aoqi@0: /*
aoqi@0:  * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: /*
aoqi@0:  * @test KeepAliveObject
aoqi@0:  * @summary This test case uses a class instance to keep the class alive.
aoqi@0:  * @library /testlibrary /testlibrary/whitebox /runtime/testlibrary
aoqi@0:  * @library classes
aoqi@0:  * @build KeepAliveObject test.Empty
aoqi@0:  * @build ClassUnloadCommon
aoqi@0:  * @run main ClassFileInstaller sun.hotspot.WhiteBox
aoqi@0:  * @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI KeepAliveObject
aoqi@0:  */
aoqi@0: 
aoqi@0: import sun.hotspot.WhiteBox;
aoqi@0: 
aoqi@0: /**
aoqi@0:  * Test that verifies that classes are not unloaded when specific types of references are kept to them.
aoqi@0:  */
aoqi@0: public class KeepAliveObject {
aoqi@0:   private static final String className = "test.Empty";
aoqi@0:   private static final WhiteBox wb = WhiteBox.getWhiteBox();
aoqi@0:   public static Object escape = null;
aoqi@0: 
aoqi@0:   public static void main(String... args) throws Exception {
aoqi@0:     ClassLoader cl = ClassUnloadCommon.newClassLoader();
aoqi@0:     Class<?> c = cl.loadClass(className);
aoqi@0:     Object o = c.newInstance();
aoqi@0:     cl = null; c = null;
aoqi@0:     escape = o;
aoqi@0: 
aoqi@0:     {
aoqi@0:         boolean isAlive = wb.isClassAlive(className);
aoqi@0:         System.out.println("testObject (1) alive: " + isAlive);
aoqi@0: 
aoqi@0:         ClassUnloadCommon.failIf(!isAlive, "should be alive");
aoqi@0:     }
aoqi@0: 
aoqi@0:     ClassUnloadCommon.triggerUnloading();
aoqi@0: 
aoqi@0:     {
aoqi@0:         boolean isAlive = wb.isClassAlive(className);
aoqi@0:         System.out.println("testObject (2) alive: " + isAlive);
aoqi@0: 
aoqi@0:         ClassUnloadCommon.failIf(!isAlive, "should be alive");
aoqi@0:     }
aoqi@0:     o = null;
aoqi@0:     escape = null;
aoqi@0:     ClassUnloadCommon.triggerUnloading();
aoqi@0: 
aoqi@0:     {
aoqi@0:         boolean isAlive = wb.isClassAlive(className);
aoqi@0:         System.out.println("testObject (3) alive: " + isAlive);
aoqi@0:         ClassUnloadCommon.failIf(isAlive, "should be unloaded");
aoqi@0:     }
aoqi@0: 
aoqi@0:   }
aoqi@0: }