util/WeakHashMap/GCDuringIteration.java

/*
 * Copyright (c) 2007, 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
 * @bug 6499848
 * @ignore until 6842353 is resolved
 * @summary Check that iterators work properly in the presence of
 *          concurrent finalization and removal of elements.
 */

import java.util.*;
import java.util.concurrent.CountDownLatch;

public class GCDuringIteration {
    private static void waitForFinalizersToRun() {
        for (int i = 0; i < 2; i++) {
            System.gc();
            final CountDownLatch fin = new CountDownLatch(1);
            new Object() { protected void finalize() { fin.countDown(); }};
            System.gc();
            try { fin.await(); }
            catch (InterruptedException ie) { throw new Error(ie); }
        }
    }

    // A class with the traditional pessimal hashCode implementation,
    // to ensure that all instances end up in the same bucket.
    static class Foo { public int hashCode() { return 42; }}

    <K,V> void put(Map<K,V> map, K k, V v) {
        check(! map.containsKey(k));
        equal(map.get(k), null);
        equal(map.put(k, v), null);
        equal(map.get(k), v);
        check(map.containsKey(k));
        equal(map.put(k, v), v);
        equal(map.get(k), v);
        check(map.containsKey(k));
        check(! map.isEmpty());
        equal(map.keySet().iterator().next(), k);
        equal(map.values().iterator().next(), v);
    }

    void checkIterator(final Iterator<Map.Entry<Foo, Integer>> it, int first) {
        final Random rnd = new Random();
        for (int i = first; i >= 0; --i) {
            if (rnd.nextBoolean()) check(it.hasNext());
            equal(it.next().getValue(), i);
        }
        if (rnd.nextBoolean())
            THROWS(NoSuchElementException.class,
                   new F(){void f(){it.next();}});
        if (rnd.nextBoolean())
            check(! it.hasNext());
    }

    <K,V> V firstValue(Map<K,V> map) {
        return map.values().iterator().next();
    }

    void test(String[] args) throws Throwable {
        final int n = 10;
        // Create array of strong refs
        final Foo[] foos = new Foo[2*n];
        final Map<Foo,Integer> map = new WeakHashMap<Foo,Integer>(foos.length);
        check(map.isEmpty());
        equal(map.size(), 0);

        for (int i = 0; i < foos.length; i++) {
            Foo foo = new Foo();
            foos[i] = foo;
            put(map, foo, i);
        }
        equal(map.size(), foos.length);

        {
            int first = firstValue(map);
            final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
            foos[first] = null; waitForFinalizersToRun();
            equal(map.size(), first);
            checkIterator(it, first-1);
            equal(map.size(), first);
            equal(firstValue(map), first-1);
        }

        {
            int first = firstValue(map);
            final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
            it.next();          // protects first entry
            System.out.println(map.values());
            foos[first] = null; waitForFinalizersToRun();
            equal(map.size(), first+1);
            System.out.println(map.values());
            checkIterator(it, first-1);
            waitForFinalizersToRun(); // first entry no longer protected
            equal(map.size(), first);
            equal(firstValue(map), first-1);
        }

        {
            int first = firstValue(map);
            final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
            it.next();          // protects first entry
            System.out.println(map.values());
            foos[first] = foos[first-1] = null; waitForFinalizersToRun();
            equal(map.size(), first);
            equal(firstValue(map), first);
            System.out.println(map.values());
            checkIterator(it, first-2);
            waitForFinalizersToRun(); // first entry no longer protected
            equal(map.size(), first-1);
            equal(firstValue(map), first-2);
        }

        {
            int first = firstValue(map);
            final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
            it.next();          // protects first entry
            it.hasNext();       // protects second entry
            System.out.println(map.values());
            foos[first] = foos[first-1] = null; waitForFinalizersToRun();
            equal(firstValue(map), first);
            equal(map.size(), first+1);
            System.out.println(map.values());
            checkIterator(it, first-1);
            waitForFinalizersToRun(); // first entry no longer protected
            equal(map.size(), first-1);
            equal(firstValue(map), first-2);
        }

        {
            int first = firstValue(map);
            final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
            it.next();          // protects first entry
            System.out.println(map.values());
            foos[first] = foos[first-1] = null; waitForFinalizersToRun();
            it.remove();
            equal(firstValue(map), first-2);
            equal(map.size(), first-1);
            System.out.println(map.values());
            checkIterator(it, first-2);
            waitForFinalizersToRun();
            equal(map.size(), first-1);
            equal(firstValue(map), first-2);
        }

        {
            int first = firstValue(map);
            final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
            it.next();          // protects first entry
            it.remove();
            it.hasNext();       // protects second entry
            System.out.println(map.values());
            foos[first] = foos[first-1] = null; waitForFinalizersToRun();
            equal(firstValue(map), first-1);
            equal(map.size(), first);
            System.out.println(map.values());
            checkIterator(it, first-1);
            waitForFinalizersToRun();
            equal(map.size(), first-1);
            equal(firstValue(map), first-2);
        }

        {
            int first = firstValue(map);
            final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
            it.hasNext();       // protects first entry
            Arrays.fill(foos, null);
            waitForFinalizersToRun();
            equal(map.size(), 1);
            System.out.println(map.values());
            equal(it.next().getValue(), first);
            check(! it.hasNext());
            waitForFinalizersToRun();
            equal(map.size(), 0);
            check(map.isEmpty());
        }
    }

    //--------------------- Infrastructure ---------------------------
    volatile int passed = 0, failed = 0;
    void pass() {passed++;}
    void fail() {failed++; Thread.dumpStack();}
    void fail(String msg) {System.err.println(msg); fail();}
    void unexpected(Throwable t) {failed++; t.printStackTrace();}
    void check(boolean cond) {if (cond) pass(); else fail();}
    void equal(Object x, Object y) {
        if (x == null ? y == null : x.equals(y)) pass();
        else fail(x + " not equal to " + y);}
    public static void main(String[] args) throws Throwable {
        new GCDuringIteration().instanceMain(args);}
    void instanceMain(String[] args) throws Throwable {
        try {test(args);} catch (Throwable t) {unexpected(t);}
        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
        if (failed > 0) throw new AssertionError("Some tests failed");}
    abstract class F {abstract void f() throws Throwable;}
    void THROWS(Class<? extends Throwable> k, F... fs) {
        for (F f : fs)
            try {f.f(); fail("Expected " + k.getName() + " not thrown");}
            catch (Throwable t) {
                if (k.isAssignableFrom(t.getClass())) pass();
                else unexpected(t);}}
}
Revision:	1.3
Committed:	Wed Nov 17 17:52:29 2010 UTC (13 years, 6 months ago) by jsr166
Branch:	MAIN
Changes since 1.2:	+22 -26 lines
Log Message:	waitForFinalizersToRun
#	User	Rev	Content
1	jsr166	1.1	/*
2	jsr166	1.2	* Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
3	jsr166	1.1	* 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	jsr166	1.2	* 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	jsr166	1.1	*/
23
24			/*
25			* @test
26			* @bug 6499848
27			* @ignore until 6842353 is resolved
28			* @summary Check that iterators work properly in the presence of
29			* concurrent finalization and removal of elements.
30			*/
31
32			import java.util.*;
33			import java.util.concurrent.CountDownLatch;
34
35			public class GCDuringIteration {
36	jsr166	1.3	private static void waitForFinalizersToRun() {
37			for (int i = 0; i < 2; i++) {
38			System.gc();
39			final CountDownLatch fin = new CountDownLatch(1);
40			new Object() { protected void finalize() { fin.countDown(); }};
41			System.gc();
42			try { fin.await(); }
43			catch (InterruptedException ie) { throw new Error(ie); }
44			}
45	jsr166	1.1	}
46
47			// A class with the traditional pessimal hashCode implementation,
48			// to ensure that all instances end up in the same bucket.
49			static class Foo { public int hashCode() { return 42; }}
50
51			<K,V> void put(Map<K,V> map, K k, V v) {
52			check(! map.containsKey(k));
53			equal(map.get(k), null);
54			equal(map.put(k, v), null);
55			equal(map.get(k), v);
56			check(map.containsKey(k));
57			equal(map.put(k, v), v);
58			equal(map.get(k), v);
59			check(map.containsKey(k));
60			check(! map.isEmpty());
61			equal(map.keySet().iterator().next(), k);
62			equal(map.values().iterator().next(), v);
63			}
64
65			void checkIterator(final Iterator<Map.Entry<Foo, Integer>> it, int first) {
66			final Random rnd = new Random();
67			for (int i = first; i >= 0; --i) {
68			if (rnd.nextBoolean()) check(it.hasNext());
69			equal(it.next().getValue(), i);
70			}
71			if (rnd.nextBoolean())
72			THROWS(NoSuchElementException.class,
73			new F(){void f(){it.next();}});
74			if (rnd.nextBoolean())
75			check(! it.hasNext());
76			}
77
78			<K,V> V firstValue(Map<K,V> map) {
79			return map.values().iterator().next();
80			}
81
82			void test(String[] args) throws Throwable {
83			final int n = 10;
84			// Create array of strong refs
85			final Foo[] foos = new Foo[2*n];
86			final Map<Foo,Integer> map = new WeakHashMap<Foo,Integer>(foos.length);
87			check(map.isEmpty());
88			equal(map.size(), 0);
89
90			for (int i = 0; i < foos.length; i++) {
91			Foo foo = new Foo();
92			foos[i] = foo;
93			put(map, foo, i);
94			}
95			equal(map.size(), foos.length);
96
97			{
98			int first = firstValue(map);
99			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
100	jsr166	1.3	foos[first] = null; waitForFinalizersToRun();
101	jsr166	1.1	equal(map.size(), first);
102			checkIterator(it, first-1);
103			equal(map.size(), first);
104			equal(firstValue(map), first-1);
105			}
106
107			{
108			int first = firstValue(map);
109			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
110			it.next(); // protects first entry
111			System.out.println(map.values());
112	jsr166	1.3	foos[first] = null; waitForFinalizersToRun();
113	jsr166	1.1	equal(map.size(), first+1);
114			System.out.println(map.values());
115			checkIterator(it, first-1);
116	jsr166	1.3	waitForFinalizersToRun(); // first entry no longer protected
117	jsr166	1.1	equal(map.size(), first);
118			equal(firstValue(map), first-1);
119			}
120
121			{
122			int first = firstValue(map);
123			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
124			it.next(); // protects first entry
125			System.out.println(map.values());
126	jsr166	1.3	foos[first] = foos[first-1] = null; waitForFinalizersToRun();
127	jsr166	1.1	equal(map.size(), first);
128			equal(firstValue(map), first);
129			System.out.println(map.values());
130			checkIterator(it, first-2);
131	jsr166	1.3	waitForFinalizersToRun(); // first entry no longer protected
132	jsr166	1.1	equal(map.size(), first-1);
133			equal(firstValue(map), first-2);
134			}
135
136			{
137			int first = firstValue(map);
138			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
139			it.next(); // protects first entry
140			it.hasNext(); // protects second entry
141			System.out.println(map.values());
142	jsr166	1.3	foos[first] = foos[first-1] = null; waitForFinalizersToRun();
143	jsr166	1.1	equal(firstValue(map), first);
144			equal(map.size(), first+1);
145			System.out.println(map.values());
146			checkIterator(it, first-1);
147	jsr166	1.3	waitForFinalizersToRun(); // first entry no longer protected
148	jsr166	1.1	equal(map.size(), first-1);
149			equal(firstValue(map), first-2);
150			}
151
152			{
153			int first = firstValue(map);
154			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
155			it.next(); // protects first entry
156			System.out.println(map.values());
157	jsr166	1.3	foos[first] = foos[first-1] = null; waitForFinalizersToRun();
158	jsr166	1.1	it.remove();
159			equal(firstValue(map), first-2);
160			equal(map.size(), first-1);
161			System.out.println(map.values());
162			checkIterator(it, first-2);
163	jsr166	1.3	waitForFinalizersToRun();
164	jsr166	1.1	equal(map.size(), first-1);
165			equal(firstValue(map), first-2);
166			}
167
168			{
169			int first = firstValue(map);
170			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
171			it.next(); // protects first entry
172			it.remove();
173			it.hasNext(); // protects second entry
174			System.out.println(map.values());
175	jsr166	1.3	foos[first] = foos[first-1] = null; waitForFinalizersToRun();
176	jsr166	1.1	equal(firstValue(map), first-1);
177			equal(map.size(), first);
178			System.out.println(map.values());
179			checkIterator(it, first-1);
180	jsr166	1.3	waitForFinalizersToRun();
181	jsr166	1.1	equal(map.size(), first-1);
182			equal(firstValue(map), first-2);
183			}
184
185			{
186			int first = firstValue(map);
187			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
188			it.hasNext(); // protects first entry
189			Arrays.fill(foos, null);
190	jsr166	1.3	waitForFinalizersToRun();
191	jsr166	1.1	equal(map.size(), 1);
192			System.out.println(map.values());
193			equal(it.next().getValue(), first);
194			check(! it.hasNext());
195	jsr166	1.3	waitForFinalizersToRun();
196	jsr166	1.1	equal(map.size(), 0);
197			check(map.isEmpty());
198			}
199			}
200
201			//--------------------- Infrastructure ---------------------------
202			volatile int passed = 0, failed = 0;
203			void pass() {passed++;}
204			void fail() {failed++; Thread.dumpStack();}
205			void fail(String msg) {System.err.println(msg); fail();}
206			void unexpected(Throwable t) {failed++; t.printStackTrace();}
207			void check(boolean cond) {if (cond) pass(); else fail();}
208			void equal(Object x, Object y) {
209			if (x == null ? y == null : x.equals(y)) pass();
210			else fail(x + " not equal to " + y);}
211			public static void main(String[] args) throws Throwable {
212			new GCDuringIteration().instanceMain(args);}
213			void instanceMain(String[] args) throws Throwable {
214			try {test(args);} catch (Throwable t) {unexpected(t);}
215			System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
216			if (failed > 0) throw new AssertionError("Some tests failed");}
217			abstract class F {abstract void f() throws Throwable;}
218			void THROWS(Class<? extends Throwable> k, F... fs) {
219			for (F f : fs)
220			try {f.f(); fail("Expected " + k.getName() + " not thrown");}
221			catch (Throwable t) {
222			if (k.isAssignableFrom(t.getClass())) pass();
223			else unexpected(t);}}
224			}