java.lang.Object
- io.arxila.atomichash.AtomicHashMap<K,V>

Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

All Implemented Interfaces:

java.io.Serializable, java.util.Map<K,V>
```
public final class AtomicHashMap<K,V>
extends java.lang.Object
implements java.util.Map<K,V>, java.io.Serializable
```
A thread-safe implementation of the Map interface providing advanced concurrency features.
This implementation is thread-safe, atomic and non-blocking for all of its methods, including both reads and writes. This includes multi-element methods such as putAll(Map) and getAll(Object...) (the latter not a part of the Map interface), as well as all other methods for retrieving, adding, modifying or removing mappings, iteration, etc.
The map can therefore never be read in a partially modified state, and its exact snapshot state for an arbitrary number of mappings can be obtained at any time.
This is achieved by internally implementing an immutable variation of a CTRIE (Concurrent Hash-Trie). This structure is composed of a tree of compact (bitmap-managed) arrays that map keys to positions in each of the tree levels depending on the value of a range of bits of its (modified) hash code.
Key hash codes (32-bit ints) are divided into five 6-bit segments plus one final 2-bit segment. Each of these segments is used, at each level of depth, to compute the position assigned to the key in the compact array (node) living at that level of depth in the ctrie structure. These are compact arrays with a maximum of 64 positions (bitmaps are long values), each of which can contain either a data entry or a link to another node at level + 1. A maximum of 6 levels can exist (0 to 5), and hash collisions only need to be managed at the deepest level. All structures are kept immutable, so modifications in an array (node) at a specific level mean the creation of new nodes from that point up to the root of the tree, and the replacement of the old root with the new one using an atomic compare-and-swap operation.
Note that, given this implementation is based on immutable tree structures, modifications typically need a higher use of memory than other common implementations of the Map interface.
New instances of this class can be created by either calling its constructor AtomicHashMap() or by calling any of its static convenience factory AtomicHashMap.of(...) methods: of(), of(k1, v1), of(k1, v1, k2, v2), of(k1, v1, k2, v2, k3, v3), etc.
Note that this implementation does not keep the insertion order. Iteration order is not guaranteed to be consistent.

See Also:

Serialized Form

Nested Class Summary
- Nested classes/interfaces inherited from interface java.util.Map
  java.util.Map.Entry<K extends java.lang.Object,V extends java.lang.Object>

Field Summary

Fields
Modifier and Type Field Description

private java.util.concurrent.atomic.AtomicReference<Root> root

private static long serialVersionUID

Constructor Summary

Constructors
Modifier Constructor Description

AtomicHashMap()

private AtomicHashMap(Root root)

AtomicHashMap(java.util.Map<? extends K,? extends V> map)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`clear()`
`V`	`compute(K key, java.util.function.BiFunction<? super K,? super V,? extends V> remappingFunction)`
`V`	`computeIfAbsent(K key, java.util.function.Function<? super K,? extends V> mappingFunction)`
`V`	`computeIfPresent(K key, java.util.function.BiFunction<? super K,? super V,? extends V> remappingFunction)`
`boolean`	`containsKey(java.lang.Object key)`
`boolean`	`containsValue(java.lang.Object value)`
`private static Entry`	`entry(int hash, java.lang.Object key, java.lang.Object value)`
`private static Entry`	`entry(java.lang.Object key, java.lang.Object value)`
`java.util.Set<java.util.Map.Entry<K,V>>`	`entrySet()`
`boolean`	`equals(java.lang.Object other)`
`void`	`forEach(java.util.function.BiConsumer<? super K,? super V> action)`
`V`	`get(java.lang.Object key)`
`java.util.Map<K,V>`	`getAll(java.lang.Object... keys)`
`V`	`getOrDefault(java.lang.Object key, V defaultValue)`
`int`	`hashCode()`
`(package private) Root`	`innerRoot()`
`boolean`	`isEmpty()`
`java.util.Set<K>`	`keySet()`
`V`	`merge(K key, V newValue, java.util.function.BiFunction<? super V,? super V,? extends V> remappingFunction)`
`static <K,V> AtomicHashMap<K,V>`	`of()`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1)`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1, K k2, V v2)`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3)`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4)`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5)`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6)`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7)`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7, K k8, V v8)`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7, K k8, V v8, K k9, V v9)`
`static <K,V> AtomicHashMap<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7, K k8, V v8, K k9, V v9, K k10, V v10)`
`V`	`put(K key, V newValue)`
`void`	`putAll(java.util.Map<? extends K,? extends V> newMappings)`
`V`	`putIfAbsent(K key, V newValue)`
`V`	`remove(java.lang.Object key)`
`boolean`	`remove(java.lang.Object key, java.lang.Object oldValue)`
`V`	`replace(K key, V newValue)`
`boolean`	`replace(K key, V oldValue, V newValue)`
`void`	`replaceAll(java.util.function.BiFunction<? super K,? super V,? extends V> function)`
`int`	`size()`
`AtomicHashStore<K,V>`	`store()`
`java.lang.String`	`toString()`
`java.util.Collection<V>`	`values()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID
```
private static final long serialVersionUID
```
See Also:

Constant Field Values

root

private final java.util.concurrent.atomic.AtomicReference<Root> root

Constructor Detail

AtomicHashMap
```
public AtomicHashMap()
```

AtomicHashMap

public AtomicHashMap(java.util.Map<? extends K,? extends V> map)

AtomicHashMap
```
private AtomicHashMap(Root root)
```

Method Detail

entry

private static Entry entry(java.lang.Object key,
                           java.lang.Object value)

entry

private static Entry entry(int hash,
                           java.lang.Object key,
                           java.lang.Object value)

of

public static <K,V> AtomicHashMap<K,V> of()

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1)

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1,
                                                      K k2,
                                                      V v2)

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1,
                                                      K k2,
                                                      V v2,
                                                      K k3,
                                                      V v3)

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1,
                                                      K k2,
                                                      V v2,
                                                      K k3,
                                                      V v3,
                                                      K k4,
                                                      V v4)

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1,
                                                      K k2,
                                                      V v2,
                                                      K k3,
                                                      V v3,
                                                      K k4,
                                                      V v4,
                                                      K k5,
                                                      V v5)

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1,
                                                      K k2,
                                                      V v2,
                                                      K k3,
                                                      V v3,
                                                      K k4,
                                                      V v4,
                                                      K k5,
                                                      V v5,
                                                      K k6,
                                                      V v6)

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1,
                                                      K k2,
                                                      V v2,
                                                      K k3,
                                                      V v3,
                                                      K k4,
                                                      V v4,
                                                      K k5,
                                                      V v5,
                                                      K k6,
                                                      V v6,
                                                      K k7,
                                                      V v7)

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1,
                                                      K k2,
                                                      V v2,
                                                      K k3,
                                                      V v3,
                                                      K k4,
                                                      V v4,
                                                      K k5,
                                                      V v5,
                                                      K k6,
                                                      V v6,
                                                      K k7,
                                                      V v7,
                                                      K k8,
                                                      V v8)

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1,
                                                      K k2,
                                                      V v2,
                                                      K k3,
                                                      V v3,
                                                      K k4,
                                                      V v4,
                                                      K k5,
                                                      V v5,
                                                      K k6,
                                                      V v6,
                                                      K k7,
                                                      V v7,
                                                      K k8,
                                                      V v8,
                                                      K k9,
                                                      V v9)

of

public static <K,V> AtomicHashMap<K,V> of(K k1,
                                                      V v1,
                                                      K k2,
                                                      V v2,
                                                      K k3,
                                                      V v3,
                                                      K k4,
                                                      V v4,
                                                      K k5,
                                                      V v5,
                                                      K k6,
                                                      V v6,
                                                      K k7,
                                                      V v7,
                                                      K k8,
                                                      V v8,
                                                      K k9,
                                                      V v9,
                                                      K k10,
                                                      V v10)

innerRoot
```
Root innerRoot()
```

store

public AtomicHashStore<K,V> store()

size
```
public int size()
```
Specified by:

size in interface java.util.Map<K,V>

isEmpty
```
public boolean isEmpty()
```
Specified by:

isEmpty in interface java.util.Map<K,V>

containsKey
```
public boolean containsKey(java.lang.Object key)
```
Specified by:

containsKey in interface java.util.Map<K,V>

containsValue
```
public boolean containsValue(java.lang.Object value)
```
Specified by:

containsValue in interface java.util.Map<K,V>

get
```
public V get(java.lang.Object key)
```
Specified by:

get in interface java.util.Map<K,V>

getOrDefault

public V getOrDefault(java.lang.Object key,
                      V defaultValue)

Specified by:: getOrDefault in interface java.util.Map<K,V>

getAll

public java.util.Map<K,V> getAll(java.lang.Object... keys)

put

public V put(K key,
             V newValue)

Specified by:: put in interface java.util.Map<K,V>

putIfAbsent

public V putIfAbsent(K key,
                     V newValue)

Specified by:: putIfAbsent in interface java.util.Map<K,V>

putAll

public void putAll(java.util.Map<? extends K,? extends V> newMappings)

Specified by:: putAll in interface java.util.Map<K,V>

remove
```
public V remove(java.lang.Object key)
```
Specified by:

remove in interface java.util.Map<K,V>

remove

public boolean remove(java.lang.Object key,
                      java.lang.Object oldValue)

Specified by:: remove in interface java.util.Map<K,V>

clear
```
public void clear()
```
Specified by:

clear in interface java.util.Map<K,V>

keySet
```
public java.util.Set<K> keySet()
```
Specified by:

keySet in interface java.util.Map<K,V>

values
```
public java.util.Collection<V> values()
```
Specified by:

values in interface java.util.Map<K,V>

entrySet

public java.util.Set<java.util.Map.Entry<K,V>> entrySet()

Specified by:: entrySet in interface java.util.Map<K,V>

forEach

public void forEach(java.util.function.BiConsumer<? super K,? super V> action)

Specified by:: forEach in interface java.util.Map<K,V>

replace

public V replace(K key,
                 V newValue)

Specified by:: replace in interface java.util.Map<K,V>

replace

public boolean replace(K key,
                       V oldValue,
                       V newValue)

Specified by:: replace in interface java.util.Map<K,V>

replaceAll

public void replaceAll(java.util.function.BiFunction<? super K,? super V,? extends V> function)

Specified by:: replaceAll in interface java.util.Map<K,V>

compute

public V compute(K key,
                 java.util.function.BiFunction<? super K,? super V,? extends V> remappingFunction)

Specified by:: compute in interface java.util.Map<K,V>

computeIfAbsent

public V computeIfAbsent(K key,
                         java.util.function.Function<? super K,? extends V> mappingFunction)

Specified by:: computeIfAbsent in interface java.util.Map<K,V>

computeIfPresent

public V computeIfPresent(K key,
                          java.util.function.BiFunction<? super K,? super V,? extends V> remappingFunction)

Specified by:: computeIfPresent in interface java.util.Map<K,V>

merge

public V merge(K key,
               V newValue,
               java.util.function.BiFunction<? super V,? super V,? extends V> remappingFunction)

Specified by:: merge in interface java.util.Map<K,V>

equals
```
public boolean equals(java.lang.Object other)
```
Specified by:

equals in interface java.util.Map<K,V>

Overrides:

equals in class java.lang.Object

hashCode
```
public int hashCode()
```
Specified by:

hashCode in interface java.util.Map<K,V>

Overrides:

hashCode in class java.lang.Object

toString
```
public java.lang.String toString()
```
Overrides:

toString in class java.lang.Object

Modifier and Type	Field	Description
`private java.util.concurrent.atomic.AtomicReference<Root>`	`root`
`private static long`	`serialVersionUID`

Modifier	Constructor	Description
	`AtomicHashMap()`
`private`	`AtomicHashMap(Root root)`
	`AtomicHashMap(java.util.Map<? extends K,? extends V> map)`

Class AtomicHashMap<K,​V>

Nested Class Summary

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

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

serialVersionUID

root

Constructor Detail

AtomicHashMap

AtomicHashMap

AtomicHashMap

Method Detail

entry

entry

of

of

of

of

of

of

of

of

of

of

of

innerRoot

store

size

isEmpty

containsKey

containsValue

get

getOrDefault

getAll

put

putIfAbsent

putAll

remove

remove

clear

keySet

values

entrySet

forEach

replace

replace

replaceAll

compute

computeIfAbsent

computeIfPresent

merge

equals

hashCode

toString

Class AtomicHashMap<K,V>