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7014637: Improve behavior of EnumSet Iterator.remove()

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Reviewed-by: mduigou, alanb
This commit is contained in:
Neil Richards 2011-03-14 14:49:52 -07:00 committed by Mike Duigou
parent 79ccccaa96
commit b96d0e610a
4 changed files with 187 additions and 3 deletions
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7
jdk/src/share/classes/java/util/JumboEnumSet.java
View File

@ -138,8 +138,11 @@ class JumboEnumSet<E extends Enum<E>> extends EnumSet<E> {
public void remove() {
if (lastReturned == 0)
throw new IllegalStateException();
elements[lastReturnedIndex] -= lastReturned;
size--;
final long oldElements = elements[lastReturnedIndex];
elements[lastReturnedIndex] &= ~lastReturned;
if (oldElements != elements[lastReturnedIndex]) {
size--;
}
lastReturned = 0;
}
}

2
jdk/src/share/classes/java/util/RegularEnumSet.java
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@ -106,7 +106,7 @@ class RegularEnumSet<E extends Enum<E>> extends EnumSet<E> {
public void remove() {
if (lastReturned == 0)
throw new IllegalStateException();
elements -= lastReturned;
elements &= ~lastReturned;
lastReturned = 0;
}
}

96
jdk/test/java/util/EnumSet/LargeEnumIteratorRemoveResilience.java Normal file
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@ -0,0 +1,96 @@
/*
* Copyright (c) 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.
*/
/*
* Portions Copyright (c) 2011 IBM Corporation
*/
/*
* @test
* @bug 7014637
* @summary EnumSet's iterator.remove() can be resilient to set's modification.
* @author Neil Richards <neil.richards@ngmr.net>, <neil_richards@uk.ibm.com>
*/
import java.util.EnumSet;
import java.util.Iterator;
import java.util.Set;
public class LargeEnumIteratorRemoveResilience {
// enum with more than 64 values
private static enum LargeEnum {
e00, e01, e02, e03, e04, e05, e06, e07,
e08, e09, e0A, e0B, e0C, e0D, e0E, e0F,
e10, e11, e12, e13, e14, e15, e16, e17,
e18, e19, e1A, e1B, e1C, e1D, e1E, e1F,
e20, e21, e22, e23, e24, e25, e26, e27,
e28, e29, e2A, e2B, e2C, e2D, e2E, e2F,
e30, e31, e32, e33, e34, e35, e36, e37,
e38, e39, e3A, e3B, e3C, e3D, e3E, e3F,
e40, e41, e42, e43, e44, e45, e46, e47,
e48, e49, e4A, e4B, e4C, e4D, e4E, e4F,
}
public static void main(final String[] args) throws Exception {
final Set<LargeEnum> set = EnumSet.noneOf(LargeEnum.class);
set.add(LargeEnum.e2D);
set.add(LargeEnum.e42);
final Iterator<LargeEnum> iterator = set.iterator();
int size = set.size();
LargeEnum element = iterator.next();
iterator.remove();
checkSetAfterRemoval(set, size, element);
size = set.size();
element = iterator.next();
set.remove(element);
checkSetAfterRemoval(set, size, element);
// The Java API declares that the behaviour here - to call
// iterator.remove() after the underlying collection has been
// modified - is "unspecified".
// However, in the case of iterators for EnumSet, it is easy to
// implement their remove() operation such that the set is
// unmodified if it is called for an element that has already been
// removed from the set - this being the naturally "resilient"
// behaviour.
iterator.remove();
checkSetAfterRemoval(set, size, element);
}
private static void checkSetAfterRemoval(final Set<LargeEnum> set,
final int origSize, final LargeEnum removedElement)
throws Exception {
if (set.size() != (origSize - 1)) {
throw new Exception("Test FAILED: Unexpected set size after removal; expected '" + (origSize - 1) + "' but found '" + set.size() + "'");
}
if (set.contains(removedElement)) {
throw new Exception("Test FAILED: Element returned from iterator unexpectedly still in set after removal.");
}
}
}

85
jdk/test/java/util/EnumSet/SmallEnumIteratorRemoveResilience.java Normal file
View File

@ -0,0 +1,85 @@
/*
* Copyright (c) 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.
*/
/*
* Portions Copyright (c) 2011 IBM Corporation
*/
/*
* @test
* @bug 7014637
* @summary EnumSet's iterator.remove() can be resilient to set's modification.
* @author Neil Richards <neil.richards@ngmr.net>, <neil_richards@uk.ibm.com>
*/
import java.util.EnumSet;
import java.util.Iterator;
import java.util.Set;
public class SmallEnumIteratorRemoveResilience {
// enum with less than 64 values
private static enum SmallEnum { e0, e1, e2 }
public static void main(final String[] args) throws Exception {
final Set<SmallEnum> set = EnumSet.noneOf(SmallEnum.class);
set.add(SmallEnum.e0);
set.add(SmallEnum.e1);
final Iterator<SmallEnum> iterator = set.iterator();
int size = set.size();
SmallEnum element = iterator.next();
iterator.remove();
checkSetAfterRemoval(set, size, element);
size = set.size();
element = iterator.next();
set.remove(element);
checkSetAfterRemoval(set, size, element);
// The Java API declares that the behaviour here - to call
// iterator.remove() after the underlying collection has been
// modified - is "unspecified".
// However, in the case of iterators for EnumSet, it is easy to
// implement their remove() operation such that the set is
// unmodified if it is called for an element that has already been
// removed from the set - this being the naturally "resilient"
// behaviour.
iterator.remove();
checkSetAfterRemoval(set, size, element);
}
private static void checkSetAfterRemoval(final Set<SmallEnum> set,
final int origSize, final SmallEnum removedElement)
throws Exception {
if (set.size() != (origSize - 1)) {
throw new Exception("Test FAILED: Unexpected set size after removal; expected '" + (origSize - 1) + "' but found '" + set.size() + "'");
}
if (set.contains(removedElement)) {
throw new Exception("Test FAILED: Element returned from iterator unexpectedly still in set after removal.");
}
}
}