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.policy.sourcemodel.attach;
  27 
  28 import java.security.AccessController;
  29 import java.security.PrivilegedAction;


  30 import java.util.WeakHashMap;
  31 
  32 /**
  33  * Simple utility ensuring that the value is cached only in case it is non-internal implementation
  34  */
  35 abstract class ContextClassloaderLocal<V> {
  36 
  37     private WeakHashMap<ClassLoader, V> CACHE = new WeakHashMap<>();


  38 
  39     public V get() throws Error {
  40         ClassLoader tccl = getContextClassLoader();
  41         V instance = CACHE.get(tccl);
  42         if (instance == null) {
  43             instance = createNewInstance();
  44             CACHE.put(tccl, instance);
  45         }
  46         return instance;
  47     }
  48 
  49     public void set(V instance) {
  50         CACHE.put(getContextClassLoader(), instance);
  51     }
  52 
  53     protected abstract V initialValue() throws Exception;
  54 
  55     private V createNewInstance() {
  56         try {
  57             return initialValue();
  58         } catch (Exception e) {
  59             throw new Error(ContextClassloaderLocalMessages.FAILED_TO_CREATE_NEW_INSTANCE(getClass().getName()), e);

  60         }




  61     }
  62 
  63     private static ClassLoader getContextClassLoader() {
  64         return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
  65             @Override
  66             public ClassLoader run() {
  67                 ClassLoader cl = null;
  68                 try {
  69                     cl = Thread.currentThread().getContextClassLoader();
  70                 } catch (SecurityException ex) {
  71                 }
  72                 return cl;
  73             }
  74         });
  75     }
  76 }
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