ConcurrentPrimitiveMap

Concurrent skip list map based on java.util.concurrent.ConcurrentSkipListMap, 
and optimized for primitive type keys (int, long, float and double).

The following methods are supported (for ConcurrentIntSkipListMap):
 - Map API methods
    public boolean containsKey(int key)
    public V get(int key)
    public V put(int key, V value)
    public V remove(int key)
    public boolean containsValue(Object value)
    public int size()
    public boolean isEmpty()
    public void clear()
 
 - ConcurrentMap API methods
    public V putIfAbsent(int key, V value)
    public boolean remove(int key, Object value)
    public boolean replace(int key, V oldValue, V newValue)
    public V replace(int key, V value)
    public int firstKey()
    public int lastKey()
 
 - Relational operations
    public MapEntry.IntKeyEntry<V> lowerEntry(int key)
    public int lowerKey(int key)
    public MapEntry.IntKeyEntry<V> floorEntry(int key)
    public int floorKey(int key) 
    public MapEntry.IntKeyEntry<V> ceilingEntry(int key)
    public int ceilingKey(int key) 
    public MapEntry.IntKeyEntry<V> higherEntry(int key)
    public int higherKey(int key)