Github user jiangxb1987 commented on a diff in the pull request:
https://github.com/apache/spark/pull/22079#discussion_r209822194
--- Diff:
sql/catalyst/src/main/java/org/apache/spark/sql/execution/RecordBinaryComparator.java
---
@@ -0,0 +1,70 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.execution;
+
+import org.apache.spark.unsafe.Platform;
+import org.apache.spark.util.collection.unsafe.sort.RecordComparator;
+
+public final class RecordBinaryComparator extends RecordComparator {
+
+ // TODO(jiangxb) Add test suite for this.
+ @Override
+ public int compare(
+ Object leftObj, long leftOff, int leftLen, Object rightObj, long
rightOff, int rightLen) {
+ int i = 0;
+ int res = 0;
+
+ // If the arrays have different length, the longer one is larger.
+ if (leftLen != rightLen) {
+ return leftLen - rightLen;
+ }
+
+ // The following logic uses `leftLen` as the length for both `leftObj`
and `rightObj`, since
+ // we have guaranteed `leftLen` == `rightLen`.
+
+ // check if stars align and we can get both offsets to be aligned
+ if ((leftOff % 8) == (rightOff % 8)) {
+ while ((leftOff + i) % 8 != 0 && i < leftLen) {
+ res = (Platform.getByte(leftObj, leftOff + i) & 0xff) -
+ (Platform.getByte(rightObj, rightOff + i) & 0xff);
+ if (res != 0) return res;
+ i += 1;
+ }
+ }
+ // for architectures that support unaligned accesses, chew it up 8
bytes at a time
+ if (Platform.unaligned() || (((leftOff + i) % 8 == 0) && ((rightOff +
i) % 8 == 0))) {
+ while (i <= leftLen - 8) {
+ res = (int) ((Platform.getLong(leftObj, leftOff + i) -
+ Platform.getLong(rightObj, rightOff + i)) %
Integer.MAX_VALUE);
+ if (res != 0) return res;
--- End diff --
As far as I can recall It's actually a mistake. At first the function
returned a Long value and later I changed the return value to Integer, let me
fix it. Thanks for discovering this @mridulm !
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