| /* |
| * Copyright (C) 2009 The Android Open Source Project |
| * |
| * Licensed 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.android.gallery3d.common; |
| |
| import java.lang.ref.ReferenceQueue; |
| import java.lang.ref.WeakReference; |
| import java.util.HashMap; |
| import java.util.LinkedHashMap; |
| import java.util.Map; |
| |
| /** |
| * An LRU cache which stores recently inserted entries and all entries ever |
| * inserted which still has a strong reference elsewhere. |
| */ |
| public class LruCache<K, V> { |
| |
| private final HashMap<K, V> mLruMap; |
| private final HashMap<K, Entry<K, V>> mWeakMap = |
| new HashMap<K, Entry<K, V>>(); |
| private ReferenceQueue<V> mQueue = new ReferenceQueue<V>(); |
| |
| @SuppressWarnings("serial") |
| public LruCache(final int capacity) { |
| mLruMap = new LinkedHashMap<K, V>(16, 0.75f, true) { |
| @Override |
| protected boolean removeEldestEntry(Map.Entry<K, V> eldest) { |
| return size() > capacity; |
| } |
| }; |
| } |
| |
| private static class Entry<K, V> extends WeakReference<V> { |
| K mKey; |
| |
| public Entry(K key, V value, ReferenceQueue<V> queue) { |
| super(value, queue); |
| mKey = key; |
| } |
| } |
| |
| @SuppressWarnings("unchecked") |
| private void cleanUpWeakMap() { |
| Entry<K, V> entry = (Entry<K, V>) mQueue.poll(); |
| while (entry != null) { |
| mWeakMap.remove(entry.mKey); |
| entry = (Entry<K, V>) mQueue.poll(); |
| } |
| } |
| |
| public synchronized boolean containsKey(K key) { |
| cleanUpWeakMap(); |
| return mWeakMap.containsKey(key); |
| } |
| |
| public synchronized V put(K key, V value) { |
| cleanUpWeakMap(); |
| mLruMap.put(key, value); |
| Entry<K, V> entry = mWeakMap.put( |
| key, new Entry<K, V>(key, value, mQueue)); |
| return entry == null ? null : entry.get(); |
| } |
| |
| public synchronized V get(K key) { |
| cleanUpWeakMap(); |
| V value = mLruMap.get(key); |
| if (value != null) return value; |
| Entry<K, V> entry = mWeakMap.get(key); |
| return entry == null ? null : entry.get(); |
| } |
| |
| public synchronized void clear() { |
| mLruMap.clear(); |
| mWeakMap.clear(); |
| mQueue = new ReferenceQueue<V>(); |
| } |
| } |