scala.collection.parallel.mutable.ResizableParArrayCombiner#CopyChainToArray

class CopyChainToArray extends Task[Unit, CopyChainToArray]

Type Members

type Result = Unit

  • Definition Classes
    • Task

Value Members From scala.collection.parallel.Task

def repr: CopyChainToArray

  • Definition Classes
    • Task

(defined at scala.collection.parallel.Task)

Instance Constructors From scala.collection.parallel.mutable.ResizableParArrayCombiner.CopyChainToArray ——————————————————————————–

new CopyChainToArray(array: Array[Any], offset: Int, howmany: Int)

(defined at scala.collection.parallel.mutable.ResizableParArrayCombiner.CopyChainToArray)

Value Members From scala.collection.parallel.mutable.ResizableParArrayCombiner.CopyChainToArray ——————————————————————————–

def leaf(prev: Option[Unit]): Unit

Body of the task - non-divisible unit of work done by this task. Optionally is provided with the result from the previous completed task or None if there was no previous task (or the previous task is uncompleted or unknown).

  • Definition Classes
    • CopyChainToArray → Task

(defined at scala.collection.parallel.mutable.ResizableParArrayCombiner.CopyChainToArray)

def split: immutable.List[CopyChainToArray]

Splits this task into a list of smaller tasks.

  • Definition Classes
    • CopyChainToArray → Task

(defined at scala.collection.parallel.mutable.ResizableParArrayCombiner.CopyChainToArray)

Value Members From Implicit scala.collection.parallel.CollectionsHaveToParArray ——————————————————————————–

def toParArray: ParArray[T]

  • Implicit information
    • This member is added by an implicit conversion from CopyChainToArray to CollectionsHaveToParArray [CopyChainToArray, T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (CopyChainToArray) ⇒ GenTraversableOnce [T] is in scope.
  • Definition Classes
    • CollectionsHaveToParArray (added by implicit convertion: scala.collection.parallel.CollectionsHaveToParArray)

Full Source:

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

package scala
package collection.parallel.mutable

import scala.collection.mutable.ArraySeq
import scala.collection.mutable.ArrayBuffer
import scala.collection.parallel.Task

/** An array combiner that uses a chain of arraybuffers to store elements. */
trait ResizableParArrayCombiner[T] extends LazyCombiner[T, ParArray[T], ExposedArrayBuffer[T]] {

  override def sizeHint(sz: Int) = if (chain.length == 1) chain(0).sizeHint(sz)

  // public method with private[mutable] type ExposedArrayBuffer in parameter type; cannot be overridden.
  final def newLazyCombiner(c: ArrayBuffer[ExposedArrayBuffer[T]]) = ResizableParArrayCombiner(c)

  def allocateAndCopy = if (chain.size > 1) {
    val arrayseq = new ArraySeq[T](size)
    val array = arrayseq.array.asInstanceOf[Array[Any]]

    combinerTaskSupport.executeAndWaitResult(new CopyChainToArray(array, 0, size))

    new ParArray(arrayseq)
  } else { // optimisation if there is only 1 array
    new ParArray(new ExposedArraySeq[T](chain(0).internalArray, size))
  }

  override def toString = "ResizableParArrayCombiner(" + size + "): " //+ chain

  /* tasks */

  class CopyChainToArray(array: Array[Any], offset: Int, howmany: Int) extends Task[Unit, CopyChainToArray] {
    var result = ()
    def leaf(prev: Option[Unit]) = if (howmany > 0) {
      var totalleft = howmany
      val (stbuff, stind) = findStart(offset)
      var buffind = stbuff
      var ind = stind
      var arrayIndex = offset
      while (totalleft > 0) {
        val currbuff = chain(buffind)
        val chunksize = if (totalleft < (currbuff.size - ind)) totalleft else currbuff.size - ind
        val until = ind + chunksize

        copyChunk(currbuff.internalArray, ind, array, arrayIndex, until)
        arrayIndex += chunksize
        ind += chunksize

        totalleft -= chunksize
        buffind += 1
        ind = 0
      }
    }
    private def copyChunk(buffarr: Array[AnyRef], buffStart: Int, ra: Array[Any], arrayStart: Int, until: Int) {
      Array.copy(buffarr, buffStart, ra, arrayStart, until - buffStart)
    }
    private def findStart(pos: Int) = {
      var left = pos
      var buffind = 0
      while (left >= chain(buffind).size) {
        left -= chain(buffind).size
        buffind += 1
      }
      (buffind, left)
    }
    def split = {
      val fp = howmany / 2
      List(new CopyChainToArray(array, offset, fp), new CopyChainToArray(array, offset + fp, howmany - fp))
    }
    def shouldSplitFurther = howmany > scala.collection.parallel.thresholdFromSize(size, combinerTaskSupport.parallelismLevel)
  }
}

object ResizableParArrayCombiner {
  def apply[T](c: ArrayBuffer[ExposedArrayBuffer[T]]): ResizableParArrayCombiner[T] = {
    new { val chain = c } with ResizableParArrayCombiner[T] // was: with EnvironmentPassingCombiner[T, ParArray[T]]
  }
  def apply[T](): ResizableParArrayCombiner[T] = apply(new ArrayBuffer[ExposedArrayBuffer[T]] += new ExposedArrayBuffer[T])
}