[SPARK-9867] [SQL] Move utilities for binary data into ByteArray

The utilities such as Substring#substringBinarySQL and BinaryPrefixComparator#computePrefix for binary data are put together in ByteArray for easy-to-read.

Author: Takeshi YAMAMURO <linguin.m.s@gmail.com>

Closes #8122 from maropu/CleanUpForBinaryType.

core/src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java

@@ -21,6 +21,7 @@ import com.google.common.primitives.UnsignedLongs;
 
 import org.apache.spark.annotation.Private;
 import org.apache.spark.unsafe.Platform;
+import org.apache.spark.unsafe.types.ByteArray;
 import org.apache.spark.unsafe.types.UTF8String;
 import org.apache.spark.util.Utils;
 
@@ -62,21 +63,7 @@ public class PrefixComparators {
     }
 
     public static long computePrefix(byte[] bytes) {
-      if (bytes == null) {
-        return 0L;
-      } else {
-        /**
-         * TODO: If a wrapper for BinaryType is created (SPARK-8786),
-         * these codes below will be in the wrapper class.
-         */
-        final int minLen = Math.min(bytes.length, 8);
-        long p = 0;
-        for (int i = 0; i < minLen; ++i) {
-          p |= (128L + Platform.getByte(bytes, Platform.BYTE_ARRAY_OFFSET + i))
-              << (56 - 8 * i);
-        }
-        return p;
-      }
+      return ByteArray.getPrefix(bytes);
     }
   }
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala

@@ -18,14 +18,12 @@
 package org.apache.spark.sql.catalyst.expressions
 
 import java.text.DecimalFormat
-import java.util.Arrays
-import java.util.{Map => JMap, HashMap}
-import java.util.Locale
+import java.util.{HashMap, Locale, Map => JMap}
 
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.expressions.codegen._
 import org.apache.spark.sql.types._
-import org.apache.spark.unsafe.types.UTF8String
+import org.apache.spark.unsafe.types.{ByteArray, UTF8String}
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // This file defines expressions for string operations.
@@ -690,34 +688,6 @@ case class StringSpace(child: Expression)
   override def prettyName: String = "space"
 }
 
-object Substring {
-  def subStringBinarySQL(bytes: Array[Byte], pos: Int, len: Int): Array[Byte] = {
-    if (pos > bytes.length) {
-      return Array[Byte]()
-    }
-
-    var start = if (pos > 0) {
-      pos - 1
-    } else if (pos < 0) {
-      bytes.length + pos
-    } else {
-      0
-    }
-
-    val end = if ((bytes.length - start) < len) {
-      bytes.length
-    } else {
-      start + len
-    }
-
-    start = Math.max(start, 0)  // underflow
-    if (start < end) {
-      Arrays.copyOfRange(bytes, start, end)
-    } else {
-      Array[Byte]()
-    }
-  }
-}
 /**
  * A function that takes a substring of its first argument starting at a given position.
  * Defined for String and Binary types.
@@ -740,18 +710,17 @@ case class Substring(str: Expression, pos: Expression, len: Expression)
     str.dataType match {
       case StringType => string.asInstanceOf[UTF8String]
         .substringSQL(pos.asInstanceOf[Int], len.asInstanceOf[Int])
-      case BinaryType => Substring.subStringBinarySQL(string.asInstanceOf[Array[Byte]],
+      case BinaryType => ByteArray.subStringSQL(string.asInstanceOf[Array[Byte]],
         pos.asInstanceOf[Int], len.asInstanceOf[Int])
     }
   }
 
   override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode): String = {
 
-    val cls = classOf[Substring].getName
     defineCodeGen(ctx, ev, (string, pos, len) => {
       str.dataType match {
         case StringType => s"$string.substringSQL($pos, $len)"
-        case BinaryType => s"$cls.subStringBinarySQL($string, $pos, $len)"
+        case BinaryType => s"${classOf[ByteArray].getName}.subStringSQL($string, $pos, $len)"
       }
     })
   }

unsafe/src/main/java/org/apache/spark/unsafe/types/ByteArray.java

@@ -19,7 +19,11 @@ package org.apache.spark.unsafe.types;
 
 import org.apache.spark.unsafe.Platform;
 
-public class ByteArray {
+import java.util.Arrays;
+
+public final class ByteArray {
+
+  public static final byte[] EMPTY_BYTE = new byte[0];
 
   /**
    * Writes the content of a byte array into a memory address, identified by an object and an
@@ -29,4 +33,45 @@ public class ByteArray {
   public static void writeToMemory(byte[] src, Object target, long targetOffset) {
     Platform.copyMemory(src, Platform.BYTE_ARRAY_OFFSET, target, targetOffset, src.length);
   }
+
+  /**
+   * Returns a 64-bit integer that can be used as the prefix used in sorting.
+   */
+  public static long getPrefix(byte[] bytes) {
+    if (bytes == null) {
+      return 0L;
+    } else {
+      final int minLen = Math.min(bytes.length, 8);
+      long p = 0;
+      for (int i = 0; i < minLen; ++i) {
+        p |= (128L + Platform.getByte(bytes, Platform.BYTE_ARRAY_OFFSET + i))
+            << (56 - 8 * i);
+      }
+      return p;
+    }
+  }
+
+  public static byte[] subStringSQL(byte[] bytes, int pos, int len) {
+    // This pos calculation is according to UTF8String#subStringSQL
+    if (pos > bytes.length) {
+      return EMPTY_BYTE;
+    }
+    int start = 0;
+    int end;
+    if (pos > 0) {
+      start = pos - 1;
+    } else if (pos < 0) {
+      start = bytes.length + pos;
+    }
+    if ((bytes.length - start) < len) {
+      end = bytes.length;
+    } else {
+      end = start + len;
+    }
+    start = Math.max(start, 0); // underflow
+    if (start >= end) {
+      return EMPTY_BYTE;
+    }
+    return Arrays.copyOfRange(bytes, start, end);
+  }
 }