ARROW-10294: [Java] Resolve problems of DecimalVector APIs on ArrowBufs

java/vector/src/main/codegen/data/ValueVectorTypes.tdd

@@ -125,7 +125,7 @@
           maxPrecisionDigits: 38, nDecimalDigits: 4, friendlyType: "BigDecimal",
           typeParams: [ {name: "scale", type: "int"}, { name: "precision", type: "int"}],
           arrowType: "org.apache.arrow.vector.types.pojo.ArrowType.Decimal",
-          fields: [{name: "start", type: "int"}, {name: "buffer", type: "ArrowBuf"}]
+          fields: [{name: "start", type: "long"}, {name: "buffer", type: "ArrowBuf"}]
         }
       ]
     },

java/vector/src/main/codegen/templates/ComplexWriters.java

@@ -139,12 +139,12 @@ public void write(NullableDecimalHolder h){
     vector.setValueCount(idx() + 1);
   }
 
-  public void writeDecimal(int start, ArrowBuf buffer){
+  public void writeDecimal(long start, ArrowBuf buffer){
     vector.setSafe(idx(), 1, start, buffer);
     vector.setValueCount(idx() + 1);
   }
 
-  public void writeDecimal(int start, ArrowBuf buffer, ArrowType arrowType){
+  public void writeDecimal(long start, ArrowBuf buffer, ArrowType arrowType){
     DecimalUtility.checkPrecisionAndScale(((ArrowType.Decimal) arrowType).getPrecision(),
       ((ArrowType.Decimal) arrowType).getScale(), vector.getPrecision(), vector.getScale());
     vector.setSafe(idx(), 1, start, buffer);

java/vector/src/main/codegen/templates/UnionFixedSizeListWriter.java

@@ -189,7 +189,7 @@ public void writeNull() {
     writer.writeNull();
   }
 
-  public void writeDecimal(int start, ArrowBuf buffer, ArrowType arrowType) {
+  public void writeDecimal(long start, ArrowBuf buffer, ArrowType arrowType) {
     if (writer.idx() >= (idx() + 1) * listSize) {
       throw new IllegalStateException(String.format("values at index %s is greater than listSize %s", idx(), listSize));
     }

java/vector/src/main/codegen/templates/UnionListWriter.java

@@ -204,12 +204,12 @@ public void writeNull() {
     writer.writeNull();
   }
 
-  public void writeDecimal(int start, ArrowBuf buffer, ArrowType arrowType) {
+  public void writeDecimal(long start, ArrowBuf buffer, ArrowType arrowType) {
     writer.writeDecimal(start, buffer, arrowType);
     writer.setPosition(writer.idx()+1);
   }
 
-  public void writeDecimal(int start, ArrowBuf buffer) {
+  public void writeDecimal(long start, ArrowBuf buffer) {
     writer.writeDecimal(start, buffer);
     writer.setPosition(writer.idx()+1);
   }

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

@@ -246,7 +246,7 @@ public void setBigEndian(int index, byte[] value) {
    * @param start    start index of data in the buffer
    * @param buffer   ArrowBuf containing decimal value.
    */
-  public void set(int index, int start, ArrowBuf buffer) {
+  public void set(int index, long start, ArrowBuf buffer) {
     BitVectorHelper.setBit(validityBuffer, index);
     valueBuffer.setBytes((long) index * TYPE_WIDTH, buffer, start, TYPE_WIDTH);
   }
@@ -258,7 +258,7 @@ public void set(int index, int start, ArrowBuf buffer) {
    * @param buffer contains the decimal in little endian bytes
    * @param length length of the value in the buffer
    */
-  public void setSafe(int index, int start, ArrowBuf buffer, int length) {
+  public void setSafe(int index, long start, ArrowBuf buffer, int length) {
     handleSafe(index);
     BitVectorHelper.setBit(validityBuffer, index);
 
@@ -285,7 +285,7 @@ public void setSafe(int index, int start, ArrowBuf buffer, int length) {
    * @param buffer contains the decimal in big endian bytes
    * @param length length of the value in the buffer
    */
-  public void setBigEndianSafe(int index, int start, ArrowBuf buffer, int length) {
+  public void setBigEndianSafe(int index, long start, ArrowBuf buffer, int length) {
     handleSafe(index);
     BitVectorHelper.setBit(validityBuffer, index);
 
@@ -394,7 +394,7 @@ public void setBigEndianSafe(int index, byte[] value) {
    * @param start    start index of data in the buffer
    * @param buffer   ArrowBuf containing decimal value.
    */
-  public void setSafe(int index, int start, ArrowBuf buffer) {
+  public void setSafe(int index, long start, ArrowBuf buffer) {
     handleSafe(index);
     set(index, start, buffer);
   }
@@ -460,7 +460,7 @@ public void setSafe(int index, DecimalHolder holder) {
    * @param start start position of the value in the buffer
    * @param buffer buffer containing the value to be stored in the vector
    */
-  public void set(int index, int isSet, int start, ArrowBuf buffer) {
+  public void set(int index, int isSet, long start, ArrowBuf buffer) {
     if (isSet > 0) {
       set(index, start, buffer);
     } else {
@@ -478,7 +478,7 @@ public void set(int index, int isSet, int start, ArrowBuf buffer) {
    * @param start start position of the value in the buffer
    * @param buffer buffer containing the value to be stored in the vector
    */
-  public void setSafe(int index, int isSet, int start, ArrowBuf buffer) {
+  public void setSafe(int index, int isSet, long start, ArrowBuf buffer) {
     handleSafe(index);
     set(index, isSet, start, buffer);
   }

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

@@ -320,7 +320,7 @@ public void write(DecimalHolder holder) {
   }
 
   @Override
-  public void writeDecimal(int start, ArrowBuf buffer, ArrowType arrowType) {
+  public void writeDecimal(long start, ArrowBuf buffer, ArrowType arrowType) {
     getWriter(MinorType.DECIMAL, new ArrowType.Decimal(MAX_DECIMAL_PRECISION,
         ((ArrowType.Decimal) arrowType).getScale())).writeDecimal(start, buffer, arrowType);
   }

java/vector/src/main/java/org/apache/arrow/vector/util/DecimalUtility.java

@@ -42,7 +42,7 @@ private DecimalUtility() {}
   public static BigDecimal getBigDecimalFromArrowBuf(ArrowBuf bytebuf, int index, int scale) {
     byte[] value = new byte[DECIMAL_BYTE_LENGTH];
     byte temp;
-    final int startIndex = index * DECIMAL_BYTE_LENGTH;
+    final long startIndex = (long) index * DECIMAL_BYTE_LENGTH;
 
     // Decimal stored as little endian, need to swap bytes to make BigDecimal
     bytebuf.getBytes(startIndex, value, 0, DECIMAL_BYTE_LENGTH);

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

@@ -21,9 +21,12 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
+import java.math.BigDecimal;
+
 import org.apache.arrow.memory.ArrowBuf;
 import org.apache.arrow.memory.BufferAllocator;
 import org.apache.arrow.memory.RootAllocator;
+import org.apache.arrow.vector.holders.NullableDecimalHolder;
 import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -114,7 +117,7 @@ public void testLargeDecimalVector() {
     final int vecLength = (int) (bufSize / DecimalVector.TYPE_WIDTH);
 
     try (BufferAllocator allocator = new RootAllocator(Long.MAX_VALUE);
-         DecimalVector largeVec = new DecimalVector("vec", allocator, 38, 16)) {
+         DecimalVector largeVec = new DecimalVector("vec", allocator, 38, 0)) {
       largeVec.allocateNew(vecLength);
 
       logger.trace("Successfully allocated a vector with capacity {}", vecLength);
@@ -139,6 +142,22 @@ public void testLargeDecimalVector() {
         }
       }
       logger.trace("Successfully read {} values", vecLength);
+
+      // try setting values with a large offset in the buffer
+      largeVec.set(vecLength - 1, 12345L);
+      assertEquals(12345L, largeVec.getObject(vecLength - 1).longValue());
+
+      NullableDecimalHolder holder = new NullableDecimalHolder();
+      holder.buffer = largeVec.valueBuffer;
+      holder.isSet = 1;
+      holder.start = (long) (vecLength - 1) * largeVec.getTypeWidth();
+      assertTrue(holder.start > Integer.MAX_VALUE);
+      largeVec.set(0, holder);
+
+      BigDecimal decimal = largeVec.getObject(0);
+      assertEquals(12345L, decimal.longValue());
+
+      logger.trace("Successfully setting values from large offsets");
     }
     logger.trace("Successfully released the large vector.");
   }