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com.mycila.xmltool.SoftHashMap Maven / Gradle / Ivy
/**
* Copyright (C) 2008 Mycila ([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 com.mycila.xmltool;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import java.util.AbstractCollection;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* @author Mathieu Carbou ([email protected] )
*/
final class SoftHashMap extends AbstractMap implements Map {
private static final int DEFAULT_INITIAL_CAPACITY = 16;
private static final int MAXIMUM_CAPACITY = 1 << 30;
private static final float DEFAULT_LOAD_FACTOR = 0.75f;
private static final Object NULL_KEY = new Object();
private Entry[] table;
private int size;
private int threshold;
private final float loadFactor;
private final ReferenceQueue queue = new ReferenceQueue();
private volatile int modCount;
private transient Set> entrySet = null;
private transient volatile Set keySet = null;
private transient volatile Collection values = null;
@SuppressWarnings({"unchecked"})
public SoftHashMap(int initialCapacity, float loadFactor) {
if (initialCapacity < 0) throw new IllegalArgumentException("Illegal Initial Capacity: " + initialCapacity);
if (initialCapacity > MAXIMUM_CAPACITY) initialCapacity = MAXIMUM_CAPACITY;
if (loadFactor <= 0 || Float.isNaN(loadFactor)) throw new IllegalArgumentException("Illegal Load factor: " + loadFactor);
int capacity = 1;
while (capacity < initialCapacity) capacity <<= 1;
table = new Entry[capacity];
this.loadFactor = loadFactor;
threshold = (int) (capacity * loadFactor);
}
public SoftHashMap(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
@SuppressWarnings({"unchecked"})
public SoftHashMap() {
this.loadFactor = DEFAULT_LOAD_FACTOR;
threshold = (int) (DEFAULT_INITIAL_CAPACITY);
table = new Entry[DEFAULT_INITIAL_CAPACITY];
}
public SoftHashMap(Map t) {
this(Math.max((int) (t.size() / DEFAULT_LOAD_FACTOR) + 1, 16), DEFAULT_LOAD_FACTOR);
putAll(t);
}
public int size() {
if (size == 0) return 0;
expungeStaleEntries();
return size;
}
public boolean isEmpty() {
return size() == 0;
}
public V get(Object key) {
Object k = maskNull(key);
int h = hash(k);
Entry[] tab = getTable();
int index = indexFor(h, tab.length);
Entry e = tab[index];
while (e != null) {
if (e.hash == h && eq(k, e.get())) return e.value;
e = e.next;
}
return null;
}
public V put(K key, V value) {
K k = SoftHashMap.maskNull(key);
int h = hash(k);
Entry[] tab = getTable();
int i = indexFor(h, tab.length);
for (Entry e = tab[i]; e != null; e = e.next) {
if (h == e.hash && eq(k, e.get())) {
V oldValue = e.value;
if (value != oldValue) e.value = value;
return oldValue;
}
}
modCount++;
Entry e = tab[i];
tab[i] = new Entry(k, value, queue, h, e);
if (++size >= threshold) resize(tab.length * 2);
return null;
}
public boolean containsKey(Object key) {
return getEntry(key) != null;
}
public void putAll(Map m) {
int numKeysToBeAdded = m.size();
if (numKeysToBeAdded == 0) return;
if (numKeysToBeAdded > threshold) {
int targetCapacity = (int) (numKeysToBeAdded / loadFactor + 1);
if (targetCapacity > MAXIMUM_CAPACITY) targetCapacity = MAXIMUM_CAPACITY;
int newCapacity = table.length;
while (newCapacity < targetCapacity) newCapacity <<= 1;
if (newCapacity > table.length) resize(newCapacity);
}
for (Iterator> i = m.entrySet().iterator(); i.hasNext();) {
Map.Entry e = i.next();
put(e.getKey(), e.getValue());
}
}
public V remove(Object key) {
Object k = maskNull(key);
int h = hash(k);
Entry[] tab = getTable();
int i = indexFor(h, tab.length);
Entry prev = tab[i];
Entry e = prev;
while (e != null) {
Entry next = e.next;
if (h == e.hash && eq(k, e.get())) {
modCount++;
size--;
if (prev == e) tab[i] = next;
else prev.next = next;
return e.value;
}
prev = e;
e = next;
}
return null;
}
public void clear() {
while (queue.poll() != null) ;
modCount++;
Entry[] tab = table;
for (int i = 0; i < tab.length; ++i) tab[i] = null;
size = 0;
while (queue.poll() != null) ;
}
public boolean containsValue(Object value) {
if (value == null) return containsNullValue();
Entry[] tab = getTable();
for (int i = tab.length; i-- > 0;)
for (Entry e = tab[i]; e != null; e = e.next)
if (value.equals(e.value))
return true;
return false;
}
public Set keySet() {
Set ks = keySet;
return (ks != null ? ks : (keySet = new KeySet()));
}
public Collection values() {
Collection vs = values;
return (vs != null ? vs : (values = new Values()));
}
public Set> entrySet() {
Set> es = entrySet;
return (es != null ? es : (entrySet = new EntrySet()));
}
private void expungeStaleEntries() {
Entry e;
while ((e = (Entry) queue.poll()) != null) {
int h = e.hash;
int i = indexFor(h, table.length);
Entry prev = table[i];
Entry p = prev;
while (p != null) {
Entry next = p.next;
if (p == e) {
if (prev == e) table[i] = next;
else prev.next = next;
e.next = null; // Help GC
e.value = null; // " "
size--;
break;
}
prev = p;
p = next;
}
}
}
private Entry[] getTable() {
expungeStaleEntries();
return table;
}
private Entry getEntry(Object key) {
Object k = maskNull(key);
int h = hash(k);
Entry[] tab = getTable();
int index = indexFor(h, tab.length);
Entry e = tab[index];
while (e != null && !(e.hash == h && eq(k, e.get()))) e = e.next;
return e;
}
@SuppressWarnings({"unchecked"})
private void resize(int newCapacity) {
Entry[] oldTable = getTable();
int oldCapacity = oldTable.length;
if (oldCapacity == MAXIMUM_CAPACITY) {
threshold = Integer.MAX_VALUE;
return;
}
Entry[] newTable = new Entry[newCapacity];
transfer(oldTable, newTable);
table = newTable;
if (size >= threshold / 2) {
threshold = (int) (newCapacity * loadFactor);
} else {
expungeStaleEntries();
transfer(newTable, oldTable);
table = oldTable;
}
}
private void transfer(Entry[] src, Entry[] dest) {
for (int j = 0; j < src.length; ++j) {
Entry e = src[j];
src[j] = null;
while (e != null) {
Entry next = e.next;
Object key = e.get();
if (key == null) {
e.next = null; // Help GC
e.value = null; // " "
size--;
} else {
int i = indexFor(e.hash, dest.length);
e.next = dest[i];
dest[i] = e;
}
e = next;
}
}
}
private Entry removeMapping(Object o) {
if (!(o instanceof Map.Entry)) return null;
Entry[] tab = getTable();
Map.Entry entry = (Map.Entry) o;
Object k = maskNull(entry.getKey());
int h = hash(k);
int i = indexFor(h, tab.length);
Entry prev = tab[i];
Entry e = prev;
while (e != null) {
Entry next = e.next;
if (h == e.hash && e.equals(entry)) {
modCount++;
size--;
if (prev == e) tab[i] = next;
else prev.next = next;
return e;
}
prev = e;
e = next;
}
return null;
}
private boolean containsNullValue() {
Entry[] tab = getTable();
for (int i = tab.length; i-- > 0;)
for (Entry e = tab[i]; e != null; e = e.next)
if (e.value == null)
return true;
return false;
}
@SuppressWarnings({"unchecked"})
private static K maskNull(Object key) {
return (K) (key == null ? NULL_KEY : key);
}
@SuppressWarnings({"unchecked"})
private static K unmaskNull(Object key) {
return (K) (key == NULL_KEY ? null : key);
}
private static boolean eq(Object x, Object y) {
return x == y || x.equals(y);
}
private static int indexFor(int h, int length) {
return h & (length - 1);
}
private static int hash(Object key) {
return hash(key.hashCode());
}
private static int hash(int h) {
h ^= (h >>> 20) ^ (h >>> 12);
return h ^ (h >>> 7) ^ (h >>> 4);
}
private static class Entry extends SoftReference implements Map.Entry {
private V value;
private final int hash;
private Entry next;
Entry(K key, V value,
ReferenceQueue queue,
int hash, Entry next) {
super(key, queue);
this.value = value;
this.hash = hash;
this.next = next;
}
public K getKey() {
return SoftHashMap.unmaskNull(get());
}
public V getValue() {
return value;
}
public V setValue(V newValue) {
V oldValue = value;
value = newValue;
return oldValue;
}
public boolean equals(Object o) {
if (!(o instanceof Map.Entry)) return false;
Map.Entry e = (Map.Entry) o;
Object k1 = getKey();
Object k2 = e.getKey();
if (k1 == k2 || (k1 != null && k1.equals(k2))) {
Object v1 = getValue();
Object v2 = e.getValue();
if (v1 == v2 || (v1 != null && v1.equals(v2))) return true;
}
return false;
}
public int hashCode() {
Object k = getKey();
Object v = getValue();
return ((k == null ? 0 : k.hashCode()) ^
(v == null ? 0 : v.hashCode()));
}
public String toString() {
return getKey() + "=" + getValue();
}
}
private abstract class HashIterator implements Iterator {
int index;
Entry entry = null;
Entry lastReturned = null;
int expectedModCount = modCount;
Object nextKey = null;
Object currentKey = null;
HashIterator() {
index = (size() != 0 ? table.length : 0);
}
public boolean hasNext() {
Entry[] t = table;
while (nextKey == null) {
Entry e = entry;
int i = index;
while (e == null && i > 0) e = t[--i];
entry = e;
index = i;
if (e == null) {
currentKey = null;
return false;
}
nextKey = e.get(); // hold on to key in strong ref
if (nextKey == null) entry = entry.next;
}
return true;
}
protected Entry nextEntry() {
if (modCount != expectedModCount) throw new ConcurrentModificationException();
if (nextKey == null && !hasNext()) throw new NoSuchElementException();
lastReturned = entry;
entry = entry.next;
currentKey = nextKey;
nextKey = null;
return lastReturned;
}
public void remove() {
if (lastReturned == null) throw new IllegalStateException();
if (modCount != expectedModCount) throw new ConcurrentModificationException();
SoftHashMap.this.remove(currentKey);
expectedModCount = modCount;
lastReturned = null;
currentKey = null;
}
}
private class ValueIterator extends HashIterator {
public V next() {
return nextEntry().value;
}
}
private class KeyIterator extends HashIterator {
public K next() {
return nextEntry().getKey();
}
}
private class EntryIterator extends HashIterator> {
public Map.Entry next() {
return nextEntry();
}
}
private class KeySet extends AbstractSet {
public Iterator iterator() {
return new KeyIterator();
}
public int size() {
return SoftHashMap.this.size();
}
public boolean contains(Object o) {
return containsKey(o);
}
public boolean remove(Object o) {
if (containsKey(o)) {
SoftHashMap.this.remove(o);
return true;
} else return false;
}
public void clear() {
SoftHashMap.this.clear();
}
public Object[] toArray() {
Collection c = new ArrayList(size());
for (Iterator i = iterator(); i.hasNext();) c.add(i.next());
return c.toArray();
}
public T[] toArray(T[] a) {
Collection c = new ArrayList(size());
for (Iterator i = iterator(); i.hasNext();) c.add(i.next());
return c.toArray(a);
}
}
private class Values extends AbstractCollection {
public Iterator iterator() {
return new ValueIterator();
}
public int size() {
return SoftHashMap.this.size();
}
public boolean contains(Object o) {
return containsValue(o);
}
public void clear() {
SoftHashMap.this.clear();
}
public Object[] toArray() {
Collection c = new ArrayList(size());
for (Iterator i = iterator(); i.hasNext();) c.add(i.next());
return c.toArray();
}
public T[] toArray(T[] a) {
Collection c = new ArrayList(size());
for (Iterator i = iterator(); i.hasNext();) c.add(i.next());
return c.toArray(a);
}
}
private class EntrySet extends AbstractSet> {
public Iterator> iterator() {
return new EntryIterator();
}
public boolean contains(Object o) {
if (!(o instanceof Map.Entry)) return false;
Map.Entry e = (Map.Entry) o;
Entry candidate = getEntry(e.getKey());
return candidate != null && candidate.equals(e);
}
public boolean remove(Object o) {
return removeMapping(o) != null;
}
public int size() {
return SoftHashMap.this.size();
}
public void clear() {
SoftHashMap.this.clear();
}
public Object[] toArray() {
Collection> c = new ArrayList>(size());
for (Iterator> i = iterator(); i.hasNext();)
c.add(new SimpleEntry(i.next()));
return c.toArray();
}
public T[] toArray(T[] a) {
Collection> c = new ArrayList>(size());
for (Iterator> i = iterator(); i.hasNext();)
c.add(new SimpleEntry(i.next()));
return c.toArray(a);
}
}
private static class SimpleEntry implements Map.Entry {
private final K key;
private V value;
public SimpleEntry(K key, V value) {
this.key = key;
this.value = value;
}
public SimpleEntry(Map.Entry e) {
this.key = e.getKey();
this.value = e.getValue();
}
public K getKey() {
return key;
}
public V getValue() {
return value;
}
public V setValue(V value) {
V oldValue = this.value;
this.value = value;
return oldValue;
}
public boolean equals(Object o) {
if (!(o instanceof Map.Entry)) return false;
Map.Entry e = (Map.Entry) o;
return eq(key, e.getKey()) && eq(value, e.getValue());
}
public int hashCode() {
return ((key == null) ? 0 : key.hashCode()) ^
((value == null) ? 0 : value.hashCode());
}
public String toString() {
return key + "=" + value;
}
private static boolean eq(Object o1, Object o2) {
return (o1 == null ? o2 == null : o1.equals(o2));
}
}
}
