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GH-44626: [Java] fix SplitAndTransfer throws for empty MapVector #44627

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Merged
lidavidm merged 1 commit into from
Nov 8, 2024
Merged

GH-44626: [Java] fix SplitAndTransfer throws for empty MapVector #44627

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32 changes: 17 additions & 15 deletions java/vector/src/main/java/org/apache/arrow/vector/complex/MapVector.java
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Original file line number Diff line number Diff line change
Expand Up @@ -211,23 +211,25 @@ public void splitAndTransfer(int startIndex, int length) {
startIndex,
length,
valueCount);
final int startPoint = offsetBuffer.getInt(startIndex * OFFSET_WIDTH);
final int sliceLength =
offsetBuffer.getInt((startIndex + length) * OFFSET_WIDTH) - startPoint;
to.clear();
to.offsetBuffer = to.allocateOffsetBuffer((length + 1) * OFFSET_WIDTH);
/* splitAndTransfer offset buffer */
for (int i = 0; i < length + 1; i++) {
final int relativeOffset =
offsetBuffer.getInt((startIndex + i) * OFFSET_WIDTH) - startPoint;
to.offsetBuffer.setInt(i * OFFSET_WIDTH, relativeOffset);
if (length > 0) {
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@vibhatha vibhatha Nov 3, 2024

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can we just return if length=0

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@myegorov myegorov Nov 4, 2024

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Can do though my personal preference would be to avoid multiple returns. Current implementation is in keeping with how splitAndTransfer is implemented for other complex types (e.g. ListVector).

final int startPoint = offsetBuffer.getInt(startIndex * OFFSET_WIDTH);
final int sliceLength =
offsetBuffer.getInt((startIndex + length) * OFFSET_WIDTH) - startPoint;
to.offsetBuffer = to.allocateOffsetBuffer((length + 1) * OFFSET_WIDTH);
/* splitAndTransfer offset buffer */
for (int i = 0; i < length + 1; i++) {
final int relativeOffset =
offsetBuffer.getInt((startIndex + i) * OFFSET_WIDTH) - startPoint;
to.offsetBuffer.setInt(i * OFFSET_WIDTH, relativeOffset);
}
/* splitAndTransfer validity buffer */
splitAndTransferValidityBuffer(startIndex, length, to);
/* splitAndTransfer data buffer */
dataTransferPair.splitAndTransfer(startPoint, sliceLength);
to.lastSet = length - 1;
to.setValueCount(length);
}
/* splitAndTransfer validity buffer */
splitAndTransferValidityBuffer(startIndex, length, to);
/* splitAndTransfer data buffer */
dataTransferPair.splitAndTransfer(startPoint, sliceLength);
to.lastSet = length - 1;
to.setValueCount(length);
}

/*
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38 changes: 38 additions & 0 deletions java/vector/src/test/java/org/apache/arrow/vector/TestSplitAndTransfer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -16,14 +16,17 @@
*/
package org.apache.arrow.vector;

import static java.util.Arrays.asList;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.arrow.memory.BufferAllocator;
import org.apache.arrow.memory.RootAllocator;
Expand All @@ -36,6 +39,7 @@
import org.apache.arrow.vector.complex.UnionVector;
import org.apache.arrow.vector.types.pojo.ArrowType;
import org.apache.arrow.vector.types.pojo.ArrowType.Struct;
import org.apache.arrow.vector.types.pojo.Field;
import org.apache.arrow.vector.types.pojo.FieldType;
import org.apache.arrow.vector.util.TransferPair;
import org.junit.jupiter.api.AfterEach;
Expand Down Expand Up @@ -223,6 +227,40 @@ public void testWithZeroVector() {
// no allocations to clear for ZeroVector
}

@Test
public void testListVectorWithEmptyMapVector() {
// List<element: Map(false)<entries: Struct<key: Utf8 not null, value: Utf8> not null>>
int valueCount = 1;
List<Field> children = new ArrayList<>();
children.add(new Field("key", FieldType.notNullable(new ArrowType.Utf8()), null));
children.add(new Field("value", FieldType.nullable(new ArrowType.Utf8()), null));
Field structField =
new Field("entries", FieldType.notNullable(ArrowType.Struct.INSTANCE), children);

Field mapField =
new Field("element", FieldType.notNullable(new ArrowType.Map(false)), asList(structField));

Field listField = new Field("list", FieldType.nullable(new ArrowType.List()), asList(mapField));

ListVector fromListVector = (ListVector) listField.createVector(allocator);
fromListVector.allocateNew();
fromListVector.setValueCount(valueCount);

// child vector is empty
MapVector dataVector = (MapVector) fromListVector.getDataVector();
dataVector.allocateNew();
// unset capacity to mimic observed failure mode
dataVector.getOffsetBuffer().capacity(0);
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@lidavidm lidavidm Nov 8, 2024

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Hmm, a list vector is supposed to have 1 offset when it's empty. But I suppose other parts of the library have this issue/"optimization"


TransferPair transferPair = fromListVector.getTransferPair(fromListVector.getAllocator());
transferPair.splitAndTransfer(0, valueCount);
ListVector toListVector = (ListVector) transferPair.getTo();

assertEquals(valueCount, toListVector.getValueCount());
fromListVector.clear();
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@vibhatha vibhatha Nov 3, 2024

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nit: use try-with-resources

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@myegorov myegorov Nov 4, 2024

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Note that there're several closeable resources here and toListVector cannot be constructed inside the same try as fromListVector. This is just to say that there'd be some ugly nesting if using try.

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@vibhatha vibhatha Nov 4, 2024

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Right. Sure.

toListVector.clear();
}

@Test /* VarCharVector */
public void test() throws Exception {
try (final VarCharVector varCharVector = new VarCharVector("myvector", allocator)) {
Expand Down