package com.esotericsoftware.kryonet.util;
import com.esotericsoftware.kryo.util.ObjectMap;
import java.util.Random;
/**
* An unordered map where the values are ints. This implementation is a cuckoo
* hash map using 3 hashes, random walking, and a small stash for problematic
* keys. Null keys are not allowed. No allocation is done except when growing
* the table size. <br>
* <br>
* 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.
*
* @author Nathan Sweet
*/
public class ObjectIntMap<K> {
@SuppressWarnings("unused")
private static final int PRIME1 = 0xbe1f14b1;
private static final int PRIME2 = 0xb4b82e39;
private static final int PRIME3 = 0xced1c241;
static Random random = new Random();
public int size;
K[] keyTable;
int[] valueTable;
int capacity, stashSize;
private float loadFactor;
private int hashShift, mask, threshold;
private int stashCapacity;
private int pushIterations;
/**
* 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.
*/
public ObjectIntMap() {
this(32, 0.8f);
}
/**
* Creates a new map with a load factor of 0.8. This map will hold
* initialCapacity * 0.8 items before growing the backing table.
*/
public ObjectIntMap(int initialCapacity) {
this(initialCapacity, 0.8f);
}
/**
* Creates a new map with the specified initial capacity and load factor.
* This map will hold initialCapacity * loadFactor items before growing the
* backing table.
*/
@SuppressWarnings("unchecked")
public ObjectIntMap(int initialCapacity, float loadFactor) {
if (initialCapacity < 0)
throw new IllegalArgumentException("initialCapacity must be >= 0: "
+ initialCapacity);
if (initialCapacity > 1 << 30)
throw new IllegalArgumentException("initialCapacity is too large: "
+ initialCapacity);
capacity = ObjectMap.nextPowerOfTwo(initialCapacity);
if (loadFactor <= 0)
throw new IllegalArgumentException("loadFactor must be > 0: "
+ loadFactor);
this.loadFactor = loadFactor;
threshold = (int) (capacity * loadFactor);
mask = capacity - 1;
hashShift = 31 - Integer.numberOfTrailingZeros(capacity);
stashCapacity = Math.max(3, (int) Math.ceil(Math.log(capacity)) * 2);
pushIterations = Math.max(Math.min(capacity, 8),
(int) Math.sqrt(capacity) / 8);
keyTable = (K[]) new Object[capacity + stashCapacity];
valueTable = new int[keyTable.length];
}
/** Creates a new map identical to the specified map. */
public ObjectIntMap(ObjectIntMap<? extends K> map) {
this(map.capacity, map.loadFactor);
stashSize = map.stashSize;
System.arraycopy(map.keyTable, 0, keyTable, 0, map.keyTable.length);
System.arraycopy(map.valueTable, 0, valueTable, 0,
map.valueTable.length);
size = map.size;
}
public void put(K key, int value) {
if (key == null)
throw new IllegalArgumentException("key cannot be null.");
K[] keyTable = this.keyTable;
// Check for existing keys.
int hashCode = key.hashCode();
int index1 = hashCode & mask;
K key1 = keyTable[index1];
if (key.equals(key1)) {
valueTable[index1] = value;
return;
}
int index2 = hash2(hashCode);
K key2 = keyTable[index2];
if (key.equals(key2)) {
valueTable[index2] = value;
return;
}
int index3 = hash3(hashCode);
K key3 = keyTable[index3];
if (key.equals(key3)) {
valueTable[index3] = value;
return;
}
// Update key in the stash.
for (int i = capacity, n = i + stashSize; i < n; i++) {
if (key.equals(keyTable[i])) {
valueTable[i] = value;
return;
}
}
// Check for empty buckets.
if (key1 == null) {
keyTable[index1] = key;
valueTable[index1] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
if (key2 == null) {
keyTable[index2] = key;
valueTable[index2] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
if (key3 == null) {
keyTable[index3] = key;
valueTable[index3] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
push(key, value, index1, key1, index2, key2, index3, key3);
}
/** Skips checks for existing keys. */
private void putResize(K key, int value) {
// Check for empty buckets.
int hashCode = key.hashCode();
int index1 = hashCode & mask;
K key1 = keyTable[index1];
if (key1 == null) {
keyTable[index1] = key;
valueTable[index1] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
int index2 = hash2(hashCode);
K key2 = keyTable[index2];
if (key2 == null) {
keyTable[index2] = key;
valueTable[index2] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
int index3 = hash3(hashCode);
K key3 = keyTable[index3];
if (key3 == null) {
keyTable[index3] = key;
valueTable[index3] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
push(key, value, index1, key1, index2, key2, index3, key3);
}
private void push(K insertKey, int insertValue, int index1, K key1,
int index2, K key2, int index3, K key3) {
K[] keyTable = this.keyTable;
int[] valueTable = this.valueTable;
int mask = this.mask;
// Push keys until an empty bucket is found.
K evictedKey;
int evictedValue;
int i = 0, pushIterations = this.pushIterations;
do {
// Replace the key and value for one of the hashes.
switch (random.nextInt(3)) {
case 0:
evictedKey = key1;
evictedValue = valueTable[index1];
keyTable[index1] = insertKey;
valueTable[index1] = insertValue;
break;
case 1:
evictedKey = key2;
evictedValue = valueTable[index2];
keyTable[index2] = insertKey;
valueTable[index2] = insertValue;
break;
default:
evictedKey = key3;
evictedValue = valueTable[index3];
keyTable[index3] = insertKey;
valueTable[index3] = insertValue;
break;
}
// If the evicted key hashes to an empty bucket, put it there and
// stop.
int hashCode = evictedKey.hashCode();
index1 = hashCode & mask;
key1 = keyTable[index1];
if (key1 == null) {
keyTable[index1] = evictedKey;
valueTable[index1] = evictedValue;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
index2 = hash2(hashCode);
key2 = keyTable[index2];
if (key2 == null) {
keyTable[index2] = evictedKey;
valueTable[index2] = evictedValue;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
index3 = hash3(hashCode);
key3 = keyTable[index3];
if (key3 == null) {
keyTable[index3] = evictedKey;
valueTable[index3] = evictedValue;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
if (++i == pushIterations)
break;
insertKey = evictedKey;
insertValue = evictedValue;
} while (true);
putStash(evictedKey, evictedValue);
}
private void putStash(K key, int value) {
if (stashSize == stashCapacity) {
// Too many pushes occurred and the stash is full, increase the
// table size.
resize(capacity << 1);
put(key, value);
return;
}
// Store key in the stash.
int index = capacity + stashSize;
keyTable[index] = key;
valueTable[index] = value;
stashSize++;
size++;
}
/**
* @param defaultValue
* Returned if the key was not associated with a value.
*/
public int get(K key, int defaultValue) {
int hashCode = key.hashCode();
int index = hashCode & mask;
if (!key.equals(keyTable[index])) {
index = hash2(hashCode);
if (!key.equals(keyTable[index])) {
index = hash3(hashCode);
if (!key.equals(keyTable[index]))
return getStash(key, defaultValue);
}
}
return valueTable[index];
}
private int getStash(K key, int defaultValue) {
K[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++)
if (key.equals(keyTable[i]))
return valueTable[i];
return defaultValue;
}
/**
* 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.
*/
public int getAndIncrement(K key, int defaultValue, int increment) {
int hashCode = key.hashCode();
int index = hashCode & mask;
if (!key.equals(keyTable[index])) {
index = hash2(hashCode);
if (!key.equals(keyTable[index])) {
index = hash3(hashCode);
if (!key.equals(keyTable[index]))
return getAndIncrementStash(key, defaultValue, increment);
}
}
int value = valueTable[index];
valueTable[index] = value + increment;
return value;
}
private int getAndIncrementStash(K key, int defaultValue, int increment) {
K[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++)
if (key.equals(keyTable[i])) {
int value = valueTable[i];
valueTable[i] = value + increment;
return value;
}
put(key, defaultValue + increment);
return defaultValue;
}
public int remove(K key, int defaultValue) {
int hashCode = key.hashCode();
int index = hashCode & mask;
if (key.equals(keyTable[index])) {
keyTable[index] = null;
int oldValue = valueTable[index];
size--;
return oldValue;
}
index = hash2(hashCode);
if (key.equals(keyTable[index])) {
keyTable[index] = null;
int oldValue = valueTable[index];
size--;
return oldValue;
}
index = hash3(hashCode);
if (key.equals(keyTable[index])) {
keyTable[index] = null;
int oldValue = valueTable[index];
size--;
return oldValue;
}
return removeStash(key, defaultValue);
}
int removeStash(K key, int defaultValue) {
K[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++) {
if (key.equals(keyTable[i])) {
int oldValue = valueTable[i];
removeStashIndex(i);
size--;
return oldValue;
}
}
return defaultValue;
}
void removeStashIndex(int index) {
// If the removed location was not last, move the last tuple to the
// removed location.
stashSize--;
int lastIndex = capacity + stashSize;
if (index < lastIndex) {
keyTable[index] = keyTable[lastIndex];
valueTable[index] = valueTable[lastIndex];
}
}
/**
* 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, the next highest power
* of two capacity is used instead.
*/
public void shrink(int maximumCapacity) {
if (maximumCapacity < 0)
throw new IllegalArgumentException("maximumCapacity must be >= 0: "
+ maximumCapacity);
if (size > maximumCapacity)
maximumCapacity = size;
if (capacity <= maximumCapacity)
return;
maximumCapacity = ObjectMap.nextPowerOfTwo(maximumCapacity);
resize(maximumCapacity);
}
/**
* Clears the map and reduces the size of the backing arrays to be the
* specified capacity if they are larger.
*/
public void clear(int maximumCapacity) {
if (capacity <= maximumCapacity) {
clear();
return;
}
size = 0;
resize(maximumCapacity);
}
public void clear() {
K[] keyTable = this.keyTable;
for (int i = capacity + stashSize; i-- > 0;)
keyTable[i] = null;
size = 0;
stashSize = 0;
}
/**
* 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.
*/
public boolean containsValue(int value) {
int[] valueTable = this.valueTable;
for (int i = capacity + stashSize; i-- > 0;)
if (valueTable[i] == value)
return true;
return false;
}
public boolean containsKey(K key) {
int hashCode = key.hashCode();
int index = hashCode & mask;
if (!key.equals(keyTable[index])) {
index = hash2(hashCode);
if (!key.equals(keyTable[index])) {
index = hash3(hashCode);
if (!key.equals(keyTable[index]))
return containsKeyStash(key);
}
}
return true;
}
private boolean containsKeyStash(K key) {
K[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++)
if (key.equals(keyTable[i]))
return true;
return false;
}
/**
* 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.
*/
public K findKey(int value) {
int[] valueTable = this.valueTable;
for (int i = capacity + stashSize; i-- > 0;)
if (valueTable[i] == value)
return keyTable[i];
return null;
}
/**
* 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.
*/
public void ensureCapacity(int additionalCapacity) {
int sizeNeeded = size + additionalCapacity;
if (sizeNeeded >= threshold)
resize(ObjectMap.nextPowerOfTwo((int) (sizeNeeded / loadFactor)));
}
@SuppressWarnings("unchecked")
private void resize(int newSize) {
int oldEndIndex = capacity + stashSize;
capacity = newSize;
threshold = (int) (newSize * loadFactor);
mask = newSize - 1;
hashShift = 31 - Integer.numberOfTrailingZeros(newSize);
stashCapacity = Math.max(3, (int) Math.ceil(Math.log(newSize)) * 2);
pushIterations = Math.max(Math.min(newSize, 8),
(int) Math.sqrt(newSize) / 8);
K[] oldKeyTable = keyTable;
int[] oldValueTable = valueTable;
keyTable = (K[]) new Object[newSize + stashCapacity];
valueTable = new int[newSize + stashCapacity];
int oldSize = size;
size = 0;
stashSize = 0;
if (oldSize > 0) {
for (int i = 0; i < oldEndIndex; i++) {
K key = oldKeyTable[i];
if (key != null)
putResize(key, oldValueTable[i]);
}
}
}
private int hash2(int h) {
h *= PRIME2;
return (h ^ h >>> hashShift) & mask;
}
private int hash3(int h) {
h *= PRIME3;
return (h ^ h >>> hashShift) & mask;
}
public String toString() {
if (size == 0)
return "{}";
StringBuilder buffer = new StringBuilder(32);
buffer.append('{');
K[] keyTable = this.keyTable;
int[] valueTable = this.valueTable;
int i = keyTable.length;
while (i-- > 0) {
K key = keyTable[i];
if (key == null)
continue;
buffer.append(key);
buffer.append('=');
buffer.append(valueTable[i]);
break;
}
while (i-- > 0) {
K key = keyTable[i];
if (key == null)
continue;
buffer.append(", ");
buffer.append(key);
buffer.append('=');
buffer.append(valueTable[i]);
}
buffer.append('}');
return buffer.toString();
}
}