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/* Copyright (c) 2008, Nathan Sweet
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided with the distribution.
* - Neither the name of Esoteric Software nor the names of its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
package com.esotericsoftware.kryo.util;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Random;
/** An unordered map. This implementation is a cuckoo hash map using 3 hashes, random walking, and a small stash for problematic
* keys. Null keys are not allowed. Null values are 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 ObjectMap {
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;
V[] 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 ObjectMap () {
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 ObjectMap (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. */
public ObjectMap (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 = 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 = (V[])new Object[keyTable.length];
}
/** Creates a new map identical to the specified map. */
public ObjectMap (ObjectMap 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;
}
/** Returns the old value associated with the specified key, or null. */
public V put (K key, V value) {
if (key == null) throw new IllegalArgumentException("key cannot be null.");
return put_internal(key, value);
}
private V put_internal (K key, V value) {
K[] keyTable = this.keyTable;
// Check for existing keys.
int hashCode = key.hashCode();
int index1 = hashCode & mask;
K key1 = keyTable[index1];
if (key.equals(key1)) {
V oldValue = valueTable[index1];
valueTable[index1] = value;
return oldValue;
}
int index2 = hash2(hashCode);
K key2 = keyTable[index2];
if (key.equals(key2)) {
V oldValue = valueTable[index2];
valueTable[index2] = value;
return oldValue;
}
int index3 = hash3(hashCode);
K key3 = keyTable[index3];
if (key.equals(key3)) {
V oldValue = valueTable[index3];
valueTable[index3] = value;
return oldValue;
}
// Update key in the stash.
for (int i = capacity, n = i + stashSize; i < n; i++) {
if (key.equals(keyTable[i])) {
V oldValue = valueTable[i];
valueTable[i] = value;
return oldValue;
}
}
// Check for empty buckets.
if (key1 == null) {
keyTable[index1] = key;
valueTable[index1] = value;
if (size++ >= threshold) resize(capacity << 1);
return null;
}
if (key2 == null) {
keyTable[index2] = key;
valueTable[index2] = value;
if (size++ >= threshold) resize(capacity << 1);
return null;
}
if (key3 == null) {
keyTable[index3] = key;
valueTable[index3] = value;
if (size++ >= threshold) resize(capacity << 1);
return null;
}
push(key, value, index1, key1, index2, key2, index3, key3);
return null;
}
public void putAll (ObjectMap map) {
ensureCapacity(map.size);
for (Entry entry : map.entries())
put(entry.key, entry.value);
}
/** Skips checks for existing keys. */
private void putResize (K key, V 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, V insertValue, int index1, K key1, int index2, K key2, int index3, K key3) {
K[] keyTable = this.keyTable;
V[] valueTable = this.valueTable;
int mask = this.mask;
// Push keys until an empty bucket is found.
K evictedKey;
V 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, V value) {
if (stashSize == stashCapacity) {
// Too many pushes occurred and the stash is full, increase the table size.
resize(capacity << 1);
put_internal(key, value);
return;
}
// Store key in the stash.
int index = capacity + stashSize;
keyTable[index] = key;
valueTable[index] = value;
stashSize++;
size++;
}
public V get (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 getStash(key);
}
}
return valueTable[index];
}
private V getStash (K key) {
K[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++)
if (key.equals(keyTable[i])) return valueTable[i];
return null;
}
/** Returns the value for the specified key, or the default value if the key is not in the map. */
public V get (K key, V 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 V getStash (K key, V 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;
}
public V remove (K key) {
int hashCode = key.hashCode();
int index = hashCode & mask;
if (key.equals(keyTable[index])) {
keyTable[index] = null;
V oldValue = valueTable[index];
valueTable[index] = null;
size--;
return oldValue;
}
index = hash2(hashCode);
if (key.equals(keyTable[index])) {
keyTable[index] = null;
V oldValue = valueTable[index];
valueTable[index] = null;
size--;
return oldValue;
}
index = hash3(hashCode);
if (key.equals(keyTable[index])) {
keyTable[index] = null;
V oldValue = valueTable[index];
valueTable[index] = null;
size--;
return oldValue;
}
return removeStash(key);
}
V removeStash (K key) {
K[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++) {
if (key.equals(keyTable[i])) {
V oldValue = valueTable[i];
removeStashIndex(i);
size--;
return oldValue;
}
}
return null;
}
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];
valueTable[lastIndex] = null;
} else
valueTable[index] = null;
}
/** 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 = 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;
V[] valueTable = this.valueTable;
for (int i = capacity + stashSize; i-- > 0;) {
keyTable[i] = null;
valueTable[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.
* @param identity If true, uses == to compare the specified value with values in the map. If false, uses
* {@link #equals(Object)}. */
public boolean containsValue (Object value, boolean identity) {
V[] valueTable = this.valueTable;
if (value == null) {
K[] keyTable = this.keyTable;
for (int i = capacity + stashSize; i-- > 0;)
if (keyTable[i] != null && valueTable[i] == null) return true;
} else if (identity) {
for (int i = capacity + stashSize; i-- > 0;)
if (valueTable[i] == value) return true;
} else {
for (int i = capacity + stashSize; i-- > 0;)
if (value.equals(valueTable[i])) 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.
* @param identity If true, uses == to compare the specified value with values in the map. If false, uses
* {@link #equals(Object)}. */
public K findKey (Object value, boolean identity) {
V[] valueTable = this.valueTable;
if (value == null) {
K[] keyTable = this.keyTable;
for (int i = capacity + stashSize; i-- > 0;)
if (keyTable[i] != null && valueTable[i] == null) return keyTable[i];
} else if (identity) {
for (int i = capacity + stashSize; i-- > 0;)
if (valueTable[i] == value) return keyTable[i];
} else {
for (int i = capacity + stashSize; i-- > 0;)
if (value.equals(valueTable[i])) 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(nextPowerOfTwo((int)(sizeNeeded / loadFactor)));
}
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;
V[] oldValueTable = valueTable;
keyTable = (K[])new Object[newSize + stashCapacity];
valueTable = (V[])new Object[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;
V[] 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();
}
/** Returns an iterator for the entries in the map. Remove is supported. */
public Entries entries () {
return new Entries(this);
}
/** Returns an iterator for the values in the map. Remove is supported. */
public Values values () {
return new Values(this);
}
/** Returns an iterator for the keys in the map. Remove is supported. */
public Keys keys () {
return new Keys(this);
}
static public class Entry {
public K key;
public V value;
public String toString () {
return key + "=" + value;
}
}
static private class MapIterator {
public boolean hasNext;
final ObjectMap map;
int nextIndex, currentIndex;
public MapIterator (ObjectMap map) {
this.map = map;
reset();
}
public void reset () {
currentIndex = -1;
nextIndex = -1;
advance();
}
void advance () {
hasNext = false;
K[] keyTable = map.keyTable;
for (int n = map.capacity + map.stashSize; ++nextIndex < n;) {
if (keyTable[nextIndex] != null) {
hasNext = true;
break;
}
}
}
public void remove () {
if (currentIndex < 0) throw new IllegalStateException("next must be called before remove.");
if (currentIndex >= map.capacity) {
map.removeStashIndex(currentIndex);
nextIndex = currentIndex - 1;
advance();
} else {
map.keyTable[currentIndex] = null;
map.valueTable[currentIndex] = null;
}
currentIndex = -1;
map.size--;
}
}
static public class Entries extends MapIterator implements Iterable>, Iterator> {
Entry entry = new Entry();
public Entries (ObjectMap map) {
super(map);
}
/** Note the same entry instance is returned each time this method is called. */
public Entry next () {
if (!hasNext) throw new NoSuchElementException();
K[] keyTable = map.keyTable;
entry.key = keyTable[nextIndex];
entry.value = map.valueTable[nextIndex];
currentIndex = nextIndex;
advance();
return entry;
}
public boolean hasNext () {
return hasNext;
}
public Iterator> iterator () {
return this;
}
}
static public class Values extends MapIterator implements Iterable, Iterator {
public Values (ObjectMap map) {
super((ObjectMap)map);
}
public boolean hasNext () {
return hasNext;
}
public V next () {
if (!hasNext) throw new NoSuchElementException();
V value = map.valueTable[nextIndex];
currentIndex = nextIndex;
advance();
return value;
}
public Iterator iterator () {
return this;
}
/** Returns a new array containing the remaining values. */
public ArrayList toArray () {
ArrayList array = new ArrayList(map.size);
while (hasNext)
array.add(next());
return array;
}
/** Adds the remaining values to the specified array. */
public void toArray (ArrayList array) {
while (hasNext)
array.add(next());
}
}
static public class Keys extends MapIterator implements Iterable, Iterator {
public Keys (ObjectMap map) {
super((ObjectMap)map);
}
public boolean hasNext () {
return hasNext;
}
public K next () {
if (!hasNext) throw new NoSuchElementException();
K key = map.keyTable[nextIndex];
currentIndex = nextIndex;
advance();
return key;
}
public Iterator iterator () {
return this;
}
/** Returns a new array containing the remaining keys. */
public ArrayList toArray () {
ArrayList array = new ArrayList(map.size);
while (hasNext)
array.add(next());
return array;
}
}
static public int nextPowerOfTwo (int value) {
if (value == 0) return 1;
value--;
value |= value >> 1;
value |= value >> 2;
value |= value >> 4;
value |= value >> 8;
value |= value >> 16;
return value + 1;
}
}
