Github user mengxr commented on a diff in the pull request:
https://github.com/apache/spark/pull/12640#discussion_r61387937
--- Diff:
sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeArrayData.java
---
@@ -336,4 +336,62 @@ public UnsafeArrayData copy() {
arrayCopy.pointTo(arrayDataCopy, Platform.BYTE_ARRAY_OFFSET,
sizeInBytes);
return arrayCopy;
}
+
+ public int[] toPrimitiveIntArray() {
+ int[] result = new int[numElements];
+ Platform.copyMemory(baseObject, baseOffset + 4 + 4 * numElements,
+ result, Platform.INT_ARRAY_OFFSET, 4 * numElements);
+ return result;
+ }
+
+ public double[] toPrimitiveDoubleArray() {
+ double[] result = new double[numElements];
+ Platform.copyMemory(baseObject, baseOffset + 4 + 4 * numElements,
+ result, Platform.DOUBLE_ARRAY_OFFSET, 8 * numElements);
+ return result;
+ }
+
+ public static UnsafeArrayData fromPrimitiveArray(int[] arr) {
+ int offsetRegionSize = 4 * arr.length;
+ int valueRegionSize = 4 * arr.length;
+ int totalSize = 4 + offsetRegionSize + valueRegionSize;
+ byte[] data = new byte[totalSize];
+
+ Platform.putInt(data, Platform.BYTE_ARRAY_OFFSET, arr.length);
+
+ int elementOffsetStart = 4 + offsetRegionSize;
+ for (int i = 0; i < arr.length; i++) {
+ Platform.putInt(data, Platform.BYTE_ARRAY_OFFSET + 4 + i * 4,
elementOffsetStart + i * 4);
--- End diff --
This has two multiplications per element, which is expensive. Try:
~~~java
int regionOffset = Platform.BYTE_ARRAY_OFFSET + 4
int elementOffset = elementOffsetStart
for (...) {
Platform.putInt(data, regionOffset, elementOffset);
regionOffset += 4;
elementOffset += 4;
}
~~~
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