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From Yonik Seeley <yo...@lucidimagination.com>
Subject Re: [VOTE] release 3.3
Date Fri, 24 Jun 2011 16:14:40 GMT
I just took a quick peek at the prevBitSet, and the implementation
looks buggy (provided that it's legal for a user to pass an "i" that
may be greater than the largest bit ever set).

Here is the current code, which will cause an exception when wlen==0.
 public int prevSetBit(int index) {
    if (index < 0) {
      return -1;
    }
    int i = index>>6;
    if (i >= wlen) {
      i = wlen - 1;
    }
    final int subIndex = index & 0x3f;      // index within the word
    long word = (bits[i] << (63-subIndex));  // skip all the bits to
the left of index

All that needs to be done is to move the negative index check to the
bottom (the first index<0 is not needed since we do a signed shift).

 public int prevSetBit(int index) {
    int i = index>>6;
    if (i >= wlen) {
      i = wlen - 1;
    }
    if (i < 0) return -1;
    final int subIndex = index & 0x3f;      // index within the word
    long word = (bits[i] << (63-subIndex));  // skip all the bits to
the left of index


-Yonik
http://www.lucidimagination.com



On Fri, Jun 24, 2011 at 11:33 AM, Robert Muir <rcmuir@gmail.com> wrote:
> And -Xint and -client
>
> On Fri, Jun 24, 2011 at 11:32 AM, Uwe Schindler <uwe@thetaphi.de> wrote:
>> The bug is *not* fixed by replacing Long.numberOfLeadingZeros(word) with BitUtils.nlz(word).
>>
>> So this is really strange. Also happens with -Xbatch.
>>
>> -----
>> Uwe Schindler
>> H.-H.-Meier-Allee 63, D-28213 Bremen
>> http://www.thetaphi.de
>> eMail: uwe@thetaphi.de
>>
>>
>>> -----Original Message-----
>>> From: Uwe Schindler [mailto:uwe@thetaphi.de]
>>> Sent: Friday, June 24, 2011 5:20 PM
>>> To: dev@lucene.apache.org
>>> Subject: RE: [VOTE] release 3.3
>>>
>>> I assume the problem is the intrinsic, I will replace by the own hacker's
>>> delight impl (like we do everywhere else in OpenBitSet, why did we use the
>>> platform method here?) and try again....
>>>
>>> Uwe
>>>
>>> -----
>>> Uwe Schindler
>>> H.-H.-Meier-Allee 63, D-28213 Bremen
>>> http://www.thetaphi.de
>>> eMail: uwe@thetaphi.de
>>>
>>>
>>> > -----Original Message-----
>>> > From: Robert Muir [mailto:rcmuir@gmail.com]
>>> > Sent: Friday, June 24, 2011 5:07 PM
>>> > To: dev@lucene.apache.org
>>> > Subject: Re: [VOTE] release 3.3
>>> >
>>> > Just some more info: i took away the seed and used -Dtests.iter=100 on
>>> > this
>>> > test:
>>> >
>>> > JAVA5:
>>> >     [junit] Testsuite: org.apache.lucene.util.TestOpenBitSet
>>> >     [junit] Tests run: 400, Failures: 0, Errors: 23, Time elapsed:
>>> > 21.793 sec
>>> >
>>> > JAVA6:
>>> > junit-sequential:
>>> >     [junit] Testsuite: org.apache.lucene.util.TestOpenBitSet
>>> >     [junit] Tests run: 400, Failures: 0, Errors: 0, Time elapsed:
>>> > 19.719 sec
>>> >
>>> > so this test fails 23% of the time on java5.
>>> >
>>> > The reason we never caught it, is that java5 is unmaintained and we
>>> > cannot even test it in hudson... aka we cannot support this monster
>>> anymore!!!!
>>> >
>>> > On Fri, Jun 24, 2011 at 11:02 AM, Robert Muir <rcmuir@gmail.com> wrote:
>>> > > On Fri, Jun 24, 2011 at 10:54 AM, Uwe Schindler <uwe@thetaphi.de>
>>> > wrote:
>>> > >> The OpenBitSet test is in all cases serious (vs. the skiplist test
>>> > >> is a test bug,
>>> > that true).
>>> > >>
>>> > >> The AIOOBE is caused inside OpenBitSet and that should never ever
>>> > happen, even if you use it incorrectly!
>>> > >
>>> > > Its not clear that its that serious, it only fails with java 5 for
>>> > > me (not java 6) :)
>>> > >
>>> > > Looks like a bug in java 5...
>>> > >
>>> >
>>> > ---------------------------------------------------------------------
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>>> > additional commands, e-mail: dev-help@lucene.apache.org
>>>
>>>
>>>
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>>
>>
>>
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>>
>>
>
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>

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