1/*
2 * Copyright (c) 2014, 2017, 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.xml.internal.ws.api.streaming;
27
28import com.sun.xml.internal.ws.resources.ContextClassloaderLocalMessages;
29
30import java.security.AccessController;
31import java.security.PrivilegedAction;
32import java.util.WeakHashMap;
33
34/**
35 * Simple utility ensuring that the value is cached only in case it is non-internal implementation
36 */
37abstract class ContextClassloaderLocal<V> {
38
39    private WeakHashMap<ClassLoader, V> CACHE = new WeakHashMap<>();
40
41    public V get() throws Error {
42        ClassLoader tccl = getContextClassLoader();
43        V instance = CACHE.get(tccl);
44        if (instance == null) {
45            instance = createNewInstance();
46            CACHE.put(tccl, instance);
47        }
48        return instance;
49    }
50
51    public void set(V instance) {
52        CACHE.put(getContextClassLoader(), instance);
53    }
54
55    protected abstract V initialValue() throws Exception;
56
57    private V createNewInstance() {
58        try {
59            return initialValue();
60        } catch (Exception e) {
61            throw new Error(ContextClassloaderLocalMessages.FAILED_TO_CREATE_NEW_INSTANCE(getClass().getName()), e);
62        }
63    }
64
65    private static ClassLoader getContextClassLoader() {
66        return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
67            @Override
68            public ClassLoader run() {
69                ClassLoader cl = null;
70                try {
71                    cl = Thread.currentThread().getContextClassLoader();
72                } catch (SecurityException ex) {
73                }
74                return cl;
75            }
76        });
77    }
78}
79