1 /* 2 * Copyright (c) 2020, 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 26 * @summary Test that hidden classes get garbage collected. 27 * @library /test/lib 28 * @modules java.compiler 29 * java.management 30 * @run main GCHiddenClass 31 */ 32 33 34 import java.lang.invoke.MethodType; 35 import java.lang.invoke.MethodHandles; 36 import java.lang.invoke.MethodHandles.Lookup; 37 import java.lang.ref.PhantomReference; 38 import java.lang.ref.Reference; 39 import java.lang.ref.ReferenceQueue; 40 41 import static java.lang.invoke.MethodHandles.Lookup.ClassOption.*; 42 import jdk.test.lib.compiler.InMemoryJavaCompiler; 43 44 // This test is based on test vmTestbase/vm/mlvm/anonloader/func/isGarbageCollected/Test.java 45 public class GCHiddenClass { 46 47 static byte klassbuf[] = InMemoryJavaCompiler.compile("TestClass", 48 "public class TestClass { " + 49 " public TestClass() { " + 50 " System.out.println(\"Hello\"); " + 51 " } } "); 52 53 // A private method is great to keep hidden Class reference local to make it 54 // GCed on the next cycle 55 private PhantomReference<Class<?>> createClass(ReferenceQueue<Class<?>> refQueue) throws Exception { 56 Lookup lookup = MethodHandles.lookup(); 57 Class<?> cl = lookup.defineHiddenClass(klassbuf, false, NESTMATE).lookupClass(); 58 return new PhantomReference<Class<?>>(cl, refQueue); 59 } 60 61 public boolean run() throws Exception { 62 ReferenceQueue<Class<?>> refQueue = new ReferenceQueue<Class<?>>(); 63 PhantomReference<Class<?>> hiddenClassRef = createClass(refQueue); 64 System.gc(); 65 Reference<? extends Class<?>> deletedObject = refQueue.remove(); 66 return hiddenClassRef.equals(deletedObject); 67 } 68 69 public static void main(String[] args) throws Throwable { 70 GCHiddenClass gcHC = new GCHiddenClass(); 71 if (!gcHC.run()) { 72 throw new RuntimeException("Test failed"); 73 } 74 } 75 }