Request for review : 7121314 : Behavior mismatch between AbstractCollection.toArray(T[] ) and its spec
David Holmes
david.holmes at oracle.com
Sun Apr 1 03:25:59 UTC 2012
Simplified testcase below.
Let's finalise this please.
Thanks,
David
On 1/04/2012 1:08 PM, Sean Chou wrote:
> Hi Ulf,
>
> This is a regression testcase, there is no performance issue or
> future refactoring.
> Please wait for David's comments.
>
> On Sun, Apr 1, 2012 at 7:22 AM, Ulf Zibis <Ulf.Zibis at gmx.de
> <mailto:Ulf.Zibis at gmx.de>> wrote:
>
> Hi Sean,
>
> thanks for your effort.
>
> Am 31.03.2012 11:43, schrieb Sean Chou:
>
> Hi David and Ulf,
>
> The new webrev is at:
> http://cr.openjdk.java.net/~__zhouyx/7121314/webrev.03/
> <http://cr.openjdk.java.net/~zhouyx/7121314/webrev.03/>
> <http://cr.openjdk.java.net/%__7Ezhouyx/7121314/webrev.03/
> <http://cr.openjdk.java.net/%7Ezhouyx/7121314/webrev.03/>> .
>
>
> About the fix, I remained the previous one.
> About the testcase, I merged the 3 files into one.
> During merging, there are 2 modifications:
> 1. I added static modifier to the 3 classes, which are enclosed
> by class ToArrayTest;
>
> You do not need the indirection via main()...run()...test() if you
> have all in 1 file. This was only necessary to feature a general
> usability of InfraStructure. You can go back to David's 1 + 1 nested
> class approach replacing TConcurrentHashMapX by TestCollection and
> maybe rename realMain() to test().
> Additionally, loading 4 classes for 1 test would have some
> performance impact on the test run, which could be avoided.
>
>
> 2. I removed field TestCollection.fixedSize, which is never read
> after Ulf fixed the bug in testcase.
>
> This field would serve to "reset" the TestCollection to fixed
> default size without the need of new instantiation for later
> refactoring or testcase addition.
>
> As just discussed before, the doc for setSizeSequence() could be
> little more specific:
> 71 /*
> 72 * Sets the values that size() will return on each use.
> The first
> 73 * call to size will return sizes[0], then sizes[1]
> etc. This
> 74 * allows us to emulate a concurrent change to the
> contents of
> 75 * the collection without having to perform concurrent
> changes.
> 76 * If sizes[n+1] contains a larger value than on last
> n-th invocation,
> 77 * the collection will appear to have shrunk when
> iterated; if a
> 78 * smaller value then the collection will appear to
> have grown.
> 79 * When the last element of sizes is reached, the
> collection will
> 80 * appear size-fixed.
> 81 */
>
>
> The link to the bug:
> http://bugs.sun.com/__bugdatabase/view_bug.do?bug___id=7121314
> <http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7121314>
> The link to the start of the thread:
> http://mail.openjdk.java.net/__pipermail/core-libs-dev/2012-__March/009512.html
> <http://mail.openjdk.java.net/pipermail/core-libs-dev/2012-March/009512.html>
>
> Good idea, to repeat these links.
>
> -Ulf
>
>
>
>
> --
> Best Regards,
> Sean Chou
>
/*
* Copyright (c) 2012, 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 7121314
* @summary AbstractCollection.toArray(T[]) doesn't return the given array
* in concurrent modification.
* @author Ulf Zibis, David Holmes
*/
import java.util.AbstractCollection;
import java.util.Arrays;
import java.util.Iterator;
public class ToArrayTest {
static class TestCollection<E> extends AbstractCollection<E> {
private final E[] elements;
private int[] sizes;
private int nextSize;
public TestCollection(E[] elements) {
this.elements = elements;
setSizeSequence(new int[]{elements.length});
}
/*
* Sets the values that size() will return on each use. The next
* call to size will return sizes[0], then sizes[1] etc. This
* allows us to emulate a concurrent change to the contents of
* the collection without having to perform concurrent changes.
* If sizes[n+1] contains a larger value, the collection will
appear to
* have shrunk when iterated; if a smaller value then the
* collection will appear to have grown when iterated
*/
void setSizeSequence(int... sizes) {
this.sizes = sizes;
nextSize = 0;
}
/* can change collection's size after each invocation */
@Override
public int size() {
return sizes[nextSize == sizes.length-1 ? nextSize :
nextSize++];
}
@Override
public Iterator<E> iterator() {
return new Iterator<E>() {
int pos = 0;
public boolean hasNext() {
return pos < sizes[nextSize];
}
public E next() {
return elements[pos++];
}
public void remove() {
throw new UnsupportedOperationException("Not
supported yet.");
}
};
}
}
static final Object[] OBJECTS = { new Object(), new Object(), new
Object() };
static final TestCollection<?> CANDIDATE = new
TestCollection<Object>(OBJECTS);
static final int CAP = OBJECTS.length; // capacity of the CANDIDATE
static final int LAST = CAP - 1; // last possible array index
Object[] a;
Object[] res;
int last() { return a.length - 1; }
protected void test() throws Throwable {
// Check array type conversion
res = new TestCollection<>(new Object[]{"1", "2"}).toArray(new
String[0]);
check(res instanceof String[]);
check(res.length == 2);
check(res[1] == "2");
// Check incompatible type of target array
try {
res = CANDIDATE.toArray(new String[CAP]);
check(false);
} catch (Throwable t) {
check(t instanceof ArrayStoreException);
}
// Check more elements than a.length
a = new Object[CAP-1]; // appears too small
res = CANDIDATE.toArray(a);
check(res != a);
check(res[LAST] != null);
// Check equal elements as a.length
a = new Object[CAP]; // appears to match
res = CANDIDATE.toArray(a);
check(res == a);
check(res[last()] != null);
// Check equal elements as a.length
a = new Object[CAP+1]; // appears too big
res = CANDIDATE.toArray(a);
check(res == a);
check(res[last()] == null);
// Check less elements than expected, but more than a.length
a = new Object[CAP-2]; // appears too small
CANDIDATE.setSizeSequence(CAP, CAP-1);
res = CANDIDATE.toArray(a);
check(res != a);
check(res.length == CAP-1);
check(res[LAST-1] != null);
// Check less elements than expected, but equal as a.length
a = Arrays.copyOf(OBJECTS, CAP); // appears to match
CANDIDATE.setSizeSequence(CAP, CAP-1);
res = CANDIDATE.toArray(a);
check(res == a);
check(res[last()] == null);
// Check more elements than expected and more than a.length
a = new Object[CAP-1]; // appears to match
CANDIDATE.setSizeSequence(CAP-1, CAP);
res = CANDIDATE.toArray(a);
check(res != a);
check(res[LAST] != null);
// Check more elements than expected, but equal as a.length
a = new Object[CAP-1]; // appears to match
CANDIDATE.setSizeSequence(CAP-2, CAP-1);
res = CANDIDATE.toArray(a);
check(res == a);
check(res[last()] != null);
// Check more elements than expected, but less than a.length
a = Arrays.copyOf(OBJECTS, CAP); // appears to match
CANDIDATE.setSizeSequence(CAP-2, CAP-1);
res = CANDIDATE.toArray(a);
check(res == a);
check(res[last()] == null);
test_7121314();
}
/*
* Major target of this testcase, bug 7121314.
*/
protected void test_7121314() throws Throwable {
// Check equal elements as a.length, but less than expected
a = new Object[CAP-1]; // appears too small
CANDIDATE.setSizeSequence(CAP, CAP-1);
res = CANDIDATE.toArray(a);
check(res == a);
check(res[last()] != null);
// Check less elements than a.length and less than expected
a = Arrays.copyOf(OBJECTS, CAP-1); // appears too small
CANDIDATE.setSizeSequence(CAP, CAP-2);
res = CANDIDATE.toArray(a);
check(res == a);
check(res[last()] == null);
}
public static void main(String[] args) throws Throwable {
ToArrayTest testcase = new ToArrayTest();
try { testcase.test(); } catch (Throwable t) { unexpected(t); }
System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
if (failed > 0) throw new Exception("Some tests failed");
}
private static volatile int passed = 0, failed = 0;
private static void pass() { passed++; }
private static void fail() { failed++; Thread.dumpStack(); }
private static void fail(String msg) { System.out.println(msg); fail(); }
private static void unexpected(Throwable t) { failed++;
t.printStackTrace(); }
static void check(boolean cond) { if (cond) pass(); else fail(); }
static void equals(Object x, Object y) {
if (x == null ? y == null : x.equals(y)) pass();
else {System.out.println(x + " not equal to " + y); fail(); }}
}
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