LUCENE-10329: Use computed mask for DirectMonotonicReader#get (#553)
* use computed mask
* CHANGES
* use block mask for getBounds too
Co-authored-by: guofeng.my <guofeng.my@bytedance.com>
diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 4003e88..4f0065f 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -104,6 +104,8 @@
Optimizations
---------------------
+* LUCENE-10329: Use computed block mask for DirectMonotonicReader#get. (Guo Feng)
+
* LUCENE-10280: Optimize BKD leaves' doc IDs codec when they are continuous. (Guo Feng)
* LUCENE-10233: Store BKD leaves' doc IDs as bitset in some cases (typically for low cardinality fields
diff --git a/lucene/core/src/java/org/apache/lucene/util/packed/DirectMonotonicReader.java b/lucene/core/src/java/org/apache/lucene/util/packed/DirectMonotonicReader.java
index 7feb7bd..884c664 100644
--- a/lucene/core/src/java/org/apache/lucene/util/packed/DirectMonotonicReader.java
+++ b/lucene/core/src/java/org/apache/lucene/util/packed/DirectMonotonicReader.java
@@ -127,6 +127,7 @@
}
private final int blockShift;
+ private final long blockMask;
private final LongValues[] readers;
private final long[] mins;
private final float[] avgs;
@@ -136,6 +137,7 @@
private DirectMonotonicReader(
int blockShift, LongValues[] readers, long[] mins, float[] avgs, byte[] bpvs) {
this.blockShift = blockShift;
+ this.blockMask = (1L << blockShift) - 1;
this.readers = readers;
this.mins = mins;
this.avgs = avgs;
@@ -157,7 +159,7 @@
@Override
public long get(long index) {
final int block = (int) (index >>> blockShift);
- final long blockIndex = index & ((1 << blockShift) - 1);
+ final long blockIndex = index & blockMask;
final long delta = readers[block].get(blockIndex);
return mins[block] + (long) (avgs[block] * blockIndex) + delta;
}
@@ -165,7 +167,7 @@
/** Get lower/upper bounds for the value at a given index without hitting the direct reader. */
private long[] getBounds(long index) {
final int block = Math.toIntExact(index >>> blockShift);
- final long blockIndex = index & ((1 << blockShift) - 1);
+ final long blockIndex = index & blockMask;
final long lowerBound = mins[block] + (long) (avgs[block] * blockIndex);
final long upperBound = lowerBound + (1L << bpvs[block]) - 1;
if (bpvs[block] == 64 || upperBound < lowerBound) { // overflow
