1/*
2 * Copyright (c) 2013, 2016, 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 * @test KeepAliveClassLoader
26 * @summary This test case uses a java.lang.ClassLoader instance to keep a class alive.
27 * @modules java.base/jdk.internal.misc
28 * @library /test/lib /runtime/testlibrary
29 * @library classes
30 * @build sun.hotspot.WhiteBox test.Empty
31 * @run main ClassFileInstaller sun.hotspot.WhiteBox
32 *                              sun.hotspot.WhiteBox$WhiteBoxPermission
33 * @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI KeepAliveClassLoader
34 */
35
36import sun.hotspot.WhiteBox;
37
38/**
39 * Test that verifies that classes are not unloaded when specific types of references are kept to them.
40 */
41public class KeepAliveClassLoader {
42  private static final String className = "test.Empty";
43  private static final WhiteBox wb = WhiteBox.getWhiteBox();
44  public static Object escape = null;
45
46
47  public static void main(String... args) throws Exception {
48    ClassLoader cl = ClassUnloadCommon.newClassLoader();
49    Class<?> c = cl.loadClass(className);
50    Object o = c.newInstance();
51    o = null; c = null;
52    escape = cl;
53
54    {
55        boolean isAlive = wb.isClassAlive(className);
56        System.out.println("testClassLoader (1) alive: " + isAlive);
57
58        ClassUnloadCommon.failIf(!isAlive, "should be alive");
59    }
60    ClassUnloadCommon.triggerUnloading();
61
62    {
63        boolean isAlive = wb.isClassAlive(className);
64        System.out.println("testClassLoader (2) alive: " + isAlive);
65
66        ClassUnloadCommon.failIf(!isAlive, "should be alive");
67    }
68    cl = null;
69    escape = null;
70    ClassUnloadCommon.triggerUnloading();
71
72    {
73        boolean isAlive = wb.isClassAlive(className);
74        System.out.println("testClassLoader (3) alive: " + isAlive);
75        ClassUnloadCommon.failIf(isAlive, "should be unloaded");
76    }
77
78  }
79}
80