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Utilities for the Network project.
/*******************************************************************************
* Copyright 2010 Mario Zechner ([email protected]), Nathan Sweet ([email protected])
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dorkbox.util.collections;
import com.esotericsoftware.kryo.util.ObjectMap;
import dorkbox.util.MathUtil;
/** 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.
*
* 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 {
@SuppressWarnings("unused")
private static final int PRIME1 = 0xbe1f14b1;
private static final int PRIME2 = 0xb4b82e39;
private static final int PRIME3 = 0xced1c241;
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);
}
this.capacity = ObjectMap.nextPowerOfTwo(initialCapacity);
if (loadFactor <= 0) {
throw new IllegalArgumentException("loadFactor must be > 0: " + loadFactor);
}
this.loadFactor = loadFactor;
this.threshold = (int)(this.capacity * loadFactor);
this.mask = this.capacity - 1;
this.hashShift = 31 - Integer.numberOfTrailingZeros(this.capacity);
this.stashCapacity = Math.max(3, (int)Math.ceil(Math.log(this.capacity)) * 2);
this.pushIterations = Math.max(Math.min(this.capacity, 8), (int)Math.sqrt(this.capacity) / 8);
this.keyTable = (K[])new Object[this.capacity + this.stashCapacity];
this.valueTable = new int[this.keyTable.length];
}
/** Creates a new map identical to the specified map. */
public ObjectIntMap (ObjectIntMap map) {
this(map.capacity, map.loadFactor);
this.stashSize = map.stashSize;
System.arraycopy(map.keyTable, 0, this.keyTable, 0, map.keyTable.length);
System.arraycopy(map.valueTable, 0, this.valueTable, 0, map.valueTable.length);
this.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 & this.mask;
K key1 = keyTable[index1];
if (key.equals(key1)) {
this.valueTable[index1] = value;
return;
}
int index2 = hash2(hashCode);
K key2 = keyTable[index2];
if (key.equals(key2)) {
this.valueTable[index2] = value;
return;
}
int index3 = hash3(hashCode);
K key3 = keyTable[index3];
if (key.equals(key3)) {
this.valueTable[index3] = value;
return;
}
// Update key in the stash.
for (int i = this.capacity, n = i + this.stashSize; i < n; i++) {
if (key.equals(keyTable[i])) {
this.valueTable[i] = value;
return;
}
}
// Check for empty buckets.
if (key1 == null) {
keyTable[index1] = key;
this.valueTable[index1] = value;
if (this.size++ >= this.threshold) {
resize(this.capacity << 1);
}
return;
}
if (key2 == null) {
keyTable[index2] = key;
this.valueTable[index2] = value;
if (this.size++ >= this.threshold) {
resize(this.capacity << 1);
}
return;
}
if (key3 == null) {
keyTable[index3] = key;
this.valueTable[index3] = value;
if (this.size++ >= this.threshold) {
resize(this.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 & this.mask;
K key1 = this.keyTable[index1];
if (key1 == null) {
this.keyTable[index1] = key;
this.valueTable[index1] = value;
if (this.size++ >= this.threshold) {
resize(this.capacity << 1);
}
return;
}
int index2 = hash2(hashCode);
K key2 = this.keyTable[index2];
if (key2 == null) {
this.keyTable[index2] = key;
this.valueTable[index2] = value;
if (this.size++ >= this.threshold) {
resize(this.capacity << 1);
}
return;
}
int index3 = hash3(hashCode);
K key3 = this.keyTable[index3];
if (key3 == null) {
this.keyTable[index3] = key;
this.valueTable[index3] = value;
if (this.size++ >= this.threshold) {
resize(this.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 (MathUtil.randomInt(2)) {
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 (this.size++ >= this.threshold) {
resize(this.capacity << 1);
}
return;
}
index2 = hash2(hashCode);
key2 = keyTable[index2];
if (key2 == null) {
keyTable[index2] = evictedKey;
valueTable[index2] = evictedValue;
if (this.size++ >= this.threshold) {
resize(this.capacity << 1);
}
return;
}
index3 = hash3(hashCode);
key3 = keyTable[index3];
if (key3 == null) {
keyTable[index3] = evictedKey;
valueTable[index3] = evictedValue;
if (this.size++ >= this.threshold) {
resize(this.capacity << 1);
}
return;
}
if (++i == pushIterations) {
break;
}
insertKey = evictedKey;
insertValue = evictedValue;
} while (true);
putStash(evictedKey, evictedValue);
}
private void putStash (K key, int value) {
if (this.stashSize == this.stashCapacity) {
// Too many pushes occurred and the stash is full, increase the table size.
resize(this.capacity << 1);
put(key, value);
return;
}
// Store key in the stash.
int index = this.capacity + this.stashSize;
this.keyTable[index] = key;
this.valueTable[index] = value;
this.stashSize++;
this.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 & this.mask;
if (!key.equals(this.keyTable[index])) {
index = hash2(hashCode);
if (!key.equals(this.keyTable[index])) {
index = hash3(hashCode);
if (!key.equals(this.keyTable[index])) {
return getStash(key, defaultValue);
}
}
}
return this.valueTable[index];
}
private int getStash (K key, int defaultValue) {
K[] keyTable = this.keyTable;
for (int i = this.capacity, n = i + this.stashSize; i < n; i++) {
if (key.equals(keyTable[i])) {
return this.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 & this.mask;
if (!key.equals(this.keyTable[index])) {
index = hash2(hashCode);
if (!key.equals(this.keyTable[index])) {
index = hash3(hashCode);
if (!key.equals(this.keyTable[index])) {
return getAndIncrementStash(key, defaultValue, increment);
}
}
}
int value = this.valueTable[index];
this.valueTable[index] = value + increment;
return value;
}
private int getAndIncrementStash (K key, int defaultValue, int increment) {
K[] keyTable = this.keyTable;
for (int i = this.capacity, n = i + this.stashSize; i < n; i++) {
if (key.equals(keyTable[i])) {
int value = this.valueTable[i];
this.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 & this.mask;
if (key.equals(this.keyTable[index])) {
this.keyTable[index] = null;
int oldValue = this.valueTable[index];
this.size--;
return oldValue;
}
index = hash2(hashCode);
if (key.equals(this.keyTable[index])) {
this.keyTable[index] = null;
int oldValue = this.valueTable[index];
this.size--;
return oldValue;
}
index = hash3(hashCode);
if (key.equals(this.keyTable[index])) {
this.keyTable[index] = null;
int oldValue = this.valueTable[index];
this.size--;
return oldValue;
}
return removeStash(key, defaultValue);
}
int removeStash (K key, int defaultValue) {
K[] keyTable = this.keyTable;
for (int i = this.capacity, n = i + this.stashSize; i < n; i++) {
if (key.equals(keyTable[i])) {
int oldValue = this.valueTable[i];
removeStashIndex(i);
this.size--;
return oldValue;
}
}
return defaultValue;
}
void removeStashIndex (int index) {
// If the removed location was not last, move the last tuple to the removed location.
this.stashSize--;
int lastIndex = this.capacity + this.stashSize;
if (index < lastIndex) {
this.keyTable[index] = this.keyTable[lastIndex];
this.valueTable[index] = this.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 (this.size > maximumCapacity) {
maximumCapacity = this.size;
}
if (this.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 (this.capacity <= maximumCapacity) {
clear();
return;
}
this.size = 0;
resize(maximumCapacity);
}
public void clear () {
K[] keyTable = this.keyTable;
for (int i = this.capacity + this.stashSize; i-- > 0;) {
keyTable[i] = null;
}
this.size = 0;
this.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 = this.capacity + this.stashSize; i-- > 0;) {
if (keyTable[i] != null && valueTable[i] == value) {
return true;
}
}
return false;
}
public boolean containsKey (K key) {
int hashCode = key.hashCode();
int index = hashCode & this.mask;
if (!key.equals(this.keyTable[index])) {
index = hash2(hashCode);
if (!key.equals(this.keyTable[index])) {
index = hash3(hashCode);
if (!key.equals(this.keyTable[index])) {
return containsKeyStash(key);
}
}
}
return true;
}
private boolean containsKeyStash (K key) {
K[] keyTable = this.keyTable;
for (int i = this.capacity, n = i + this.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 = this.capacity + this.stashSize; i-- > 0;) {
if (keyTable[i] != null && valueTable[i] == value) {
return this.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 = this.size + additionalCapacity;
if (sizeNeeded >= this.threshold) {
resize(ObjectMap.nextPowerOfTwo((int)(sizeNeeded / this.loadFactor)));
}
}
@SuppressWarnings("unchecked")
private void resize (int newSize) {
int oldEndIndex = this.capacity + this.stashSize;
this.capacity = newSize;
this.threshold = (int)(newSize * this.loadFactor);
this.mask = newSize - 1;
this.hashShift = 31 - Integer.numberOfTrailingZeros(newSize);
this.stashCapacity = Math.max(3, (int)Math.ceil(Math.log(newSize)) * 2);
this.pushIterations = Math.max(Math.min(newSize, 8), (int)Math.sqrt(newSize) / 8);
K[] oldKeyTable = this.keyTable;
int[] oldValueTable = this.valueTable;
this.keyTable = (K[])new Object[newSize + this.stashCapacity];
this.valueTable = new int[newSize + this.stashCapacity];
int oldSize = this.size;
this.size = 0;
this.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 >>> this.hashShift) & this.mask;
}
private int hash3 (int h) {
h *= PRIME3;
return (h ^ h >>> this.hashShift) & this.mask;
}
@Override
public String toString () {
if (this.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();
}
}
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