1 /* 2 * Copyright (c) 2017, 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 /* @test 25 * @bug 8166188 26 * @requires vm.opt.ExplicitGCInvokesConcurrent != true 27 * @summary Test return of JNI weak global refs from native calls. 28 * @modules java.base 29 * @run main/othervm/native -Xint ReturnJNIWeak 30 * @run main/othervm/native -Xcomp ReturnJNIWeak 31 */ 32 33 public final class ReturnJNIWeak { 34 35 static { 36 System.loadLibrary("ReturnJNIWeak"); 37 } 38 39 private static final class TestObject { 40 public final int value; 41 42 public TestObject(int value) { 43 this.value = value; 44 } 45 } 46 47 private static volatile TestObject testObject = null; 48 49 private static native void registerObject(Object o); 50 private static native void unregisterObject(); 51 private static native Object getObject(); 52 53 // Create the test object and record it both strongly and weakly. 54 private static void remember(int value) { 55 TestObject o = new TestObject(value); 56 registerObject(o); 57 testObject = o; 58 } 59 60 // Remove both strong and weak references to the current test object. 61 private static void forget() { 62 unregisterObject(); 63 testObject = null; 64 } 65 66 // Verify the weakly recorded object 67 private static void checkValue(int value) throws Exception { 68 Object o = getObject(); 69 if (o == null) { 70 throw new RuntimeException("Weak reference unexpectedly null"); 71 } 72 TestObject t = (TestObject)o; 73 if (t.value != value) { 74 throw new RuntimeException("Incorrect value"); 75 } 76 } 77 78 // Verify we can create a weak reference and get it back. 79 private static void testSanity() throws Exception { 80 System.out.println("running testSanity"); 81 int value = 5; 82 try { 83 remember(value); 84 checkValue(value); 85 } finally { 86 forget(); 87 } 88 } 89 90 // Verify weak ref value survives across collection if strong ref exists. 91 private static void testSurvival() throws Exception { 92 System.out.println("running testSurvival"); 93 int value = 10; 94 try { 95 remember(value); 96 checkValue(value); 97 System.gc(); 98 // Verify weak ref still has expected value. 99 checkValue(value); 100 } finally { 101 forget(); 102 } 103 } 104 105 // Verify weak ref cleared if no strong ref exists. 106 private static void testClear() throws Exception { 107 System.out.println("running testClear"); 108 int value = 15; 109 try { 110 remember(value); 111 checkValue(value); 112 // Verify still good. 113 checkValue(value); 114 // Drop reference. 115 testObject = null; 116 System.gc(); 117 // Verify weak ref cleared as expected. 118 Object recorded = getObject(); 119 if (recorded != null) { 120 throw new RuntimeException("expected clear"); 121 } 122 } finally { 123 forget(); 124 } 125 } 126 127 public static void main(String[] args) throws Exception { 128 testSanity(); 129 testSurvival(); 130 testClear(); 131 } 132 }