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From: BryanCutler <git@git.apache.org>
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Subject: [GitHub] spark pull request #15821: [SPARK-13534][PySpark] Using Apache Arrow to incr...
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Message-Id: <20170427014535.EBC5EE1103@git1-us-west.apache.org>
Date: Thu, 27 Apr 2017 01:45:35 +0000 (UTC)
archived-at: Thu, 27 Apr 2017 01:45:38 -0000

Github user BryanCutler commented on a diff in the pull request:

    https://github.com/apache/spark/pull/15821#discussion_r113600189
  
    --- Diff: sql/core/src/main/scala/org/apache/spark/sql/ArrowConverters.scala ---
    @@ -0,0 +1,432 @@
    +/*
    +* 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 java.io.ByteArrayOutputStream
    +import java.nio.ByteBuffer
    +import java.nio.channels.{Channels, SeekableByteChannel}
    +
    +import scala.collection.JavaConverters._
    +
    +import io.netty.buffer.ArrowBuf
    +import org.apache.arrow.memory.{BaseAllocator, RootAllocator}
    +import org.apache.arrow.vector._
    +import org.apache.arrow.vector.BaseValueVector.BaseMutator
    +import org.apache.arrow.vector.file.{ArrowReader, ArrowWriter}
    +import org.apache.arrow.vector.schema.{ArrowFieldNode, ArrowRecordBatch}
    +import org.apache.arrow.vector.types.{FloatingPointPrecision, TimeUnit}
    +import org.apache.arrow.vector.types.pojo.{ArrowType, Field, Schema}
    +
    +import org.apache.spark.sql.catalyst.InternalRow
    +import org.apache.spark.sql.types._
    +import org.apache.spark.util.Utils
    +
    +
    +/**
    + * ArrowReader requires a seekable byte channel.
    + * TODO: This is available in arrow-vector now with ARROW-615, to be included in 0.2.1 release
    + */
    +private[sql] class ByteArrayReadableSeekableByteChannel(var byteArray: Array[Byte])
    +  extends SeekableByteChannel {
    +  var _position: Long = 0L
    +
    +  override def isOpen: Boolean = {
    +    byteArray != null
    +  }
    +
    +  override def close(): Unit = {
    +    byteArray = null
    +  }
    +
    +  override def read(dst: ByteBuffer): Int = {
    +    val remainingBuf = byteArray.length - _position
    +    val length = Math.min(dst.remaining(), remainingBuf).toInt
    +    dst.put(byteArray, _position.toInt, length)
    +    _position += length
    +    length
    +  }
    +
    +  override def position(): Long = _position
    +
    +  override def position(newPosition: Long): SeekableByteChannel = {
    +    _position = newPosition.toLong
    +    this
    +  }
    +
    +  override def size: Long = {
    +    byteArray.length.toLong
    +  }
    +
    +  override def write(src: ByteBuffer): Int = {
    +    throw new UnsupportedOperationException("Read Only")
    +  }
    +
    +  override def truncate(size: Long): SeekableByteChannel = {
    +    throw new UnsupportedOperationException("Read Only")
    +  }
    +}
    +
    +/**
    + * Intermediate data structure returned from Arrow conversions
    + */
    +private[sql] abstract class ArrowPayload extends Iterator[ArrowRecordBatch]
    +
    +/**
    + * Build a payload from existing ArrowRecordBatches
    + */
    +private[sql] class ArrowStaticPayload(batches: ArrowRecordBatch*) extends ArrowPayload {
    +  private val iter = batches.iterator
    +  override def next(): ArrowRecordBatch = iter.next()
    +  override def hasNext: Boolean = iter.hasNext
    +}
    +
    +/**
    + * Class that wraps an Arrow RootAllocator used in conversion
    + */
    +private[sql] class ArrowConverters {
    +  private val _allocator = new RootAllocator(Long.MaxValue)
    +
    +  private[sql] def allocator: RootAllocator = _allocator
    +
    +  /**
    +   * Iterate over the rows and convert to an ArrowPayload, using RootAllocator from this class
    +   */
    +  def interalRowIterToPayload(rowIter: Iterator[InternalRow], schema: StructType): ArrowPayload = {
    +    val batch = ArrowConverters.internalRowIterToArrowBatch(rowIter, schema, _allocator)
    +    new ArrowStaticPayload(batch)
    +  }
    +
    +  /**
    +   * Read an Array of Arrow Record batches as byte Arrays into an ArrowPayload, using
    +   * RootAllocator from this class
    +   */
    +  def readPayloadByteArrays(payloadByteArrays: Array[Array[Byte]]): ArrowPayload = {
    +    val batches = scala.collection.mutable.ArrayBuffer.empty[ArrowRecordBatch]
    +    var i = 0
    +    while (i < payloadByteArrays.length) {
    +      val payloadBytes = payloadByteArrays(i)
    +      val in = new ByteArrayReadableSeekableByteChannel(payloadBytes)
    +      val reader = new ArrowReader(in, _allocator)
    +      val footer = reader.readFooter()
    +      val batchBlocks = footer.getRecordBatches.asScala.toArray
    +      batchBlocks.foreach(block => batches += reader.readRecordBatch(block))
    +      i += 1
    +    }
    +    new ArrowStaticPayload(batches: _*)
    +  }
    +
    +  /**
    +   * Call when done using this converter, will close RootAllocator so any ArrowBuffers should be
    +   * closed first
    +   */
    +  def close(): Unit = {
    +    _allocator.close()
    +  }
    +}
    +
    +private[sql] object ArrowConverters {
    +
    +  /**
    +   * Map a Spark Dataset type to ArrowType.
    +   */
    +  private[sql] def sparkTypeToArrowType(dataType: DataType): ArrowType = {
    --- End diff --
    
    My latest update needed to use this outside of the object, but I will change it to `private[arrow]`


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