1 /*
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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).
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19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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22  */
23 
24 /* @test
25  * @summary Basic functional test of reference objects
26  * @author Mark Reinhold
27  */
28 package test.java.lang.ref;
29 
30 import java.lang.ref.*;
31 import java.util.Vector;
32 
33 import org.testng.annotations.Test;
34 
35 public class BasicTest {
36 
37     static ReferenceQueue q = new ReferenceQueue();
38     static ReferenceQueue q2 = new ReferenceQueue();
39     static Reference rw, rw2, rp, rp2;
40     static Vector keep = new Vector();
41     static boolean finalized = false;
42 
43     public static class ClearFinalizerThread {
finalize()44         protected void finalize() {
45             System.err.println("Cleared finalizer thread");
46         }
47     };
48 
finalize()49     protected void finalize() {
50         BasicTest.finalized = true;
51         System.err.println("Finalized " + this);
52     }
53 
54     public static class Sub { };
55 
56     Object sub = new Sub();
57 
fork(Runnable proc)58     static void fork(Runnable proc) throws InterruptedException {
59         Thread t = new Thread(proc);
60         t.start();
61         t.join();
62     }
63 
showReferences()64     static void showReferences() throws InterruptedException {
65         fork(new Runnable() {
66             public void run() {
67                 System.err.println("References: W " + rw.get()
68                                    + ", W2 " + rw2.get()
69                                    + ", P " + rp.get()
70                                    + ", P2 " + rp2.get());
71             }
72         });
73     }
74 
createNoise()75     static void createNoise() throws InterruptedException {
76         fork(new Runnable() {
77             public void run() {
78                 keep.addElement(new PhantomReference(new Object(), q2));
79             }
80         });
81     }
82 
83     @Test
test()84     public void test() throws Exception {
85 
86         fork(new Runnable() {
87             public void run() {
88                 BasicTest s = new BasicTest();
89                 rw = new WeakReference(s, q);
90                 rw2 = new WeakReference(s);
91                 rp = new PhantomReference(s, q);
92                 rp2 = new PhantomReference(s.sub, q);
93                 s = null;
94             }
95         });
96 
97         showReferences();
98 
99         int ndq = 0;
100         boolean prevFinalized = false;
101     outer:
102         for (int i = 1;; i++) {
103             Reference r;
104 
105             createNoise();
106             System.err.println("GC " + i);
107             Thread.sleep(10);
108             System.gc();
109             System.runFinalization();
110 
111             showReferences();
112             while ((r = q2.poll()) != null) {
113                 System.err.println("Noise " + r);
114             }
115 
116             /* Cause a dummy object to be finalized, since the finalizer thread
117                might retain a reference to the Basic instance after it's been
118                finalized (this happens with java_g) */
119             if (BasicTest.finalized && !prevFinalized) {
120                 fork(new Runnable() {
121                     public void run() {
122                         new ClearFinalizerThread();
123                     }});
124                 prevFinalized = true;
125             }
126 
127             while ((r = q.poll()) != null) {
128                 ndq++;
129                 if (r != null) {
130                     System.err.println("Dequeued " + r);
131                     if (ndq == 3) break outer;
132                 }
133             }
134 
135             if (i >= 10) break;
136 
137         }
138 
139         if (ndq != 3) {
140             throw new Exception("Expected to dequeue 3 reference objects,"
141                                 + " but only got " + ndq);
142         }
143 
144         if (! BasicTest.finalized) {
145             throw new Exception("Test object not finalized");
146         }
147 
148     }
149 
150 }
151