Class IdentityObjectIntMap<K>

java.lang.Object
com.esotericsoftware.kryo.util.IdentityObjectIntMap<K>

public class IdentityObjectIntMap<K> extends Object
An unordered map where identity comparison is used for keys and the values are ints. This implementation is a cuckoo hash map using 3 hashes (if table size is less than 2^16) or 4 hashes (if table size is greater than or equal to 2^16), random walking, and a small stash for problematic keys. Null keys are not allowed. No allocation is done except when growing the table size.

This map performs very fast get, containsKey, and remove (typically O(1), worst case O(log(n))). Put may be a bit slower, depending on hash collisions. Load factors greater than 0.91 greatly increase the chances the map will have to rehash to the next higher POT size.
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private boolean
     
    (package private) int
     
    private int
     
    (package private) K[]
     
    private float
     
    private int
     
    private static final int
     
    private static final int
     
    private static final int
     
    private int
     
    int
     
    private int
     
    (package private) int
     
    private int
     
    (package private) int[]
     
  • Constructor Summary

    Constructors
    Constructor
    Description
    Creates a new map with an initial capacity of 32 and a load factor of 0.8.
    IdentityObjectIntMap(int initialCapacity)
    Creates a new map with a load factor of 0.8.
    IdentityObjectIntMap(int initialCapacity, float loadFactor)
    Creates a new map with the specified initial capacity and load factor.
  • Method Summary

    Modifier and Type
    Method
    Description
    void
     
    void
    clear(int maximumCapacity)
    Clears the map and reduces the size of the backing arrays to be the specified capacity if they are larger.
    boolean
     
    private boolean
     
    boolean
    containsValue(int value)
    Returns true if the specified value is in the map.
    void
    ensureCapacity(int additionalCapacity)
    Increases the size of the backing array to acommodate the specified number of additional items.
    findKey(int value)
    Returns the key for the specified value, or null if it is not in the map.
    int
    get(K key, int defaultValue)
     
    int
    getAndIncrement(K key, int defaultValue, int increment)
    Returns the key's current value and increments the stored value.
    private int
    getAndIncrementStash(K key, int defaultValue, int increment)
     
    private int
    getStash(K key, int defaultValue)
     
    private int
    hash2(int h)
     
    private int
    hash3(int h)
     
    private int
    hash4(int h)
     
    private void
    push(K insertKey, int insertValue, int index1, K key1, int index2, K key2, int index3, K key3, int index4, K key4)
     
    void
    put(K key, int value)
     
    private void
    putResize(K key, int value)
    Skips checks for existing keys.
    private void
    putStash(K key, int value)
     
    int
    remove(K key, int defaultValue)
     
    (package private) int
    removeStash(K key, int defaultValue)
     
    (package private) void
    removeStashIndex(int index)
     
    private void
    resize(int newSize)
     
    void
    shrink(int maximumCapacity)
    Reduces the size of the backing arrays to be the specified capacity or less.
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
  • Field Details

    • PRIME2

      private static final int PRIME2
      See Also:
    • PRIME3

      private static final int PRIME3
      See Also:
    • PRIME4

      private static final int PRIME4
      See Also:
    • size

      public int size
    • keyTable

      K[] keyTable
    • valueTable

      int[] valueTable
    • capacity

      int capacity
    • stashSize

      int stashSize
    • loadFactor

      private float loadFactor
    • hashShift

      private int hashShift
    • mask

      private int mask
    • threshold

      private int threshold
    • stashCapacity

      private int stashCapacity
    • pushIterations

      private int pushIterations
    • bigTable

      private boolean bigTable
  • Constructor Details

    • IdentityObjectIntMap

      public IdentityObjectIntMap()
      Creates a new map with an initial capacity of 32 and a load factor of 0.8. This map will hold 25 items before growing the backing table.
    • IdentityObjectIntMap

      public IdentityObjectIntMap(int initialCapacity)
      Creates a new map with a load factor of 0.8. This map will hold initialCapacity * 0.8 items before growing the backing table.
    • IdentityObjectIntMap

      public IdentityObjectIntMap(int initialCapacity, float loadFactor)
      Creates a new map with the specified initial capacity and load factor. This map will hold initialCapacity * loadFactor items before growing the backing table.
  • Method Details

    • put

      public void put(K key, int value)
    • putResize

      private void putResize(K key, int value)
      Skips checks for existing keys.
    • push

      private void push(K insertKey, int insertValue, int index1, K key1, int index2, K key2, int index3, K key3, int index4, K key4)
    • putStash

      private void putStash(K key, int value)
    • get

      public int get(K key, int defaultValue)
      Parameters:
      defaultValue - Returned if the key was not associated with a value.
    • getStash

      private int getStash(K key, int defaultValue)
    • getAndIncrement

      public int getAndIncrement(K key, int defaultValue, int increment)
      Returns the key's current value and increments the stored value. If the key is not in the map, defaultValue + increment is put into the map.
    • getAndIncrementStash

      private int getAndIncrementStash(K key, int defaultValue, int increment)
    • remove

      public int remove(K key, int defaultValue)
    • removeStash

      int removeStash(K key, int defaultValue)
    • removeStashIndex

      void removeStashIndex(int index)
    • shrink

      public void shrink(int maximumCapacity)
      Reduces the size of the backing arrays to be the specified capacity or less. If the capacity is already less, nothing is done. If the map contains more items than the specified capacity, nothing is done.
    • clear

      public void clear(int maximumCapacity)
      Clears the map and reduces the size of the backing arrays to be the specified capacity if they are larger.
    • clear

      public void clear()
    • containsValue

      public boolean containsValue(int value)
      Returns true if the specified value is in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.
    • containsKey

      public boolean containsKey(K key)
    • containsKeyStash

      private boolean containsKeyStash(K key)
    • findKey

      public K findKey(int value)
      Returns the key for the specified value, or null if it is not in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.
    • ensureCapacity

      public void ensureCapacity(int additionalCapacity)
      Increases the size of the backing array to acommodate the specified number of additional items. Useful before adding many items to avoid multiple backing array resizes.
    • resize

      private void resize(int newSize)
    • hash2

      private int hash2(int h)
    • hash3

      private int hash3(int h)
    • hash4

      private int hash4(int h)
    • toString

      public String toString()
      Overrides:
      toString in class Object