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feilong is a suite of core and expanded libraries that include utility classes, http, excel,cvs, io classes, and much much more.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.feilong.lib.beanutils;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.WeakHashMap;
/**
*
* A customized implementation of java.util.HashMap designed
* to operate in a multithreaded environment where the large majority of
* method calls are read-only, instead of structural changes. When operating
* in "fast" mode, read calls are non-synchronized and write calls perform the
* following steps:
*
*
* - Clone the existing collection
*
- Perform the modification on the clone
*
- Replace the existing collection with the (modified) clone
*
*
* When first created, objects of this class default to "slow" mode, where
* all accesses of any type are synchronized but no cloning takes place. This
* is appropriate for initially populating the collection, followed by a switch
* to "fast" mode (by calling setFast(true)) after initialization
* is complete.
*
*
*
* NOTE: If you are creating and accessing a
* HashMap only within a single thread, you should use
* java.util.HashMap directly (with no synchronization), for
* maximum performance.
*
*
*
* NOTE: This class is not cross-platform.
* Using it may cause unexpected failures on some architectures.
* It suffers from the same problems as the double-checked locking idiom.
* In particular, the instruction that clones the internal collection and the
* instruction that sets the internal reference to the clone can be executed
* or perceived out-of-order. This means that any read operation might fail
* unexpectedly, as it may be reading the state of the internal collection
* before the internal collection is fully formed.
* For more information on the double-checked locking idiom, see the
*
* Double-Checked Locking Idiom Is Broken Declaration.
*
*
* @since Commons Collections 1.0
* @version $Id$
*/
class WeakFastHashMap extends HashMap{
/**
*
*/
private static final long serialVersionUID = -3735140271616448807L;
/**
* The underlying map we are managing.
*/
private Map map = null;
/**
* Are we currently operating in "fast" mode?
*/
private boolean fast = false;
// Constructors
// ----------------------------------------------------------------------
/**
* Construct an empty map.
*/
public WeakFastHashMap(){
super();
this.map = createMap();
}
/**
* Construct an empty map with the specified capacity.
*
* @param capacity
* the initial capacity of the empty map
*/
public WeakFastHashMap(final int capacity){
super();
this.map = createMap(capacity);
}
/**
* Construct an empty map with the specified capacity and load factor.
*
* @param capacity
* the initial capacity of the empty map
* @param factor
* the load factor of the new map
*/
public WeakFastHashMap(final int capacity, final float factor){
super();
this.map = createMap(capacity, factor);
}
/**
* Construct a new map with the same mappings as the specified map.
*
* @param map
* the map whose mappings are to be copied
*/
public WeakFastHashMap(final Map map){
super();
this.map = createMap(map);
}
// Property access
// ----------------------------------------------------------------------
/**
* Returns true if this map is operating in fast mode.
*
* @return true if this map is operating in fast mode
*/
public boolean getFast(){
return (this.fast);
}
/**
* Sets whether this map is operating in fast mode.
*
* @param fast
* true if this map should operate in fast mode
*/
public void setFast(final boolean fast){
this.fast = fast;
}
// Map access
// ----------------------------------------------------------------------
// These methods can forward straight to the wrapped Map in 'fast' mode.
// (because they are query methods)
/**
* Return the value to which this map maps the specified key. Returns
* null if the map contains no mapping for this key, or if
* there is a mapping with a value of null. Use the
* containsKey() method to disambiguate these cases.
*
* @param key
* the key whose value is to be returned
* @return the value mapped to that key, or null
*/
@Override
public V get(final Object key){
if (fast){
return (map.get(key));
}else{
synchronized (map){
return (map.get(key));
}
}
}
/**
* Return the number of key-value mappings in this map.
*
* @return the current size of the map
*/
@Override
public int size(){
if (fast){
return (map.size());
}
synchronized (map){
return (map.size());
}
}
/**
* Return true if this map contains no mappings.
*
* @return is the map currently empty
*/
@Override
public boolean isEmpty(){
if (fast){
return (map.isEmpty());
}else{
synchronized (map){
return (map.isEmpty());
}
}
}
/**
* Return true if this map contains a mapping for the
* specified key.
*
* @param key
* the key to be searched for
* @return true if the map contains the key
*/
@Override
public boolean containsKey(final Object key){
if (fast){
return (map.containsKey(key));
}
synchronized (map){
return (map.containsKey(key));
}
}
/**
* Return true if this map contains one or more keys mapping
* to the specified value.
*
* @param value
* the value to be searched for
* @return true if the map contains the value
*/
@Override
public boolean containsValue(final Object value){
if (fast){
return (map.containsValue(value));
}else{
synchronized (map){
return (map.containsValue(value));
}
}
}
// Map modification
// ----------------------------------------------------------------------
// These methods perform special behaviour in 'fast' mode.
// The map is cloned, updated and then assigned back.
// See the comments at the top as to why this won't always work.
/**
* Associate the specified value with the specified key in this map.
* If the map previously contained a mapping for this key, the old
* value is replaced and returned.
*
* @param key
* the key with which the value is to be associated
* @param value
* the value to be associated with this key
* @return the value previously mapped to the key, or null
*/
@Override
public V put(final K key,final V value){
if (fast){
synchronized (this){
final Map temp = cloneMap(map);
final V result = temp.put(key, value);
map = temp;
return (result);
}
}else{
synchronized (map){
return (map.put(key, value));
}
}
}
/**
* Copy all of the mappings from the specified map to this one, replacing
* any mappings with the same keys.
*
* @param in
* the map whose mappings are to be copied
*/
@Override
public void putAll(final Map in){
if (fast){
synchronized (this){
final Map temp = cloneMap(map);
temp.putAll(in);
map = temp;
}
}else{
synchronized (map){
map.putAll(in);
}
}
}
/**
* Remove any mapping for this key, and return any previously
* mapped value.
*
* @param key
* the key whose mapping is to be removed
* @return the value removed, or null
*/
@Override
public V remove(final Object key){
if (fast){
synchronized (this){
final Map temp = cloneMap(map);
final V result = temp.remove(key);
map = temp;
return (result);
}
}
synchronized (map){
return (map.remove(key));
}
}
/**
* Remove all mappings from this map.
*/
@Override
public void clear(){
if (fast){
synchronized (this){
map = createMap();
}
}else{
synchronized (map){
map.clear();
}
}
}
// Basic object methods
// ----------------------------------------------------------------------
/**
* Compare the specified object with this list for equality. This
* implementation uses exactly the code that is used to define the
* list equals function in the documentation for the
* Map.equals method.
*
* @param o
* the object to be compared to this list
* @return true if the two maps are equal
*/
@Override
public boolean equals(final Object o){
// Simple tests that require no synchronization
if (o == this){
return (true);
}else if (!(o instanceof Map)){
return (false);
}
final Map mo = (Map) o;
// Compare the two maps for equality
if (fast){
if (mo.size() != map.size()){
return (false);
}
for (final Map.Entry e : map.entrySet()){
final K key = e.getKey();
final V value = e.getValue();
if (value == null){
if (!(mo.get(key) == null && mo.containsKey(key))){
return (false);
}
}else{
if (!value.equals(mo.get(key))){
return (false);
}
}
}
return (true);
}else{
synchronized (map){
if (mo.size() != map.size()){
return (false);
}
for (final Map.Entry e : map.entrySet()){
final K key = e.getKey();
final V value = e.getValue();
if (value == null){
if (!(mo.get(key) == null && mo.containsKey(key))){
return (false);
}
}else{
if (!value.equals(mo.get(key))){
return (false);
}
}
}
return (true);
}
}
}
/**
* Return the hash code value for this map. This implementation uses
* exactly the code that is used to define the list hash function in the
* documentation for the Map.hashCode method.
*
* @return suitable integer hash code
*/
@Override
public int hashCode(){
if (fast){
int h = 0;
for (final Map.Entry e : map.entrySet()){
h += e.hashCode();
}
return (h);
}else{
synchronized (map){
int h = 0;
for (final Map.Entry e : map.entrySet()){
h += e.hashCode();
}
return (h);
}
}
}
/**
* Return a shallow copy of this FastHashMap instance.
* The keys and values themselves are not copied.
*
* @return a clone of this map
*/
@Override
public Object clone(){
WeakFastHashMap results = null;
if (fast){
results = new WeakFastHashMap<>(map);
}else{
synchronized (map){
results = new WeakFastHashMap<>(map);
}
}
results.setFast(getFast());
return (results);
}
// Map views
// ----------------------------------------------------------------------
/**
* Return a collection view of the mappings contained in this map. Each
* element in the returned collection is a Map.Entry.
*
* @return the set of map Map entries
*/
@Override
public Set> entrySet(){
return new EntrySet();
}
/**
* Return a set view of the keys contained in this map.
*
* @return the set of the Map's keys
*/
@Override
public Set keySet(){
return new KeySet();
}
/**
* Return a collection view of the values contained in this map.
*
* @return the set of the Map's values
*/
@Override
public Collection values(){
return new Values();
}
// Abstractions on Map creations (for subclasses such as WeakFastHashMap)
// ----------------------------------------------------------------------
protected Map createMap(){
return new WeakHashMap<>();
}
protected Map createMap(final int capacity){
return new WeakHashMap<>(capacity);
}
protected Map createMap(final int capacity,final float factor){
return new WeakHashMap<>(capacity, factor);
}
protected Map createMap(final Map map){
return new WeakHashMap<>(map);
}
protected Map cloneMap(final Map map){
return createMap(map);
}
// Map view inner classes
// ----------------------------------------------------------------------
/**
* Abstract collection implementation shared by keySet(), values() and entrySet().
*
* @param
* the element type
*/
private abstract class CollectionView implements Collection{
public CollectionView(){
}
protected abstract Collection get(Map map);
protected abstract E iteratorNext(Map.Entry entry);
@Override
public void clear(){
if (fast){
synchronized (WeakFastHashMap.this){
map = createMap();
}
}else{
synchronized (map){
get(map).clear();
}
}
}
@Override
public boolean remove(final Object o){
if (fast){
synchronized (WeakFastHashMap.this){
final Map temp = cloneMap(map);
final boolean r = get(temp).remove(o);
map = temp;
return r;
}
}
synchronized (map){
return get(map).remove(o);
}
}
@Override
public boolean removeAll(final Collection o){
if (fast){
synchronized (WeakFastHashMap.this){
final Map temp = cloneMap(map);
final boolean r = get(temp).removeAll(o);
map = temp;
return r;
}
}
synchronized (map){
return get(map).removeAll(o);
}
}
@Override
public boolean retainAll(final Collection o){
if (fast){
synchronized (WeakFastHashMap.this){
final Map temp = cloneMap(map);
final boolean r = get(temp).retainAll(o);
map = temp;
return r;
}
}else{
synchronized (map){
return get(map).retainAll(o);
}
}
}
@Override
public int size(){
if (fast){
return get(map).size();
}else{
synchronized (map){
return get(map).size();
}
}
}
@Override
public boolean isEmpty(){
if (fast){
return get(map).isEmpty();
}else{
synchronized (map){
return get(map).isEmpty();
}
}
}
@Override
public boolean contains(final Object o){
if (fast){
return get(map).contains(o);
}else{
synchronized (map){
return get(map).contains(o);
}
}
}
@Override
public boolean containsAll(final Collection o){
if (fast){
return get(map).containsAll(o);
}
synchronized (map){
return get(map).containsAll(o);
}
}
@Override
public T[] toArray(final T[] o){
if (fast){
return get(map).toArray(o);
}else{
synchronized (map){
return get(map).toArray(o);
}
}
}
@Override
public Object[] toArray(){
if (fast){
return get(map).toArray();
}else{
synchronized (map){
return get(map).toArray();
}
}
}
@Override
public boolean equals(final Object o){
if (o == this){
return true;
}
if (fast){
return get(map).equals(o);
}else{
synchronized (map){
return get(map).equals(o);
}
}
}
@Override
public int hashCode(){
if (fast){
return get(map).hashCode();
}else{
synchronized (map){
return get(map).hashCode();
}
}
}
@Override
public boolean add(final E o){
throw new UnsupportedOperationException();
}
@Override
public boolean addAll(final Collection c){
throw new UnsupportedOperationException();
}
@Override
public Iterator iterator(){
return new CollectionViewIterator();
}
private class CollectionViewIterator implements Iterator{
private Map expected;
private Map.Entry lastReturned = null;
private final Iterator> iterator;
public CollectionViewIterator(){
this.expected = map;
this.iterator = expected.entrySet().iterator();
}
@Override
public boolean hasNext(){
if (expected != map){
throw new ConcurrentModificationException();
}
return iterator.hasNext();
}
@Override
public E next(){
if (expected != map){
throw new ConcurrentModificationException();
}
lastReturned = iterator.next();
return iteratorNext(lastReturned);
}
@Override
public void remove(){
if (lastReturned == null){
throw new IllegalStateException();
}
if (fast){
synchronized (WeakFastHashMap.this){
if (expected != map){
throw new ConcurrentModificationException();
}
WeakFastHashMap.this.remove(lastReturned.getKey());
lastReturned = null;
expected = map;
}
}else{
iterator.remove();
lastReturned = null;
}
}
}
}
/**
* Set implementation over the keys of the FastHashMap
*/
private class KeySet extends CollectionView implements Set{
@Override
protected Collection get(final Map map){
return map.keySet();
}
@Override
protected K iteratorNext(final Map.Entry entry){
return entry.getKey();
}
}
/**
* Collection implementation over the values of the FastHashMap
*/
private class Values extends CollectionView{
@Override
protected Collection get(final Map map){
return map.values();
}
@Override
protected V iteratorNext(final Map.Entry entry){
return entry.getValue();
}
}
/**
* Set implementation over the entries of the FastHashMap
*/
private class EntrySet extends CollectionView> implements Set>{
@Override
protected Collection> get(final Map map){
return map.entrySet();
}
@Override
protected Map.Entry iteratorNext(final Map.Entry entry){
return entry;
}
}
}