Re: Reply： what to do next to fix JDK-8230557. thanks
Ivan Gerasimov
ivan.gerasimov at oracle.com
Thu Sep 5 09:22:12 UTC 2019
Hello!
BitSet is known to be flawed in many ways: its size(), length(),
cardinality() and nextClearBit() can return meaningless negative values.
I was thinking about disallowing setting any index greater than
(Integer.MAX_VALUE - 63), for example by throwing OutOfMemoryError.
We could do it without changing the specification.
With kind regards,
Ivan
On 9/5/19 1:16 AM, 未来阳光 wrote:
> Hi, Peter.
>
>
> I understand your point, but I think it's unreasonable for the reason that source code compatibility problem, it's really a bug.
>
>
> User can't understand why the size method return a negative number.
>
>
>
>
>
>
> Best, lamber-ken
>
>
>
>
> ------------------ 原始邮件 ------------------
> 发件人: "Peter Levart"<peter.levart at gmail.com>;
> 发送时间: 2019年9月5日(星期四) 下午3:51
> 收件人: "未来阳光"<2217232293 at qq.com>;"core-libs-dev"<core-libs-dev at openjdk.java.net>;
> 抄送: "David Holmes"<david.holmes at oracle.com>;
> 主题: Re: 回复： 回复： what to do next to fix JDK-8230557. thanks
>
>
>
> Hi 未来阳光,
>
> As David has pointed out, your proposed fix would break binary and
> source compatibility of BitSet.size() method, so it is not acceptable.
>
> BitSet API allows addressing individual bits using non-negative 'int'
> typed indexes (analogous to indexes of Java arrays). The range of
> indexes is: 0 ... 2^31 - 1 (0 ... Integer.MAX_VALUE). The maximum "size"
> of BitSet is therefore 2^31. Unfortunately, this value can't be
> "corectly" represented with signed 32 bit integer (int). Only in this
> corner case, - 2^31 (Integer.MIN_VALUE) is the interpreted value
> returned from size(). If one would interpret it as unsigned 32 bit
> integer value, it is entirely correct. For example, this holds:
>
> Integer.toUnsignedLong(new BitSet(Integer.MAX_VALUE).size()) == 1L << 31
>
> It is also always true what javadoc says about size(): "The maximum
> element in the set is the size - 1st element"
>
> The following holds also for this corner case:
>
> new BitSet(Integer.MAX_VALUE).size() - 1 == Integer.MAX_VALUE;
>
> So perhaps, the fix could be just to describe this corner case in the
> spec. And perhaps, to support the following use case in the corner case:
>
> BitSet set1 = ...
> ...
>
> BitSet set2 = new BitSet(set1.size());
>
> ... by modifying the BitSet constructor to accept the Integer.MIN_VALUE
> in addition to all the non-negative values as the 'nbits' parameter.
>
> What do you think?
>
> Regards, Peter
>
> On 9/5/19 8:31 AM, David Holmes wrote:
> > Hi,
> >
> > On 5/09/2019 4:11 pm, 未来阳光 wrote:
> >>
> >> Thanks very much.
> >>
> >> *BUG-LINK:* https://bugs.openjdk.java.net/browse/JDK-8230557
> >>
> >> *Describe: *
> >> the return type of the method BitSet#size is int, so the method may
> >> return a negative value in some case, for example, will return
> >> -2147483648.
> >> ```
> >> BitSet bitSet = new BitSet(Integer.MAX_VALUE);
> >> for (int i = 0; i < Integer.MAX_VALUE - 1000; i++) {
> >> bitSet.set(i);
> >> }
> >> System.out.println(bitSet.size());
> >> ```
> >> EXPECTED: 2147483648, but ACTUAL: -2147483648.
> >>
> >> *FIX*
> >> I have put the patch in the attachment of the mail.
> >
> > In case the attachment got stripped form the mailing list the proposed
> > fix is:
> >
> > - public int size() {
> > - return words.length * BITS_PER_WORD;
> > + public long size() {
> > + return (long) words.length * BITS_PER_WORD;
> >
> > Unfortunately this simple fix it not possible. You can't just change
> > the return type of the method to long as that is a source-incompatible
> > change and would not be approved [1]. Instead the return value should
> > be capped at Integer.MAX_VALUE - but I'll leave that for someone from
> > core-libs team to pick up. Also look at the evaluation in:
> >
> > https://bugs.openjdk.java.net/browse/JDK-4213570
> >
> > Cheers,
> > David
> >
> > [1] https://wiki.openjdk.java.net/display/csr/CSR+FAQs
> >
> >
> >
> >>
> >> ------------------ 原始邮件 ------------------
> >> *发件人:* "David Holmes"<david.holmes at oracle.com>;
> >> *发送时间:* 2019年9月5日(星期四) 下午2:00
> >> *收件人:* "未来阳光"<2217232293 at qq.com>;"core-libs-dev"<core-libs-
> >> dev at openjdk.java.net>;
> >> *主题:* Re: 回复： what to do next to fix JDK-8230557. thanks
> >>
> >> On 5/09/2019 3:46 pm, 未来阳光 wrote:
> >> >
> >> > hi, developers.
> >> >
> >> > Can someone help me? thanks very much !!
> >>
> >> Help you how exactly. As I stated your are up to step 2 of the how to
> >> contribute process. If you have a suggested fix for the bug then put
> >> that in an email as described.
> >>
> >> Thanks,
> >> David
> >>
> >> >
> >> > ------------------ 原始邮件 ------------------
> >> > *发件人:* "David Holmes"<david.holmes at oracle.com>;
> >> > *发送时间:* 2019年9月5日(星期四) 中午1:44
> >> > *收件人:* "未来阳光"<2217232293 at qq.com>;"core-libs-dev"<core-libs-
> >> > dev at openjdk.java.net>;
> >> > *主题:* Re: what to do next to fix JDK-8230557. thanks
> >> >
> >> > On 5/09/2019 3:35 pm, 未来阳光 wrote:
> >> > > Hi, leaders.
> >> >
> >> > Hi,
> >> >
> >> > No "leaders" here only developers :)
> >> >
> >> > >
> >> > > A few days ago, I report a bug in core lib[1]. According to the
> >> > contribute document[2], I had send oca to oracle and my name has
> >> > been listed on oca[3].
> >> >
> >> > Welcome aboard!
> >> >
> >> > > But I still can't push my changes to jdk, can someone tell me
> >> how to
> >> > do next? thanks very match!!
> >> >
> >> > You can't push anything until you become a Committer and before
> >> that you
> >> > have to become an Author. The steps for contributing are outlined
> >> here:
> >> >
> >> > http://openjdk.java.net/contribute/
> >> >
> >> > and you would seem to be up to step 2. :)
> >> >
> >> > Cheers,
> >> > David
> >> >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > [1]https://bugs.openjdk.java.net/browse/JDK-8230557
> >> > >
> >> > > [2]http://openjdk.java.net/contribute/
> >> > > [3]https://www.oracle.com/technetwork/community/oca-486395.html
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > ------------------ 原始邮件 ------------------
> >> > > 发件人: "Bug Report
> >> > Notification"<Bug-Report-Daemon_WW at ORACLE.COM>;
> >> > > 发送时间: 2019年9月5日(星期四) 凌晨3:33
> >> > > 收件人: "未来阳光"<2217232293 at qq.com>;
> >> > >
> >> > > 主题: Update Notification: Bug Report - JDK-8230557
> >> > >
> >> > >
> >> > >
> >> > >
> >> > [This is an automated response. Please
> >> do not
> >> > reply.]
> >> > > Dear Java Developer,
> >> > > We have finished evaluating your report and have assigned it a Bug
> >> > ID: JDK-8230557. The issue is visible on bugs.java.com at the
> >> following
> >> > url JDK-8230557.
> >> > > To provide more information about this issue,
> >> > click here.
> >> > > We work to resolve the issues that are
> >> submitted to
> >> > us according to their impact to the community as a whole, and make no
> >> > promises as to the time or release in which a bug might be fixed. If
> >> > this issue has a significant impact on your project you may want to
> >> > consider using one of the technical support offerings available at
> >> > Oracle Support.
> >> > > Regards,
> >> > > Java Developer Support
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > Java SE
> >> > > Java SE Documentation
> >> > > Java SE Downloads
> >> > > Java Developer Forums
> >> > > Oracle Java SE Advanced
> >> > > Bug Database
> >> > >
> >> > Copyright © Oracle
> >> and/or
> >> > its affiliates. All rights reserved.
> >> > >
> >> > Terms of Use |
> >> Privacy
> >> > >
--
With kind regards,
Ivan Gerasimov
More information about the core-libs-dev
mailing list