1/* 2 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package com.sun.jmx.mbeanserver; 27 28import java.lang.ref.WeakReference; 29import java.util.WeakHashMap; 30import javax.management.Descriptor; 31import javax.management.ImmutableDescriptor; 32import javax.management.JMX; 33 34public class DescriptorCache { 35 private DescriptorCache() { 36 } 37 38 static DescriptorCache getInstance() { 39 return instance; 40 } 41 42 public static DescriptorCache getInstance(JMX proof) { 43 if (proof != null) 44 return instance; 45 else 46 return null; 47 } 48 49 public ImmutableDescriptor get(ImmutableDescriptor descriptor) { 50 WeakReference<ImmutableDescriptor> wr = map.get(descriptor); 51 ImmutableDescriptor got = (wr == null) ? null : wr.get(); 52 if (got != null) 53 return got; 54 map.put(descriptor, new WeakReference<ImmutableDescriptor>(descriptor)); 55 return descriptor; 56 } 57 58 public ImmutableDescriptor union(Descriptor... descriptors) { 59 return get(ImmutableDescriptor.union(descriptors)); 60 } 61 62 private final static DescriptorCache instance = new DescriptorCache(); 63 private final WeakHashMap<ImmutableDescriptor, 64 WeakReference<ImmutableDescriptor>> 65 map = new WeakHashMap<ImmutableDescriptor, 66 WeakReference<ImmutableDescriptor>>(); 67} 68