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new c3601a97a0 GH-44344: [Java] fix VectorSchemaRoot.getTransferPair for
NullVector (#44631)
c3601a97a0 is described below
commit c3601a97a0718ae47726e6c134cbed4b98bd1a36
Author: Maksim Yegorov <[email protected]>
AuthorDate: Tue Nov 5 19:07:06 2024 -0500
GH-44344: [Java] fix VectorSchemaRoot.getTransferPair for NullVector
(#44631)
### Rationale for this change
Do not throw [UnsupportedOperationException("Tried to get allocator from
NullVector")](https://github.com/apache/arrow/blob/release-18.0.0-rc0/java/vector/src/main/java/org/apache/arrow/vector/NullVector.java#L160)
from
[VectorSchemaRoot.slice()](https://github.com/apache/arrow/blob/release-18.0.0-rc0/java/vector/src/main/java/org/apache/arrow/vector/VectorSchemaRoot.java#L341)
when slicing a VSR containing a NullVector or ZeroVector. Details in
https://github.com/apache/arrow/issues/44344
### Are these changes tested?
Added unit test that would trigger an UnsupportedOperationException on the
legacy path.
* GitHub Issue: #44344
Authored-by: Maksim Yegorov
<[email protected]>
Signed-off-by: David Li <[email protected]>
---
.../java/org/apache/arrow/vector/NullVector.java | 9 +++++++-
.../java/org/apache/arrow/vector/ValueVector.java | 6 ++++++
.../apache/arrow/vector/TestSplitAndTransfer.java | 25 ++++++++++++++++++++++
3 files changed, 39 insertions(+), 1 deletion(-)
diff --git a/java/vector/src/main/java/org/apache/arrow/vector/NullVector.java
b/java/vector/src/main/java/org/apache/arrow/vector/NullVector.java
index 227ca716f6..6bfe540d23 100644
--- a/java/vector/src/main/java/org/apache/arrow/vector/NullVector.java
+++ b/java/vector/src/main/java/org/apache/arrow/vector/NullVector.java
@@ -155,9 +155,16 @@ public class NullVector implements FieldVector,
ValueIterableVector<Object> {
@Override
public void reAlloc() {}
+ /*
+ * IMPORTANT NOTE
+ * It's essential that NullVector (and ZeroVector) do not require
BufferAllocator for any data storage.
+ * However, some methods of the parent interface may require passing in a
BufferAllocator, even if null.
+ *
+ * @return null
+ */
@Override
public BufferAllocator getAllocator() {
- throw new UnsupportedOperationException("Tried to get allocator from
NullVector");
+ return null;
}
@Override
diff --git a/java/vector/src/main/java/org/apache/arrow/vector/ValueVector.java
b/java/vector/src/main/java/org/apache/arrow/vector/ValueVector.java
index 724941aa2a..0a45409eb9 100644
--- a/java/vector/src/main/java/org/apache/arrow/vector/ValueVector.java
+++ b/java/vector/src/main/java/org/apache/arrow/vector/ValueVector.java
@@ -80,6 +80,12 @@ public interface ValueVector extends Closeable,
Iterable<ValueVector> {
*/
void reAlloc();
+ /**
+ * Get the allocator associated with the vector. CAVEAT: Some ValueVector
subclasses (e.g.
+ * NullVector) do not require an allocator for data storage and may return
null.
+ *
+ * @return Returns nullable allocator.
+ */
BufferAllocator getAllocator();
/**
diff --git
a/java/vector/src/test/java/org/apache/arrow/vector/TestSplitAndTransfer.java
b/java/vector/src/test/java/org/apache/arrow/vector/TestSplitAndTransfer.java
index a3f25bc520..6aace95621 100644
---
a/java/vector/src/test/java/org/apache/arrow/vector/TestSplitAndTransfer.java
+++
b/java/vector/src/test/java/org/apache/arrow/vector/TestSplitAndTransfer.java
@@ -198,6 +198,31 @@ public class TestSplitAndTransfer {
toDUV.clear();
}
+ @Test
+ public void testWithNullVector() {
+ int valueCount = 123;
+ int startIndex = 10;
+ NullVector fromNullVector = new NullVector("nullVector");
+ fromNullVector.setValueCount(valueCount);
+ TransferPair transferPair =
fromNullVector.getTransferPair(fromNullVector.getAllocator());
+ transferPair.splitAndTransfer(startIndex, valueCount - startIndex);
+ NullVector toNullVector = (NullVector) transferPair.getTo();
+
+ assertEquals(valueCount - startIndex, toNullVector.getValueCount());
+ // no allocations to clear for NullVector
+ }
+
+ @Test
+ public void testWithZeroVector() {
+ ZeroVector fromZeroVector = new ZeroVector("zeroVector");
+ TransferPair transferPair =
fromZeroVector.getTransferPair(fromZeroVector.getAllocator());
+ transferPair.splitAndTransfer(0, 0);
+ ZeroVector toZeroVector = (ZeroVector) transferPair.getTo();
+
+ assertEquals(0, toZeroVector.getValueCount());
+ // no allocations to clear for ZeroVector
+ }
+
@Test /* VarCharVector */
public void test() throws Exception {
try (final VarCharVector varCharVector = new VarCharVector("myvector",
allocator)) {
