org.tools4j.nobark.queue

Class MergeConflationQueue<K,V>

java.lang.Object

org.tools4j.nobark.queue.MergeConflationQueue<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>, ExchangeConflationQueue<K,V>

public class MergeConflationQueue<K,V>
extends java.lang.Object
implements ExchangeConflationQueue<K,V>

A conflation queue implementation that merges old and new value if a value is enqueued and another one already exists in the queue with the same conflation key. The backing queue is supplied to the constructor and it determines whether single or multiple producers and consumers are supported.

Each producer should acquire its own appender from the producing thread, and similarly every consumer should call poller() from the consuming thread. Note that appender listener and poller listener must be thread safe if multiple producers or consumers are used, e.g. use AppenderListener.threadLocalSupplier(Supplier) and PollerListener.threadLocalSupplier(Supplier) to create separate listener instances per producer/consumer thread.

Nested Class Summary

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

ExchangeConflationQueue.ExchangePoller<K,V>

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
MergeConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, Merger<? super K,V> merger) Constructor with queue factory and merger.
MergeConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, Merger<? super K,V> merger, java.util.List<? extends K> allConflationKeys) Constructor with queue factory, merger and the exhaustive list of conflation keys.
MergeConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, Merger<? super K,V> merger, java.util.List<? extends K> allConflationKeys, java.util.function.Supplier<? extends AppenderListener<? super K,? super V>> appenderListenerSupplier, java.util.function.Supplier<? extends PollerListener<? super K,? super V>> pollerListenerSupplier) Constructor with queue factory, merger and the exhaustive list of conflation keys.
MergeConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, Merger<? super K,V> merger, java.util.function.Supplier<? extends AppenderListener<? super K,? super V>> appenderListenerSupplier, java.util.function.Supplier<? extends PollerListener<? super K,? super V>> pollerListenerSupplier) Constructor with queue factory and merger.

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> MergeConflationQueue<K,V>	forEnumConflationKey(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, Merger<? super K,V> merger, java.lang.Class<K> conflationKeyClass) Static constructor method for a conflation queue with queue factory, merger and the conflation key enum class.
static <K extends java.lang.Enum<K>,V> MergeConflationQueue<K,V>	forEnumConflationKey(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory, Merger<? super K,V> merger, java.lang.Class<K> conflationKeyClass, java.util.function.Supplier<? extends AppenderListener<? super K,? super V>> appenderListenerSupplier, java.util.function.Supplier<? extends PollerListener<? super K,? super V>> pollerListenerSupplier) Static constructor method for a conflation queue with queue factory, merger and the conflation key enum class.
ExchangeConflationQueue.ExchangePoller<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

Methods inherited from interface org.tools4j.nobark.queue.ExchangeConflationQueue

nullSafe, nullSafe

Constructor Detail

MergeConflationQueue

public MergeConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                            Merger<? super K,V> merger)

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

Parameters:

queueFactory - the factory to create the backing queue

merger - the merge strategy to use if conflation occurs

MergeConflationQueue

public MergeConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                            Merger<? super K,V> merger,
                            java.util.function.Supplier<? extends AppenderListener<? super K,? super V>> appenderListenerSupplier,
                            java.util.function.Supplier<? extends PollerListener<? super K,? super V>> pollerListenerSupplier)

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

Parameters:

queueFactory - the factory to create the backing queue

merger - the merge strategy to use if conflation occurs

appenderListenerSupplier - a supplier for a listener to monitor the enqueue operations

pollerListenerSupplier - a supplier for a listener to monitor the poll operations

MergeConflationQueue

public MergeConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                            Merger<? super K,V> merger,
                            java.util.List<? extends K> allConflationKeys)

Constructor with queue factory, merger 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

merger - the merge strategy to use if conflation occurs

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

MergeConflationQueue

public MergeConflationQueue(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                            Merger<? super K,V> merger,
                            java.util.List<? extends K> allConflationKeys,
                            java.util.function.Supplier<? extends AppenderListener<? super K,? super V>> appenderListenerSupplier,
                            java.util.function.Supplier<? extends PollerListener<? super K,? super V>> pollerListenerSupplier)

Constructor with queue factory, merger 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

merger - the merge strategy to use if conflation occurs

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

appenderListenerSupplier - a supplier for a listener to monitor the enqueue operations

pollerListenerSupplier - a supplier for a listener to monitor the poll operations

Method Detail

forEnumConflationKey

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

Static constructor method for a conflation queue with queue factory, merger 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

merger - the merge strategy to use if conflation occurs

conflationKeyClass - the conflation key enum class

Returns:

the new conflation queue instance

forEnumConflationKey

public static <K extends java.lang.Enum<K>,V> MergeConflationQueue<K,V> forEnumConflationKey(java.util.function.Supplier<? extends java.util.Queue<java.lang.Object>> queueFactory,
                                                                                             Merger<? super K,V> merger,
                                                                                             java.lang.Class<K> conflationKeyClass,
                                                                                             java.util.function.Supplier<? extends AppenderListener<? super K,? super V>> appenderListenerSupplier,
                                                                                             java.util.function.Supplier<? extends PollerListener<? super K,? super V>> pollerListenerSupplier)

Static constructor method for a conflation queue with queue factory, merger 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

merger - the merge strategy to use if conflation occurs

conflationKeyClass - the conflation key enum class

appenderListenerSupplier - a supplier for a listener to monitor the enqueue operations

pollerListenerSupplier - a supplier for 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>

Specified by:

appender in interface ExchangeConflationQueue<K,V>

Returns:

the appender object used to enqueue values

poller

public ExchangeConflationQueue.ExchangePoller<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>

Specified by:

poller in interface ExchangeConflationQueue<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