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Remove some BitSet#nextSetBit code duplication (#13625)

This commit is contained in:
Greg Miller 2024-08-01 19:16:39 -07:00 committed by GitHub
parent 836c8e76ad
commit 99f35e3f8b
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4 changed files with 43 additions and 63 deletions
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6
lucene/core/src/java/org/apache/lucene/util/BitSet.java
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@ -90,7 +90,11 @@ public abstract class BitSet implements Bits, Accountable {
* Returns the index of the first set bit starting at the index specified. {@link
* DocIdSetIterator#NO_MORE_DOCS} is returned if there are no more set bits.
*/
public abstract int nextSetBit(int index);
public int nextSetBit(int index) {
// Default implementation. Subclasses may be able to override with a more performant
// implementation.
return nextSetBit(index, length());
}
/**
* Returns the index of the first set bit from start (inclusive) until end (exclusive). {@link

38
lucene/core/src/java/org/apache/lucene/util/FixedBitSet.java
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@ -272,27 +272,23 @@ public final class FixedBitSet extends BitSet {
@Override
public int nextSetBit(int index) {
// Depends on the ghost bits being clear!
assert index >= 0 && index < numBits : "index=" + index + ", numBits=" + numBits;
int i = index >> 6;
long word = bits[i] >> index; // skip all the bits to the right of index
if (word != 0) {
return index + Long.numberOfTrailingZeros(word);
}
while (++i < numWords) {
word = bits[i];
if (word != 0) {
return (i << 6) + Long.numberOfTrailingZeros(word);
}
}
return DocIdSetIterator.NO_MORE_DOCS;
// Override with a version that skips the bound check on the result since we know it will not
// go OOB:
return nextSetBitInRange(index, numBits);
}
@Override
public int nextSetBit(int start, int upperBound) {
int res = nextSetBitInRange(start, upperBound);
return res < upperBound ? res : DocIdSetIterator.NO_MORE_DOCS;
}
/**
* Returns the next set bit in the specified range, but treats `upperBound` as a best-effort hint
* rather than a hard requirement. Note that this may return a result that is >= upperBound in
* some cases, so callers must add their own check if `upperBound` is a hard requirement.
*/
private int nextSetBitInRange(int start, int upperBound) {
// Depends on the ghost bits being clear!
assert start >= 0 && start < numBits : "index=" + start + ", numBits=" + numBits;
assert start < upperBound : "index=" + start + ", upperBound=" + upperBound;
@ -301,16 +297,14 @@ public final class FixedBitSet extends BitSet {
long word = bits[i] >> start; // skip all the bits to the right of index
if (word != 0) {
int res = start + Long.numberOfTrailingZeros(word);
return res < upperBound ? res : DocIdSetIterator.NO_MORE_DOCS;
return start + Long.numberOfTrailingZeros(word);
}
int limit = bits2words(upperBound);
int limit = upperBound == numBits ? numWords : bits2words(upperBound);
while (++i < limit) {
word = bits[i];
if (word != 0) {
int res = (i << 6) + Long.numberOfTrailingZeros(word);
return res < upperBound ? res : DocIdSetIterator.NO_MORE_DOCS;
return (i << 6) + Long.numberOfTrailingZeros(word);
}
}

50
lucene/core/src/java/org/apache/lucene/util/SparseFixedBitSet.java
View File

@ -337,36 +337,26 @@ public class SparseFixedBitSet extends BitSet {
@Override
public int nextSetBit(int i) {
assert i < length;
final int i4096 = i >>> 12;
final long index = indices[i4096];
final long[] bitArray = this.bits[i4096];
int i64 = i >>> 6;
int o = Long.bitCount(index & ((1L << i64) - 1));
if ((index & (1L << i64)) != 0) {
// There is at least one bit that is set in the current long, check if
// one of them is after i
final long bits = bitArray[o] >>> i; // shifts are mod 64
if (bits != 0) {
return i + Long.numberOfTrailingZeros(bits);
}
o += 1;
}
final long indexBits = index >>> i64 >>> 1;
if (indexBits == 0) {
// no more bits are set in the current block of 4096 bits, go to the next one
return firstDoc(i4096 + 1, indices.length);
}
// there are still set bits
i64 += 1 + Long.numberOfTrailingZeros(indexBits);
final long bits = bitArray[o];
return (i64 << 6) | Long.numberOfTrailingZeros(bits);
// Override with a version that skips the bound check on the result since we know it will not
// go OOB:
return nextSetBitInRange(i, length);
}
@Override
public int nextSetBit(int start, int upperBound) {
int res = nextSetBitInRange(start, upperBound);
return res < upperBound ? res : DocIdSetIterator.NO_MORE_DOCS;
}
/**
* Returns the next set bit in the specified range, but treats `upperBound` as a best-effort hint
* rather than a hard requirement. Note that this may return a result that is >= upperBound in
* some cases, so callers must add their own check if `upperBound` is a hard requirement.
*/
private int nextSetBitInRange(int start, int upperBound) {
assert start < length;
assert upperBound > start;
assert upperBound > start && upperBound <= length
: "upperBound=" + upperBound + ", start=" + start + ", length=" + length;
final int i4096 = start >>> 12;
final long index = indices[i4096];
final long[] bitArray = this.bits[i4096];
@ -378,22 +368,20 @@ public class SparseFixedBitSet extends BitSet {
// one of them is after i
final long bits = bitArray[o] >>> start; // shifts are mod 64
if (bits != 0) {
int res = start + Long.numberOfTrailingZeros(bits);
return res < upperBound ? res : DocIdSetIterator.NO_MORE_DOCS;
return start + Long.numberOfTrailingZeros(bits);
}
o += 1;
}
final long indexBits = index >>> i64 >>> 1;
if (indexBits == 0) {
// no more bits are set in the current block of 4096 bits, go to the next one
int res = firstDoc(i4096 + 1, blockCount(upperBound));
return res < upperBound ? res : DocIdSetIterator.NO_MORE_DOCS;
int i4096upper = upperBound == length ? indices.length : blockCount(upperBound);
return firstDoc(i4096 + 1, i4096upper);
}
// there are still set bits
i64 += 1 + Long.numberOfTrailingZeros(indexBits);
final long bits = bitArray[o];
int res = (i64 << 6) | Long.numberOfTrailingZeros(bits);
return res < upperBound ? res : DocIdSetIterator.NO_MORE_DOCS;
return (i64 << 6) | Long.numberOfTrailingZeros(bits);
}
/** Return the last document that occurs on or before the provided block index. */

12
lucene/test-framework/src/java/org/apache/lucene/tests/util/BaseBitSetTestCase.java
View File

@ -341,18 +341,12 @@ public abstract class BaseBitSetTestCase<T extends BitSet> extends LuceneTestCas
}
@Override
public int nextSetBit(int i) {
int next = bitSet.nextSetBit(i);
if (next == -1) {
public int nextSetBit(int start, int upperBound) {
int next = bitSet.nextSetBit(start);
if (next == -1 || next >= upperBound) {
next = DocIdSetIterator.NO_MORE_DOCS;
}
return next;
}
@Override
public int nextSetBit(int start, int upperBound) {
int res = nextSetBit(start);
return res < upperBound ? res : DocIdSetIterator.NO_MORE_DOCS;
}
}
}