Scala example source code file (ParFlatHashTable.scala)

This example Scala source code file (ParFlatHashTable.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

collection, int, iterablesplitter, parallel, parflathashtable, parflathashtableiterator, seq, sizemap, sizemaputils, table, traversed/total

The ParFlatHashTable.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

package scala
package collection
package parallel.mutable

import scala.collection.parallel.IterableSplitter

/** Parallel flat hash table.
 *
 *  @tparam T      type of the elements in the $coll.
 *  @define coll   table
 *  @define Coll   `ParFlatHashTable`
 *
 *  @author Aleksandar Prokopec
 */
trait ParFlatHashTable[T] extends scala.collection.mutable.FlatHashTable[T] {

  override def alwaysInitSizeMap = true

  abstract class ParFlatHashTableIterator(var idx: Int, val until: Int, val totalsize: Int)
  extends IterableSplitter[T] with SizeMapUtils {
    import scala.collection.DebugUtils._

    private[this] var traversed = 0
    private[this] val itertable = table

    if (hasNext) scan()

    private[this] def scan() {
      while (itertable(idx) eq null) {
        idx += 1
      }
    }

    def newIterator(index: Int, until: Int, totalsize: Int): IterableSplitter[T]

    def remaining = totalsize - traversed
    def hasNext = traversed < totalsize
    def next() = if (hasNext) {
      val r = entryToElem(itertable(idx))
      traversed += 1
      idx += 1
      if (hasNext) scan()
      r
    } else Iterator.empty.next()
    def dup = newIterator(idx, until, totalsize)
    def split = if (remaining > 1) {
      val divpt = (until + idx) / 2

      val fstidx = idx
      val fstuntil = divpt
      val fsttotal = calcNumElems(idx, divpt, itertable.length, sizeMapBucketSize)
      val fstit = newIterator(fstidx, fstuntil, fsttotal)

      val sndidx = divpt
      val snduntil = until
      val sndtotal = remaining - fsttotal
      val sndit = newIterator(sndidx, snduntil, sndtotal)

      Seq(fstit, sndit)
    } else Seq(this)

    override def debugInformation = buildString {
      append =>
      append("Parallel flat hash table iterator")
      append("---------------------------------")
      append("Traversed/total: " + traversed + " / " + totalsize)
      append("Table idx/until: " + idx + " / " + until)
      append("Table length: " + itertable.length)
      append("Table: ")
      append(arrayString(itertable, 0, itertable.length))
      append("Sizemap: ")
      append(arrayString(sizemap, 0, sizemap.length))
    }

    protected def countElems(from: Int, until: Int) = {
      var count = 0
      var i = from
      while (i < until) {
        if (itertable(i) ne null) count += 1
        i += 1
      }
      count
    }

    protected def countBucketSizes(frombucket: Int, untilbucket: Int) = {
      var count = 0
      var i = frombucket
      while (i < untilbucket) {
        count += sizemap(i)
        i += 1
      }
      count
    }
  }
}