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https://issues.apache.org/jira/browse/COLLECTIONS-823?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alex Herbert resolved COLLECTIONS-823.
--------------------------------------
Resolution: Done
> BloomFilter: Optimize ArrayCountingBloomFilter.ForEachBitMap
> ------------------------------------------------------------
>
> Key: COLLECTIONS-823
> URL: https://issues.apache.org/jira/browse/COLLECTIONS-823
> Project: Commons Collections
> Issue Type: Improvement
> Components: Collection
> Affects Versions: 4.5
> Reporter: Claude Warren
> Assignee: Claude Warren
> Priority: Minor
> Labels: bloom-filter
> Fix For: 4.5
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
>
>
> Member
> h3.
> !https://avatars.githubusercontent.com/u/886334?s=48&v=4|width=24,height=24!
> *[aherbert|https://github.com/aherbert]* [on 27
> Feb|https://github.com/apache/commons-collections/pull/258#discussion_r812499923]
> This converts all the non zero indices to a bitmap long[] array. But to do so
> requires using the {{forEachIndex}} method with a conditional boolean check
> on each loop iteration. I wonder if this should be brought inline for
> efficiency:
> {noformat}
> @Override
> public boolean forEachBitMap(LongPredicate consumer) {
> Objects.requireNonNull(consumer, "consumer");
> long[] result = new
> long[BitMap.numberOfBitMaps(shape.getNumberOfBits())];
> for (int i = 0; i < counts.length; i++) {
> if (counts[i] != 0) {
> // Avoids a second check on the predicate result in
> forEachIndex
> BitMap.set(result, i);
> }
> }
> return BitMapProducer.fromBitMapArray(result).forEachBitMap(consumer);
> }
> {noformat}
> Or better yet, avoid the {{long[]}} array:
> {noformat}
> int blocksm1 = BitMap.numberOfBitMaps(shape.getNumberOfBits()) - 1;
> int i = 0;
> long value;
> for (int j = 0; j < blocksm1; j++) {
> value = 0;
> for (int k = 0; k < Long.SIZE; k++) {
> if (counts[i++] != 0) {
> value |= BitMap.getLongBit(k);
> }
> }
> if (!consumer.test(value)) {
> return false;
> }
> }
> // Final block
> value = 0;
> for (int k = 0; i < counts.length; k++) {
> if (counts[i++] != 0) {
> value |= BitMap.getLongBit(k);
> }
> }
> return consumer.test(value);
> {noformat}
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