1 /*

     2  * Copyright (c) 2019, 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.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 import java.io.File;

    26 import java.net.URL;

    27 import java.net.URLClassLoader;

    28 import sun.hotspot.WhiteBox;

    29 

    30 public class HelloUnload {

    31     private static String className = "CustomLoadee";

    32 

    33     public static void main(String args[]) throws Exception {

    34         if (args.length != 3) {

    35             throw new RuntimeException("Unexpected number of arguments: expected 3, actual " + args.length);

    36         }

    37 

    38         String path = args[0];

    39         URL url = new File(path).toURI().toURL();

    40         URL[] urls = new URL[] {url};

    41         System.out.println(path);

    42         System.out.println(url);

    43 

    44         // unload the custom class loader

    45         boolean doUnload = false;

    46         if (args[1].equals("true")) {

    47             doUnload = true;

    48         } else if (args[1].equals("false")) {

    49             doUnload = false;

    50         } else {

    51             throw new RuntimeException("args[1] can only be either \"true\" or \"false\", actual " + args[1]);

    52         }

    53 

    54         // should the CustomLoadee class be in the shared archive

    55         boolean inArchive = false;

    56         if (args[2].equals("true")) {

    57             inArchive = true;

    58         } else if (args[2].equals("false")) {

    59             inArchive = false;

    60         } else {

    61             throw new RuntimeException("args[2] can only be either \"true\" or \"false\", actual " + args[1]);

    62         }

    63 

    64         URLClassLoader urlClassLoader =

    65             new URLClassLoader("HelloClassLoader", urls, null);

    66         Class c = Class.forName(className, true, urlClassLoader);

    67         System.out.println(c);

    68         System.out.println(c.getClassLoader());

    69         Object o = c.newInstance();

    70 

    71         // [1] Check that CustomLoadee is defined by the correct loader

    72         if (c.getClassLoader() != urlClassLoader) {

    73             throw new RuntimeException("c.getClassLoader() == " + c.getClassLoader() +

    74                                        ", expected == " + urlClassLoader);

    75         }

    76 

    77         // [2] Check that CustomLoadee is loaded from shared archive.

    78         WhiteBox wb = WhiteBox.getWhiteBox();

    79         if(wb.isSharedClass(HelloUnload.class)) {

    80             if (inArchive && !wb.isSharedClass(c)) {

    81                 throw new RuntimeException("wb.isSharedClass(c) should be true");

    82             }

    83         }

    84 

    85         ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should be live here");

    86 

    87         if (doUnload) {

    88             String loaderName = urlClassLoader.getName();

    89             int loadedRefcount = wb.getSymbolRefcount(loaderName);

    90             System.out.println("Refcount of symbol " + loaderName + " is " + loadedRefcount);

    91 

    92             urlClassLoader = null; c = null; o = null;

    93             ClassUnloadCommon.triggerUnloading();

    94             System.out.println("Is CustomLoadee alive? " + wb.isClassAlive(className));

    95             ClassUnloadCommon.failIf(wb.isClassAlive(className), "should have been unloaded");

    96 

    97             int unloadedRefcount = wb.getSymbolRefcount(loaderName);

    98             System.out.println("Refcount of symbol " + loaderName + " is " + unloadedRefcount);

    99 

   100             // refcount of a permanent symbol will not be decremented

   101             if (loadedRefcount != 65535) {

   102                 ClassUnloadCommon.failIf(unloadedRefcount != (loadedRefcount - 1), "Refcount must be decremented");

   103             }

   104         }

   105     }

   106 }