cern.entwined

Class TransactionalQueue<E>

java.lang.Object

cern.entwined.SemiPersistent<TransactionalQueue<E>>

cern.entwined.TransactionalQueue<E>

All Implemented Interfaces:

Iterable<E>, Collection<E>, Queue<E>

public class TransactionalQueue<E>
extends SemiPersistent<TransactionalQueue<E>>
implements Queue<E>

Transactional queue implementation. It supports non-conflicting simultaneous reading from the head and writing to the tail.

Author:

Ivan Koblik

Constructor Summary

Constructors

Constructor and Description
TransactionalQueue() Creates an empty TransactionalQueue.
TransactionalQueue(Collection<E> sourceCollection) Creates a new TransactionalQueue initializing it with the given collection of elements.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	add(E e)
boolean	addAll(Collection<? extends E> c)
protected TransactionalQueue<E>	cleanCopy() Creates a new transactional entity from the current one discarding all the local changes.
void	clear()
TransactionalQueue<E>	commit(TransactionalQueue<E> globalState) For performance purposes returned global state is initialized with empty iterator, therefore polling data from the collection is not possible.
boolean	contains(Object o) This operation is not supported.
boolean	containsAll(Collection<?> c) This operation is not supported.
protected TransactionalQueue<E>	dirtyCopy() Copies references to the source data along with local changes and read/write logs.
void	drainTo(Collection<E> collection) Polls all the elements from the queue and adds them to the collection.
E	element()
boolean	isEmpty()
Iterator<E>	iterator() This operation is not supported.
boolean	offer(E e)
E	peek()
E	poll()
E	remove()
boolean	remove(Object o) This operation is not supported.
boolean	removeAll(Collection<?> c) This operation is not supported.
boolean	retainAll(Collection<?> c) This operation is not supported.
int	size()
Object[]	toArray() This operation is not supported.
<T> T[]	toArray(T[] a) This operation is not supported.
protected void	update(TransactionalQueue<E> changes, boolean onlyReadLogs) Updates local changes and change logs using change logs of the arguments.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

equals, hashCode

Constructor Detail

TransactionalQueue

public TransactionalQueue()

Creates an empty TransactionalQueue.

TransactionalQueue

public TransactionalQueue(Collection<E> sourceCollection)

Creates a new TransactionalQueue initializing it with the given collection of elements.

Parameters:

sourceCollection - The Collection of elements copy of which will be used as TransactionalQueue initial state.

Method Detail

cleanCopy

protected TransactionalQueue<E> cleanCopy()

Description copied from class: SemiPersistent

Creates a new transactional entity from the current one discarding all the local changes.

Specified by:

cleanCopy in class SemiPersistent<TransactionalQueue<E>>

Returns:

The new entity with no local changes.

dirtyCopy

protected TransactionalQueue<E> dirtyCopy()

Description copied from class: SemiPersistent

Copies references to the source data along with local changes and read/write logs.
Note: It is very important to copy source data by reference, otherwise SemiPersistent#update(Object) will not work.

Specified by:

dirtyCopy in class SemiPersistent<TransactionalQueue<E>>

Returns:

Dirty copy of this collection, with all the local changes and read/write logs preserved.

update

protected void update(TransactionalQueue<E> changes,
          boolean onlyReadLogs)

Description copied from class: SemiPersistent

Updates local changes and change logs using change logs of the arguments. Argument must be constructed from this using SemiPersistent.dirtyCopy().
Note: Any changes done to this collections after branching will be discarded.

Specified by:

update in class SemiPersistent<TransactionalQueue<E>>

Parameters:

changes - The branched collection possibly with updates.

onlyReadLogs - If true only read logs are updated. Useful for read-only transactions.

commit

public TransactionalQueue<E> commit(TransactionalQueue<E> globalState)

For performance purposes returned global state is initialized with empty iterator, therefore polling data from the collection is not possible. As it should never be done to the global state, it is safe to do that. This however does not affect clean or dirty copies.

drainTo

public void drainTo(Collection<E> collection)

Polls all the elements from the queue and adds them to the collection.

Parameters:

collection - The collection to be populated with elements from the queue.

offer

public boolean offer(E e)

Specified by:

offer in interface Queue<E>

peek

public E peek()

Specified by:

peek in interface Queue<E>

poll

public E poll()

Specified by:

poll in interface Queue<E>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<E>

size

public int size()

Specified by:

size in interface Collection<E>

add

public boolean add(E e)

Specified by:

add in interface Collection<E>

Specified by:

add in interface Queue<E>

element

public E element()

Specified by:

element in interface Queue<E>

remove

public E remove()

Specified by:

remove in interface Queue<E>

addAll

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

Specified by:

addAll in interface Collection<E>

clear

public void clear()

Specified by:

clear in interface Collection<E>

containsAll

public boolean containsAll(Collection<?> c)

This operation is not supported.

Specified by:

containsAll in interface Collection<E>

Throws:

UnsupportedOperationException - immediately on invocation.

contains

public boolean contains(Object o)

This operation is not supported.

Specified by:

contains in interface Collection<E>

Throws:

UnsupportedOperationException - immediately on invocation.

iterator

public Iterator<E> iterator()

This operation is not supported.

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Collection<E>

Throws:

UnsupportedOperationException - immediately on invocation.

remove

public boolean remove(Object o)

This operation is not supported.

Specified by:

remove in interface Collection<E>

Throws:

UnsupportedOperationException - immediately on invocation.

removeAll

public boolean removeAll(Collection<?> c)

This operation is not supported.

Specified by:

removeAll in interface Collection<E>

Throws:

UnsupportedOperationException - immediately on invocation.

retainAll

public boolean retainAll(Collection<?> c)

This operation is not supported.

Specified by:

retainAll in interface Collection<E>

Throws:

UnsupportedOperationException - immediately on invocation.

toArray

public Object[] toArray()

This operation is not supported.

Specified by:

toArray in interface Collection<E>

Throws:

UnsupportedOperationException - immediately on invocation.

toArray

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

This operation is not supported.

Specified by:

toArray in interface Collection<E>

Throws:

UnsupportedOperationException - immediately on invocation.