org.glassfish.jersey.internal.util.collection
Class DataStructures

java.lang.Object
  org.glassfish.jersey.internal.util.collection.DataStructures

public final class DataStructures
extends Object

Utility class, which tries to pickup the best collection implementation depending on running environment.

Since:

2.3

Author:

Gustav Trede, Marek Potociar (marek.potociar at oracle.com)

Field Summary

static int

DEFAULT_CONCURENCY_LEVEL Default concurrency level calculated based on the number of available CPUs.

Constructor Summary

DataStructures()

Method Summary

static <K,V> ConcurrentMap<K,V>	createConcurrentMap() Creates a new, empty map with a default initial capacity (16), load factor (0.75) and concurrencyLevel (16).
static <K,V> ConcurrentMap<K,V>	createConcurrentMap(int initialCapacity) Creates a new, empty map with an initial table size accommodating the specified number of elements without the need to dynamically resize.
static <K,V> ConcurrentMap<K,V>	createConcurrentMap(int initialCapacity, float loadFactor, int concurrencyLevel) Creates a new, empty map with an initial table size based on the given number of elements (initialCapacity), table density (loadFactor), and number of concurrently updating threads (concurrencyLevel).
static <K,V> ConcurrentMap<K,V>	createConcurrentMap(Map<? extends K,? extends V> map) Creates a new map with the same mappings as the given map.
static <E> BlockingQueue<E>	createLinkedTransferQueue() Create an instance of a BlockingQueue that is based on LinkedTransferQueue implementation from JDK 7.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CONCURENCY_LEVEL

public static final int DEFAULT_CONCURENCY_LEVEL

Default concurrency level calculated based on the number of available CPUs.

Constructor Detail

DataStructures

public DataStructures()

Method Detail

createLinkedTransferQueue

public static <E> BlockingQueue<E> createLinkedTransferQueue()

Create an instance of a BlockingQueue that is based on LinkedTransferQueue implementation from JDK 7.

When running on JDK 7 or higher, JDK LinkedTransferQueue implementation is used, on JDK 6 an internal Jersey implementation class is used.

Type Parameters:

E - the type of elements held in the queue.

Returns:

new instance of a BlockingQueue that is based on LinkedTransferQueue implementation from JDK 7.

createConcurrentMap

public static <K,V> ConcurrentMap<K,V> createConcurrentMap()

Creates a new, empty map with a default initial capacity (16), load factor (0.75) and concurrencyLevel (16).

On Oracle JDK, the factory method will return an instance of ConcurrentHashMapV8 that is supposed to be available in JDK 8 and provides better performance and memory characteristics than ConcurrentHashMap implementation from JDK 7 or earlier. On non-Oracle JDK, the factory instantiates the standard ConcurrentHashMap from JDK.

Returns:

the map.

createConcurrentMap

public static <K,V> ConcurrentMap<K,V> createConcurrentMap(Map<? extends K,? extends V> map)

Creates a new map with the same mappings as the given map.

On Oracle JDK, the factory method will return an instance of ConcurrentHashMapV8 that is supposed to be available in JDK 8 and provides better performance and memory characteristics than ConcurrentHashMap implementation from JDK 7 or earlier. On non-Oracle JDK, the factory instantiates the standard ConcurrentHashMap from JDK.

Parameters:

map - the map.

createConcurrentMap

public static <K,V> ConcurrentMap<K,V> createConcurrentMap(int initialCapacity)

Creates a new, empty map with an initial table size accommodating the specified number of elements without the need to dynamically resize.

On Oracle JDK, the factory method will return an instance of ConcurrentHashMapV8 that is supposed to be available in JDK 8 and provides better performance and memory characteristics than ConcurrentHashMap implementation from JDK 7 or earlier. On non-Oracle JDK, the factory instantiates the standard ConcurrentHashMap from JDK.

Parameters:

initialCapacity - The implementation performs internal sizing to accommodate this many elements.

Throws:

IllegalArgumentException - if the initial capacity of elements is negative.

createConcurrentMap

public static <K,V> ConcurrentMap<K,V> createConcurrentMap(int initialCapacity,
                                                           float loadFactor,
                                                           int concurrencyLevel)

Creates a new, empty map with an initial table size based on the given number of elements (initialCapacity), table density (loadFactor), and number of concurrently updating threads (concurrencyLevel).

On Oracle JDK, the factory method will return an instance of ConcurrentHashMapV8 that is supposed to be available in JDK 8 and provides better performance and memory characteristics than ConcurrentHashMap implementation from JDK 7 or earlier. On non-Oracle JDK, the factory instantiates the standard ConcurrentHashMap from JDK.

Parameters:

initialCapacity - the initial capacity. The implementation performs internal sizing to accommodate this many elements, given the specified load factor.

loadFactor - the load factor (table density) for establishing the initial table size.

concurrencyLevel - the estimated number of concurrently updating threads. The implementation may use this value as a sizing hint.

Throws:

IllegalArgumentException - if the initial capacity is negative or the load factor or concurrencyLevel are not positive.