Package com.esotericsoftware.kryo.util
Class IdentityObjectIntMap<K>
java.lang.Object
com.esotericsoftware.kryo.util.IdentityObjectIntMap<K>
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.
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.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate 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[]
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Constructor Summary
ConstructorsConstructorDescriptionCreates 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 TypeMethodDescriptionvoid
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.findKey
(int value) Returns the key for the specified value, or null if it is not in the map.int
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
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
private void
Skips checks for existing keys.private void
int
(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.toString()
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Field Details
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PRIME2
private static final int PRIME2- See Also:
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PRIME3
private static final int PRIME3- See Also:
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PRIME4
private static final int PRIME4- See Also:
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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
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Constructor Details
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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.
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Method Details
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put
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putResize
Skips checks for existing keys. -
push
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putStash
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get
- Parameters:
defaultValue
- Returned if the key was not associated with a value.
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getStash
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getAndIncrement
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
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remove
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removeStash
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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
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containsKeyStash
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findKey
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
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