org.tools4j.nobark.queue

Class AtomicConflationQueue<K,V>

java.lang.Object

org.tools4j.nobark.queue.AtomicConflationQueue<K,V>

Type Parameters:

K - the type of the conflation key

V - the type of elements in the queue

All Implemented Interfaces:

ConflationQueue<K,V>

public class AtomicConflationQueue<K,V>
extends java.lang.Object
implements ConflationQueue<K,V>

A conflation queue implementation that atomically evicts old values from the queue if a new one is enqueued with the same conflation key. The EvictConflationQueue is very similar but not atomic and it supports value exchange on polling, which this queue does not. A backing queue is supplied to the constructor and it determines whether single or multiple producers and consumers are supported.

Appender and poller() are both stateless and hence thread-safe. Note that appender listener and poller listener must also be thread safe if multiple producers or consumers are used, e.g. use AppenderListener.threadLocal(Supplier) and PollerListener.threadLocal(Supplier) to create thread local listener instances.

Nested Class Summary

Nested classes/interfaces inherited from interface org.tools4j.nobark.queue.ConflationQueue

ConflationQueue.Appender<K,V>, ConflationQueue.Poller<K,V>

Constructor Summary

Constructors

Constructor and Description
AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory) Constructor with queue factory.
AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, AppenderListener<? super K,? super V> appenderListener, PollerListener<? super K,? super V> pollerListener) Constructor with queue factory.
AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, java.util.List<? extends K> allConflationKeys) Constructor with queue factory and the exhaustive list of conflation keys.
AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, java.util.List<? extends K> allConflationKeys, AppenderListener<? super K,? super V> appenderListener, PollerListener<? super K,? super V> pollerListener) Constructor with queue factory and the exhaustive list of conflation keys.
AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, java.util.function.Supplier<? extends java.util.Map<java.lang.Object,java.lang.Object>> entryMapFactory, AppenderListener<? super K,? super V> appenderListener, PollerListener<? super K,? super V> pollerListener) Constructor with queue factory and entry map factory.

Method Summary

Modifier and Type	Method and Description
ConflationQueue.Appender<K,V>	appender() Returns the appender object used by the producer to enqueue values.
static <K extends java.lang.Enum<K>,V> AtomicConflationQueue<K,V>	forEnumConflationKey(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, java.lang.Class<K> conflationKeyClass) Static constructor method for a conflation queue with queue factory and the conflation key enum class.
static <K extends java.lang.Enum<K>,V> AtomicConflationQueue<K,V>	forEnumConflationKey(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, java.lang.Class<K> conflationKeyClass, AppenderListener<? super K,? super V> appenderListener, PollerListener<? super K,? super V> pollerListener) Static constructor method for a conflation queue with queue factory and the conflation key enum class.
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.

Methods inherited from class java.lang.Object

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

Constructor Detail

AtomicConflationQueue

public AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory)

Constructor with queue factory. A concurrent hash map is used to manage entries per conflation key.

Parameters:

queueFactory - the factory to create the backing queue

AtomicConflationQueue

public AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                             AppenderListener<? super K,? super V> appenderListener,
                             PollerListener<? super K,? super V> pollerListener)

Constructor with queue factory. A concurrent hash map is used to manage entries per conflation key.

Parameters:

queueFactory - the factory to create the backing queue

appenderListener - a listener to monitor the enqueue operations

pollerListener - a listener to monitor the poll operations

AtomicConflationQueue

public AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                             java.util.function.Supplier<? extends java.util.Map<java.lang.Object,java.lang.Object>> entryMapFactory,
                             AppenderListener<? super K,? super V> appenderListener,
                             PollerListener<? super K,? super V> pollerListener)

Constructor with queue factory and entry map factory.

Parameters:

queueFactory - the factory to create the backing queue

entryMapFactory - the factory to create the map that manages entries per conflation key

appenderListener - a listener to monitor the enqueue operations

pollerListener - a listener to monitor the poll operations

AtomicConflationQueue

public AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                             java.util.List<? extends K> allConflationKeys)

Constructor with queue factory and the exhaustive list of conflation keys. A hash map is pre-initialized with all the conflation keys and pre-allocated entries.

Parameters:

queueFactory - the factory to create the backing queue

allConflationKeys - all conflation keys that will ever be used with this conflation queue instance

AtomicConflationQueue

public AtomicConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                             java.util.List<? extends K> allConflationKeys,
                             AppenderListener<? super K,? super V> appenderListener,
                             PollerListener<? super K,? super V> pollerListener)

Constructor with queue factory and the exhaustive list of conflation keys. A hash map is pre-initialized with all the conflation keys and pre-allocated entries.

Parameters:

queueFactory - the factory to create the backing queue

allConflationKeys - all conflation keys that will ever be used with this conflation queue instance

appenderListener - a listener to monitor the enqueue operations

pollerListener - a listener to monitor the poll operations

Method Detail

forEnumConflationKey

public static <K extends java.lang.Enum<K>,V> AtomicConflationQueue<K,V> forEnumConflationKey(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                                                                                              java.lang.Class<K> conflationKeyClass)

Static constructor method for a conflation queue with queue factory and the conflation key enum class. An enum map is pre-initialized with all the conflation keys and pre-allocated entries.

Type Parameters:

K - the type of the conflation key

V - the type of elements in the queue

Parameters:

queueFactory - the factory to create the backing queue

conflationKeyClass - the conflation key enum class

Returns:

the new conflation queue instance

forEnumConflationKey

public static <K extends java.lang.Enum<K>,V> AtomicConflationQueue<K,V> forEnumConflationKey(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                                                                                              java.lang.Class<K> conflationKeyClass,
                                                                                              AppenderListener<? super K,? super V> appenderListener,
                                                                                              PollerListener<? super K,? super V> pollerListener)

Static constructor method for a conflation queue with queue factory and the conflation key enum class. An enum map is pre-initialized with all the conflation keys and pre-allocated entries.

Type Parameters:

K - the type of the conflation key

V - the type of elements in the queue

Parameters:

queueFactory - the factory to create the backing queue

conflationKeyClass - the conflation key enum class

appenderListener - a listener to monitor the enqueue operations

pollerListener - a listener to monitor the poll operations

Returns:

the new conflation queue instance

appender

public ConflationQueue.Appender<K,V> appender()

Description copied from interface: ConflationQueue

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.

Specified by:

appender in interface ConflationQueue<K,V>

Returns:

the appender object used to enqueue values

poller

public ConflationQueue.Poller<K,V> poller()

Description copied from interface: ConflationQueue

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.

Specified by:

poller in interface ConflationQueue<K,V>

Returns:

the poller object used to poll values

size

public int size()

Description copied from interface: ConflationQueue

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.

Specified by:

size in interface ConflationQueue<K,V>

Returns:

the number of elements in this queue