Class BatchArrayQueue<T>

java.lang.Object

org.cometd.server.ext.BatchArrayQueue<T>

Type Parameters:

T - the type of elements

All Implemented Interfaces:

Iterable<T>, Collection<T>, Queue<T>

public class BatchArrayQueue<T>
extends Object
implements Queue<T>

A concurrent queue that groups elements in batches.

The elements are stored in a growable circular array along with their batch number:

           head             tail
             |               |
 elements: [E1, E2, E3, E4, E5]
 batches : [ 1,  1,  2,  3,  3]
 

Elements E1 and E2 belong to batch 1, only element E3 belongs to batch 2, etc.

The batch can be "closed" and a new one "opened" by calling nextBatch().

The elements can be copied with exportMessagesToBatch(Queue, long) into a different queue, and removed with clearToBatch(long).

Constructor Summary

Constructors

Constructor	Description
BatchArrayQueue(int initial, Lock lock)

Method Summary

Modifier and Type	Method	Description
boolean	add(T t)
boolean	addAll(Collection<? extends T> items)
void	clear()	Removes all the elements from this queue and resets the batch number to 1.
void	clearToBatch(long batch)	Removes all the elements up to the given batch number.
boolean	contains(Object o)
boolean	containsAll(Collection<?> items)
T	element()
void	exportMessagesToBatch(Queue<T> target, long batch)	Copies the elements of this queue into the given queue, up to the given batch number.
long	getBatch()
boolean	isEmpty()
Iterator<T>	iterator()
void	nextBatch()	Closes the current batch and starts a new batch.
boolean	offer(T t)	Adds the given element to this queue, under the current batch as returned by getBatch().
T	peek()
T	poll()
T	remove()
boolean	remove(Object o)
boolean	removeAll(Collection<?> c)
boolean	retainAll(Collection<?> c)
int	size()
Object[]	toArray()
<E> E[]	toArray(E[] a)
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

equals, hashCode, parallelStream, removeIf, spliterator, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Constructor Details

BatchArrayQueue

public BatchArrayQueue(int initial,
 Lock lock)

Method Details

offer

public boolean offer(T t)

Adds the given element to this queue, under the current batch as returned by getBatch().

Specified by:

offer in interface Queue<T>

Parameters:

t - the element to add

Returns:

true

add

public boolean add(T t)

Specified by:

add in interface Collection<T>

Specified by:

add in interface Queue<T>

peek

public T peek()

Specified by:

peek in interface Queue<T>

element

public T element()

Specified by:

element in interface Queue<T>

poll

public T poll()

Specified by:

poll in interface Queue<T>

remove

public T remove()

Specified by:

remove in interface Queue<T>

remove

public boolean remove(Object o)

Specified by:

remove in interface Collection<T>

addAll

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

Specified by:

addAll in interface Collection<T>

removeAll

public boolean removeAll(Collection<?> c)

Specified by:

removeAll in interface Collection<T>

retainAll

public boolean retainAll(Collection<?> c)

Specified by:

retainAll in interface Collection<T>

containsAll

public boolean containsAll(Collection<?> items)

Specified by:

containsAll in interface Collection<T>

contains

public boolean contains(Object o)

Specified by:

contains in interface Collection<T>

iterator

public Iterator<T> iterator()

Specified by:

iterator in interface Collection<T>

Specified by:

iterator in interface Iterable<T>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<T>

size

public int size()

Specified by:

size in interface Collection<T>

toArray

public Object[] toArray()

Specified by:

toArray in interface Collection<T>

toArray

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

Specified by:

toArray in interface Collection<T>

clear

public void clear()

Removes all the elements from this queue and resets the batch number to 1.

Specified by:

clear in interface Collection<T>

getBatch

public long getBatch()

Returns:

the current batch number

nextBatch

public void nextBatch()

Closes the current batch and starts a new batch.

The next element offered to this queue will belong to the new batch.

clearToBatch

public void clearToBatch(long batch)

Removes all the elements up to the given batch number.

For example, given:

           head             tail
             |               |
 elements: [E1, E2, E3, E4, E5]
 batches : [ 1,  1,  2,  3,  3]
 

then calling clearToBatch(1) would leave the queue in this state:

                        head   tail
                         |       |
 elements: [null, null, E3, E4, E5]
 batches : [   0,    0,  2,  3,  3]
 

Parameters:

batch - the batch number

See Also:

• exportMessagesToBatch(Queue, long)

exportMessagesToBatch

public void exportMessagesToBatch(Queue<T> target,
 long batch)

Copies the elements of this queue into the given queue, up to the given batch number.

For example, given:

 this queue:
           head             tail
             |               |
 elements: [E1, E2, E3, E4, E5]
 batches : [ 1,  1,  2,  3,  3]

 target queue: []
 

then calling exportMessagesToBatch(2) would copy the elements belonging to batches up to 2 into the target queue, leaving this queue unchanged:

 this queue:
           head             tail
             |               |
 elements: [E1, E2, E3, E4, E5]
 batches : [ 1,  1,  2,  3,  3]

 target queue: [E1, E2, E3]
 

Parameters:

target - the target queue

batch - the batch number

See Also:

• clearToBatch(long)

toString

public String toString()

Overrides:

toString in class Object