Package com.esotericsoftware.kryo.util

Class IdentityObjectIntMap<K>

  • public class IdentityObjectIntMap<K>
extends java.lang.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.

    • Constructor Summary

      Constructors 
      Constructor Description
      IdentityObjectIntMap()
      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

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()  
      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 containsKey​(K key)  
      private boolean containsKeyStash​(K key)  
      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.
      K 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.
      java.lang.String toString()  

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • 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 Detail

      • 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 Detail

      • 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 java.lang.String toString()
        Overrides:
        toString in class java.lang.Object