reactor.util.concurrent

Class Queues

java.lang.Object

reactor.util.concurrent.Queues

public final class Queues
extends java.lang.Object

Queue utilities and suppliers for 1-producer/1-consumer ready queues adapted for various given capacities.

Field Summary

Fields

Modifier and Type	Field and Description
static int	CAPACITY_UNSURE
static int	SMALL_BUFFER_SIZE A small default of available slots in a given container, compromise between intensive pipelines, small subscribers numbers and memory use.
static int	XS_BUFFER_SIZE An allocation friendly default of available slots in a given container, e.g.

Method Summary

Modifier and Type	Method and Description
static int	capacity(java.util.Queue q) Return the capacity of a given Queue in a best effort fashion.
static int	ceilingNextPowerOfTwo(int x) Calculate the next power of 2, greater than or equal to x.
static <T> java.util.function.Supplier<java.util.Queue<T>>	empty() A Supplier for an empty immutable Queue, to be used as a placeholder in methods that require a Queue when one doesn't expect to store any data in said Queue.
static <T> java.util.function.Supplier<java.util.Queue<T>>	get(int batchSize)
static boolean	isPowerOfTwo(int x)
static <T> java.util.function.Supplier<java.util.Queue<T>>	one()
static <T> java.util.function.Supplier<java.util.Queue<T>>	small()
static <T> java.util.function.Supplier<java.util.Queue<T>>	unbounded()
static <T> java.util.function.Supplier<java.util.Queue<T>>	unbounded(int linkSize) Returns an unbounded, linked-array-based Queue.
static <T> java.util.function.Supplier<java.util.Queue<T>>	unboundedMultiproducer() Returns an unbounded queue suitable for multi-producer/single-consumer (MPSC) scenarios.
static <T> java.util.function.Supplier<java.util.Queue<T>>	xs()

Methods inherited from class java.lang.Object

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

Field Detail

CAPACITY_UNSURE

public static final int CAPACITY_UNSURE

See Also:

Constant Field Values

XS_BUFFER_SIZE

public static final int XS_BUFFER_SIZE

An allocation friendly default of available slots in a given container, e.g. slow publishers and or fast/few subscribers

SMALL_BUFFER_SIZE

public static final int SMALL_BUFFER_SIZE

A small default of available slots in a given container, compromise between intensive pipelines, small subscribers numbers and memory use.

Method Detail

capacity

public static final int capacity(java.util.Queue q)

Return the capacity of a given Queue in a best effort fashion. Queues that are known to be unbounded will return Integer.MAX_VALUE and queues that have a known bounded capacity will return that capacity. For other Queue implementations not recognized by this method or not providing this kind of information, CAPACITY_UNSURE (Integer.MIN_VALUE) is returned.

Parameters:

q - the Queue to try to get a capacity for

Returns:

the capacity of the queue, if discoverable with confidence, or CAPACITY_UNSURE negative constant.

ceilingNextPowerOfTwo

public static int ceilingNextPowerOfTwo(int x)

Calculate the next power of 2, greater than or equal to x.

From Hacker's Delight, Chapter 3, Harry S. Warren Jr.

Parameters:

x - Value to round up

Returns:

The next power of 2 from x inclusive

get

public static <T> java.util.function.Supplier<java.util.Queue<T>> get(int batchSize)

Type Parameters:

T - the reified Queue generic type

Parameters:

batchSize - the bounded or unbounded (int.max) queue size

Returns:

an unbounded or bounded Queue Supplier

isPowerOfTwo

public static boolean isPowerOfTwo(int x)

Parameters:

x - the int to test

Returns:

true if x is a power of 2

empty

public static <T> java.util.function.Supplier<java.util.Queue<T>> empty()

A Supplier for an empty immutable Queue, to be used as a placeholder in methods that require a Queue when one doesn't expect to store any data in said Queue.

Type Parameters:

T - the reified Queue generic type

Returns:

an immutable empty Queue Supplier

one

public static <T> java.util.function.Supplier<java.util.Queue<T>> one()

Type Parameters:

T - the reified Queue generic type

Returns:

a bounded Queue Supplier

small

public static <T> java.util.function.Supplier<java.util.Queue<T>> small()

Type Parameters:

T - the reified Queue generic type

Returns:

a bounded Queue Supplier

unbounded

public static <T> java.util.function.Supplier<java.util.Queue<T>> unbounded()

Type Parameters:

T - the reified Queue generic type

Returns:

an unbounded Queue Supplier

unbounded

public static <T> java.util.function.Supplier<java.util.Queue<T>> unbounded(int linkSize)

Returns an unbounded, linked-array-based Queue. Integer.max sized link will return the default SMALL_BUFFER_SIZE size.

Type Parameters:

T - the reified Queue generic type

Parameters:

linkSize - the link size

Returns:

an unbounded Queue Supplier

xs

public static <T> java.util.function.Supplier<java.util.Queue<T>> xs()

Type Parameters:

T - the reified Queue generic type

Returns:

a bounded Queue Supplier

unboundedMultiproducer

public static <T> java.util.function.Supplier<java.util.Queue<T>> unboundedMultiproducer()

Returns an unbounded queue suitable for multi-producer/single-consumer (MPSC) scenarios.

Type Parameters:

T - the reified Queue generic type

Returns:

an unbounded MPSC Queue Supplier