| /* |
| * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| ******************************************************************************* |
| * Copyright (C) 2009-2010, International Business Machines Corporation and * |
| * others. All Rights Reserved. * |
| ******************************************************************************* |
| */ |
| package sun.util.locale; |
| |
| import java.lang.ref.ReferenceQueue; |
| import java.lang.ref.SoftReference; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.ConcurrentMap; |
| |
| public abstract class LocaleObjectCache<K, V> { |
| private ConcurrentMap<K, CacheEntry<K, V>> map; |
| private ReferenceQueue<V> queue = new ReferenceQueue<>(); |
| |
| public LocaleObjectCache() { |
| this(16, 0.75f, 16); |
| } |
| |
| public LocaleObjectCache(int initialCapacity, float loadFactor, int concurrencyLevel) { |
| map = new ConcurrentHashMap<>(initialCapacity, loadFactor, concurrencyLevel); |
| } |
| |
| public V get(K key) { |
| V value = null; |
| |
| cleanStaleEntries(); |
| CacheEntry<K, V> entry = map.get(key); |
| if (entry != null) { |
| value = entry.get(); |
| } |
| if (value == null) { |
| V newVal = createObject(key); |
| // make sure key is normalized *after* the object creation |
| // so that newVal is assured to be created from a valid key. |
| key = normalizeKey(key); |
| if (key == null || newVal == null) { |
| // subclass must return non-null key/value object |
| return null; |
| } |
| |
| CacheEntry<K, V> newEntry = new CacheEntry<>(key, newVal, queue); |
| |
| entry = map.putIfAbsent(key, newEntry); |
| if (entry == null) { |
| value = newVal; |
| } else { |
| value = entry.get(); |
| if (value == null) { |
| map.put(key, newEntry); |
| value = newVal; |
| } |
| } |
| } |
| return value; |
| } |
| |
| protected V put(K key, V value) { |
| CacheEntry<K, V> entry = new CacheEntry<>(key, value, queue); |
| CacheEntry<K, V> oldEntry = map.put(key, entry); |
| return (oldEntry == null) ? null : oldEntry.get(); |
| } |
| |
| @SuppressWarnings("unchecked") |
| private void cleanStaleEntries() { |
| CacheEntry<K, V> entry; |
| while ((entry = (CacheEntry<K, V>)queue.poll()) != null) { |
| map.remove(entry.getKey()); |
| } |
| } |
| |
| protected abstract V createObject(K key); |
| |
| protected K normalizeKey(K key) { |
| return key; |
| } |
| |
| private static class CacheEntry<K, V> extends SoftReference<V> { |
| private K key; |
| |
| CacheEntry(K key, V value, ReferenceQueue<V> queue) { |
| super(value, queue); |
| this.key = key; |
| } |
| |
| K getKey() { |
| return key; |
| } |
| } |
| } |