com.esotericsoftware.kryo.util.IdentityMap Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of kryo-slf4j-shaded Show documentation
Show all versions of kryo-slf4j-shaded Show documentation
Fork of Esoteric Software's Kryo built by Nathan Sweet that replaces Minlog with slf4j as the logging facade. This contains the shaded reflectasm jar to prevent conflicts with other versions of asm.
The newest version!
/*******************************************************************************
* Copyright 2011 See AUTHORS file.
*
* 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 com.esotericsoftware.kryo.util;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.NoSuchElementException;
/** An unordered map that uses identity comparison for keys. 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 IdentityMap {
private static final int PRIME1 = 0xbe1f14b1;
private static final int PRIME2 = 0xb4b82e39;
private static final int PRIME3 = 0xced1c241;
public int size;
K[] keyTable;
V[] valueTable;
int capacity, stashSize;
private float loadFactor;
private int hashShift, mask, threshold;
private int stashCapacity;
private int pushIterations;
private Entries entries;
private Values values;
private Keys keys;
/** 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 IdentityMap () {
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 IdentityMap (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 IdentityMap (int initialCapacity, float loadFactor) {
if (initialCapacity < 0) throw new IllegalArgumentException("initialCapacity must be >= 0: " + initialCapacity);
if (capacity > 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 = (V[])new Object[keyTable.length];
}
public V put (K key, V value) {
if (key == null) throw new IllegalArgumentException("key cannot be null.");
K[] keyTable = this.keyTable;
// Check for existing keys.
int hashCode = System.identityHashCode(key);
int index1 = hashCode & mask;
K key1 = keyTable[index1];
if (key1 == key) {
V oldValue = valueTable[index1];
valueTable[index1] = value;
return oldValue;
}
int index2 = hash2(hashCode);
K key2 = keyTable[index2];
if (key2 == key) {
V oldValue = valueTable[index2];
valueTable[index2] = value;
return oldValue;
}
int index3 = hash3(hashCode);
K key3 = keyTable[index3];
if (key3 == key) {
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 (keyTable[i] == key) {
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;
}
/** Skips checks for existing keys. */
private void putResize (K key, V value) {
// Check for empty buckets.
int hashCode = System.identityHashCode(key);
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 (ObjectMap.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 = System.identityHashCode(evictedKey);
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(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 = System.identityHashCode(key);
int index = hashCode & mask;
if (key != keyTable[index]) {
index = hash2(hashCode);
if (key != keyTable[index]) {
index = hash3(hashCode);
if (key != keyTable[index]) return getStash(key, null);
}
}
return valueTable[index];
}
public V get (K key, V defaultValue) {
int hashCode = System.identityHashCode(key);
int index = hashCode & mask;
if (key != keyTable[index]) {
index = hash2(hashCode);
if (key != keyTable[index]) {
index = hash3(hashCode);
if (key != 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 (keyTable[i] == key) return valueTable[i];
return defaultValue;
}
public V remove (K key) {
int hashCode = System.identityHashCode(key);
int index = hashCode & mask;
if (keyTable[index] == key) {
keyTable[index] = null;
V oldValue = valueTable[index];
valueTable[index] = null;
size--;
return oldValue;
}
index = hash2(hashCode);
if (keyTable[index] == key) {
keyTable[index] = null;
V oldValue = valueTable[index];
valueTable[index] = null;
size--;
return oldValue;
}
index = hash3(hashCode);
if (keyTable[index] == key) {
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 (keyTable[i] == key) {
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, nothing is done. */
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;
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 = System.identityHashCode(key);
int index = hashCode & mask;
if (key != keyTable[index]) {
index = hash2(hashCode);
if (key != keyTable[index]) {
index = hash3(hashCode);
if (key != 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 (keyTable[i] == key) 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(ObjectMap.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. Note that the same iterator instance is returned each
* time this method is called. Use the {@link Entries} constructor for nested or multithreaded iteration. */
public Entries entries () {
if (entries == null)
entries = new Entries(this);
else
entries.reset();
return entries;
}
/** Returns an iterator for the values in the map. Remove is supported. Note that the same iterator instance is returned each
* time this method is called. Use the {@link Entries} constructor for nested or multithreaded iteration. */
public Values values () {
if (values == null)
values = new Values(this);
else
values.reset();
return values;
}
/** Returns an iterator for the keys in the map. Remove is supported. Note that the same iterator instance is returned each time
* this method is called. Use the {@link Entries} constructor for nested or multithreaded iteration. */
public Keys keys () {
if (keys == null)
keys = new Keys(this);
else
keys.reset();
return keys;
}
static public class Entry {
public K key;
public V value;
public String toString () {
return key + "=" + value;
}
}
static private class MapIterator {
public boolean hasNext;
final IdentityMap map;
int nextIndex, currentIndex;
public MapIterator (IdentityMap map) {
this.map = map;
reset();
}
public void reset () {
currentIndex = -1;
nextIndex = -1;
findNextIndex();
}
void findNextIndex () {
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;
findNextIndex();
} else {
map.keyTable[currentIndex] = null;
map.valueTable[currentIndex] = null;
}
currentIndex = -1;
map.size--;
}
}
static public class Entries extends MapIterator implements Iterable>, Iterator> {
private Entry entry = new Entry();
public Entries (IdentityMap 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;
findNextIndex();
return entry;
}
public boolean hasNext () {
return hasNext;
}
public Iterator> iterator () {
return this;
}
}
static public class Values extends MapIterator implements Iterable, Iterator {
public Values (IdentityMap map) {
super((IdentityMap)map);
}
public boolean hasNext () {
return hasNext;
}
public V next () {
V value = map.valueTable[nextIndex];
currentIndex = nextIndex;
findNextIndex();
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;
}
/** Returns a new array containing the remaining values. */
public void toArray (ArrayList array) {
while (hasNext)
array.add(next());
}
}
static public class Keys extends MapIterator implements Iterable, Iterator {
public Keys (IdentityMap map) {
super((IdentityMap)map);
}
public boolean hasNext () {
return hasNext;
}
public K next () {
K key = map.keyTable[nextIndex];
currentIndex = nextIndex;
findNextIndex();
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;
}
}
}