Class ShortObjectHashMap<V>

java.lang.Object
io.netty.util.collection.ShortObjectHashMap<V>
Type Parameters:
V - The value type stored in the map.
All Implemented Interfaces:
ShortObjectMap<V>, java.util.Map<java.lang.Short, V>
public class ShortObjectHashMap<V> extends java.lang.Object implements ShortObjectMap<V>
A hash map implementation of ShortObjectMap that uses open addressing for keys. To minimize the memory footprint, this class uses open addressing rather than chaining. Collisions are resolved using linear probing. Deletions implement compaction, so cost of remove can approach O(N) for full maps, which makes a small loadFactor recommended.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    private final class 
    ShortObjectHashMap.EntrySet
    Set implementation for iterating over the entries of the map.
    private final class 
    ShortObjectHashMap.KeySet
    Set implementation for iterating over the keys.
    (package private) final class 
    ShortObjectHashMap.MapEntry
    A single entry in the map.
    private final class 
    ShortObjectHashMap.MapIterator
    Iterator used by the Map interface.
    private final class 
    ShortObjectHashMap.PrimitiveIterator
    Iterator over primitive entries.

    Nested classes/interfaces inherited from interface java.util.Map

    java.util.Map.Entry<K,V>

    Nested classes/interfaces inherited from interface ShortObjectMap

    ShortObjectMap.PrimitiveEntry<V>

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    DEFAULT_CAPACITY
    Default initial capacity.
    static final float
    DEFAULT_LOAD_FACTOR
    Default load factor.
    private final java.lang.Iterable<ShortObjectMap.PrimitiveEntry<V>>
    entries
     
    private final java.util.Set<java.util.Map.Entry<java.lang.Short, V>>
    entrySet
     
    private short[]
    keys
     
    private final java.util.Set<java.lang.Short>
    keySet
     
    private final float
    loadFactor
    The load factor for the map.
    private int
    mask
     
    private int
    maxSize
    The maximum number of elements allowed without allocating more space.
    private static final java.lang.Object
    NULL_VALUE
    Placeholder for null values, so we can use the actual null to mean available.
    private int
    size
     
    private V[]
    values
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    ShortObjectHashMap()
     
    ShortObjectHashMap(int initialCapacity)
     
    ShortObjectHashMap(int initialCapacity, float loadFactor)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    private int
    calcMaxSize(int capacity)
    Calculates the maximum size allowed before rehashing.
    void
    clear()
     
    boolean
    containsKey(short key)
    Indicates whether or not this map contains a value for the specified key.
    boolean
    containsKey(java.lang.Object key)
     
    boolean
    containsValue(java.lang.Object value)
     
    java.lang.Iterable<ShortObjectMap.PrimitiveEntry<V>>
    entries()
    Gets an iterable to traverse over the primitive entries contained in this map.
    java.util.Set<java.util.Map.Entry<java.lang.Short, V>>
    entrySet()
     
    boolean
    equals(java.lang.Object obj)
     
    V
    get(short key)
    Gets the value in the map with the specified key.
    V
    get(java.lang.Object key)
     
    private void
    growSize()
    Grows the map size after an insertion.
    int
    hashCode()
     
    private static int
    hashCode(short key)
    Returns the hash code for the key.
    private int
    hashIndex(short key)
    Returns the hashed index for the given key.
    private int
    indexOf(short key)
    Locates the index for the given key.
    boolean
    isEmpty()
     
    java.util.Set<java.lang.Short>
    keySet()
     
    protected java.lang.String
    keyToString(short key)
    Helper method called by toString() in order to convert a single map key into a string.
    private short
    objectToKey(java.lang.Object key)
     
    private int
    probeNext(int index)
    Get the next sequential index after index and wraps if necessary.
    V
    put(short key, V value)
    Puts the given entry into the map.
    V
    put(java.lang.Short key, V value)
     
    void
    putAll(java.util.Map<? extends java.lang.Short, ? extends V> sourceMap)
     
    private void
    rehash(int newCapacity)
    Rehashes the map for the given capacity.
    V
    remove(short key)
    Removes the entry with the specified key.
    V
    remove(java.lang.Object key)
     
    private boolean
    removeAt(int index)
    Removes entry at the given index position.
    int
    size()
     
    private static <T> T
    toExternal(T value)
     
    private static <T> T
    toInternal(T value)
     
    java.lang.String
    toString()
     
    java.util.Collection<V>
    values()
     

    Methods inherited from class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface java.util.Map

    compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

  • Field Details

    • DEFAULT_CAPACITY

      public static final int DEFAULT_CAPACITY
      Default initial capacity. Used if not specified in the constructor
      See Also:

    • DEFAULT_LOAD_FACTOR

      public static final float DEFAULT_LOAD_FACTOR
      Default load factor. Used if not specified in the constructor
      See Also:

    • NULL_VALUE

      private static final java.lang.Object NULL_VALUE
      Placeholder for null values, so we can use the actual null to mean available. (Better than using a placeholder for available: less references for GC processing.)

    • maxSize

      private int maxSize
      The maximum number of elements allowed without allocating more space.

    • loadFactor

      private final float loadFactor
      The load factor for the map. Used to calculate maxSize.

    • keys

      private short[] keys

    • values

      private V[] values

    • size

      private int size

    • mask

      private int mask

    • keySet

      private final java.util.Set<java.lang.Short> keySet

    • entrySet

      private final java.util.Set<java.util.Map.Entry<java.lang.Short, V>> entrySet

    • entries

      private final java.lang.Iterable<ShortObjectMap.PrimitiveEntry<V>> entries

  • Constructor Details

    • ShortObjectHashMap

      public ShortObjectHashMap()

    • ShortObjectHashMap

      public ShortObjectHashMap(int initialCapacity)

    • ShortObjectHashMap

      public ShortObjectHashMap(int initialCapacity, float loadFactor)

  • Method Details

    • toExternal

      private static <T> T toExternal(T value)

    • toInternal

      private static <T> T toInternal(T value)

    • get

      public V get(short key)
      Description copied from interface: ShortObjectMap
      Gets the value in the map with the specified key.
      Specified by:
      get in interface ShortObjectMap<V>
      Parameters:
      key - the key whose associated value is to be returned.
      Returns:
      the value or null if the key was not found in the map.

    • put

      public V put(short key, V value)
      Description copied from interface: ShortObjectMap
      Puts the given entry into the map.
      Specified by:
      put in interface ShortObjectMap<V>
      Parameters:
      key - the key of the entry.
      value - the value of the entry.
      Returns:
      the previous value for this key or null if there was no previous mapping.

    • putAll

      public void putAll(java.util.Map<? extends java.lang.Short, ? extends V> sourceMap)
      Specified by:
      putAll in interface java.util.Map<java.lang.Short, V>

    • remove

      public V remove(short key)
      Description copied from interface: ShortObjectMap
      Removes the entry with the specified key.
      Specified by:
      remove in interface ShortObjectMap<V>
      Parameters:
      key - the key for the entry to be removed from this map.
      Returns:
      the previous value for the key, or null if there was no mapping.

    • size

      public int size()
      Specified by:
      size in interface java.util.Map<java.lang.Short, V>

    • isEmpty

      public boolean isEmpty()
      Specified by:
      isEmpty in interface java.util.Map<java.lang.Short, V>

    • clear

      public void clear()
      Specified by:
      clear in interface java.util.Map<java.lang.Short, V>

    • containsKey

      public boolean containsKey(short key)
      Description copied from interface: ShortObjectMap
      Indicates whether or not this map contains a value for the specified key.
      Specified by:
      containsKey in interface ShortObjectMap<V>

    • containsValue

      public boolean containsValue(java.lang.Object value)
      Specified by:
      containsValue in interface java.util.Map<java.lang.Short, V>

    • entries

      public java.lang.Iterable<ShortObjectMap.PrimitiveEntry<V>> entries()
      Description copied from interface: ShortObjectMap
      Gets an iterable to traverse over the primitive entries contained in this map. As an optimization, the ShortObjectMap.PrimitiveEntrys returned by the
      invalid reference 
      Iterator
      may change as the
      invalid reference 
      Iterator
      progresses. The caller should not rely on ShortObjectMap.PrimitiveEntry key/value stability.
      Specified by:
      entries in interface ShortObjectMap<V>

    • values

      public java.util.Collection<V> values()
      Specified by:
      values in interface java.util.Map<java.lang.Short, V>

    • hashCode

      public int hashCode()
      Specified by:
      hashCode in interface java.util.Map<java.lang.Short, V>
      Overrides:
      hashCode in class java.lang.Object

    • equals

      public boolean equals(java.lang.Object obj)
      Specified by:
      equals in interface java.util.Map<java.lang.Short, V>
      Overrides:
      equals in class java.lang.Object

    • containsKey

      public boolean containsKey(java.lang.Object key)
      Specified by:
      containsKey in interface java.util.Map<java.lang.Short, V>

    • get

      public V get(java.lang.Object key)
      Specified by:
      get in interface java.util.Map<java.lang.Short, V>

    • put

      public V put(java.lang.Short key, V value)
      Specified by:
      put in interface java.util.Map<java.lang.Short, V>

    • remove

      public V remove(java.lang.Object key)
      Specified by:
      remove in interface java.util.Map<java.lang.Short, V>

    • keySet

      public java.util.Set<java.lang.Short> keySet()
      Specified by:
      keySet in interface java.util.Map<java.lang.Short, V>

    • entrySet

      public java.util.Set<java.util.Map.Entry<java.lang.Short, V>> entrySet()
      Specified by:
      entrySet in interface java.util.Map<java.lang.Short, V>

    • objectToKey

      private short objectToKey(java.lang.Object key)

    • indexOf

      private int indexOf(short key)
      Locates the index for the given key. This method probes using double hashing.
      Parameters:
      key - the key for an entry in the map.
      Returns:
      the index where the key was found, or -1 if no entry is found for that key.

    • hashIndex

      private int hashIndex(short key)
      Returns the hashed index for the given key.

    • hashCode

      private static int hashCode(short key)
      Returns the hash code for the key.

    • probeNext

      private int probeNext(int index)
      Get the next sequential index after index and wraps if necessary.

    • growSize

      private void growSize()
      Grows the map size after an insertion. If necessary, performs a rehash of the map.

    • removeAt

      private boolean removeAt(int index)
      Removes entry at the given index position. Also performs opportunistic, incremental rehashing if necessary to not break conflict chains.
      Parameters:
      index - the index position of the element to remove.
      Returns:
      true if the next item was moved back. false otherwise.

    • calcMaxSize

      private int calcMaxSize(int capacity)
      Calculates the maximum size allowed before rehashing.

    • rehash

      private void rehash(int newCapacity)
      Rehashes the map for the given capacity.
      Parameters:
      newCapacity - the new capacity for the map.

    • toString

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

    • keyToString

      protected java.lang.String keyToString(short key)
      Helper method called by toString() in order to convert a single map key into a string. This is protected to allow subclasses to override the appearance of a given key.