io.reactivex.rxjava3.operators

Class SpscLinkedArrayQueue<T>

java.lang.Object

io.reactivex.rxjava3.operators.SpscLinkedArrayQueue<T>

Type Parameters:

T - the contained value type

All Implemented Interfaces:

SimplePlainQueue<T>, SimpleQueue<T>

public final class SpscLinkedArrayQueue<T>
extends Object
implements SimplePlainQueue<T>

A single-producer single-consumer array-backed queue which can allocate new arrays in case the consumer is slower than the producer.

Since:

3.1.1

Constructor Summary

Constructors

Constructor and Description
SpscLinkedArrayQueue(int bufferSize) Constructs a linked array-based queue instance with the given island size rounded up to the next power of 2.

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all enqueued items from this queue.
boolean	isEmpty() Returns true if the queue is empty.
boolean	offer(T e) Atomically enqueue a single value.
boolean	offer(T first, T second) Offer two elements at the same time.
T	peek() Returns the next element in this queue without removing it or null if this queue is empty
T	poll() Tries to dequeue a value (non-null) or returns null if the queue is empty.
int	size() Returns the number of elements in the queue.

Methods inherited from class java.lang.Object

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

Constructor Detail

SpscLinkedArrayQueue

public SpscLinkedArrayQueue(int bufferSize)

Constructs a linked array-based queue instance with the given island size rounded up to the next power of 2.

Parameters:

bufferSize - the maximum number of elements per island

Method Detail

offer

public boolean offer(T e)

Atomically enqueue a single value.

This implementation is correct for single producer thread use only.

Specified by:

offer in interface SimpleQueue<T>

Parameters:

e - the value to enqueue, not null

Returns:

true if successful, false if the value was not enqueued likely due to reaching the queue capacity)

poll

@Nullable
public T poll()

Tries to dequeue a value (non-null) or returns null if the queue is empty.

If the producer uses SimpleQueue.offer(Object, Object) and when polling in pairs, if the first poll() returns a non-null item, the second poll() is guaranteed to return a non-null item as well.

This implementation is correct for single consumer thread use only.

Specified by:

poll in interface SimplePlainQueue<T>

Specified by:

poll in interface SimpleQueue<T>

Returns:

the item or null to indicate an empty queue

peek

@Nullable
public T peek()

Returns the next element in this queue without removing it or null if this queue is empty

Returns:

the next element or null

clear

public void clear()

Description copied from interface: SimpleQueue

Removes all enqueued items from this queue.

Specified by:

clear in interface SimpleQueue<T>

size

public int size()

Returns the number of elements in the queue.

Returns:

the number of elements in the queue

isEmpty

public boolean isEmpty()

Description copied from interface: SimpleQueue

Returns true if the queue is empty.

Note however that due to potential fused functions in SimpleQueue.poll() it is possible this method returns false but then poll() returns null because the fused function swallowed the available item(s).

Specified by:

isEmpty in interface SimpleQueue<T>

Returns:

true if the queue is empty

offer

public boolean offer(T first,
                     T second)

Offer two elements at the same time.

Don't use the regular offer() with this at all!

Specified by:

offer in interface SimpleQueue<T>

Parameters:

first - the first value, not null

second - the second value, not null

Returns:

true if the queue accepted the two new values