Fix conversion for String type; refactor related functions to Arrow.scala

changed tests to use existing SQLTestData and removed unused files

closes apache#14

Author: icexelloss

sql/core/src/main/scala/org/apache/spark/sql/Arrow.scala

@@ -0,0 +1,228 @@
+/*
+* 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
+
+import scala.collection.JavaConverters._
+import scala.language.implicitConversions
+
+import io.netty.buffer.ArrowBuf
+import org.apache.arrow.memory.RootAllocator
+import org.apache.arrow.vector.BitVector
+import org.apache.arrow.vector.schema.{ArrowFieldNode, ArrowRecordBatch}
+import org.apache.arrow.vector.types.FloatingPointPrecision
+import org.apache.arrow.vector.types.pojo.{ArrowType, Field, Schema}
+
+import org.apache.spark.sql.catalyst.InternalRow
+import org.apache.spark.sql.types._
+
+object Arrow {
+
+  /**
+   * Compute the number of bytes needed to build validity map. According to
+   * [Arrow Layout](https://github.com/apache/arrow/blob/master/format/Layout.md#null-bitmaps),
+   * the length of the validity bitmap should be multiples of 64 bytes.
+   */
+  private def numBytesOfBitmap(numOfRows: Int): Int = {
+    Math.ceil(numOfRows / 64.0).toInt * 8
+  }
+
+  private def fillArrow(buf: ArrowBuf, dataType: DataType): Unit = {
+    dataType match {
+      case NullType =>
+      case BooleanType =>
+        buf.writeBoolean(false)
+      case ShortType =>
+        buf.writeShort(0)
+      case IntegerType =>
+        buf.writeInt(0)
+      case LongType =>
+        buf.writeLong(0L)
+      case FloatType =>
+        buf.writeFloat(0f)
+      case DoubleType =>
+        buf.writeDouble(0d)
+      case ByteType =>
+        buf.writeByte(0)
+      case _ =>
+        throw new UnsupportedOperationException(
+          s"Unsupported data type ${dataType.simpleString}")
+    }
+  }
+
+  /**
+   * Get an entry from the InternalRow, and then set to ArrowBuf.
+   * Note: No Null check for the entry.
+   */
+  private def getAndSetToArrow(
+      row: InternalRow,
+      buf: ArrowBuf,
+      dataType: DataType,
+      ordinal: Int): Unit = {
+    dataType match {
+      case NullType =>
+      case BooleanType =>
+        buf.writeBoolean(row.getBoolean(ordinal))
+      case ShortType =>
+        buf.writeShort(row.getShort(ordinal))
+      case IntegerType =>
+        buf.writeInt(row.getInt(ordinal))
+      case LongType =>
+        buf.writeLong(row.getLong(ordinal))
+      case FloatType =>
+        buf.writeFloat(row.getFloat(ordinal))
+      case DoubleType =>
+        buf.writeDouble(row.getDouble(ordinal))
+      case ByteType =>
+        buf.writeByte(row.getByte(ordinal))
+      case _ =>
+        throw new UnsupportedOperationException(
+          s"Unsupported data type ${dataType.simpleString}")
+    }
+  }
+
+  /**
+   * Transfer an array of InternalRow to an ArrowRecordBatch.
+   */
+  def internalRowsToArrowRecordBatch(
+      rows: Array[InternalRow],
+      schema: StructType,
+      allocator: RootAllocator): ArrowRecordBatch = {
+    val bufAndField = schema.fields.zipWithIndex.map { case (field, ordinal) =>
+      internalRowToArrowBuf(rows, ordinal, field, allocator)
+    }
+
+    val buffers = bufAndField.flatMap(_._1).toList.asJava
+    val fieldNodes = bufAndField.flatMap(_._2).toList.asJava
+
+    new ArrowRecordBatch(rows.length, fieldNodes, buffers)
+  }
+
+  /**
+   * Convert an array of InternalRow to an ArrowBuf.
+   */
+  def internalRowToArrowBuf(
+      rows: Array[InternalRow],
+      ordinal: Int,
+      field: StructField,
+      allocator: RootAllocator): (Array[ArrowBuf], Array[ArrowFieldNode]) = {
+    val numOfRows = rows.length
+
+    field.dataType match {
+      case IntegerType | LongType | DoubleType | FloatType | BooleanType | ByteType =>
+        val validityVector = new BitVector("validity", allocator)
+        val validityMutator = validityVector.getMutator
+        validityVector.allocateNew(numOfRows)
+        validityMutator.setValueCount(numOfRows)
+
+        val buf = allocator.buffer(numOfRows * field.dataType.defaultSize)
+        var nullCount = 0
+        var index = 0
+        while (index < rows.length) {
+          val row = rows(index)
+          if (row.isNullAt(ordinal)) {
+            nullCount += 1
+            validityMutator.set(index, 0)
+            fillArrow(buf, field.dataType)
+          } else {
+            validityMutator.set(index, 1)
+            getAndSetToArrow(row, buf, field.dataType, ordinal)
+          }
+          index += 1
+        }
+
+        val fieldNode = new ArrowFieldNode(numOfRows, nullCount)
+
+        (Array(validityVector.getBuffer, buf), Array(fieldNode))
+
+      case StringType =>
+        val validityVector = new BitVector("validity", allocator)
+        val validityMutator = validityVector.getMutator()
+        validityVector.allocateNew(numOfRows)
+        validityMutator.setValueCount(numOfRows)
+
+        val bufOffset = allocator.buffer((numOfRows + 1) * IntegerType.defaultSize)
+        var bytesCount = 0
+        bufOffset.writeInt(bytesCount)
+        val bufValues = allocator.buffer(1024)
+        var nullCount = 0
+        rows.zipWithIndex.foreach { case (row, index) =>
+          if (row.isNullAt(ordinal)) {
+            nullCount += 1
+            validityMutator.set(index, 0)
+            bufOffset.writeInt(bytesCount)
+          } else {
+            validityMutator.set(index, 1)
+            val bytes = row.getUTF8String(ordinal).getBytes
+            bytesCount += bytes.length
+            bufOffset.writeInt(bytesCount)
+            bufValues.writeBytes(bytes)
+          }
+        }
+
+        val fieldNode = new ArrowFieldNode(numOfRows, nullCount)
+
+        (Array(validityVector.getBuffer, bufOffset, bufValues),
+            Array(fieldNode))
+    }
+  }
+
+  private[sql] def schemaToArrowSchema(schema: StructType): Schema = {
+    val arrowFields = schema.fields.map(sparkFieldToArrowField(_))
+    new Schema(arrowFields.toList.asJava)
+  }
+
+  private[sql] def sparkFieldToArrowField(sparkField: StructField): Field = {
+    val name = sparkField.name
+    val dataType = sparkField.dataType
+    val nullable = sparkField.nullable
+
+    dataType match {
+      case StructType(fields) =>
+        val childrenFields = fields.map(sparkFieldToArrowField(_)).toList.asJava
+        new Field(name, nullable, ArrowType.Struct.INSTANCE, childrenFields)
+      case _ =>
+        new Field(name, nullable, dataTypeToArrowType(dataType), List.empty[Field].asJava)
+    }
+  }
+
+  /**
+   * Transform Spark DataType to Arrow ArrowType.
+   */
+  private[sql] def dataTypeToArrowType(dt: DataType): ArrowType = {
+    dt match {
+      case IntegerType =>
+        new ArrowType.Int(8 * IntegerType.defaultSize, true)
+      case LongType =>
+        new ArrowType.Int(8 * LongType.defaultSize, true)
+      case StringType =>
+        ArrowType.Utf8.INSTANCE
+      case DoubleType =>
+        new ArrowType.FloatingPoint(FloatingPointPrecision.DOUBLE)
+      case FloatType =>
+        new ArrowType.FloatingPoint(FloatingPointPrecision.SINGLE)
+      case BooleanType =>
+        ArrowType.Bool.INSTANCE
+      case ByteType =>
+        new ArrowType.Int(8, false)
+      case StructType(_) =>
+        ArrowType.Struct.INSTANCE
+      case _ =>
+        throw new IllegalArgumentException(s"Unsupported data type")
+    }
+  }
+}