10888a09821a98ac0680fad765217302858e70fa4Paul Duffin/* 20888a09821a98ac0680fad765217302858e70fa4Paul Duffin * Copyright (C) 2009 The Guava Authors 30888a09821a98ac0680fad765217302858e70fa4Paul Duffin * 40888a09821a98ac0680fad765217302858e70fa4Paul Duffin * Licensed under the Apache License, Version 2.0 (the "License"); 50888a09821a98ac0680fad765217302858e70fa4Paul Duffin * you may not use this file except in compliance with the License. 60888a09821a98ac0680fad765217302858e70fa4Paul Duffin * You may obtain a copy of the License at 70888a09821a98ac0680fad765217302858e70fa4Paul Duffin * 80888a09821a98ac0680fad765217302858e70fa4Paul Duffin * http://www.apache.org/licenses/LICENSE-2.0 90888a09821a98ac0680fad765217302858e70fa4Paul Duffin * 100888a09821a98ac0680fad765217302858e70fa4Paul Duffin * Unless required by applicable law or agreed to in writing, software 110888a09821a98ac0680fad765217302858e70fa4Paul Duffin * distributed under the License is distributed on an "AS IS" BASIS, 120888a09821a98ac0680fad765217302858e70fa4Paul Duffin * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 130888a09821a98ac0680fad765217302858e70fa4Paul Duffin * See the License for the specific language governing permissions and 140888a09821a98ac0680fad765217302858e70fa4Paul Duffin * limitations under the License. 150888a09821a98ac0680fad765217302858e70fa4Paul Duffin */ 160888a09821a98ac0680fad765217302858e70fa4Paul Duffin 170888a09821a98ac0680fad765217302858e70fa4Paul Duffinpackage java.util.concurrent; 180888a09821a98ac0680fad765217302858e70fa4Paul Duffin 190888a09821a98ac0680fad765217302858e70fa4Paul Duffinimport java.util.AbstractMap; 200888a09821a98ac0680fad765217302858e70fa4Paul Duffinimport java.util.Collections; 210888a09821a98ac0680fad765217302858e70fa4Paul Duffinimport java.util.Enumeration; 220888a09821a98ac0680fad765217302858e70fa4Paul Duffinimport java.util.HashMap; 230888a09821a98ac0680fad765217302858e70fa4Paul Duffinimport java.util.Map; 240888a09821a98ac0680fad765217302858e70fa4Paul Duffinimport java.util.Set; 250888a09821a98ac0680fad765217302858e70fa4Paul Duffin 260888a09821a98ac0680fad765217302858e70fa4Paul Duffin/** 270888a09821a98ac0680fad765217302858e70fa4Paul Duffin * Minimal emulation of {@link java.util.concurrent.ConcurrentHashMap}. 280888a09821a98ac0680fad765217302858e70fa4Paul Duffin * Note that javascript intepreter is <a 290888a09821a98ac0680fad765217302858e70fa4Paul Duffin * href="http://code.google.com/docreader/#p=google-web-toolkit-doc-1-5&t=DevGuideJavaCompatibility"> 300888a09821a98ac0680fad765217302858e70fa4Paul Duffin * single-threaded</a>, it is essentially a {@link java.util.HashMap}, 310888a09821a98ac0680fad765217302858e70fa4Paul Duffin * implementing the new methods introduced by {@link ConcurrentMap}. 320888a09821a98ac0680fad765217302858e70fa4Paul Duffin * 330888a09821a98ac0680fad765217302858e70fa4Paul Duffin * @author Hayward Chan 340888a09821a98ac0680fad765217302858e70fa4Paul Duffin */ 350888a09821a98ac0680fad765217302858e70fa4Paul Duffinpublic class ConcurrentHashMap<K, V> 360888a09821a98ac0680fad765217302858e70fa4Paul Duffin extends AbstractMap<K, V> implements ConcurrentMap<K, V> { 370888a09821a98ac0680fad765217302858e70fa4Paul Duffin 380888a09821a98ac0680fad765217302858e70fa4Paul Duffin private final Map<K, V> backingMap; 390888a09821a98ac0680fad765217302858e70fa4Paul Duffin 400888a09821a98ac0680fad765217302858e70fa4Paul Duffin public ConcurrentHashMap() { 410888a09821a98ac0680fad765217302858e70fa4Paul Duffin this.backingMap = new HashMap<K, V>(); 420888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 430888a09821a98ac0680fad765217302858e70fa4Paul Duffin 440888a09821a98ac0680fad765217302858e70fa4Paul Duffin public ConcurrentHashMap(int initialCapacity) { 450888a09821a98ac0680fad765217302858e70fa4Paul Duffin this.backingMap = new HashMap<K, V>(initialCapacity); 460888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 470888a09821a98ac0680fad765217302858e70fa4Paul Duffin 480888a09821a98ac0680fad765217302858e70fa4Paul Duffin public ConcurrentHashMap(int initialCapacity, float loadFactor) { 490888a09821a98ac0680fad765217302858e70fa4Paul Duffin this.backingMap = new HashMap<K, V>(initialCapacity, loadFactor); 500888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 510888a09821a98ac0680fad765217302858e70fa4Paul Duffin 520888a09821a98ac0680fad765217302858e70fa4Paul Duffin public ConcurrentHashMap(Map<? extends K, ? extends V> t) { 530888a09821a98ac0680fad765217302858e70fa4Paul Duffin this.backingMap = new HashMap<K, V>(t); 540888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 550888a09821a98ac0680fad765217302858e70fa4Paul Duffin 560888a09821a98ac0680fad765217302858e70fa4Paul Duffin public V putIfAbsent(K key, V value) { 570888a09821a98ac0680fad765217302858e70fa4Paul Duffin if (!containsKey(key)) { 580888a09821a98ac0680fad765217302858e70fa4Paul Duffin return put(key, value); 590888a09821a98ac0680fad765217302858e70fa4Paul Duffin } else { 600888a09821a98ac0680fad765217302858e70fa4Paul Duffin return get(key); 610888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 620888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 630888a09821a98ac0680fad765217302858e70fa4Paul Duffin 640888a09821a98ac0680fad765217302858e70fa4Paul Duffin public boolean remove(Object key, Object value) { 650888a09821a98ac0680fad765217302858e70fa4Paul Duffin if (containsKey(key) && get(key).equals(value)) { 660888a09821a98ac0680fad765217302858e70fa4Paul Duffin remove(key); 670888a09821a98ac0680fad765217302858e70fa4Paul Duffin return true; 680888a09821a98ac0680fad765217302858e70fa4Paul Duffin } else { 690888a09821a98ac0680fad765217302858e70fa4Paul Duffin return false; 700888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 710888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 720888a09821a98ac0680fad765217302858e70fa4Paul Duffin 730888a09821a98ac0680fad765217302858e70fa4Paul Duffin public boolean replace(K key, V oldValue, V newValue) { 740888a09821a98ac0680fad765217302858e70fa4Paul Duffin if (oldValue == null || newValue == null) { 750888a09821a98ac0680fad765217302858e70fa4Paul Duffin throw new NullPointerException(); 760888a09821a98ac0680fad765217302858e70fa4Paul Duffin } else if (containsKey(key) && get(key).equals(oldValue)) { 770888a09821a98ac0680fad765217302858e70fa4Paul Duffin put(key, newValue); 780888a09821a98ac0680fad765217302858e70fa4Paul Duffin return true; 790888a09821a98ac0680fad765217302858e70fa4Paul Duffin } else { 800888a09821a98ac0680fad765217302858e70fa4Paul Duffin return false; 810888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 820888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 830888a09821a98ac0680fad765217302858e70fa4Paul Duffin 840888a09821a98ac0680fad765217302858e70fa4Paul Duffin public V replace(K key, V value) { 850888a09821a98ac0680fad765217302858e70fa4Paul Duffin if (value == null) { 860888a09821a98ac0680fad765217302858e70fa4Paul Duffin throw new NullPointerException(); 870888a09821a98ac0680fad765217302858e70fa4Paul Duffin } else if (containsKey(key)) { 880888a09821a98ac0680fad765217302858e70fa4Paul Duffin return put(key, value); 890888a09821a98ac0680fad765217302858e70fa4Paul Duffin } else { 900888a09821a98ac0680fad765217302858e70fa4Paul Duffin return null; 910888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 920888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 930888a09821a98ac0680fad765217302858e70fa4Paul Duffin 940888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public boolean containsKey(Object key) { 950888a09821a98ac0680fad765217302858e70fa4Paul Duffin if (key == null) { 960888a09821a98ac0680fad765217302858e70fa4Paul Duffin throw new NullPointerException(); 970888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 980888a09821a98ac0680fad765217302858e70fa4Paul Duffin return backingMap.containsKey(key); 990888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1000888a09821a98ac0680fad765217302858e70fa4Paul Duffin 1010888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public V get(Object key) { 1020888a09821a98ac0680fad765217302858e70fa4Paul Duffin if (key == null) { 1030888a09821a98ac0680fad765217302858e70fa4Paul Duffin throw new NullPointerException(); 1040888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1050888a09821a98ac0680fad765217302858e70fa4Paul Duffin return backingMap.get(key); 1060888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1070888a09821a98ac0680fad765217302858e70fa4Paul Duffin 1080888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public V put(K key, V value) { 1090888a09821a98ac0680fad765217302858e70fa4Paul Duffin if (key == null || value == null) { 1100888a09821a98ac0680fad765217302858e70fa4Paul Duffin throw new NullPointerException(); 1110888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1120888a09821a98ac0680fad765217302858e70fa4Paul Duffin return backingMap.put(key, value); 1130888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1140888a09821a98ac0680fad765217302858e70fa4Paul Duffin 1150888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public boolean containsValue(Object value) { 1160888a09821a98ac0680fad765217302858e70fa4Paul Duffin if (value == null) { 1170888a09821a98ac0680fad765217302858e70fa4Paul Duffin throw new NullPointerException(); 1180888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1190888a09821a98ac0680fad765217302858e70fa4Paul Duffin return backingMap.containsValue(value); 1200888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1210888a09821a98ac0680fad765217302858e70fa4Paul Duffin 1220888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public V remove(Object key) { 1230888a09821a98ac0680fad765217302858e70fa4Paul Duffin if (key == null) { 1240888a09821a98ac0680fad765217302858e70fa4Paul Duffin throw new NullPointerException(); 1250888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1260888a09821a98ac0680fad765217302858e70fa4Paul Duffin return backingMap.remove(key); 1270888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1280888a09821a98ac0680fad765217302858e70fa4Paul Duffin 1290888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public Set<Entry<K, V>> entrySet() { 1300888a09821a98ac0680fad765217302858e70fa4Paul Duffin return backingMap.entrySet(); 1310888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1320888a09821a98ac0680fad765217302858e70fa4Paul Duffin 1330888a09821a98ac0680fad765217302858e70fa4Paul Duffin public boolean contains(Object value) { 1340888a09821a98ac0680fad765217302858e70fa4Paul Duffin return containsValue(value); 1350888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1360888a09821a98ac0680fad765217302858e70fa4Paul Duffin 1370888a09821a98ac0680fad765217302858e70fa4Paul Duffin public Enumeration<V> elements() { 1380888a09821a98ac0680fad765217302858e70fa4Paul Duffin return Collections.enumeration(values()); 1390888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1400888a09821a98ac0680fad765217302858e70fa4Paul Duffin 1410888a09821a98ac0680fad765217302858e70fa4Paul Duffin public Enumeration<K> keys() { 1420888a09821a98ac0680fad765217302858e70fa4Paul Duffin return Collections.enumeration(keySet()); 1430888a09821a98ac0680fad765217302858e70fa4Paul Duffin } 1440888a09821a98ac0680fad765217302858e70fa4Paul Duffin} 145