util/WeakHashMap/GCDuringIteration.java

/*
 * Copyright (c) 2007, 2011, 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.
 * @key randomness
 */

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

public class GCDuringIteration {
    private static void waitForFinalizersToRun() {
        for (int i = 0; i < 2; i++)
            tryWaitForFinalizersToRun();
    }

    private static void tryWaitForFinalizersToRun() {
        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;
            for (int i = 0; i < 10 && map.size() != first; i++)
                tryWaitForFinalizersToRun();
            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;
            tryWaitForFinalizersToRun()
            equal(map.size(), first+1);
            System.out.println(map.values());
            checkIterator(it, first-1);
            // first entry no longer protected
            for (int i = 0; i < 10 && map.size() != first; i++)
                tryWaitForFinalizersToRun();
            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;
            tryWaitForFinalizersToRun();
            equal(map.size(), first);
            equal(firstValue(map), first);
            System.out.println(map.values());
            checkIterator(it, first-2);
            // first entry no longer protected
            for (int i = 0; i < 10 && map.size() != first-1; i++)
                tryWaitForFinalizersToRun();
            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;
            tryWaitForFinalizersToRun();
            equal(firstValue(map), first);
            equal(map.size(), first+1);
            System.out.println(map.values());
            checkIterator(it, first-1);
            // first entry no longer protected
            for (int i = 0; i < 10 && map.size() != first-1; i++)
                tryWaitForFinalizersToRun();
            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;
            tryWaitForFinalizersToRun();
            it.remove();
            equal(firstValue(map), first-2);
            equal(map.size(), first-1);
            System.out.println(map.values());
            checkIterator(it, first-2);
            // first entry no longer protected
            for (int i = 0; i < 10 && map.size() != first-1; i++)
                tryWaitForFinalizersToRun();
            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;
            tryWaitForFinalizersToRun();
            equal(firstValue(map), first-1);
            equal(map.size(), first);
            System.out.println(map.values());
            checkIterator(it, first-1);
            for (int i = 0; i < 10 && map.size() != first-1; i++)
                tryWaitForFinalizersToRun();
            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);
            tryWaitForFinalizersToRun();
            equal(map.size(), 1);
            System.out.println(map.values());
            equal(it.next().getValue(), first);
            check(! it.hasNext());
            for (int i = 0; i < 10 && map.size() != 0; i++)
                tryWaitForFinalizersToRun();
            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:	1.5
Committed:	Sun May 24 04:40:44 2015 UTC (9 years ago) by jsr166
Branch:	MAIN
Changes since 1.4:	+2 -1 lines
Log Message:	sync with upstream
#	User	Rev	Content
1	jsr166	1.1	/*
2	jsr166	1.5	* Copyright (c) 2007, 2011, 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	jsr166	1.5	* @key randomness
31	jsr166	1.1	*/
32
33			import java.util.*;
34			import java.util.concurrent.CountDownLatch;
35
36			public class GCDuringIteration {
37	jsr166	1.3	private static void waitForFinalizersToRun() {
38	jsr166	1.4	for (int i = 0; i < 2; i++)
39			tryWaitForFinalizersToRun();
40			}
41
42			private static void tryWaitForFinalizersToRun() {
43			System.gc();
44			final CountDownLatch fin = new CountDownLatch(1);
45			new Object() { protected void finalize() { fin.countDown(); }};
46			System.gc();
47			try { fin.await(); }
48			catch (InterruptedException ie) { throw new Error(ie); }
49	jsr166	1.1	}
50
51			// A class with the traditional pessimal hashCode implementation,
52			// to ensure that all instances end up in the same bucket.
53			static class Foo { public int hashCode() { return 42; }}
54
55			<K,V> void put(Map<K,V> map, K k, V v) {
56			check(! map.containsKey(k));
57			equal(map.get(k), null);
58			equal(map.put(k, v), null);
59			equal(map.get(k), v);
60			check(map.containsKey(k));
61			equal(map.put(k, v), v);
62			equal(map.get(k), v);
63			check(map.containsKey(k));
64			check(! map.isEmpty());
65			equal(map.keySet().iterator().next(), k);
66			equal(map.values().iterator().next(), v);
67			}
68
69			void checkIterator(final Iterator<Map.Entry<Foo, Integer>> it, int first) {
70			final Random rnd = new Random();
71			for (int i = first; i >= 0; --i) {
72			if (rnd.nextBoolean()) check(it.hasNext());
73			equal(it.next().getValue(), i);
74			}
75			if (rnd.nextBoolean())
76			THROWS(NoSuchElementException.class,
77			new F(){void f(){it.next();}});
78			if (rnd.nextBoolean())
79			check(! it.hasNext());
80			}
81
82			<K,V> V firstValue(Map<K,V> map) {
83			return map.values().iterator().next();
84			}
85
86			void test(String[] args) throws Throwable {
87			final int n = 10;
88			// Create array of strong refs
89			final Foo[] foos = new Foo[2*n];
90			final Map<Foo,Integer> map = new WeakHashMap<Foo,Integer>(foos.length);
91			check(map.isEmpty());
92			equal(map.size(), 0);
93
94			for (int i = 0; i < foos.length; i++) {
95			Foo foo = new Foo();
96			foos[i] = foo;
97			put(map, foo, i);
98			}
99			equal(map.size(), foos.length);
100
101			{
102			int first = firstValue(map);
103			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
104	jsr166	1.4	foos[first] = null;
105			for (int i = 0; i < 10 && map.size() != first; i++)
106			tryWaitForFinalizersToRun();
107	jsr166	1.1	equal(map.size(), first);
108			checkIterator(it, first-1);
109			equal(map.size(), first);
110			equal(firstValue(map), first-1);
111			}
112
113			{
114			int first = firstValue(map);
115			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
116			it.next(); // protects first entry
117			System.out.println(map.values());
118	jsr166	1.4	foos[first] = null;
119			tryWaitForFinalizersToRun()
120	jsr166	1.1	equal(map.size(), first+1);
121			System.out.println(map.values());
122			checkIterator(it, first-1);
123	jsr166	1.4	// first entry no longer protected
124			for (int i = 0; i < 10 && map.size() != first; i++)
125			tryWaitForFinalizersToRun();
126	jsr166	1.1	equal(map.size(), first);
127			equal(firstValue(map), first-1);
128			}
129
130			{
131			int first = firstValue(map);
132			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
133			it.next(); // protects first entry
134			System.out.println(map.values());
135	jsr166	1.4	foos[first] = foos[first-1] = null;
136			tryWaitForFinalizersToRun();
137	jsr166	1.1	equal(map.size(), first);
138			equal(firstValue(map), first);
139			System.out.println(map.values());
140			checkIterator(it, first-2);
141	jsr166	1.4	// first entry no longer protected
142			for (int i = 0; i < 10 && map.size() != first-1; i++)
143			tryWaitForFinalizersToRun();
144	jsr166	1.1	equal(map.size(), first-1);
145			equal(firstValue(map), first-2);
146			}
147
148			{
149			int first = firstValue(map);
150			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
151			it.next(); // protects first entry
152			it.hasNext(); // protects second entry
153			System.out.println(map.values());
154	jsr166	1.4	foos[first] = foos[first-1] = null;
155			tryWaitForFinalizersToRun();
156	jsr166	1.1	equal(firstValue(map), first);
157			equal(map.size(), first+1);
158			System.out.println(map.values());
159			checkIterator(it, first-1);
160	jsr166	1.4	// first entry no longer protected
161			for (int i = 0; i < 10 && map.size() != first-1; i++)
162			tryWaitForFinalizersToRun();
163	jsr166	1.1	equal(map.size(), first-1);
164			equal(firstValue(map), first-2);
165			}
166
167			{
168			int first = firstValue(map);
169			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
170			it.next(); // protects first entry
171			System.out.println(map.values());
172	jsr166	1.4	foos[first] = foos[first-1] = null;
173			tryWaitForFinalizersToRun();
174	jsr166	1.1	it.remove();
175			equal(firstValue(map), first-2);
176			equal(map.size(), first-1);
177			System.out.println(map.values());
178			checkIterator(it, first-2);
179	jsr166	1.4	// first entry no longer protected
180			for (int i = 0; i < 10 && map.size() != first-1; i++)
181			tryWaitForFinalizersToRun();
182	jsr166	1.1	equal(map.size(), first-1);
183			equal(firstValue(map), first-2);
184			}
185
186			{
187			int first = firstValue(map);
188			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
189			it.next(); // protects first entry
190			it.remove();
191			it.hasNext(); // protects second entry
192			System.out.println(map.values());
193	jsr166	1.4	foos[first] = foos[first-1] = null;
194			tryWaitForFinalizersToRun();
195	jsr166	1.1	equal(firstValue(map), first-1);
196			equal(map.size(), first);
197			System.out.println(map.values());
198			checkIterator(it, first-1);
199	jsr166	1.4	for (int i = 0; i < 10 && map.size() != first-1; i++)
200			tryWaitForFinalizersToRun();
201	jsr166	1.1	equal(map.size(), first-1);
202			equal(firstValue(map), first-2);
203			}
204
205			{
206			int first = firstValue(map);
207			final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
208			it.hasNext(); // protects first entry
209			Arrays.fill(foos, null);
210	jsr166	1.4	tryWaitForFinalizersToRun();
211	jsr166	1.1	equal(map.size(), 1);
212			System.out.println(map.values());
213			equal(it.next().getValue(), first);
214			check(! it.hasNext());
215	jsr166	1.4	for (int i = 0; i < 10 && map.size() != 0; i++)
216			tryWaitForFinalizersToRun();
217	jsr166	1.1	equal(map.size(), 0);
218			check(map.isEmpty());
219			}
220			}
221
222			//--------------------- Infrastructure ---------------------------
223			volatile int passed = 0, failed = 0;
224			void pass() {passed++;}
225			void fail() {failed++; Thread.dumpStack();}
226			void fail(String msg) {System.err.println(msg); fail();}
227			void unexpected(Throwable t) {failed++; t.printStackTrace();}
228			void check(boolean cond) {if (cond) pass(); else fail();}
229			void equal(Object x, Object y) {
230			if (x == null ? y == null : x.equals(y)) pass();
231			else fail(x + " not equal to " + y);}
232			public static void main(String[] args) throws Throwable {
233			new GCDuringIteration().instanceMain(args);}
234			void instanceMain(String[] args) throws Throwable {
235			try {test(args);} catch (Throwable t) {unexpected(t);}
236			System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
237			if (failed > 0) throw new AssertionError("Some tests failed");}
238			abstract class F {abstract void f() throws Throwable;}
239			void THROWS(Class<? extends Throwable> k, F... fs) {
240			for (F f : fs)
241			try {f.f(); fail("Expected " + k.getName() + " not thrown");}
242			catch (Throwable t) {
243			if (k.isAssignableFrom(t.getClass())) pass();
244			else unexpected(t);}}
245			}