QtConcurrent::run spike solution

qtconcurrentspike

#include <QList>
#include <QtAlgorithms>
#include <QDebug>
#include <QtConcurrentRun>

QList<int> sort(QList<int> unsorted, int chunkId){
  qDebug() << "starting to sort chunk " << chunkId;
  qSort(unsorted);
  qDebug() << "finished to sort chunk " << chunkId;
  return unsorted;
}

void printList(const QList<int> &list){
 foreach(const int i, list){
    qDebug() << i;
  }
}

int main(int argc, char *argv[]) {

  QList<QList<int> > chunks;
  int chunkCount = 1<<4;
  int chunkSize = 1<<22;
  for(int i = 0; i != chunkCount; ++i){
    qDebug() << "creating Chunk " << i;
    QList<int> actChunk;
    for(int j = 0; j != chunkSize; ++j){
      actChunk.append(qrand());
    }
    chunks.append(actChunk);
  }

  qDebug() << "chunks created";
  qDebug() << "sorting";

  QList<QFuture<QList<int> > > sortedChunkFutures;
  for(int i = 0; i != chunkCount; ++i){
    QList<int> actChunk = chunks.at(i);
    QFuture<QList<int> > actChunkSortedFuture;
    actChunkSortedFuture = QtConcurrent::run(sort, actChunk, i);
    sortedChunkFutures.append(actChunkSortedFuture);
  }

  qDebug() << "joining in same order";
  for(int i = 0; i != chunkCount; ++i){
    QFuture<QList<int> > actChunkSortedFuture;
    actChunkSortedFuture = sortedChunkFutures.at(i);
    qDebug() << "joining " << i;
    QList<int> sortedChunk = actChunkSortedFuture.result();
    qDebug() << "joined " << i;
  }
 
  qDebug() << "finished";
	return 0;
}