Re: Reply： what to do next to fix JDK-8230557. thanks

[Ivan Gerasimov]

Hi Peter!

On 9/5/19 7:24 AM, Peter Levart wrote:
Hi Ivan,
On 9/5/19 11:22 AM, Ivan Gerasimov wrote:
Hello!

BitSet is known to be flawed in many ways:?0?2 its size(), length(), 
cardinality() and nextClearBit?6?7() can return meaningless negative 
values.

I was thinking about disallowing setting any index greater than 
(Integer.MAX_VALUE - 63), for example by throwing OutOfMemoryError.

An index of Integer.MAX_VALUE - 64 would be the greatest index then, 
an index of Integer.MAX_VALUE - 63 already needs an array of longs of 
length 2^25 which results in BitSet size() of 2^31 ...


We could do it without changing the specification.

The calls to: new BitSet(Integer.MAX_VALUE - 63) ... new 
BitSet(Integer.MAX_VALUE) would also have to throw then.
BitSet.valueOf(...) methods don't even check the passed in arguments 
lengths, so size() can really return a meaningless negative or 
positive number. They all would have to throw if the passed-in length 
of array/buffer is too large.

So would you not specify when those methods throw?

Yes.?0?2 My point was that any method that requires memory allocation 
should be expected to possibly throw OOM, so we don't have to specify it 
explicitly.

A similar thing happened with compact Strings, for example.?0?2 When the 
internal storage was changed to byte[] array, all of a sudden, it became 
impossible to create UTF16 Strings (or StringBuilders) of length > 
(Integer.MAX_VALUE / 2).

W.r.t. BitSet, personally, I would rather not fix its current behavior 
unless there is a very strong demand for the change.

Just wanted to mention one approach, which would limit usage of this 
class to the boundaries it was originally designed for.

With kind regards,

Ivan


Regards, Peter


With kind regards,

Ivan


On 9/5/19 1:16 AM, ???????? 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




------------------ ???????? ------------------
??????:&nbsp;"Peter Levart"<peter.lev...@gmail.com&gt;;
????????:&nbsp;2019??9??5??(??????) ????3:51
??????:&nbsp;"????????"<2217232...@qq.com&gt;;"core-libs-dev"<core-libs-dev@openjdk.java.net&gt;; 

????:&nbsp;"David Holmes"<david.hol...@oracle.com&gt;;
????:&nbsp;Re: ?????? ?????? what to do next to fix JDK-8230557. thanks



Hi ????????,

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:
&gt; Hi,
&gt;
&gt; On 5/09/2019 4:11 pm, ???????? wrote:
&gt;&gt;
&gt;&gt; Thanks very much.
&gt;&gt;
&gt;&gt; *BUG-LINK:* https://bugs.openjdk.java.net/browse/JDK-8230557
&gt;&gt;
&gt;&gt; *Describe: *
&gt;&gt; the return type of the method BitSet#size is int, so the 
method may
&gt;&gt; return a negative value in some case, for example, will return
&gt;&gt; -2147483648.
&gt;&gt; ```
&gt;&gt; BitSet bitSet = new BitSet(Integer.MAX_VALUE);
&gt;&gt; for (int i = 0; i < Integer.MAX_VALUE - 1000; i++) {
&gt;&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;bitSet.set(i);
&gt;&gt; }
&gt;&gt; System.out.println(bitSet.size());
&gt;&gt; ```
&gt;&gt; EXPECTED: 2147483648, but ACTUAL: -2147483648.
&gt;&gt;
&gt;&gt; *FIX*
&gt;&gt; I have put the patch in the attachment of the mail.
&gt;
&gt; In case the attachment got stripped form the mailing list the 
proposed
&gt; fix is:
&gt;
&gt; -&nbsp;&nbsp;&nbsp; public int size() {
&gt; -&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return words.length 
* BITS_PER_WORD;
&gt; +&nbsp;&nbsp;&nbsp; public long size() {
&gt; +&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return (long) 
words.length * BITS_PER_WORD;
&gt;
&gt; Unfortunately this simple fix it not possible. You can't just 
change
&gt; the return type of the method to long as that is a 
source-incompatible
&gt; change and would not be approved [1]. Instead the return value 
should
&gt; be capped at Integer.MAX_VALUE - but I'll leave that for 
someone from
&gt; core-libs team to pick up. Also look at the evaluation in:
&gt;
&gt; https://bugs.openjdk.java.net/browse/JDK-4213570
&gt;
&gt; Cheers,
&gt; David
&gt;
&gt; [1] https://wiki.openjdk.java.net/display/csr/CSR+FAQs
&gt;
&gt;
&gt;
&gt;&gt;
&gt;&gt; ------------------&nbsp;????????&nbsp;------------------
&gt;&gt; *??????:*&nbsp;"David Holmes"<david.hol...@oracle.com&gt;;
&gt;&gt; *????????:*&nbsp;2019??9??5??(??????) ????2:00
&gt;&gt; 
*??????:*&nbsp;"????????"<2217232...@qq.com&gt;;"core-libs-dev"<core-libs-
&gt;&gt; d...@openjdk.java.net&gt;;
&gt;&gt; *????:*&nbsp;Re: ?????? what to do next to fix JDK-8230557. 
thanks
&gt;&gt;
&gt;&gt; On 5/09/2019 3:46 pm, ???????? wrote:
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; hi, developers.
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; Can someone help me? thanks very much !!
&gt;&gt;
&gt;&gt; Help you how exactly. As I stated your are up to step 2 of 
the how to
&gt;&gt; contribute process. If you have a suggested fix for the bug 
then put
&gt;&gt; that in an email as described.
&gt;&gt;
&gt;&gt; Thanks,
&gt;&gt; David
&gt;&gt;
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; 
------------------&nbsp;????????&nbsp;------------------
&gt;&gt; &nbsp;&gt; *??????:*&nbsp;"David 
Holmes"<david.hol...@oracle.com&gt;;
&gt;&gt; &nbsp;&gt; *????????:*&nbsp;2019??9??5??(??????) ????1:44
&gt;&gt; &nbsp;&gt; 
*??????:*&nbsp;"????????"<2217232...@qq.com&gt;;"core-libs-dev"<core-libs-
&gt;&gt; &nbsp;&gt; d...@openjdk.java.net&gt;;
&gt;&gt; &nbsp;&gt; *????:*&nbsp;Re: what to do next to fix 
JDK-8230557. thanks
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; On 5/09/2019 3:35 pm, ???????? wrote:
&gt;&gt; &nbsp;&gt;&nbsp; &gt; Hi, leaders.
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; Hi,
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; No "leaders" here only developers :)
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt; A few days ago, I report a bug in 
core lib[1]. According to the
&gt;&gt; &nbsp;&gt; contribute document[2], I had send oca to oracle 
and&amp;nbsp;my name has
&gt;&gt; &nbsp;&gt; been listed on&amp;nbsp;oca[3].
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; Welcome aboard!
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt; But I still can't push my changes to 
jdk, can someone tell me
&gt;&gt; how to
&gt;&gt; &nbsp;&gt; do next? thanks very match!!
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; You can't push anything until you become a 
Committer and before
&gt;&gt; that you
&gt;&gt; &nbsp;&gt; have to become an Author. The steps for 
contributing are outlined
&gt;&gt; here:
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; http://openjdk.java.net/contribute/
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; and you would seem to be up to step 2. :)
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt; Cheers,
&gt;&gt; &nbsp;&gt; David
&gt;&gt; &nbsp;&gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt; 
[1]https://bugs.openjdk.java.net/browse/JDK-8230557
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt; [2]http://openjdk.java.net/contribute/
&gt;&gt; &nbsp;&gt;&nbsp; &gt; 
[3]https://www.oracle.com/technetwork/community/oca-486395.html
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt; 
------------------&amp;nbsp;????????&amp;nbsp;------------------
&gt;&gt; &nbsp;&gt;&nbsp; &gt; ??????:&amp;nbsp;"Bug Report
&gt;&gt; &nbsp;&gt; 
Notification"<bug-report-daemon...@oracle.com&amp;gt;;
&gt;&gt; &nbsp;&gt;&nbsp; &gt; ????????:&amp;nbsp;2019??9??5??(??????) 
????3:33
&gt;&gt; &nbsp;&gt;&nbsp; &gt; 
??????:&amp;nbsp;"????????"<2217232...@qq.com&amp;gt;;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt; ????:&amp;nbsp;Update Notification: Bug 
Report&nbsp; - JDK-8230557
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; &gt;
&gt;&gt; &nbsp;&gt;&nbsp; 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
[This is an automated response. Please
&gt;&gt; do not
&gt;&gt; &nbsp;&gt; reply.]
&gt;&gt; &nbsp;&gt;&nbsp; &gt; Dear Java Developer,
&gt;&gt; &nbsp;&gt;&nbsp; &gt; We have finished evaluating your 
report and have assigned it a Bug
&gt;&gt; &nbsp;&gt; ID: JDK-8230557. The issue is visible on 
bugs.java.com at the
&gt;&gt; following
&gt;&gt; &nbsp;&gt; url JDK-8230557.
&gt;&gt; &nbsp;&gt;&nbsp; 
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
To provide more information about this issue,
&gt;&gt; &nbsp;&gt; click&nbsp; here.
&gt;&gt; &nbsp;&gt;&nbsp; 
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
We work to resolve the issues that are
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&gt;&gt; &nbsp;&gt; us according to their impact to the community as 
a whole, and make no
&gt;&gt; &nbsp;&gt; promises as to the time or release in which a 
bug might be fixed. If
&gt;&gt; &nbsp;&gt; this issue has a significant impact on your 
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&gt;&gt; &nbsp;&gt; consider using one of the technical support 
offerings available at
&gt;&gt; &nbsp;&gt; Oracle Support.
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Regards,
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--
With kind regards,
Ivan Gerasimov