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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     public void check() throws NotActiveException {
     64         if (thread != null && thread != Thread.currentThread()) {
     65             throw new NotActiveException(
     66                 "expected thread: " + thread + ", but got: " + Thread.currentThread());
     67         }
     68     }
     69 
     70     private void checkAndSetUsed() throws NotActiveException {
     71         if (thread != Thread.currentThread()) {
     72              throw new NotActiveException(
     73               "not in readObject invocation or fields already read");
     74         }
     75         thread = null;
     76     }
     77 
     78     public void setUsed() {
     79         thread = null;
     80     }
     81 }
     82