1666ea1b28a76aeba74744148b15099254d918671Owen Lin/* 2666ea1b28a76aeba74744148b15099254d918671Owen Lin * Copyright (C) 2009 The Android Open Source Project 3666ea1b28a76aeba74744148b15099254d918671Owen Lin * 4666ea1b28a76aeba74744148b15099254d918671Owen Lin * Licensed under the Apache License, Version 2.0 (the "License"); 5666ea1b28a76aeba74744148b15099254d918671Owen Lin * you may not use this file except in compliance with the License. 6666ea1b28a76aeba74744148b15099254d918671Owen Lin * You may obtain a copy of the License at 7666ea1b28a76aeba74744148b15099254d918671Owen Lin * 8666ea1b28a76aeba74744148b15099254d918671Owen Lin * http://www.apache.org/licenses/LICENSE-2.0 9666ea1b28a76aeba74744148b15099254d918671Owen Lin * 10666ea1b28a76aeba74744148b15099254d918671Owen Lin * Unless required by applicable law or agreed to in writing, software 11666ea1b28a76aeba74744148b15099254d918671Owen Lin * distributed under the License is distributed on an "AS IS" BASIS, 12666ea1b28a76aeba74744148b15099254d918671Owen Lin * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13666ea1b28a76aeba74744148b15099254d918671Owen Lin * See the License for the specific language governing permissions and 14666ea1b28a76aeba74744148b15099254d918671Owen Lin * limitations under the License. 15666ea1b28a76aeba74744148b15099254d918671Owen Lin */ 16666ea1b28a76aeba74744148b15099254d918671Owen Lin 17666ea1b28a76aeba74744148b15099254d918671Owen Linpackage com.android.camera.gallery; 18666ea1b28a76aeba74744148b15099254d918671Owen Lin 19666ea1b28a76aeba74744148b15099254d918671Owen Linimport java.lang.ref.ReferenceQueue; 20666ea1b28a76aeba74744148b15099254d918671Owen Linimport java.lang.ref.WeakReference; 21666ea1b28a76aeba74744148b15099254d918671Owen Linimport java.util.HashMap; 22666ea1b28a76aeba74744148b15099254d918671Owen Linimport java.util.LinkedHashMap; 23666ea1b28a76aeba74744148b15099254d918671Owen Linimport java.util.Map; 24666ea1b28a76aeba74744148b15099254d918671Owen Lin 25666ea1b28a76aeba74744148b15099254d918671Owen Linpublic class LruCache<K, V> { 26666ea1b28a76aeba74744148b15099254d918671Owen Lin 27666ea1b28a76aeba74744148b15099254d918671Owen Lin private final HashMap<K, V> mLruMap; 28666ea1b28a76aeba74744148b15099254d918671Owen Lin private final HashMap<K, Entry<K, V>> mWeakMap = 29666ea1b28a76aeba74744148b15099254d918671Owen Lin new HashMap<K, Entry<K, V>>(); 30666ea1b28a76aeba74744148b15099254d918671Owen Lin private ReferenceQueue<V> mQueue = new ReferenceQueue<V>(); 31666ea1b28a76aeba74744148b15099254d918671Owen Lin 32666ea1b28a76aeba74744148b15099254d918671Owen Lin @SuppressWarnings("serial") 33666ea1b28a76aeba74744148b15099254d918671Owen Lin public LruCache(final int capacity) { 34666ea1b28a76aeba74744148b15099254d918671Owen Lin mLruMap = new LinkedHashMap<K, V>(16, 0.75f, true) { 35666ea1b28a76aeba74744148b15099254d918671Owen Lin @Override 36666ea1b28a76aeba74744148b15099254d918671Owen Lin protected boolean removeEldestEntry(Map.Entry<K, V> eldest) { 37666ea1b28a76aeba74744148b15099254d918671Owen Lin return size() > capacity; 38666ea1b28a76aeba74744148b15099254d918671Owen Lin } 39666ea1b28a76aeba74744148b15099254d918671Owen Lin }; 40666ea1b28a76aeba74744148b15099254d918671Owen Lin } 41666ea1b28a76aeba74744148b15099254d918671Owen Lin 42666ea1b28a76aeba74744148b15099254d918671Owen Lin private static class Entry<K, V> extends WeakReference<V> { 43666ea1b28a76aeba74744148b15099254d918671Owen Lin K mKey; 44666ea1b28a76aeba74744148b15099254d918671Owen Lin 45666ea1b28a76aeba74744148b15099254d918671Owen Lin public Entry(K key, V value, ReferenceQueue<V> queue) { 46666ea1b28a76aeba74744148b15099254d918671Owen Lin super(value, queue); 47666ea1b28a76aeba74744148b15099254d918671Owen Lin mKey = key; 48666ea1b28a76aeba74744148b15099254d918671Owen Lin } 49666ea1b28a76aeba74744148b15099254d918671Owen Lin } 50666ea1b28a76aeba74744148b15099254d918671Owen Lin 51666ea1b28a76aeba74744148b15099254d918671Owen Lin @SuppressWarnings("unchecked") 52666ea1b28a76aeba74744148b15099254d918671Owen Lin private void cleanUpWeakMap() { 53666ea1b28a76aeba74744148b15099254d918671Owen Lin Entry<K, V> entry = (Entry<K, V>) mQueue.poll(); 54666ea1b28a76aeba74744148b15099254d918671Owen Lin while (entry != null) { 55666ea1b28a76aeba74744148b15099254d918671Owen Lin mWeakMap.remove(entry.mKey); 56666ea1b28a76aeba74744148b15099254d918671Owen Lin entry = (Entry<K, V>) mQueue.poll(); 57666ea1b28a76aeba74744148b15099254d918671Owen Lin } 58666ea1b28a76aeba74744148b15099254d918671Owen Lin } 59666ea1b28a76aeba74744148b15099254d918671Owen Lin 60666ea1b28a76aeba74744148b15099254d918671Owen Lin public synchronized V put(K key, V value) { 61666ea1b28a76aeba74744148b15099254d918671Owen Lin cleanUpWeakMap(); 62666ea1b28a76aeba74744148b15099254d918671Owen Lin mLruMap.put(key, value); 63666ea1b28a76aeba74744148b15099254d918671Owen Lin Entry<K, V> entry = mWeakMap.put( 64666ea1b28a76aeba74744148b15099254d918671Owen Lin key, new Entry<K, V>(key, value, mQueue)); 65666ea1b28a76aeba74744148b15099254d918671Owen Lin return entry == null ? null : entry.get(); 66666ea1b28a76aeba74744148b15099254d918671Owen Lin } 67666ea1b28a76aeba74744148b15099254d918671Owen Lin 68666ea1b28a76aeba74744148b15099254d918671Owen Lin public synchronized V get(K key) { 69666ea1b28a76aeba74744148b15099254d918671Owen Lin cleanUpWeakMap(); 70666ea1b28a76aeba74744148b15099254d918671Owen Lin V value = mLruMap.get(key); 71666ea1b28a76aeba74744148b15099254d918671Owen Lin if (value != null) return value; 72666ea1b28a76aeba74744148b15099254d918671Owen Lin Entry<K, V> entry = mWeakMap.get(key); 73666ea1b28a76aeba74744148b15099254d918671Owen Lin return entry == null ? null : entry.get(); 74666ea1b28a76aeba74744148b15099254d918671Owen Lin } 75666ea1b28a76aeba74744148b15099254d918671Owen Lin 76666ea1b28a76aeba74744148b15099254d918671Owen Lin public synchronized void clear() { 77666ea1b28a76aeba74744148b15099254d918671Owen Lin mLruMap.clear(); 78666ea1b28a76aeba74744148b15099254d918671Owen Lin mWeakMap.clear(); 79666ea1b28a76aeba74744148b15099254d918671Owen Lin mQueue = new ReferenceQueue<V>(); 80666ea1b28a76aeba74744148b15099254d918671Owen Lin } 81666ea1b28a76aeba74744148b15099254d918671Owen Lin} 82