scala.collection.parallel.mutable.ResizableParArrayCombiner

trait ResizableParArrayCombiner[T] extends LazyCombiner[T, ParArray[T], ExposedArrayBuffer[T]]

An array combiner that uses a chain of arraybuffers to store elements.

Type Members

class CopyChainToArray extends Task[Unit, CopyChainToArray]

Concrete Value Members From scala.collection.generic.Growable

def ++=(xs: TraversableOnce[T]): ResizableParArrayCombiner.this.type

adds all elements produced by a TraversableOnce to this growable collection.

  • xs
    • the TraversableOnce producing the elements to add.
  • returns
    • the growable collection itself.
  • Definition Classes
    • Growable

(defined at scala.collection.generic.Growable)

def +=(elem1: T, elem2: T, elems: T*): ResizableParArrayCombiner.this.type

adds two or more elements to this growable collection.

  • elem1
    • the first element to add.
  • elem2
    • the second element to add.
  • elems
    • the remaining elements to add.
  • returns
    • the growable collection itself
  • Definition Classes
    • Growable

(defined at scala.collection.generic.Growable)

Concrete Value Members From scala.collection.mutable.Builder

def mapResult[NewTo](f: (ParArray[T]) ⇒ NewTo): Builder[T, NewTo]

Creates a new builder by applying a transformation function to the results of this builder.

  • NewTo
    • the type of collection returned by f .
  • f
    • the transformation function.
  • returns
    • a new builder which is the same as the current builder except that a transformation function is applied to this builder’s result.
  • Definition Classes
    • Builder
  • Note
    • The original builder should no longer be used after mapResult is called.

(defined at scala.collection.mutable.Builder)

def sizeHint(coll: TraversableLike[_, _]): Unit

Gives a hint that one expects the result of this builder to have the same size as the given collection, plus some delta. This will provide a hint only if the collection is known to have a cheap size method. Currently this is assumed to be the case if and only if the collection is of type IndexedSeqLike . Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • coll
    • the collection which serves as a hint for the result’s size.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

def sizeHint(coll: TraversableLike[_, _], delta: Int): Unit

Gives a hint that one expects the result of this builder to have the same size as the given collection, plus some delta. This will provide a hint only if the collection is known to have a cheap size method. Currently this is assumed to be the case if and only if the collection is of type IndexedSeqLike . Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • coll
    • the collection which serves as a hint for the result’s size.
  • delta
    • a correction to add to the coll.size to produce the size hint.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

def sizeHintBounded(size: Int, boundingColl: TraversableLike[_, _]): Unit

Gives a hint how many elements are expected to be added when the next result is called, together with an upper bound given by the size of some other collection. Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • size
    • the hint how many elements will be added.
  • boundingColl
    • the bounding collection. If it is an IndexedSeqLike, then sizes larger than collection’s size are reduced.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

Concrete Value Members From scala.collection.parallel.Combiner

var _combinerTaskSupport: TaskSupport

  • Definition Classes
    • Combiner

(defined at scala.collection.parallel.Combiner)

def combinerTaskSupport: TaskSupport

  • Definition Classes
    • Combiner

(defined at scala.collection.parallel.Combiner)

def combinerTaskSupport_=(cts: TaskSupport): Unit

  • Definition Classes
    • Combiner

(defined at scala.collection.parallel.Combiner)

def resultWithTaskSupport: ParArray[T]

Constructs the result and sets the appropriate tasksupport object to the resulting collection if this is applicable.

  • Definition Classes
    • Combiner

(defined at scala.collection.parallel.Combiner)

Abstract Value Members From scala.collection.parallel.mutable.LazyCombiner

abstract val chain: ArrayBuffer[ExposedArrayBuffer[T]]

  • Definition Classes
    • LazyCombiner

(defined at scala.collection.parallel.mutable.LazyCombiner)

Concrete Value Members From scala.collection.parallel.mutable.LazyCombiner

def +=(elem: T): ResizableParArrayCombiner.this.type

Adds a single element to the builder.

  • elem
    • the element to be added.
  • returns
    • the builder itself.
  • Definition Classes
    • LazyCombiner → Builder → Growable

(defined at scala.collection.parallel.mutable.LazyCombiner)

def combine[N <: T, NewTo >: ParArray[T]](other: Combiner[N, NewTo]): Combiner[N, NewTo]

Combines the contents of the receiver builder and the other builder, producing a new builder containing both their elements.

This method may combine the two builders by copying them into a larger collection, by producing a lazy view that gets evaluated once result is invoked, or use a merge operation specific to the data structure in question.

Note that both the receiver builder and other builder become invalidated after the invocation of this method, and should be cleared (see clear ) if they are to be used again.

Also, combining two combiners c1 and c2 for which c1 eq c2 is true , that is, they are the same objects in memory:

c1.combine(c2)

always does nothing and returns c1 .

  • N
    • the type of elements contained by the other builder
  • NewTo
    • the type of collection produced by the other builder
  • other
    • the other builder
  • returns
    • the parallel builder containing both the elements of this and the other builder
  • Definition Classes
    • LazyCombiner → Combiner

(defined at scala.collection.parallel.mutable.LazyCombiner)

val lastbuff: ExposedArrayBuffer[T]

  • Definition Classes
    • LazyCombiner

(defined at scala.collection.parallel.mutable.LazyCombiner)

def result(): ParArray[T]

Produces a collection from the added elements. This is a terminal operation: the builder’s contents are undefined after this operation, and no further methods should be called.

  • returns
    • a collection containing the elements added to this builder.
  • Definition Classes
    • LazyCombiner → Builder

(defined at scala.collection.parallel.mutable.LazyCombiner)

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

def allocateAndCopy: ParArray[T]

Method that allocates the data structure and copies elements into it using size and chain members.

  • Definition Classes
    • ResizableParArrayCombiner → LazyCombiner

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

final def newLazyCombiner(c: ArrayBuffer[ExposedArrayBuffer[T]]): ResizableParArrayCombiner[T]

  • Definition Classes
    • ResizableParArrayCombiner → LazyCombiner

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

def sizeHint(sz: Int): Unit

Gives a hint how many elements are expected to be added when the next result is called. Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • Definition Classes
    • ResizableParArrayCombiner → Builder

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

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

def toParArray: ParArray[T]

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