jpountz commented on code in PR #12841:
URL: https://github.com/apache/lucene/pull/12841#discussion_r1415213374
##########
lucene/core/src/java/org/apache/lucene/store/ByteBuffersDataInput.java:
##########
@@ -212,6 +213,46 @@ public long readLong() throws IOException {
}
}
+ @Override
+ public void readGroupVInts(long[] dst, int limit) throws IOException {
+ int i;
+ for (i = 0; i <= limit - 4; i += 4) {
+ readGroupVInt(dst, i);
+ }
+ for (; i < limit; ++i) {
+ dst[i] = readVInt();
+ }
+ }
+
+ private void readGroupVInt(long[] dst, int offset) throws IOException {
+ ByteBuffer block = blocks[blockIndex(pos)];
+ int blockOffset = blockOffset(pos);
+ if (block.limit() - blockOffset < GroupVIntUtil.MAX_LENGTH_PER_GROUP) {
+ GroupVIntUtil.fallbackReadGroupVInt(this, dst, 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);
Review Comment:
We already computed `blockOffset()` above, can we avoid computing it twice,
e.g. by replacing the `readByte()` call with `block.get(blockOffset++)`?
##########
lucene/core/src/java/org/apache/lucene/store/DataOutput.java:
##########
@@ -29,6 +30,7 @@
* internal state like file position).
*/
public abstract class DataOutput {
+ private BytesRefBuilder groupVIntBytes = new BytesRefBuilder();
Review Comment:
Can it be made final?
##########
lucene/test-framework/src/java/org/apache/lucene/tests/store/BaseDirectoryTestCase.java:
##########
@@ -1438,4 +1440,68 @@ public void testListAllIsSorted() throws IOException {
assertArrayEquals(expected, actual);
}
}
+
+ public void testDataTypes() throws IOException {
+ final long[] values = new long[] {43, 12345, 123456, 1234567890};
+ try (Directory dir = getDirectory(createTempDir("testDataTypes"))) {
+ IndexOutput out = dir.createOutput("test", IOContext.DEFAULT);
+ out.writeByte((byte) 43);
+ out.writeShort((short) 12345);
+ out.writeInt(1234567890);
+ out.writeGroupVInts(values, 4);
+ out.writeLong(1234567890123456789L);
+ out.close();
+
+ long[] restored = new long[4];
+ IndexInput in = dir.openInput("test", IOContext.DEFAULT);
+ assertEquals(43, in.readByte());
+ assertEquals(12345, in.readShort());
+ assertEquals(1234567890, in.readInt());
+ in.readGroupVInts(restored, 4);
+ assertArrayEquals(values, restored);
+ assertEquals(1234567890123456789L, in.readLong());
+ in.close();
+ }
+ }
+
+ public void testGroupVInt() throws IOException {
+ try (Directory dir = getDirectory(createTempDir("testGroupVInt"))) {
+ // test fallbackReadGroupVInt
+ doTestGroupVInt(dir, 5, 1, 6, 8);
+
+ // test large data to covers multiple blocks in ByteBuffersDataInput
Review Comment:
adding it explicitly since this is probably the most important case to cover
```suggestion
// test large data to covers multiple blocks in ByteBuffersDataInput
and MMapDirectory via TestMultiMMap
```
##########
lucene/core/src/java21/org/apache/lucene/store/MemorySegmentIndexInput.java:
##########
@@ -303,6 +304,48 @@ public byte readByte(long pos) throws IOException {
}
}
+ @Override
+ public void readGroupVInts(long[] dst, int limit) throws IOException {
+ int i;
+ for (i = 0; i <= limit - 4; i += 4) {
+ readGroupVInt(dst, i);
+ }
+ for (; i < limit; ++i) {
+ dst[i] = readVInt();
+ }
+ }
+
+ private void readGroupVInt(long[] dst, int offset) throws IOException {
+ if (curSegment.byteSize() - curPosition <
GroupVIntUtil.MAX_LENGTH_PER_GROUP) {
+ GroupVIntUtil.fallbackReadGroupVInt(this, dst, offset);
+ return;
+ }
+
+ try {
+ final int flag = readByte() & 0xFF;
Review Comment:
Since we already did the job of checking that we have enough bytes left, we
don't need `readByte()` to do it for us?
```suggestion
final int flag = curSegment.get(LAYOUT_BYTE, curPosition++) & 0xFF;
```
##########
lucene/core/src/java21/org/apache/lucene/store/MemorySegmentIndexInput.java:
##########
@@ -303,6 +304,48 @@ public byte readByte(long pos) throws IOException {
}
}
+ @Override
+ public void readGroupVInts(long[] dst, int limit) throws IOException {
+ int i;
+ for (i = 0; i <= limit - 4; i += 4) {
+ readGroupVInt(dst, i);
+ }
+ for (; i < limit; ++i) {
+ dst[i] = readVInt();
+ }
+ }
+
+ private void readGroupVInt(long[] dst, int offset) throws IOException {
+ if (curSegment.byteSize() - curPosition <
GroupVIntUtil.MAX_LENGTH_PER_GROUP) {
+ GroupVIntUtil.fallbackReadGroupVInt(this, dst, offset);
+ return;
+ }
+
Review Comment:
Maybe copy `curSegment` to a local variable here, e.g. `MemorySegment
curSegment = this.curSegment` so that the JVM doesn't have to worry about
`curSegment` getting updated?
##########
lucene/core/src/java/org/apache/lucene/util/GroupVIntUtil.java:
##########
@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.lucene.util;
+
+import java.io.IOException;
+import org.apache.lucene.store.DataInput;
+
+/**
+ * This class contains utility methods and constants for group varint
+ *
+ * @lucene.internal
+ */
+public final class GroupVIntUtil {
+ // the maximum length of a single group-varint is 4 integers + 1 byte flag.
+ public static final int MAX_LENGTH_PER_GROUP = 17;
+ public static final int[] GROUP_VINT_MASKS = new int[] {0xFF, 0xFFFF,
0xFFFFFF, 0xFFFFFFFF};
+
+ /**
+ * Read single group varint. we need a long[] because this is what postings
are using.
+ *
+ * @param dst the array to read ints into.
+ * @param offset the offset in the array to start storing ints.
+ */
+ public static void fallbackReadGroupVInt(DataInput in, long[] dst, int
offset)
Review Comment:
It doesn't need `fallback` as a prefix anymore now that it's in its own
class. Let's document that this is a default implementation and that it is
recommended to use `DataInput#readGroupVInts` directly rather than this method?
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