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Update the AbstractBloomFilter to not use BitSet for cardinality.

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The cardinality can be performed without memory allocation using
Long.bitCount.
This commit is contained in:
Alex Herbert 2020-02-24 23:01:39 +00:00
parent e08f0be55b
commit 9a496dc61c
1 changed files with 39 additions and 39 deletions
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78
src/main/java/org/apache/commons/collections4/bloomfilter/AbstractBloomFilter.java
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@ -16,8 +16,8 @@
*/
package org.apache.commons.collections4.bloomfilter;
import java.util.BitSet;
import java.util.PrimitiveIterator.OfInt;
import java.util.function.LongBinaryOperator;
import org.apache.commons.collections4.bloomfilter.hasher.HashFunctionIdentity;
import org.apache.commons.collections4.bloomfilter.hasher.Hasher;
@ -66,11 +66,11 @@ public abstract class AbstractBloomFilter implements BloomFilter {
final long[] mine = getBits();
final long[] theirs = other.getBits();
final int limit = Integer.min(mine.length, theirs.length);
final long[] result = new long[limit];
int count = 0;
for (int i = 0; i < limit; i++) {
result[i] = mine[i] & theirs[i];
count += Long.bitCount(mine[i] & theirs[i]);
}
return BitSet.valueOf(result).cardinality();
return count;
}
/**
@ -80,7 +80,11 @@ public abstract class AbstractBloomFilter implements BloomFilter {
*/
@Override
public int cardinality() {
return BitSet.valueOf(getBits()).cardinality();
int count = 0;
for (final long bits : getBits()) {
count += Long.bitCount(bits);
}
return count;
}
/**
@ -182,27 +186,8 @@ public abstract class AbstractBloomFilter implements BloomFilter {
@Override
public int orCardinality(final BloomFilter other) {
verifyShape(other);
final long[] mine = getBits();
final long[] theirs = other.getBits();
long[] remainder = null;
long[] result = null;
if (mine.length > theirs.length) {
result = new long[mine.length];
remainder = mine;
} else {
result = new long[theirs.length];
remainder = theirs;
}
final int limit = Integer.min(mine.length, theirs.length);
for (int i = 0; i < limit; i++) {
result[i] = mine[i] | theirs[i];
}
if (limit < result.length) {
System.arraycopy(remainder, limit, result, limit, result.length - limit);
}
return BitSet.valueOf(result).cardinality();
// Logical OR
return opCardinality(other, (a, b) -> a | b);
}
/**
@ -253,26 +238,41 @@ public abstract class AbstractBloomFilter implements BloomFilter {
*/
@Override
public int xorCardinality(final BloomFilter other) {
// Logical XOR
return opCardinality(other, (a, b) -> a ^ b);
}
/**
* Perform the operation on the matched longs from this filter and the other filter
* and count the cardinality.
*
* <p>The remaining unmatched longs from the larger filter are always counted. This
* method is suitable for OR and XOR cardinality.
*
* @param other the other Bloom filter.
* @param operation the operation (e.g. OR, XOR)
* @return the cardinality
*/
private int opCardinality(final BloomFilter other, LongBinaryOperator operation) {
verifyShape(other);
final long[] mine = getBits();
final long[] theirs = other.getBits();
long[] remainder = null;
long[] result = null;
long[] small;
long[] big;
if (mine.length > theirs.length) {
result = new long[mine.length];
remainder = mine;
big = mine;
small = theirs;
} else {
result = new long[theirs.length];
remainder = theirs;
small = mine;
big = theirs;
}
final int limit = Integer.min(mine.length, theirs.length);
for (int i = 0; i < limit; i++) {
result[i] = mine[i] ^ theirs[i];
int count = 0;
for (int i = 0; i < small.length; i++) {
count += Long.bitCount(operation.applyAsLong(small[i], big[i]));
}
if (limit < result.length) {
System.arraycopy(remainder, limit, result, limit, result.length - limit);
for (int i = small.length; i < big.length; i++) {
count += Long.bitCount(big[i]);
}
return BitSet.valueOf(result).cardinality();
return count;
}
}