear() Clears the write buffer.
void	commit() Called from the writing thread to apply the buffer changes to the readable view.
boolean	contains(java.lang.Object o)
boolean	containsAll(java.util.Collection<?> c)
boolean	equals(java.lang.Object o)
java.util.Set<E>	getSnapshot() Returns a snapshot of the readable view of this HashSet at the time this method is called.
java.util.Set<E>	getTransaction() Returns the transactional buffer.
int	hashCode()
boolean	isEmpty()
java.util.Iterator<E>	iterator()
boolean	remove(java.lang.Object o) Updates the write buffer to reflect the removal of the specified element.
boolean	removeAll(java.util.Collection<?> c) Updates the write buffer to reflect the removal of the specified elements.
boolean	retainAll(java.util.Collection<?> c) Updates the write buffer to reflect the retention of the specified elements.
int	size()
java.lang.Object[]	toArray()
<T> T[]	toArray(T[] a)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Set

spliterator

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Methods inherited from interface java.lang.Iterable

forEach

Constructor Detail

BufferedHashSet

public BufferedHashSet()

Method Detail

getTransaction

public java.util.Set<E> getTransaction()

Returns the transactional buffer. Note: access to this is only thread safe from the writing thread.

commit

public void commit()

Called from the writing thread to apply the buffer changes to the readable view.

getSnapshot

public java.util.Set<E> getSnapshot()

Returns a snapshot of the readable view of this HashSet at the time this method is called. Subsequent commits will not affect this view.

size

public int size()

Specified by:

size in interface java.util.Collection<E>

Specified by:

size in interface java.util.Set<E>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface java.util.Collection<E>

Specified by:

isEmpty in interface java.util.Set<E>

contains

public boolean contains(java.lang.Object o)

Specified by:

contains in interface java.util.Collection<E>

Specified by:

contains in interface java.util.Set<E>

iterator

public java.util.Iterator<E> iterator()

Specified by:

iterator in interface java.lang.Iterable<E>

Specified by:

iterator in interface java.util.Collection<E>

Specified by:

iterator in interface java.util.Set<E>

toArray

public java.lang.Object[] toArray()

Specified by:

toArray in interface java.util.Collection<E>

Specified by:

toArray in interface java.util.Set<E>

toArray

public <T> T[] toArray(T[] a)

Specified by:

toArray in interface java.util.Collection<E>

Specified by:

toArray in interface java.util.Set<E>

add

public boolean add(E e)

Updates the write buffer to reflect the addition of the specified element. This won't show up to the read methods until a commit() is performed. Callers wishing to see data in the buffer must use the Set returned from getTransaction().

Specified by:

add in interface java.util.Collection<E>

Specified by:

add in interface java.util.Set<E>

remove

public boolean remove(java.lang.Object o)

Updates the write buffer to reflect the removal of the specified element. This won't show up to the read methods until a commit() is performed. Callers wishing to see data in the buffer must use the Set returned from getTransaction().

Specified by:

remove in interface java.util.Collection<E>

Specified by:

remove in interface java.util.Set<E>

containsAll

public boolean containsAll(java.util.Collection<?> c)

Specified by:

containsAll in interface java.util.Collection<E>

Specified by:

containsAll in interface java.util.Set<E>

addAll

public boolean addAll(java.util.Collection<? extends E> c)

Updates the write buffer to reflect the removal of the specified elements. This won't show up to the read methods until a commit() is performed. Callers wishing to see data in the buffer must use the Set returned from getTransaction().

Specified by:

addAll in interface java.util.Collection<E>

Specified by:

addAll in interface java.util.Set<E>

retainAll

public boolean retainAll(java.util.Collection<?> c)

Updates the write buffer to reflect the retention of the specified elements. This won't show up to the read methods until a commit() is performed. Callers wishing to see data in the buffer must use the Set returned from getTransaction().

Specified by:

retainAll in interface java.util.Collection<E>

Specified by:

retainAll in interface java.util.Set<E>

removeAll

public boolean removeAll(java.util.Collection<?> c)

Updates the write buffer to reflect the removal of the specified elements. This won't show up to the read methods until a commit() is performed. Callers wishing to see data in the buffer must use the Set returned from getTransaction().

Specified by:

removeAll in interface java.util.Collection<E>

Specified by:

removeAll in interface java.util.Set<E>

clear

public void clear()

Clears the write buffer. This won't show up to the read methods until a commit() is performed. Callers wishing to see data in the buffer must use the Set returned from getTransaction().

Specified by:

clear in interface java.util.Collection<E>

Specified by:

clear in interface java.util.Set<E>

equals

public boolean equals(java.lang.Object o)

Specified by:

equals in interface java.util.Collection<E>

Specified by:

equals in interface java.util.Set<E>

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Specified by:

hashCode in interface java.util.Collection<E>

Specified by:

hashCode in interface java.util.Set<E>

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object