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https://issues.apache.org/jira/browse/DERBY-2191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12468263
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Dyre Tjeldvoll commented on DERBY-2191:
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I agree that the javadoc comment for anySetBit should be improved, and will
include this in the next version of the patch.
I'll take a look at ResultColumnList.generateHolderMethod() and see if anything
can be done.
Wrt. firstSet(): I did consider your approach, but that will always result in 4
comparisons. The current approach will give an average of 4 comparisons if the
set bits are uniformly distributed in the byte. If you look at how firstSet is
used in anySetBit(int) you'll see that the argument is frequently shifted a
number of bits to the left. So the bits are not uniformly distributed, but
rather clustered in the beginning of the byte.
> Cleanup of FormatableBitSet
> ---------------------------
>
> Key: DERBY-2191
> URL: https://issues.apache.org/jira/browse/DERBY-2191
> Project: Derby
> Issue Type: Improvement
> Components: Miscellaneous
> Affects Versions: 10.2.1.6
> Reporter: Dyre Tjeldvoll
> Assigned To: Dyre Tjeldvoll
> Priority: Trivial
> Fix For: 10.3.0.0
>
> Attachments: anysetbit.v1.diff, anysetbit.v1.stat, bitops.v1.diff,
> bitops.v1.stat, bitops.v2.diff, bitops.v2.stat, bitops.v3.diff,
> bitopt.v1.diff, bitopt.v1.stat, bitopt.v2.diff, boundarycheck.v1.diff,
> boundarycheck.v1.stat, cleanup2191.diff, cleanup2191.stat, deadcode.v1.diff,
> deadcode.v2.diff, fbstst.v1.diff, fbstst.v1.stat, FormatableBitSetTest.java,
> numbitsset.v1.diff, numbitsset.v1.stat, unusedmethods.v1.diff,
> unusedmethods.v1.stat, valuenotnull.v1.diff, valuenotnull.v1.stat
>
>
> The implementation of FormatableBitSet could be streamlined. Dead code can be
> removed and the implementation of some methods can be simplified.
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