[SPARK-12856] [SQL] speed up hashCode of unsafe array

We iterate the bytes to calculate hashCode before, but now we have `Murmur3_x86_32.hashUnsafeBytes` that don't require the bytes to be word algned, we should use that instead.

A simple benchmark shows it's about 3 X faster, benchmark code: https://gist.github.com/cloud-fan/fa77713ccebf0823b2ab#file-arrayhashbenchmark-scala

Author: Wenchen Fan <wenchen@databricks.com>

Closes #10784 from cloud-fan/array-hashcode.

1 files changed, 2 insertions, 5 deletions

diff --git a/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeArrayData.java b/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeArrayData.java
index 3d80df2271..648625b2cc 100644
--- a/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeArrayData.java
+++ b/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeArrayData.java
@@ -25,6 +25,7 @@ import org.apache.spark.sql.catalyst.util.ArrayData;
 import org.apache.spark.sql.types.*;
 import org.apache.spark.unsafe.Platform;
 import org.apache.spark.unsafe.array.ByteArrayMethods;
+import org.apache.spark.unsafe.hash.Murmur3_x86_32;
 import org.apache.spark.unsafe.types.CalendarInterval;
 import org.apache.spark.unsafe.types.UTF8String;
 
@@ -299,11 +300,7 @@ public class UnsafeArrayData extends ArrayData {
 
   @Override
   public int hashCode() {
-    int result = 37;
-    for (int i = 0; i < sizeInBytes; i++) {
-      result = 37 * result + Platform.getByte(baseObject, baseOffset + i);
-    }
-    return result;
+    return Murmur3_x86_32.hashUnsafeBytes(baseObject, baseOffset, sizeInBytes, 42);
   }
 
   @Override