jpountz commented on code in PR #12841:
URL: https://github.com/apache/lucene/pull/12841#discussion_r1412795418
##########
lucene/core/src/java/org/apache/lucene/store/DataOutput.java:
##########
@@ -324,4 +326,41 @@ public void writeSetOfStrings(Set<String> set) throws
IOException {
writeString(value);
}
}
+
+ /**
+ * Encode integers using group-varint. It uses VInt to encode tail values
that are not enough for
Review Comment:
Add a javadoc link to #writeVInt? Also mention that all longs are actually
required to be integers?
##########
lucene/core/src/java/org/apache/lucene/store/ByteBuffersDataInput.java:
##########
@@ -212,6 +224,51 @@ public long readLong() throws IOException {
}
}
+ @Override
+ public void readGroupVInts(long[] docs, int limit) throws IOException {
+ if (asReadOnlyBuffer == true) {
+ super.readGroupVInts(docs, limit);
+ return;
+ }
+
+ int i;
+ for (i = 0; i <= limit - 4; i += 4) {
+ readGroupVInt(docs, i);
+ }
+ for (; i < limit; ++i) {
+ docs[i] = readVInt();
+ }
+ }
+
+ private void readGroupVInt(long[] docs, int offset) throws IOException {
+ int blockOffset = blockOffset(pos);
+ if (blockOffset + MAX_LENGTH_PER_GROUP <= blockMask) {
+ super.fallbackReadGroupVInt(docs, offset);
+ return;
+ }
+
+ final int flag = readByte() & 0xFF;
+
+ final int n1Minus1 = flag >> 6;
+ final int n2Minus1 = (flag >> 4) & 0x03;
+ final int n3Minus1 = (flag >> 2) & 0x03;
+ final int n4Minus1 = flag & 0x03;
+
+ blockOffset = blockOffset(pos);
+ int curPosition = blockOffset;
+
+ byte[] bytes = blocks[blockIndex(pos)].array();
+ docs[offset] = (int) BitUtil.VH_LE_INT.get(bytes, curPosition) &
GROUP_VINT_MASKS[n1Minus1];
Review Comment:
I'd rather work on the ByteBuffer (ie. do ByteBuffer#getInt rather than
using var handles on the underlying byte[]), even if performance is a bit
better by working directly on the byte[].
##########
lucene/core/src/java/org/apache/lucene/store/DataInput.java:
##########
@@ -38,6 +38,9 @@
* positioned independently.
*/
public abstract class DataInput implements Cloneable {
+ // the maximum length of a single group-varint is 4 integers + 1 byte flag.
+ static final int MAX_LENGTH_PER_GROUP = 17;
+ static final int[] GROUP_VINT_MASKS = new int[] {0xFF, 0xFFFF, 0xFFFFFF,
0xFFFFFFFF};
Review Comment:
Nit: I would like it better if these constants and `fallbackReadGroupVInt`
were moved to a helper class, e.g. `org.apache.lucene.util.GroupVIntUtil`.
##########
lucene/core/src/test/org/apache/lucene/codecs/lucene99/TestGroupVInt.java:
##########
@@ -18,38 +18,144 @@
import com.carrotsearch.randomizedtesting.generators.RandomNumbers;
import java.io.IOException;
-import org.apache.lucene.store.ByteArrayDataInput;
-import org.apache.lucene.store.ByteArrayDataOutput;
+import java.nio.file.Files;
+import java.util.Locale;
+import java.util.function.BiFunction;
+import org.apache.lucene.store.ByteBuffersDataInput;
+import org.apache.lucene.store.ByteBuffersDataOutput;
+import org.apache.lucene.store.ByteBuffersDirectory;
+import org.apache.lucene.store.ByteBuffersIndexInput;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.store.FilterDirectory;
+import org.apache.lucene.store.FilterIndexInput;
+import org.apache.lucene.store.IOContext;
+import org.apache.lucene.store.IndexInput;
+import org.apache.lucene.store.IndexOutput;
+import org.apache.lucene.store.MMapDirectory;
+import org.apache.lucene.store.NIOFSDirectory;
+import org.apache.lucene.store.SingleInstanceLockFactory;
import org.apache.lucene.tests.util.LuceneTestCase;
import org.apache.lucene.tests.util.TestUtil;
import org.apache.lucene.util.ArrayUtil;
import org.apache.lucene.util.packed.PackedInts;
public class TestGroupVInt extends LuceneTestCase {
Review Comment:
Should we move these tests to BaseDirectoryTestCase now, to automatically
get coverage across all directories?
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