use ArrowBuf.getLong

Author: jhrotko

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

@@ -16,6 +16,7 @@
  */
 package org.apache.arrow.vector;
 
+import static org.apache.arrow.memory.util.MemoryUtil.LITTLE_ENDIAN;
 import static org.apache.arrow.vector.extension.UuidType.UUID_BYTE_WIDTH;
 
 import java.nio.ByteBuffer;
@@ -156,13 +157,17 @@ public int isSet(int index) {
    */
   public void get(int index, UuidHolder holder) {
     Preconditions.checkArgument(index >= 0, "Cannot get negative index in UUID vector.");
-    if (NullCheckingForGet.NULL_CHECKING_ENABLED && this.isSet(index) == 0) {
-      holder.isSet = 0;
+    final ArrowBuf dataBuffer = getUnderlyingVector().getDataBuffer();
+    final long start = (long) index * UUID_BYTE_WIDTH;
+    final long next = start + Long.BYTES;
+    // UUIDs are stored in big-endian byte order in Arrow buffers.
+    // ArrowBuf.getLong() reads in native byte order, so we need to reverse bytes on LE systems.
+    if (LITTLE_ENDIAN) {
+      holder.mostSigBits = Long.reverseBytes(dataBuffer.getLong(start));
+      holder.leastSigBits = Long.reverseBytes(dataBuffer.getLong(next));
     } else {
-      holder.isSet = 1;
-      final ByteBuffer bb = ByteBuffer.wrap(getUnderlyingVector().getObject(index));
-      holder.mostSigBits = bb.getLong();
-      holder.leastSigBits = bb.getLong();
+      holder.mostSigBits = dataBuffer.getLong(start);
+      holder.leastSigBits = dataBuffer.getLong(next);
     }
   }
 
@@ -178,9 +183,17 @@ public void get(int index, NullableUuidHolder holder) {
       holder.isSet = 0;
     } else {
       holder.isSet = 1;
-      final ByteBuffer bb = ByteBuffer.wrap(getUnderlyingVector().getObject(index));
-      holder.mostSigBits = bb.getLong();
-      holder.leastSigBits = bb.getLong();
+      final ArrowBuf dataBuffer = getUnderlyingVector().getDataBuffer();
+      final long offset = (long) index * UUID_BYTE_WIDTH;
+      // UUIDs are stored in big-endian byte order in Arrow buffers.
+      // ArrowBuf.getLong() reads in native byte order, so we need to reverse bytes on LE systems.
+      if (LITTLE_ENDIAN) {
+        holder.mostSigBits = Long.reverseBytes(dataBuffer.getLong(offset));
+        holder.leastSigBits = Long.reverseBytes(dataBuffer.getLong(offset + Long.BYTES));
+      } else {
+        holder.mostSigBits = dataBuffer.getLong(offset);
+        holder.leastSigBits = dataBuffer.getLong(offset + Long.BYTES);
+      }
     }
   }
 
@@ -244,8 +257,8 @@ public void set(int index, ArrowBuf source, int sourceOffset) {
 
     BitVectorHelper.setBit(getUnderlyingVector().getValidityBuffer(), index);
     getUnderlyingVector()
-            .getDataBuffer()
-            .setBytes((long) index * UUID_BYTE_WIDTH, source, sourceOffset, UUID_BYTE_WIDTH);
+        .getDataBuffer()
+        .setBytes((long) index * UUID_BYTE_WIDTH, source, sourceOffset, UUID_BYTE_WIDTH);
   }
 
   /**

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

@@ -16,7 +16,6 @@
  */
 package org.apache.arrow.vector.complex.impl;
 
-import java.util.UUID;
 import org.apache.arrow.vector.holders.ExtensionHolder;
 import org.apache.arrow.vector.holders.NullableUuidHolder;
 import org.apache.arrow.vector.holders.UuidHolder;
@@ -107,4 +106,3 @@ public Object readObject() {
     return holder.getUuid();
   }
 }
-

vector/src/main/java/org/apache/arrow/vector/holders/NullableUuidHolder.java

@@ -36,8 +36,13 @@ public class NullableUuidHolder extends ExtensionHolder {
   /** The least significant 64 bits of the UUID. */
   public long leastSigBits;
 
+  /**
+   * Converts the holder's two longs to a UUID object.
+   *
+   * @return the UUID represented by this holder, or null if isSet is 0
+   */
   public UUID getUuid() {
-    if(this.isSet == 0) {
+    if (this.isSet == 0) {
       return null;
     }
     return new UUID(mostSigBits, leastSigBits);

vector/src/main/java/org/apache/arrow/vector/holders/UuidHolder.java

@@ -39,6 +39,11 @@ public UuidHolder() {
     this.isSet = 1;
   }
 
+  /**
+   * Converts the holder's two longs to a UUID object.
+   *
+   * @return the UUID represented by this holder
+   */
   public UUID getUuid() {
     return new UUID(mostSigBits, leastSigBits);
   }