/*
* $Header: /home/cvs/jakarta-struts/src/share/org/apache/struts/util/FastTreeMap.java,v 1.2 2001/02/12 00:32:13 craigmcc Exp $
* $Revision: 1.2 $
* $Date: 2001/02/12 00:32:13 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. 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.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Struts", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Group.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
* ITS 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.struts.util;
import java.io.Serializable;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
/**
* <p>A customized implementation of <code>java.util.TreeMap</code> 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:</p>
* <ul>
* <li>Clone the existing collection
* <li>Perform the modification on the clone
* <li>Replace the existing collection with the (modified) clone
* </ul>
* <p>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 <code>setFast(true)</code>) after initialization
* is complete.</p>
*
* <p><strong>NOTE</strong>: If you are creating and accessing a
* <code>TreeMap</code> only within a single thread, you should use
* <code>java.util.TreeMap</code> directly (with no synchronization), for
* maximum performance.</p>
*
* <p><strong>NOTE</strong>: The following methods are <strong>NOT</strong>
* overridden: clone(), equals(Object), hashCode().</p>
*
* @author Craig R. McClanahan
* @version $Revision: 1.2 $ $Date: 2001/02/12 00:32:13 $
*/
public class FastTreeMap implements Map, Cloneable, Serializable {
// ----------------------------------------------------------- Constructors
/**
* Construct a an empty map.
*/
public FastTreeMap() {
super();
this.map = new TreeMap();
}
/**
* Construct an empty map with the specified comparator.
*
* @param comparator The comparator to use for ordering tree elements
*/
public FastTreeMap(Comparator comparator) {
super();
this.map = new TreeMap(comparator);
}
/**
* Construct a new map with the same mappings as the specified map,
* sorted according to the keys's natural order
*
* @param map The map whose mappings are to be copied
*/
public FastTreeMap(Map map) {
super();
this.map = new TreeMap(map);
}
/**
* Construct a new map with the same mappings as the specified map,
* sorted according to the same ordering
*
* @param map The map whose mappings are to be copied
*/
public FastTreeMap(SortedMap map) {
super();
this.map = new TreeMap(map);
}
// ----------------------------------------------------- Instance Variables
/**
* The underlying map we are managing.
*/
protected TreeMap map = null;
// ------------------------------------------------------------- Properties
/**
* Are we operating in "fast" mode?
*/
protected boolean fast = false;
public boolean getFast() {
return (this.fast);
}
public void setFast(boolean fast) {
this.fast = fast;
}
// --------------------------------------------------------- Public Methods
/**
* Remove all mappings from this map.
*/
public void clear() {
if (fast) {
synchronized (this) {
TreeMap temp = (TreeMap) map.clone();
temp.clear();
map = temp;
}
} else {
synchronized (map) {
map.clear();
}
}
}
/**
* Return the comparator used to order this map, or <code>null</code>
* if this map uses its keys' natural order.
*/
public Comparator comparator() {
if (fast) {
return (map.comparator());
} else {
synchronized (map) {
return (map.comparator());
}
}
}
/**
* Return <code>true</code> if this map contains a mapping for the
* specified key.
*
* @param key Key to be searched for
*/
public boolean containsKey(Object key) {
if (fast) {
return (map.containsKey(key));
} else {
synchronized (map) {
return (map.containsKey(key));
}
}
}
/**
* Return <code>true</code> if this map contains one or more keys mapping
* to the specified value.
*
* @param value Value to be searched for
*/
public boolean containsValue(Object value) {
if (fast) {
return (map.containsValue(value));
} else {
synchronized (map) {
return (map.containsValue(value));
}
}
}
/**
* Return a collection view of the mappings contained in this map. Each
* element in the returned collection is a <code>Map.Entry</code>.
*/
public Set entrySet() {
if (fast) {
return (map.entrySet());
} else {
synchronized (map) {
return (map.entrySet());
}
}
}
/**
* Return the first (lowest) key currently in this sorted map.
*/
public Object firstKey() {
if (fast) {
return (map.firstKey());
} else {
synchronized (map) {
return (map.firstKey());
}
}
}
/**
* Return the value to which this map maps the specified key. Returns
* <code>null</code> if the map contains no mapping for this key, or if
* there is a mapping with a value of <code>null</code>. Use the
* <code>containsKey()</code> method to disambiguate these cases.
*
* @param key Key whose value is to be returned
*/
public Object get(Object key) {
if (fast) {
return (map.get(key));
} else {
synchronized (map) {
return (map.get(key));
}
}
}
/**
* Return a view of the portion of this map whose keys are strictly
* less than the specified key.
*
* @param key Key higher than any in the returned map
*/
public SortedMap headMap(Object key) {
if (fast) {
return (map.headMap(key));
} else {
synchronized (map) {
return (map.headMap(key));
}
}
}
/**
* Test if this list has no elements.
*/
public boolean isEmpty() {
if (fast) {
return (map.isEmpty());
} else {
synchronized (map) {
return (map.isEmpty());
}
}
}
/**
* Return a set view of the keys contained in this map.
*/
public Set keySet() {
if (fast) {
return (map.keySet());
} else {
synchronized (map) {
return (map.keySet());
}
}
}
/**
* Return the last (highest) key currently in this sorted map.
*/
public Object lastKey() {
if (fast) {
return (map.lastKey());
} else {
synchronized (map) {
return (map.lastKey());
}
}
}
/**
* 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
*/
public Object put(Object key, Object value) {
if (fast) {
synchronized (this) {
TreeMap temp = (TreeMap) map.clone();
Object 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 Map whose mappings are to be copied
*/
public void putAll(Map in) {
if (fast) {
synchronized (this) {
TreeMap temp = (TreeMap) map.clone();
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 Key whose mapping is to be removed
*/
public Object remove(Object key) {
if (fast) {
synchronized (this) {
TreeMap temp = (TreeMap) map.clone();
Object result = temp.remove(key);
map = temp;
return (result);
}
} else {
synchronized (map) {
return (map.remove(key));
}
}
}
/**
* Return the number of key-value mappings in this map.
*/
public int size() {
if (fast) {
return (map.size());
} else {
synchronized (map) {
return (map.size());
}
}
}
/**
* Return a view of the portion of this map whose keys are in the
* range fromKey (inclusive) to toKey (exclusive).
*
* @param fromKey Lower limit of keys for the returned map
* @param toKey Upper limit of keys for the returned map
*/
public SortedMap subMap(Object fromKey, Object toKey) {
if (fast) {
return (map.subMap(fromKey, toKey));
} else {
synchronized (map) {
return (map.subMap(fromKey, toKey));
}
}
}
/**
* Return a view of the portion of this map whose keys are greater than
* or equal to the specified key.
*
* @param key Key less than or equal to any in the returned map
*/
public SortedMap tailMap(Object key) {
if (fast) {
return (map.tailMap(key));
} else {
synchronized (map) {
return (map.tailMap(key));
}
}
}
/**
* Return a collection view of the values contained in this map.
*/
public Collection values() {
if (fast) {
return (map.values());
} else {
synchronized (map) {
return (map.values());
}
}
}
}