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package org.infinispan.commons.util;
import java.io.IOException;
import java.io.Serializable;
import java.util.AbstractCollection;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import org.infinispan.commons.logging.Log;
import org.infinispan.commons.logging.LogFactory;
/**
* A HashMap that is optimized for fast shallow copies.
*
* Null keys are not supported.
*
* @author Jason T. Greene
* @since 4.0
*/
public class FastCopyHashMap extends AbstractMap implements Map, Cloneable, Serializable {
private static final Log log = LogFactory.getLog(FastCopyHashMap.class);
/**
* Serialization ID
*/
private static final long serialVersionUID = 10929568968762L;
/**
* Same default as HashMap, must be a power of 2
*/
private static final int DEFAULT_CAPACITY = 8;
/**
* MAX_INT - 1
*/
private static final int MAXIMUM_CAPACITY = 1 << 30;
/**
* 67%, just like IdentityHashMap
*/
private static final float DEFAULT_LOAD_FACTOR = 0.67f;
/**
* The open-addressed table
*/
private transient Entry[] table;
/**
* The current number of key-value pairs
*/
private transient int size;
/**
* The next resize
*/
private transient int threshold;
/**
* The user defined load factor which defines when to resize
*/
private final float loadFactor;
/**
* Counter used to detect changes made outside of an iterator
*/
private transient int modCount;
public FastCopyHashMap(int initialCapacity, float loadFactor) {
if (initialCapacity < 0)
throw new IllegalArgumentException("Can not have a negative size table!");
if (initialCapacity > MAXIMUM_CAPACITY)
initialCapacity = MAXIMUM_CAPACITY;
if (!(loadFactor > 0F && loadFactor <= 1F))
throw new IllegalArgumentException("Load factor must be greater than 0 and less than or equal to 1");
this.loadFactor = loadFactor;
init(initialCapacity, loadFactor);
}
@SuppressWarnings("unchecked")
public FastCopyHashMap(Map map) {
if (map instanceof FastCopyHashMap) {
FastCopyHashMap fast = (FastCopyHashMap) map;
this.table = (Entry[]) fast.table.clone();
this.loadFactor = fast.loadFactor;
this.size = fast.size;
this.threshold = fast.threshold;
} else {
this.loadFactor = DEFAULT_LOAD_FACTOR;
init(map.size(), this.loadFactor);
putAll(map);
}
}
@SuppressWarnings("unchecked")
private void init(int initialCapacity, float loadFactor) {
int c = 1;
while (c < initialCapacity) c <<= 1;
this.table = new Entry[c];
threshold = (int) (c * loadFactor);
}
public FastCopyHashMap(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
public FastCopyHashMap() {
this(DEFAULT_CAPACITY);
}
private int nextIndex(int index, int length) {
index = (index >= length - 1) ? 0 : index + 1;
return index;
}
private static int index(int hashCode, int length) {
return hashCode & (length - 1);
}
@Override
public int size() {
return size;
}
@Override
public boolean isEmpty() {
return size == 0;
}
@Override
public V get(Object key) {
assertKeyNotNull(key);
int hash = hash(key);
int length = table.length;
int index = index(hash, length);
for (; ;) {
Entry e = table[index];
if (e == null)
return null;
if (e.hash == hash && eq(key, e.key))
return e.value;
index = nextIndex(index, length);
}
}
@Override
public boolean containsKey(Object key) {
assertKeyNotNull(key);
int hash = hash(key);
int length = table.length;
int index = index(hash, length);
for (; ;) {
Entry e = table[index];
if (e == null)
return false;
if (e.hash == hash && eq(key, e.key))
return true;
index = nextIndex(index, length);
}
}
/**
* Returns a string representation of this map. The string representation
* consists of a list of key-value mappings in the order returned by the
* map's entrySet view's iterator, enclosed in braces
* ("{}"). Adjacent mappings are separated by the characters
* ", " (comma and space). Each key-value mapping is rendered as
* the key followed by an equals sign ("=") followed by the
* associated value. Keys and values are converted to strings as by
* {@link String#valueOf(Object)}.
*
* @return a string representation of this map
*/
public String toString() {
Iterator> i = entrySet().iterator();
if (! i.hasNext())
return "{}";
StringBuilder sb = new StringBuilder();
sb.append('{');
for (;;) {
java.util.Map.Entry e = i.next();
K key = e.getKey();
V value = e.getValue();
sb.append(key == this ? "(this Map)" : key);
sb.append('=');
sb.append(value == this ? "(this Map)" : value);
if (! i.hasNext())
return sb.append('}').toString();
sb.append(", ");
}
}
@Override
public boolean containsValue(Object value) {
for (Entry e : table)
if (e != null && eq(value, e.value))
return true;
return false;
}
@Override
public V put(K key, V value) {
assertKeyNotNull(key);
Entry[] table = this.table;
int hash = hash(key);
int length = table.length;
int start = index(hash, length);
int index = start;
for (; ;) {
Entry e = table[index];
if (e == null)
break;
if (e.hash == hash && eq(key, e.key)) {
table[index] = new Entry(e.key, e.hash, value);
return e.value;
}
index = nextIndex(index, length);
if (index == start)
throw new IllegalStateException("Table is full!");
}
modCount++;
table[index] = new Entry(key, hash, value);
if (++size >= threshold)
resize(length);
return null;
}
@SuppressWarnings("unchecked")
private void resize(int from) {
int newLength = from << 1;
// Can't get any bigger
if (newLength > MAXIMUM_CAPACITY || newLength <= from)
return;
Entry[] newTable = new Entry[newLength];
Entry[] old = table;
for (Entry e : old) {
if (e == null)
continue;
int index = index(e.hash, newLength);
while (newTable[index] != null)
index = nextIndex(index, newLength);
newTable[index] = e;
}
threshold = (int) (loadFactor * newLength);
table = newTable;
}
@Override
public void putAll(Map map) {
int size = map.size();
if (size == 0)
return;
if (size > threshold) {
if (size > MAXIMUM_CAPACITY)
size = MAXIMUM_CAPACITY;
int length = table.length;
while (length < size) length <<= 1;
resize(length);
}
for (Map.Entry e : map.entrySet())
put(e.getKey(), e.getValue());
}
@Override
public V remove(Object key) {
assertKeyNotNull(key);
Entry[] table = this.table;
int length = table.length;
int hash = hash(key);
int start = index(hash, length);
for (int index = start; ;) {
Entry e = table[index];
if (e == null)
return null;
if (e.hash == hash && eq(key, e.key)) {
table[index] = null;
relocate(index);
modCount++;
size--;
return e.value;
}
index = nextIndex(index, length);
if (index == start)
return null;
}
}
private void relocate(int start) {
Entry[] table = this.table;
int length = table.length;
int current = nextIndex(start, length);
for (; ;) {
Entry e = table[current];
if (e == null)
return;
// A Doug Lea variant of Knuth's Section 6.4 Algorithm R.
// This provides a non-recursive method of relocating
// entries to their optimal positions once a gap is created.
int prefer = index(e.hash, length);
if ((current < prefer && (prefer <= start || start <= current))
|| (prefer <= start && start <= current)) {
table[start] = e;
table[current] = null;
start = current;
}
current = nextIndex(current, length);
}
}
@Override
public void clear() {
modCount++;
Entry[] table = this.table;
for (int i = 0; i < table.length; i++)
table[i] = null;
size = 0;
}
@Override
@SuppressWarnings("unchecked")
public FastCopyHashMap clone() {
try {
FastCopyHashMap clone = (FastCopyHashMap) super.clone();
clone.table = table.clone();
clone.entrySet = null;
clone.values = null;
clone.keySet = null;
return clone;
}
catch (CloneNotSupportedException e) {
// should never happen
throw new IllegalStateException(e);
}
}
public void printDebugStats() {
int optimal = 0;
int total = 0;
int totalSkew = 0;
int maxSkew = 0;
for (int i = 0; i < table.length; i++) {
Entry e = table[i];
if (e != null) {
total++;
int target = index(e.hash, table.length);
if (i == target)
optimal++;
else {
int skew = Math.abs(i - target);
if (skew > maxSkew) maxSkew = skew;
totalSkew += skew;
}
}
}
System.out.println(" Size: " + size);
System.out.println(" Real Size: " + total);
System.out.println(" Optimal: " + optimal + " (" + (float) optimal * 100 / total + "%)");
System.out.println(" Average Distnce: " + ((float) totalSkew / (total - optimal)));
System.out.println(" Max Distance: " + maxSkew);
}
@SuppressWarnings("unchecked")
private void readObject(java.io.ObjectInputStream s) throws IOException, ClassNotFoundException {
s.defaultReadObject();
int size = s.readInt();
init(size, loadFactor);
for (int i = 0; i < size; i++) {
K key = (K) s.readObject();
V value = (V) s.readObject();
putForCreate(key, value);
}
}
@SuppressWarnings("unchecked")
private void putForCreate(K key, V value) {
Entry[] table = this.table;
int hash = hash(key);
int length = table.length;
int index = index(hash, length);
Entry e = table[index];
while (e != null) {
index = nextIndex(index, length);
e = table[index];
}
table[index] = new Entry(key, hash, value);
}
private void writeObject(java.io.ObjectOutputStream s) throws IOException {
s.defaultWriteObject();
s.writeInt(size);
for (Entry e : table) {
if (e != null) {
s.writeObject(e.key);
s.writeObject(e.value);
}
}
}
private abstract class FasyCopyHashMapIterator implements Iterator {
private int next = 0;
private int expectedCount = modCount;
private int current = -1;
private boolean hasNext;
Entry table[] = FastCopyHashMap.this.table;
@Override
public boolean hasNext() {
if (hasNext)
return true;
Entry table[] = this.table;
for (int i = next; i < table.length; i++) {
if (table[i] != null) {
next = i;
return hasNext = true;
}
}
next = table.length;
return false;
}
protected Entry nextEntry() {
if (modCount != expectedCount)
throw new ConcurrentModificationException();
if (!hasNext && !hasNext())
throw new NoSuchElementException();
current = next++;
hasNext = false;
return table[current];
}
@Override
@SuppressWarnings("unchecked")
public void remove() {
if (modCount != expectedCount)
throw new ConcurrentModificationException();
int current = this.current;
int delete = current;
if (current == -1)
throw new IllegalStateException();
// Invalidate current (prevents multiple remove)
this.current = -1;
// Start were we relocate
next = delete;
Entry[] table = this.table;
if (table != FastCopyHashMap.this.table) {
FastCopyHashMap.this.remove(table[delete].key);
table[delete] = null;
expectedCount = modCount;
return;
}
int length = table.length;
int i = delete;
table[delete] = null;
size--;
for (; ;) {
i = nextIndex(i, length);
Entry e = table[i];
if (e == null)
break;
int prefer = index(e.hash, length);
if ((i < prefer && (prefer <= delete || delete <= i))
|| (prefer <= delete && delete <= i)) {
// Snapshot the unseen portion of the table if we have
// to relocate an entry that was already seen by this iterator
if (i < current && current <= delete && table == FastCopyHashMap.this.table) {
int remaining = length - current;
Entry[] newTable = new Entry[remaining];
System.arraycopy(table, current, newTable, 0, remaining);
// Replace iterator's table.
// Leave table local var pointing to the real table
this.table = newTable;
next = 0;
}
// Do the swap on the real table
table[delete] = e;
table[i] = null;
delete = i;
}
}
}
}
private class KeyIterator extends FasyCopyHashMapIterator {
@Override
public K next() {
return nextEntry().key;
}
}
private class ValueIterator extends FasyCopyHashMapIterator {
@Override
public V next() {
return nextEntry().value;
}
}
private class EntryIterator extends FasyCopyHashMapIterator> {
private class WriteThroughEntry extends AbstractMap.SimpleEntry {
WriteThroughEntry(K key, V value) {
super(key, value);
}
@Override
public V setValue(V value) {
if (table != FastCopyHashMap.this.table)
FastCopyHashMap.this.put(getKey(), value);
return super.setValue(value);
}
}
@Override
public Map.Entry next() {
Entry e = nextEntry();
return new WriteThroughEntry(e.key, e.value);
}
}
@Override
public Collection values() {
if (values == null) values = new Values();
return values;
}
public final class Values extends AbstractCollection {
@Override
public Iterator iterator() {
return new ValueIterator();
}
@Override
public int size() {
return FastCopyHashMap.this.size();
}
@Override
public boolean contains(Object o) {
return containsValue(o);
}
@Override
public void clear() {
FastCopyHashMap.this.clear();
}
}
@Override
public Set keySet() {
if (keySet == null) keySet = new KeySet();
return keySet;
}
public class KeySet extends AbstractSet {
@Override
public Iterator iterator() {
return new KeyIterator();
}
@Override
public void clear() {
FastCopyHashMap.this.clear();
}
@Override
public boolean contains(Object o) {
return containsKey(o);
}
@Override
public boolean remove(Object o) {
int size = size();
FastCopyHashMap.this.remove(o);
return size() < size;
}
@Override
public int size() {
return FastCopyHashMap.this.size();
}
}
@Override
public Set> entrySet() {
if (entrySet == null) entrySet = new EntrySet();
return entrySet;
}
public class EntrySet extends AbstractSet> {
@Override
public Iterator> iterator() {
return new EntryIterator();
}
@Override
public boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry entry = (Map.Entry) o;
Object value = get(entry.getKey());
return eq(entry.getValue(), value);
}
@Override
public void clear() {
FastCopyHashMap.this.clear();
}
@Override
public boolean isEmpty() {
return FastCopyHashMap.this.isEmpty();
}
@Override
public int size() {
return FastCopyHashMap.this.size();
}
}
private static final class Entry {
final K key;
final int hash;
final V value;
Entry(K key, int hash, V value) {
this.key = key;
this.hash = hash;
this.value = value;
}
}
}
