[WIP] in-memory columnar compression support

* Added two more compression schemes (RLE & dictionary encoding)
* Moved compression support code to columnar.compression
* Various refactoring

sql/core/src/main/scala/org/apache/spark/sql/columnar/ColumnAccessor.scala

@@ -21,6 +21,7 @@ import java.nio.{ByteOrder, ByteBuffer}
 
 import org.apache.spark.sql.catalyst.types.{BinaryType, NativeType, DataType}
 import org.apache.spark.sql.catalyst.expressions.MutableRow
+import org.apache.spark.sql.columnar.compression.CompressibleColumnAccessor
 
 /**
  * An `Iterator` like trait used to extract values from columnar byte buffer. When a value is
@@ -53,17 +54,17 @@ private[sql] abstract class BasicColumnAccessor[T <: DataType, JvmType](
     columnType.setField(row, ordinal, extractSingle(buffer))
   }
 
-  def extractSingle(buffer: ByteBuffer) = columnType.extract(buffer)
+  def extractSingle(buffer: ByteBuffer): JvmType = columnType.extract(buffer)
 
   protected def underlyingBuffer = buffer
 }
 
 private[sql] abstract class NativeColumnAccessor[T <: NativeType](
-    buffer: ByteBuffer,
-    columnType: NativeColumnType[T])
+    override protected val buffer: ByteBuffer,
+    override protected val columnType: NativeColumnType[T])
   extends BasicColumnAccessor(buffer, columnType)
   with NullableColumnAccessor
-  with CompressedColumnAccessor[T]
+  with CompressibleColumnAccessor[T]
 
 private[sql] class BooleanColumnAccessor(buffer: ByteBuffer)
   extends NativeColumnAccessor(buffer, BOOLEAN)
@@ -98,9 +99,8 @@ private[sql] class GenericColumnAccessor(buffer: ByteBuffer)
   with NullableColumnAccessor
 
 private[sql] object ColumnAccessor {
-  def apply(b: ByteBuffer): ColumnAccessor = {
-    // The first 4 bytes in the buffer indicates the column type.
-    val buffer = b.duplicate().order(ByteOrder.nativeOrder())
+  def apply(buffer: ByteBuffer): ColumnAccessor = {
+    // The first 4 bytes in the buffer indicate the column type.
     val columnTypeId = buffer.getInt()
 
     columnTypeId match {

sql/core/src/main/scala/org/apache/spark/sql/columnar/ColumnBuilder.scala

@@ -22,6 +22,7 @@ import java.nio.{ByteBuffer, ByteOrder}
 import org.apache.spark.sql.Row
 import org.apache.spark.sql.catalyst.types._
 import org.apache.spark.sql.columnar.ColumnBuilder._
+import org.apache.spark.sql.columnar.compression.{AllCompressionSchemes, CompressibleColumnBuilder}
 
 private[sql] trait ColumnBuilder {
   /**
@@ -30,22 +31,23 @@ private[sql] trait ColumnBuilder {
   def initialize(initialSize: Int, columnName: String = "")
 
   /**
-   * Gathers statistics information from `row(ordinal)`.
+   * Appends `row(ordinal)` to the column builder.
    */
-  def gatherStats(row: Row, ordinal: Int) {}
+  def appendFrom(row: Row, ordinal: Int)
 
   /**
-   * Appends `row(ordinal)` to the column builder.
+   * Column statistics information
    */
-  def appendFrom(row: Row, ordinal: Int)
+  def columnStats: ColumnStats[_, _]
 
   /**
    * Returns the final columnar byte buffer.
    */
   def build(): ByteBuffer
 }
 
-private[sql] abstract class BasicColumnBuilder[T <: DataType, JvmType](
+private[sql] class BasicColumnBuilder[T <: DataType, JvmType](
+    val columnStats: ColumnStats[T, JvmType],
     val columnType: ColumnType[T, JvmType])
   extends ColumnBuilder {
 
@@ -74,20 +76,20 @@ private[sql] abstract class BasicColumnBuilder[T <: DataType, JvmType](
   }
 }
 
-private[sql] abstract class NativeColumnBuilder[T <: NativeType](
-    protected val columnStats: ColumnStats[T],
-    columnType: NativeColumnType[T])
-  extends BasicColumnBuilder(columnType)
+private[sql] abstract class ComplexColumnBuilder[T <: DataType, JvmType](
+    columnType: ColumnType[T, JvmType])
+  extends BasicColumnBuilder[T, JvmType](new NoopColumnStats[T, JvmType], columnType)
   with NullableColumnBuilder
-  with CompressedColumnBuilder[T] {
 
-  override def gatherStats(row: Row, ordinal: Int) {
-    columnStats.gatherStats(row, ordinal)
-  }
-}
+private[sql] abstract class NativeColumnBuilder[T <: NativeType](
+    override val columnStats: NativeColumnStats[T],
+    override val columnType: NativeColumnType[T])
+  extends BasicColumnBuilder[T, T#JvmType](columnStats, columnType)
+  with NullableColumnBuilder
+  with AllCompressionSchemes
+  with CompressibleColumnBuilder[T]
 
-private[sql] class BooleanColumnBuilder
-  extends NativeColumnBuilder(new BooleanColumnStats, BOOLEAN)
+private[sql] class BooleanColumnBuilder extends NativeColumnBuilder(new BooleanColumnStats, BOOLEAN)
 
 private[sql] class IntColumnBuilder extends NativeColumnBuilder(new IntColumnStats, INT)
 
@@ -101,16 +103,12 @@ private[sql] class DoubleColumnBuilder extends NativeColumnBuilder(new DoubleCol
 
 private[sql] class FloatColumnBuilder extends NativeColumnBuilder(new FloatColumnStats, FLOAT)
 
-private[sql] class StringColumnBuilder extends NativeColumnBuilder(new StringColumnStates, STRING)
+private[sql] class StringColumnBuilder extends NativeColumnBuilder(new StringColumnStats, STRING)
 
-private[sql] class BinaryColumnBuilder
-  extends BasicColumnBuilder[BinaryType.type, Array[Byte]](BINARY)
-  with NullableColumnBuilder
+private[sql] class BinaryColumnBuilder extends ComplexColumnBuilder(BINARY)
 
 // TODO (lian) Add support for array, struct and map
-private[sql] class GenericColumnBuilder
-  extends BasicColumnBuilder[DataType, Array[Byte]](GENERIC)
-  with NullableColumnBuilder
+private[sql] class GenericColumnBuilder extends ComplexColumnBuilder(GENERIC)
 
 private[sql] object ColumnBuilder {
   val DEFAULT_INITIAL_BUFFER_SIZE = 10 * 1024 * 104