| /* |
| * Copyright (c) 2013, 2016, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| * @test KeepAliveSoftReference |
| * @summary This test case uses a java.lang.ref.SoftReference referencing a class instance to keep a class alive. |
| * @modules java.base/jdk.internal.misc |
| * @library /test/lib /runtime/testlibrary |
| * @library classes |
| * @build sun.hotspot.WhiteBox test.Empty |
| * @run main ClassFileInstaller sun.hotspot.WhiteBox |
| * sun.hotspot.WhiteBox$WhiteBoxPermission |
| * @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI KeepAliveSoftReference |
| */ |
| |
| import java.lang.ref.SoftReference; |
| import sun.hotspot.WhiteBox; |
| |
| /** |
| * Test that verifies that classes are not unloaded when specific types of references are kept to them. |
| */ |
| public class KeepAliveSoftReference { |
| private static final String className = "test.Empty"; |
| private static final WhiteBox wb = WhiteBox.getWhiteBox(); |
| |
| public static void main(String... args) throws Exception { |
| ClassLoader cl = ClassUnloadCommon.newClassLoader(); |
| Class<?> c = cl.loadClass(className); |
| Object o = c.newInstance(); |
| SoftReference<Object> sr = new SoftReference(o); |
| o = null; c = null; cl = null; |
| |
| { |
| boolean isAlive = wb.isClassAlive(className); |
| System.out.println("testSoftReference (1) alive: " + isAlive); |
| boolean cleared = (sr.get() == null); |
| boolean shouldBeAlive = !cleared; |
| ClassUnloadCommon.failIf(isAlive != shouldBeAlive, "" + isAlive + " != " + shouldBeAlive); |
| } |
| |
| ClassUnloadCommon.triggerUnloading(); |
| |
| { |
| boolean isAlive = wb.isClassAlive(className); |
| System.out.println("testSoftReference (2) alive: " + isAlive); |
| boolean cleared = (sr.get() == null); |
| boolean shouldBeAlive = !cleared; |
| ClassUnloadCommon.failIf(isAlive != shouldBeAlive, "" + isAlive + " != " + shouldBeAlive); |
| } |
| sr.clear(); |
| ClassUnloadCommon.triggerUnloading(); |
| |
| { |
| boolean isAlive = wb.isClassAlive(className); |
| System.out.println("testSoftReference (3) alive: " + isAlive); |
| boolean cleared = (sr.get() == null); |
| boolean shouldBeAlive = !cleared; |
| ClassUnloadCommon.failIf(isAlive != shouldBeAlive, "" + isAlive + " != " + shouldBeAlive); |
| } |
| } |
| } |