Package io.javago.sync

Class Map<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

java.util.concurrent.ConcurrentHashMap<K,V>

io.javago.sync.Map<K,V>

Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

All Implemented Interfaces:

Serializable, ConcurrentMap<K,V>, Map<K,V>

public class Map<K,V>
extends ConcurrentHashMap<K,V>

The Map class implements Go's sync.Map. A thread-safe map that extends ConcurrentHashMap and provides additional utility methods.

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.concurrent.ConcurrentHashMap

ConcurrentHashMap.KeySetView<K,V>

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

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

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor	Description
Map()	Creates a new, empty map with the default initial capacity, load factor, and concurrency level.
Map(int initialCapacity)	Creates a new, empty map with the specified initial capacity, and with the default load factor and concurrency level.
Map(int initialCapacity, float loadFactor)	Creates a new, empty map with the specified initial capacity and load factor, and with the default concurrency level.
Map(int initialCapacity, float loadFactor, int concurrencyLevel)	Creates a new, empty map with the specified initial capacity, load factor, and concurrency level.
Map(Map<? extends K,? extends V> m)	Creates a new map with the same mappings as the specified map.

Method Summary

Modifier and Type	Method	Description
boolean	compareAndDelete(K key, V value)	Removes the entry for a key only if currently mapped to a given value.
boolean	compareAndSwap(K key, V oldValue, V newValue)	Replaces the entry for a key only if currently mapped to a given value.
void	delete(K key)	Removes the mapping for a key from this map if it is present.
V	load(K key)	Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.
V	loadAndDelete(K key)	Removes the mapping for a key from this map if it is present and returns the associated value.
V	loadOrStore(K key, V value)	If the specified key is not already associated with a value, associates it with the given value and returns null, else returns the current value.
void	range(BiConsumer<? super K,? super V> consumer)	Performs the given action for each entry in this map until all entries have been processed or the action throws an exception.
void	store(K key, V value)	Associates the specified value with the specified key in this map.
V	swap(K key, V value)	Associates the specified value with the specified key in this map and returns the previous value associated with the key, or null if there was no mapping for the key.

Methods inherited from class java.util.concurrent.ConcurrentHashMap

clear, compute, computeIfAbsent, computeIfPresent, contains, containsKey, containsValue, elements, entrySet, equals, forEach, forEach, forEach, forEachEntry, forEachEntry, forEachKey, forEachKey, forEachValue, forEachValue, get, getOrDefault, hashCode, isEmpty, keys, keySet, keySet, mappingCount, merge, newKeySet, newKeySet, put, putAll, putIfAbsent, reduce, reduceEntries, reduceEntries, reduceEntriesToDouble, reduceEntriesToInt, reduceEntriesToLong, reduceKeys, reduceKeys, reduceKeysToDouble, reduceKeysToInt, reduceKeysToLong, reduceToDouble, reduceToInt, reduceToLong, reduceValues, reduceValues, reduceValuesToDouble, reduceValuesToInt, reduceValuesToLong, remove, remove, replace, replace, replaceAll, search, searchEntries, searchKeys, searchValues, size, toString, values

Methods inherited from class java.util.AbstractMap

clone

Methods inherited from class java.lang.Object

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

Constructor Details

Map

public Map()

Creates a new, empty map with the default initial capacity, load factor, and concurrency level.

Map

public Map(int initialCapacity)

Creates a new, empty map with the specified initial capacity, and with the default load factor and concurrency level.

Parameters:

initialCapacity - the initial capacity. The implementation performs internal sizing to accommodate this many elements.

Map

public Map(Map<? extends K,? extends V> m)

Creates a new map with the same mappings as the specified map.

Parameters:

m - the map whose mappings are to be placed in this map

Map

public Map(int initialCapacity,
 float loadFactor)

Creates a new, empty map with the specified initial capacity and load factor, and with the default concurrency level.

Parameters:

initialCapacity - the initial capacity. The implementation performs internal sizing to accommodate this many elements.

loadFactor - the load factor threshold, used to control resizing. Resizing may be performed when the average number of elements per bin exceeds this threshold.

Map

public Map(int initialCapacity,
 float loadFactor,
 int concurrencyLevel)

Creates a new, empty map with the specified initial capacity, load factor, and concurrency level.

Parameters:

initialCapacity - the initial capacity. The implementation performs internal sizing to accommodate this many elements.

loadFactor - the load factor threshold, used to control resizing. Resizing may be performed when the average number of elements per bin exceeds this threshold.

concurrencyLevel - the estimated number of concurrently updating threads. The implementation performs internal sizing to try to accommodate this many threads.

Method Details

compareAndDelete

public boolean compareAndDelete(K key,
 V value)

Removes the entry for a key only if currently mapped to a given value.

Parameters:

key - the key whose associated value is to be removed

value - the value expected to be associated with the specified key

Returns:

true if the value was removed

compareAndSwap

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

Replaces the entry for a key only if currently mapped to a given value.

Parameters:

key - the key with which the specified value is associated

oldValue - the value expected to be associated with the specified key

newValue - the value to be associated with the specified key

Returns:

true if the value was replaced

delete

public void delete(K key)

Removes the mapping for a key from this map if it is present.

Parameters:

key - the key whose mapping is to be removed from the map

load

public V load(K key)

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

Parameters:

key - the key whose associated value is to be returned

Returns:

the value to which the specified key is mapped, or null if this map contains no mapping for the key

loadAndDelete

public V loadAndDelete(K key)

Removes the mapping for a key from this map if it is present and returns the associated value.

Parameters:

key - the key whose mapping is to be removed from the map

Returns:

the previous value associated with key, or null if there was no mapping for key

loadOrStore

public V loadOrStore(K key,
 V value)

If the specified key is not already associated with a value, associates it with the given value and returns null, else returns the current value.

Parameters:

key - the key with which the specified value is to be associated

value - the value to be associated with the specified key

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key

range

public void range(BiConsumer<? super K,? super V> consumer)

Performs the given action for each entry in this map until all entries have been processed or the action throws an exception.

Parameters:

consumer - the action to be performed for each entry

store

public void store(K key,
 V value)

Associates the specified value with the specified key in this map.

Parameters:

key - the key with which the specified value is to be associated

value - the value to be associated with the specified key

swap

public V swap(K key,
 V value)

Associates the specified value with the specified key in this map and returns the previous value associated with the key, or null if there was no mapping for the key.

Parameters:

key - the key with which the specified value is to be associated

value - the value to be associated with the specified key

Returns:

the previous value associated with key, or null if there was no mapping for key