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 
  26 package com.sun.xml.internal.ws.api.streaming;
  27 
  28 import com.sun.xml.internal.ws.resources.ContextClassloaderLocalMessages;
  29 
  30 import java.security.AccessController;
  31 import java.security.PrivilegedAction;
  32 import java.util.WeakHashMap;
  33 
  34 /**
  35  * Simple utility ensuring that the value is cached only in case it is non-internal implementation
  36  */
  37 abstract 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 }