org.tools4j.nobark.queue

Interface ConflationQueue<K,V>

Type Parameters:

K - the type of the conflation key

V - the type of values in the queue

All Known Subinterfaces:

ExchangeConflationQueue<K,V>

All Known Implementing Classes:

AtomicConflationQueue, EvictConflationQueue, MergeConflationQueue

public interface ConflationQueue<K,V>

A conflation queue is a queue with a safety mechanism to prevent overflow. Values are enqueued with a conflation key, and if a value with the same key already resides in the queue then the two values will be "conflated". Conflation in the simplest case means that the most recent value survives and replaces older values; some more advanced implementations support merging when conflation occurs.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	ConflationQueue.Appender<K,V> Appender used by the producer to enqueue values.
static interface	ConflationQueue.Poller<K,V> Poller object used by the consumer to poll values.

Method Summary

Modifier and Type	Method and Description
ConflationQueue.Appender<K,V>	appender() Returns the appender object used by the producer to enqueue values.
ConflationQueue.Poller<K,V>	poller() Returns the poller object used by the consumer to poll values.
int	size() Returns the number of elements in this queue.

Method Detail

appender

ConflationQueue.Appender<K,V> appender()

Returns the appender object used by the producer to enqueue values. Some conflation queue implementations return thread-safe appender instances, other implementations return an instance per caller thread. Hence it is highly recommended to access the appender via this method directly from the producer thread and not share it between threads.

Returns:

the appender object used to enqueue values

poller

ConflationQueue.Poller<K,V> poller()

Returns the poller object used by the consumer to poll values. Some conflation queue implementations return thread-safe poller instances, other implementations return an instance per caller thread. Hence it is highly recommended to access the poller via this method directly from the consumer thread and not share it between threads.

Returns:

the poller object used to poll values

size

int size()

Returns the number of elements in this queue.

Beware that, unlike in most collections, this method may NOT be a constant-time operation. Because of the asynchronous nature of concurrent queues, determining the current number of elements may require an O(n) traversal. Additionally, if elements are added or removed during execution of this method, the returned result may be inaccurate. Thus, this method is typically not very useful in concurrent applications.

Returns:

the number of elements in this queue