Par Bottom up

bottom-up-par.scala

trait ParallelAncestorManager {
  def getAncestor(id: Int): ParSeq[Int]
  def getParVertices: ParSeq[Int]
}

trait PBottomUpUpdater extends FrontierUpdater with ParallelAncestorManager {

  def update(frontier: Seq[Int], parents: Array[Int]):Seq[Int] = {
    val next = BitSet()
    val frontierSet = frontier.toSet

    getParVertices.filter(parents(_) == -1).foreach { node =>
      val parNeighbors = getAncestor(node)
      parNeighbors.find(x => frontierSet.contains(x)) match {
        case Some(ancestor) => {
          parents(node) = ancestor
          next(node) = true
        }
        case None => None
      }
    }
    next.toBuffer
  }
}