1 /* 2 * Copyright (c) 1997, 1998, 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 * @summary Basic functional test of reference objects 26 * @author Mark Reinhold 27 */ 28 29 30 import java.lang.ref.*; 31 import java.util.Vector; 32 33 34 public class Basic { 35 36 static ReferenceQueue q = new ReferenceQueue(); 37 static ReferenceQueue q2 = new ReferenceQueue(); 38 static Reference rw, rw2, rp, rp2; 39 static Vector keep = new Vector(); 40 static boolean finalized = false; 41 42 public static class ClearFinalizerThread { 43 protected void finalize() { 44 System.err.println("Cleared finalizer thread"); 45 } 46 }; 47 48 protected void finalize() { 49 Basic.finalized = true; 50 System.err.println("Finalized " + this); 51 } 52 53 public static class Sub { }; 54 55 Object sub = new Sub(); 56 57 static void fork(Runnable proc) throws InterruptedException { 58 Thread t = new Thread(proc); 59 t.start(); 60 t.join(); 61 } 62 63 static void showReferences() throws InterruptedException { 64 fork(new Runnable() { 65 public void run() { 66 System.err.println("References: W " + rw.get() 67 + ", W2 " + rw2.get() 68 + ", P " + rp.get() 69 + ", P2 " + rp2.get()); 70 } 71 }); 72 } 73 74 static void createNoise() throws InterruptedException { 75 fork(new Runnable() { 76 public void run() { 77 keep.addElement(new PhantomReference(new Object(), q2)); 78 } 79 }); 80 } 81 82 83 public static void main(String[] args) throws Exception { 84 85 fork(new Runnable() { 86 public void run() { 87 Basic s = new Basic(); 88 rw = new WeakReference(s, q); 89 rw2 = new WeakReference(s); 90 rp = new PhantomReference(s, q); 91 rp2 = new PhantomReference(s.sub, q); 92 s = null; 93 } 94 }); 95 96 showReferences(); 97 98 int ndq = 0; 99 boolean prevFinalized = false; 100 outer: 101 for (int i = 1;; i++) { 102 Reference r; 103 104 createNoise(); 105 System.err.println("GC " + i); 106 Thread.sleep(10); 107 System.gc(); 108 109 showReferences(); 110 while ((r = q2.poll()) != null) { 111 System.err.println("Noise " + r); 112 } 113 114 /* Cause a dummy object to be finalized, since the finalizer thread 115 might retain a reference to the Basic instance after it's been 116 finalized (this happens with java_g) */ 117 if (Basic.finalized && !prevFinalized) { 118 fork(new Runnable() { 119 public void run() { 120 new ClearFinalizerThread(); 121 }}); 122 prevFinalized = true; 123 } 124 125 while ((r = q.poll()) != null) { 126 ndq++; 127 if (r != null) { 128 System.err.println("Dequeued " + r); 129 if (ndq == 3) break outer; 130 } 131 } 132 133 if (i >= 10) break; 134 135 } 136 137 if (ndq != 3) { 138 throw new Exception("Expected to dequeue 3 reference objects," 139 + " but only got " + ndq); 140 } 141 142 if (! Basic.finalized) { 143 throw new Exception("Test object not finalized"); 144 } 145 146 } 147 148 }