[SQL][minor] Simplify UnsafeRow.calculateBitSetWidthInBytes.

Author: Reynold Xin <rxin@databricks.com>

Closes #7897 from rxin/calculateBitSetWidthInBytes and squashes the following commits:

2e73b3a [Reynold Xin] [SQL][minor] Simplify UnsafeRow.calculateBitSetWidthInBytes.

2 files changed, 11 insertions, 1 deletions

diff --git a/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeRow.java b/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeRow.java
index f4230cfaba..e6750fce4f 100644
--- a/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeRow.java
+++ b/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeRow.java
@@ -59,7 +59,7 @@ public final class UnsafeRow extends MutableRow {
   //////////////////////////////////////////////////////////////////////////////
 
   public static int calculateBitSetWidthInBytes(int numFields) {
-    return ((numFields / 64) + (numFields % 64 == 0 ? 0 : 1)) * 8;
+    return ((numFields + 63)/ 64) * 8;
   }
 
   /**
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/UnsafeRowSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/UnsafeRowSuite.scala
index c5faaa663e..89bad1bfda 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/UnsafeRowSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/UnsafeRowSuite.scala
@@ -28,6 +28,16 @@ import org.apache.spark.unsafe.memory.MemoryAllocator
 import org.apache.spark.unsafe.types.UTF8String
 
 class UnsafeRowSuite extends SparkFunSuite {
+
+  test("bitset width calculation") {
+    assert(UnsafeRow.calculateBitSetWidthInBytes(0) === 0)
+    assert(UnsafeRow.calculateBitSetWidthInBytes(1) === 8)
+    assert(UnsafeRow.calculateBitSetWidthInBytes(32) === 8)
+    assert(UnsafeRow.calculateBitSetWidthInBytes(64) === 8)
+    assert(UnsafeRow.calculateBitSetWidthInBytes(65) === 16)
+    assert(UnsafeRow.calculateBitSetWidthInBytes(128) === 16)
+  }
+
   test("writeToStream") {
     val row = InternalRow.apply(UTF8String.fromString("hello"), UTF8String.fromString("world"), 123)
     val arrayBackedUnsafeRow: UnsafeRow =