org.jctools.queues

Class IndexedQueueSizeUtil

java.lang.Object

org.jctools.queues.IndexedQueueSizeUtil

public final class IndexedQueueSizeUtil
extends Object

A note to maintainers on index assumptions: in a single threaded world it would seem intuitive to assume:

 producerIndex >= consumerIndex
 

As an invariant, but in a concurrent, long running settings all of the following need to be considered:

• consumerIndex > producerIndex : due to counter overflow (unlikey with longs, but easy to reason)
• consumerIndex > producerIndex : due to consumer FastFlow like implementation discovering the element before the counter is updated.
• producerIndex - consumerIndex < 0 : due to above.
• producerIndex - consumerIndex > Integer.MAX_VALUE : as linked buffers allow constructing queues with more than Integer.MAX_VALUE elements.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	IndexedQueueSizeUtil.IndexedQueue

Field Summary

Fields

Modifier and Type	Field and Description
static int	IGNORE_PARITY_DIVISOR
static int	PLAIN_DIVISOR

Constructor Summary

Constructors

Constructor and Description
IndexedQueueSizeUtil()

Method Summary

Modifier and Type	Method and Description
static boolean	isEmpty(IndexedQueueSizeUtil.IndexedQueue iq)
static int	sanitizedSize(int capacity, long size)
static int	size(IndexedQueueSizeUtil.IndexedQueue iq, int divisor)

Methods inherited from class java.lang.Object

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

Field Detail

PLAIN_DIVISOR

public static final int PLAIN_DIVISOR

See Also:

Constant Field Values

IGNORE_PARITY_DIVISOR

public static final int IGNORE_PARITY_DIVISOR

See Also:

Constant Field Values

Constructor Detail

IndexedQueueSizeUtil

public IndexedQueueSizeUtil()

Method Detail

size

public static int size(IndexedQueueSizeUtil.IndexedQueue iq,
                       int divisor)

sanitizedSize

public static int sanitizedSize(int capacity,
                                long size)

isEmpty

public static boolean isEmpty(IndexedQueueSizeUtil.IndexedQueue iq)