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1   /*
2    * Copyright (c) 2006, 2012, 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 java.io;
27  
28  /**
29   * Context during upcalls from object stream to class-defined
30   * readObject/writeObject methods.
31   * Holds object currently being deserialized and descriptor for current class.
32   *
33   * This context keeps track of the thread it was constructed on, and allows
34   * only a single call of defaultReadObject, readFields, defaultWriteObject
35   * or writeFields which must be invoked on the same thread before the class's
36   * readObject/writeObject method has returned.
37   * If not set to the current thread, the getObj method throws NotActiveException.
38   */
39  final class SerialCallbackContext {
40      private final Object obj;
41      private final ObjectStreamClass desc;
42      /**
43       * Thread this context is in use by.
44       * As this only works in one thread, we do not need to worry about thread-safety.
45       */
46      private Thread thread;
47  
48      public SerialCallbackContext(Object obj, ObjectStreamClass desc) {
49          this.obj = obj;
50          this.desc = desc;
51          this.thread = Thread.currentThread();
52      }
53  
54      public Object getObj() throws NotActiveException {
55          checkAndSetUsed();
56          return obj;
57      }
58  
59      public ObjectStreamClass getDesc() {
60          return desc;
61      }
62  
63      private void checkAndSetUsed() throws NotActiveException {
64          if (thread != Thread.currentThread()) {
65               throw new NotActiveException(
66                "not in readObject invocation or fields already read");
67          }
68          thread = null;
69      }
70  
71      public void setUsed() {
72          thread = null;
73      }
74  }