[SPARK-25114][CORE] Fix RecordBinaryComparator when subtraction between two words is divisible by Integer.MAX_VALUE.

#22079 (comment) It is possible for two objects to be unequal and yet we consider them as equal with this code, if the long values are separated by Int.MaxValue.
This PR fixes the issue.

Add new test cases in `RecordBinaryComparatorSuite`.

Closes #22101 from jiangxb1987/fix-rbc.

Authored-by: Xingbo Jiang <xingbo.jiang@databricks.com>
Signed-off-by: Xiao Li <gatorsmile@gmail.com>
(cherry picked from commit 4fb96e5)
Signed-off-by: Xiao Li <gatorsmile@gmail.com>

Author: jiangxb1987

sql/catalyst/src/main/java/org/apache/spark/sql/execution/RecordBinaryComparator.java

@@ -22,12 +22,10 @@
 
 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) {
@@ -40,27 +38,33 @@ public int compare(
     // 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;
+        final int v1 = Platform.getByte(leftObj, leftOff + i) & 0xff;
+        final int v2 = Platform.getByte(rightObj, rightOff + i) & 0xff;
+        if (v1 != v2) {
+          return v1 > v2 ? 1 : -1;
+        }
         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;
+        final long v1 = Platform.getLong(leftObj, leftOff + i);
+        final long v2 = Platform.getLong(rightObj, rightOff + i);
+        if (v1 != v2) {
+          return v1 > v2 ? 1 : -1;
+        }
         i += 8;
       }
     }
     // this will finish off the unaligned comparisons, or do the entire aligned comparison
     // whichever is needed.
     while (i < leftLen) {
-      res = (Platform.getByte(leftObj, leftOff + i) & 0xff) -
-              (Platform.getByte(rightObj, rightOff + i) & 0xff);
-      if (res != 0) return res;
+      final int v1 = Platform.getByte(leftObj, leftOff + i) & 0xff;
+      final int v2 = Platform.getByte(rightObj, rightOff + i) & 0xff;
+      if (v1 != v2) {
+        return v1 > v2 ? 1 : -1;
+      }
       i += 1;
     }
 

sql/core/src/test/java/test/org/apache/spark/sql/execution/sort/RecordBinaryComparatorSuite.java

@@ -0,0 +1,322 @@
+/*
+ * 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 test.org.apache.spark.sql.execution.sort;
+
+import org.apache.spark.SparkConf;
+import org.apache.spark.memory.TaskMemoryManager;
+import org.apache.spark.memory.TestMemoryConsumer;
+import org.apache.spark.memory.TestMemoryManager;
+import org.apache.spark.sql.catalyst.expressions.UnsafeArrayData;
+import org.apache.spark.sql.catalyst.expressions.UnsafeRow;
+import org.apache.spark.sql.execution.RecordBinaryComparator;
+import org.apache.spark.unsafe.Platform;
+import org.apache.spark.unsafe.UnsafeAlignedOffset;
+import org.apache.spark.unsafe.array.LongArray;
+import org.apache.spark.unsafe.memory.MemoryBlock;
+import org.apache.spark.unsafe.types.UTF8String;
+import org.apache.spark.util.collection.unsafe.sort.*;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * Test the RecordBinaryComparator, which compares two UnsafeRows by their binary form.
+ */
+public class RecordBinaryComparatorSuite {
+
+  private final TaskMemoryManager memoryManager = new TaskMemoryManager(
+      new TestMemoryManager(new SparkConf().set("spark.memory.offHeap.enabled", "false")), 0);
+  private final TestMemoryConsumer consumer = new TestMemoryConsumer(memoryManager);
+
+  private final int uaoSize = UnsafeAlignedOffset.getUaoSize();
+
+  private MemoryBlock dataPage;
+  private long pageCursor;
+
+  private LongArray array;
+  private int pos;
+
+  @Before
+  public void beforeEach() {
+    // Only compare between two input rows.
+    array = consumer.allocateArray(2);
+    pos = 0;
+
+    dataPage = memoryManager.allocatePage(4096, consumer);
+    pageCursor = dataPage.getBaseOffset();
+  }
+
+  @After
+  public void afterEach() {
+    consumer.freePage(dataPage);
+    dataPage = null;
+    pageCursor = 0;
+
+    consumer.freeArray(array);
+    array = null;
+    pos = 0;
+  }
+
+  private void insertRow(UnsafeRow row) {
+    Object recordBase = row.getBaseObject();
+    long recordOffset = row.getBaseOffset();
+    int recordLength = row.getSizeInBytes();
+
+    Object baseObject = dataPage.getBaseObject();
+    assert(pageCursor + recordLength <= dataPage.getBaseOffset() + dataPage.size());
+    long recordAddress = memoryManager.encodePageNumberAndOffset(dataPage, pageCursor);
+    UnsafeAlignedOffset.putSize(baseObject, pageCursor, recordLength);
+    pageCursor += uaoSize;
+    Platform.copyMemory(recordBase, recordOffset, baseObject, pageCursor, recordLength);
+    pageCursor += recordLength;
+
+    assert(pos < 2);
+    array.set(pos, recordAddress);
+    pos++;
+  }
+
+  private int compare(int index1, int index2) {
+    Object baseObject = dataPage.getBaseObject();
+
+    long recordAddress1 = array.get(index1);
+    long baseOffset1 = memoryManager.getOffsetInPage(recordAddress1) + uaoSize;
+    int recordLength1 = UnsafeAlignedOffset.getSize(baseObject, baseOffset1 - uaoSize);
+
+    long recordAddress2 = array.get(index2);
+    long baseOffset2 = memoryManager.getOffsetInPage(recordAddress2) + uaoSize;
+    int recordLength2 = UnsafeAlignedOffset.getSize(baseObject, baseOffset2 - uaoSize);
+
+    return binaryComparator.compare(baseObject, baseOffset1, recordLength1, baseObject,
+        baseOffset2, recordLength2);
+  }
+
+  private final RecordComparator binaryComparator = new RecordBinaryComparator();
+
+  // Compute the most compact size for UnsafeRow's backing data.
+  private int computeSizeInBytes(int originalSize) {
+    // All the UnsafeRows in this suite contains less than 64 columns, so the bitSetSize shall
+    // always be 8.
+    return 8 + (originalSize + 7) / 8 * 8;
+  }
+
+  // Compute the relative offset of variable-length values.
+  private long relativeOffset(int numFields) {
+    // All the UnsafeRows in this suite contains less than 64 columns, so the bitSetSize shall
+    // always be 8.
+    return 8 + numFields * 8L;
+  }
+
+  @Test
+  public void testBinaryComparatorForSingleColumnRow() throws Exception {
+    int numFields = 1;
+
+    UnsafeRow row1 = new UnsafeRow(numFields);
+    byte[] data1 = new byte[100];
+    row1.pointTo(data1, computeSizeInBytes(numFields * 8));
+    row1.setInt(0, 11);
+
+    UnsafeRow row2 = new UnsafeRow(numFields);
+    byte[] data2 = new byte[100];
+    row2.pointTo(data2, computeSizeInBytes(numFields * 8));
+    row2.setInt(0, 42);
+
+    insertRow(row1);
+    insertRow(row2);
+
+    assert(compare(0, 0) == 0);
+    assert(compare(0, 1) < 0);
+  }
+
+  @Test
+  public void testBinaryComparatorForMultipleColumnRow() throws Exception {
+    int numFields = 5;
+
+    UnsafeRow row1 = new UnsafeRow(numFields);
+    byte[] data1 = new byte[100];
+    row1.pointTo(data1, computeSizeInBytes(numFields * 8));
+    for (int i = 0; i < numFields; i++) {
+      row1.setDouble(i, i * 3.14);
+    }
+
+    UnsafeRow row2 = new UnsafeRow(numFields);
+    byte[] data2 = new byte[100];
+    row2.pointTo(data2, computeSizeInBytes(numFields * 8));
+    for (int i = 0; i < numFields; i++) {
+      row2.setDouble(i, 198.7 / (i + 1));
+    }
+
+    insertRow(row1);
+    insertRow(row2);
+
+    assert(compare(0, 0) == 0);
+    assert(compare(0, 1) < 0);
+  }
+
+  @Test
+  public void testBinaryComparatorForArrayColumn() throws Exception {
+    int numFields = 1;
+
+    UnsafeRow row1 = new UnsafeRow(numFields);
+    byte[] data1 = new byte[100];
+    UnsafeArrayData arrayData1 = UnsafeArrayData.fromPrimitiveArray(new int[]{11, 42, -1});
+    row1.pointTo(data1, computeSizeInBytes(numFields * 8 + arrayData1.getSizeInBytes()));
+    row1.setLong(0, (relativeOffset(numFields) << 32) | (long) arrayData1.getSizeInBytes());
+    Platform.copyMemory(arrayData1.getBaseObject(), arrayData1.getBaseOffset(), data1,
+        row1.getBaseOffset() + relativeOffset(numFields), arrayData1.getSizeInBytes());
+
+    UnsafeRow row2 = new UnsafeRow(numFields);
+    byte[] data2 = new byte[100];
+    UnsafeArrayData arrayData2 = UnsafeArrayData.fromPrimitiveArray(new int[]{22});
+    row2.pointTo(data2, computeSizeInBytes(numFields * 8 + arrayData2.getSizeInBytes()));
+    row2.setLong(0, (relativeOffset(numFields) << 32) | (long) arrayData2.getSizeInBytes());
+    Platform.copyMemory(arrayData2.getBaseObject(), arrayData2.getBaseOffset(), data2,
+        row2.getBaseOffset() + relativeOffset(numFields), arrayData2.getSizeInBytes());
+
+    insertRow(row1);
+    insertRow(row2);
+
+    assert(compare(0, 0) == 0);
+    assert(compare(0, 1) > 0);
+  }
+
+  @Test
+  public void testBinaryComparatorForMixedColumns() throws Exception {
+    int numFields = 4;
+
+    UnsafeRow row1 = new UnsafeRow(numFields);
+    byte[] data1 = new byte[100];
+    UTF8String str1 = UTF8String.fromString("Milk tea");
+    row1.pointTo(data1, computeSizeInBytes(numFields * 8 + str1.numBytes()));
+    row1.setInt(0, 11);
+    row1.setDouble(1, 3.14);
+    row1.setInt(2, -1);
+    row1.setLong(3, (relativeOffset(numFields) << 32) | (long) str1.numBytes());
+    Platform.copyMemory(str1.getBaseObject(), str1.getBaseOffset(), data1,
+        row1.getBaseOffset() + relativeOffset(numFields), str1.numBytes());
+
+    UnsafeRow row2 = new UnsafeRow(numFields);
+    byte[] data2 = new byte[100];
+    UTF8String str2 = UTF8String.fromString("Java");
+    row2.pointTo(data2, computeSizeInBytes(numFields * 8 + str2.numBytes()));
+    row2.setInt(0, 11);
+    row2.setDouble(1, 3.14);
+    row2.setInt(2, -1);
+    row2.setLong(3, (relativeOffset(numFields) << 32) | (long) str2.numBytes());
+    Platform.copyMemory(str2.getBaseObject(), str2.getBaseOffset(), data2,
+        row2.getBaseOffset() + relativeOffset(numFields), str2.numBytes());
+
+    insertRow(row1);
+    insertRow(row2);
+
+    assert(compare(0, 0) == 0);
+    assert(compare(0, 1) > 0);
+  }
+
+  @Test
+  public void testBinaryComparatorForNullColumns() throws Exception {
+    int numFields = 3;
+
+    UnsafeRow row1 = new UnsafeRow(numFields);
+    byte[] data1 = new byte[100];
+    row1.pointTo(data1, computeSizeInBytes(numFields * 8));
+    for (int i = 0; i < numFields; i++) {
+      row1.setNullAt(i);
+    }
+
+    UnsafeRow row2 = new UnsafeRow(numFields);
+    byte[] data2 = new byte[100];
+    row2.pointTo(data2, computeSizeInBytes(numFields * 8));
+    for (int i = 0; i < numFields - 1; i++) {
+      row2.setNullAt(i);
+    }
+    row2.setDouble(numFields - 1, 3.14);
+
+    insertRow(row1);
+    insertRow(row2);
+
+    assert(compare(0, 0) == 0);
+    assert(compare(0, 1) > 0);
+  }
+
+  @Test
+  public void testBinaryComparatorWhenSubtractionIsDivisibleByMaxIntValue() throws Exception {
+    int numFields = 1;
+
+    UnsafeRow row1 = new UnsafeRow(numFields);
+    byte[] data1 = new byte[100];
+    row1.pointTo(data1, computeSizeInBytes(numFields * 8));
+    row1.setLong(0, 11);
+
+    UnsafeRow row2 = new UnsafeRow(numFields);
+    byte[] data2 = new byte[100];
+    row2.pointTo(data2, computeSizeInBytes(numFields * 8));
+    row2.setLong(0, 11L + Integer.MAX_VALUE);
+
+    insertRow(row1);
+    insertRow(row2);
+
+    assert(compare(0, 1) < 0);
+  }
+
+  @Test
+  public void testBinaryComparatorWhenSubtractionCanOverflowLongValue() throws Exception {
+    int numFields = 1;
+
+    UnsafeRow row1 = new UnsafeRow(numFields);
+    byte[] data1 = new byte[100];
+    row1.pointTo(data1, computeSizeInBytes(numFields * 8));
+    row1.setLong(0, Long.MIN_VALUE);
+
+    UnsafeRow row2 = new UnsafeRow(numFields);
+    byte[] data2 = new byte[100];
+    row2.pointTo(data2, computeSizeInBytes(numFields * 8));
+    row2.setLong(0, 1);
+
+    insertRow(row1);
+    insertRow(row2);
+
+    assert(compare(0, 1) < 0);
+  }
+
+  @Test
+  public void testBinaryComparatorWhenOnlyTheLastColumnDiffers() throws Exception {
+    int numFields = 4;
+
+    UnsafeRow row1 = new UnsafeRow(numFields);
+    byte[] data1 = new byte[100];
+    row1.pointTo(data1, computeSizeInBytes(numFields * 8));
+    row1.setInt(0, 11);
+    row1.setDouble(1, 3.14);
+    row1.setInt(2, -1);
+    row1.setLong(3, 0);
+
+    UnsafeRow row2 = new UnsafeRow(numFields);
+    byte[] data2 = new byte[100];
+    row2.pointTo(data2, computeSizeInBytes(numFields * 8));
+    row2.setInt(0, 11);
+    row2.setDouble(1, 3.14);
+    row2.setInt(2, -1);
+    row2.setLong(3, 1);
+
+    insertRow(row1);
+    insertRow(row2);
+
+    assert(compare(0, 1) < 0);
+  }
+}