apacheGH-40038: [Java] The offset buffer of empty vector with variabl…

…e-size layout should not be empty

java/adapter/jdbc/src/test/java/org/apache/arrow/adapter/jdbc/ResultSetUtilityTest.java

@@ -50,6 +50,7 @@ public void testZeroRowResultSet() throws Exception {
         assertNotNull("VectorSchemaRoot from first next() result should never be null", root);
         assertEquals("VectorSchemaRoot from empty ResultSet should have zero rows", 0, root.getRowCount());
         assertFalse("hasNext() should return false on empty ResultSets after initial next() call", iter.hasNext());
+        root.close();
       }
     }
   }

java/flight/flight-core/src/test/java/org/apache/arrow/flight/TestDictionaryUtils.java

@@ -87,6 +87,8 @@ public void testCreateSchema() {
 
       assertEquals(1, dictionaryUsed.size());
       assertEquals(0, dictionaryUsed.first());
+
+      dictVec.close();
     }
   }
 }

java/vector/src/main/java/org/apache/arrow/vector/BaseLargeVariableWidthVector.java

@@ -73,7 +73,8 @@ public BaseLargeVariableWidthVector(Field field, final BufferAllocator allocator
     lastValueCapacity = INITIAL_VALUE_ALLOCATION - 1;
     valueCount = 0;
     lastSet = -1;
-    offsetBuffer = allocator.getEmpty();
+    // According to Arrow spec, the offsets buffer contains length + 1 elements
+    allocateOffsetBuffer(OFFSET_WIDTH);
     validityBuffer = allocator.getEmpty();
     valueBuffer = allocator.getEmpty();
   }

java/vector/src/main/java/org/apache/arrow/vector/BaseVariableWidthVector.java

@@ -74,7 +74,8 @@ public BaseVariableWidthVector(Field field, final BufferAllocator allocator) {
     lastValueCapacity = INITIAL_VALUE_ALLOCATION - 1;
     valueCount = 0;
     lastSet = -1;
-    offsetBuffer = allocator.getEmpty();
+    // According to Arrow spec, the offsets buffer contains length + 1 elements
+    allocateOffsetBuffer(OFFSET_WIDTH);
     validityBuffer = allocator.getEmpty();
     valueBuffer = allocator.getEmpty();
   }

java/vector/src/main/java/org/apache/arrow/vector/complex/AbstractStructVector.java

@@ -233,6 +233,11 @@ public <T extends FieldVector> T getChild(String name, Class<T> clazz) {
 
   protected ValueVector add(String childName, FieldType fieldType) {
     FieldVector vector = fieldType.createNewSingleVector(childName, allocator, callBack);
+
+    if (conflictPolicy == ConflictPolicy.CONFLICT_REPLACE && vectors.containsKey(childName)) {
+      vectors.getAll(childName).forEach(c -> c.close());
+    }
+
     putChild(childName, vector);
     if (callBack != null) {
       callBack.doWork();

java/vector/src/main/java/org/apache/arrow/vector/complex/BaseRepeatedValueVector.java

@@ -68,7 +68,8 @@ protected BaseRepeatedValueVector(String name, BufferAllocator allocator, CallBa
   protected BaseRepeatedValueVector(String name, BufferAllocator allocator, FieldVector vector, CallBack callBack) {
     super(allocator);
     this.name = name;
-    this.offsetBuffer = allocator.getEmpty();
+    // According to Arrow spec, the offsets buffer contains length + 1 elements
+    allocateOffsetBuffer(OFFSET_WIDTH, true);
     this.vector = Preconditions.checkNotNull(vector, "data vector cannot be null");
     this.repeatedCallBack = callBack;
     this.valueCount = 0;
@@ -83,7 +84,7 @@ public String getName() {
   public boolean allocateNewSafe() {
     boolean dataAlloc = false;
     try {
-      allocateOffsetBuffer(offsetAllocationSizeInBytes);
+      allocateOffsetBuffer(offsetAllocationSizeInBytes, false);
       dataAlloc = vector.allocateNewSafe();
     } catch (Exception e) {
       e.printStackTrace();
@@ -97,11 +98,13 @@ public boolean allocateNewSafe() {
     return dataAlloc;
   }
 
-  protected void allocateOffsetBuffer(final long size) {
+  protected void allocateOffsetBuffer(final long size, boolean init) {
     final int curSize = (int) size;
     offsetBuffer = allocator.buffer(curSize);
     offsetBuffer.readerIndex(0);
-    offsetAllocationSizeInBytes = curSize;
+    if (!init) {
+      offsetAllocationSizeInBytes = curSize;
+    }
     offsetBuffer.setZero(0, offsetBuffer.capacity());
   }
 
@@ -112,7 +115,12 @@ public void reAlloc() {
   }
 
   protected void reallocOffsetBuffer() {
-    final long currentBufferCapacity = offsetBuffer.capacity();
+    final long currentBufferCapacity;
+    if (offsetBuffer.capacity() <= OFFSET_WIDTH) {
+      currentBufferCapacity = 0;
+    } else {
+      currentBufferCapacity = offsetBuffer.capacity();
+    }
     long newAllocationSize = currentBufferCapacity * 2;
     if (newAllocationSize == 0) {
       if (offsetAllocationSizeInBytes > 0) {

java/vector/src/main/java/org/apache/arrow/vector/complex/ListVector.java

@@ -535,7 +535,7 @@ public void splitAndTransfer(int startIndex, int length) {
       final int startPoint = offsetBuffer.getInt(startIndex * OFFSET_WIDTH);
       final int sliceLength = offsetBuffer.getInt((startIndex + length) * OFFSET_WIDTH) - startPoint;
       to.clear();
-      to.allocateOffsetBuffer((length + 1) * OFFSET_WIDTH);
+      to.allocateOffsetBuffer((length + 1) * OFFSET_WIDTH, false);
       /* splitAndTransfer offset buffer */
       for (int i = 0; i < length + 1; i++) {
         final int relativeOffset = offsetBuffer.getInt((startIndex + i) * OFFSET_WIDTH) - startPoint;

java/vector/src/main/java/org/apache/arrow/vector/complex/MapVector.java

@@ -209,7 +209,7 @@ public void splitAndTransfer(int startIndex, int length) {
       final int startPoint = offsetBuffer.getInt(startIndex * OFFSET_WIDTH);
       final int sliceLength = offsetBuffer.getInt((startIndex + length) * OFFSET_WIDTH) - startPoint;
       to.clear();
-      to.allocateOffsetBuffer((length + 1) * OFFSET_WIDTH);
+      to.allocateOffsetBuffer((length + 1) * OFFSET_WIDTH, false);
       /* splitAndTransfer offset buffer */
       for (int i = 0; i < length + 1; i++) {
         final int relativeOffset = offsetBuffer.getInt((startIndex + i) * OFFSET_WIDTH) - startPoint;

java/vector/src/main/java/org/apache/arrow/vector/complex/impl/UnionListReader.java

@@ -56,7 +56,7 @@ public boolean isSet() {
   @Override
   public void setPosition(int index) {
     super.setPosition(index);
-    if (vector.getOffsetBuffer().capacity() == 0) {
+    if (vector.getOffsetBuffer().capacity() <= OFFSET_WIDTH) {
       currentOffset = 0;
       maxOffset = 0;
     } else {

java/vector/src/test/java/org/apache/arrow/vector/TestDenseUnionVector.java

@@ -360,6 +360,8 @@ public void testGetFieldTypeInfo() throws Exception {
     VectorWithOrdinal varcharChild = vector.getChildVectorWithOrdinal("varchar");
     assertEquals(1, varcharChild.ordinal);
     assertEquals(varcharChild.vector.getField(), children.get(1));
+
+    vector.close();
   }
 
   @Test

java/vector/src/test/java/org/apache/arrow/vector/TestListVector.java

@@ -1153,6 +1153,8 @@ public void testGetTransferPairWithField() {
       final ListVector toVector = (ListVector) transferPair.getTo();
       // Field inside a new vector created by reusing a field should be the same in memory as the original field.
       assertSame(toVector.getField(), fromVector.getField());
+
+      toVector.close();
     }
   }
 

java/vector/src/test/java/org/apache/arrow/vector/TestUnionVector.java

@@ -415,6 +415,8 @@ public void testGetFieldTypeInfo() throws Exception {
     VectorWithOrdinal varcharChild = vector.getChildVectorWithOrdinal("varchar");
     assertEquals(1, varcharChild.ordinal);
     assertEquals(varcharChild.vector.getField(), children.get(1));
+
+    vector.close();
   }
 
   @Test

java/vector/src/test/java/org/apache/arrow/vector/TestValueVector.java

@@ -1139,7 +1139,8 @@ public void testSplitAndTransfer1() {
 
         // split and transfer with slice starting at the beginning: this should not allocate anything new
         sourceVector.splitAndTransferTo(0, 2, targetVector);
-        assertEquals(allocatedMem, allocator.getAllocatedMemory());
+        // `allocatedMem` contains initial 4 bytes for the offset buffer
+        assertEquals(allocatedMem - 4, allocator.getAllocatedMemory());
         // The validity and offset buffers are sliced from a same buffer.See BaseFixedWidthVector#allocateBytes.
         // Therefore, the refcnt of the validity buffer is increased once since the startIndex is 0. The refcnt of the
         // offset buffer is increased as well for the same reason. This amounts to a total of 2.
@@ -1173,7 +1174,8 @@ public void testSplitAndTransfer2() {
 
         // split and transfer with slice starting at the beginning: this should not allocate anything new
         sourceVector.splitAndTransferTo(0, 2, targetVector);
-        assertEquals(allocatedMem, allocator.getAllocatedMemory());
+        // `allocatedMem` contains initial 4 bytes for the offset buffer
+        assertEquals(allocatedMem - 4, allocator.getAllocatedMemory());
         // The validity and offset buffers are sliced from a same buffer.See BaseFixedWidthVector#allocateBytes.
         // Therefore, the refcnt of the validity buffer is increased once since the startIndex is 0. The refcnt of the
         // offset buffer is increased as well for the same reason. This amounts to a total of 2.
@@ -1215,7 +1217,8 @@ public void testSplitAndTransfer3() {
       final long validitySize =
           DefaultRoundingPolicy.DEFAULT_ROUNDING_POLICY.getRoundedSize(
               BaseValueVector.getValidityBufferSizeFromCount(2));
-      assertEquals(allocatedMem + validitySize, allocator.getAllocatedMemory());
+      // `allocatedMem` contains initial 4 bytes for the offset buffer
+      assertEquals(allocatedMem + validitySize - 4, allocator.getAllocatedMemory());
       // The validity and offset buffers are sliced from a same buffer.See BaseFixedWidthVector#allocateBytes.
       // Since values up to the startIndex are empty/null, the offset buffer doesn't need to be reallocated and
       // therefore its refcnt is increased by 1.
@@ -3216,7 +3219,7 @@ public void testEmptyBufBehavior() {
       assertEquals(1, vector.getOffsetBuffer().refCnt());
       assertEquals(0, vector.getDataBuffer().capacity());
       assertEquals(0, vector.getValidityBuffer().capacity());
-      assertEquals(0, vector.getOffsetBuffer().capacity());
+      assertEquals(4, vector.getOffsetBuffer().capacity());
 
       vector.allocateNew(valueCount);
       assertEquals(1, vector.getDataBuffer().refCnt());
@@ -3239,7 +3242,7 @@ public void testEmptyBufBehavior() {
       assertEquals(1, vector.getValidityBuffer().refCnt());
       assertEquals(1, vector.getOffsetBuffer().refCnt());
       assertEquals(0, vector.getValidityBuffer().capacity());
-      assertEquals(0, vector.getOffsetBuffer().capacity());
+      assertEquals(4, vector.getOffsetBuffer().capacity());
 
       vector.setValueCount(valueCount);
       vector.allocateNewSafe();