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https://issues.apache.org/jira/browse/LUCENE-1990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12854151#action_12854151
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Toke Eskildsen commented on LUCENE-1990:
----------------------------------------
I did a checkout with
{code}
svn co https://svn.apache.org/repos/asf/lucene/dev/trunk/lucene lucene-flex
{code}
and added the following method to TestPackedInts
{code}
public void testSecondaryBlockChange() throws IOException {
PackedInts.Mutable mutable = new Packed64(26, 5);
mutable.set(24, 31);
assertEquals("The value #24 should be correct", 31, mutable.get(24));
mutable.set(4, 16);
assertEquals("The value #24 should remain unchanged", 31, mutable.get(24));
}
{code}
after which I ran
{code}
ant test-core
{code}
which gave me
{code}
[junit] Testsuite: org.apache.lucene.util.packed.TestPackedInts
[junit] Testcase:
testSecondaryBlockChange(org.apache.lucene.util.packed.TestPackedInts): FAILED
[junit] The value #24 should remain unchanged expected:<31> but was:<28>
[junit] junit.framework.AssertionFailedError: The value #24 should remain
unchanged expected:<31> but was:<28>
[junit] at
org.apache.lucene.util.packed.TestPackedInts.testSecondaryBlockChange(TestPackedInts.java:106)
[junit] at
org.apache.lucene.util.LuceneTestCase.runBare(LuceneTestCase.java:276)
{code}
then I added
{code}
if (bitPos <= BLOCK_SIZE - elementBits) { // Second block not used
currentMasks[base+1] = ~0; // Keep all bits
currentMasks[base+2] = 0; // Or with 0
}
{code}
to the relevant parts of Packed32 and Packed, as described above and ran
{code}
ant test-core
{code}
again, which gave me
{code}
[junit] Testsuite: org.apache.lucene.util.packed.TestPackedInts
[junit] Tests run: 7, Failures: 0, Errors: 0, Time elapsed: 5.463 sec
{code}
My initial unit-test contained an error, which I corrected after a minute or
two (as far as I remember). Maybe you used the first version?
It seems that the bug is indeed in trunk. It corrupts the value of the block
after the current block in certain cases: Sequential assignment of values works
fine, but out-of-order assignments corrupts the array.
> Add unsigned packed int impls in oal.util
> -----------------------------------------
>
> Key: LUCENE-1990
> URL: https://issues.apache.org/jira/browse/LUCENE-1990
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Affects Versions: Flex Branch
> Reporter: Michael McCandless
> Priority: Minor
> Fix For: Flex Branch
>
> Attachments: generated_performance-te20100226.txt,
> LUCENE-1990-te20100122.patch, LUCENE-1990-te20100210.patch,
> LUCENE-1990-te20100212.patch, LUCENE-1990-te20100223.patch,
> LUCENE-1990-te20100226.patch, LUCENE-1990-te20100226b.patch,
> LUCENE-1990-te20100226c.patch, LUCENE-1990-te20100301.patch,
> LUCENE-1990.patch, LUCENE-1990.patch, LUCENE-1990.patch,
> LUCENE-1990_PerformanceMeasurements20100104.zip, perf-mkm-20100227.txt,
> performance-20100301.txt, performance-te20100226.txt
>
>
> There are various places in Lucene that could take advantage of an
> efficient packed unsigned int/long impl. EG the terms dict index in
> the standard codec in LUCENE-1458 could subsantially reduce it's RAM
> usage. FieldCache.StringIndex could as well. And I think "load into
> RAM" codecs like the one in TestExternalCodecs could use this too.
> I'm picturing something very basic like:
> {code}
> interface PackedUnsignedLongs {
> long get(long index);
> void set(long index, long value);
> }
> {code}
> Plus maybe an iterator for getting and maybe also for setting. If it
> helps, most of the usages of this inside Lucene will be "write once"
> so eg the set could make that an assumption/requirement.
> And a factory somewhere:
> {code}
> PackedUnsignedLongs create(int count, long maxValue);
> {code}
> I think we should simply autogen the code (we can start from the
> autogen code in LUCENE-1410), or, if there is an good existing impl
> that has a compatible license that'd be great.
> I don't have time near-term to do this... so if anyone has the itch,
> please jump!
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