Method RequestData

Filters/Parallel/vtkAggregateDataSetFilter.cxx:64–188

------------------------------------------------------------------------------ We should avoid marshalling more than once.

//------------------------------------------------------------------------------
// We should avoid marshalling more than once.
int vtkAggregateDataSetFilter::RequestData(
  vtkInformation*, vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  vtkDataSet* input = nullptr;
  vtkDataSet* output = vtkDataSet::GetData(outputVector, 0);

  if (inputVector[0]->GetNumberOfInformationObjects() > 0)
  {
    input = vtkDataSet::GetData(inputVector[0], 0);
  }

  vtkMultiProcessController* controller = vtkMultiProcessController::GetGlobalController();

  int numberOfProcesses = controller->GetNumberOfProcesses();
  if (numberOfProcesses == this->NumberOfTargetProcesses)
  {
    if (input)
    {
      output->ShallowCopy(input);
    }
    return 1;
  }

  if (input->IsA("vtkImageData") || input->IsA("vtkRectilinearGrid") ||
    input->IsA("vtkStructuredGrid"))
  {
    vtkErrorMacro("Must build with the vtkFiltersParallelDIY2 module enabled to "
      << "aggregate topologically regular grids with MPI");

    return 0;
  }

  // create a subcontroller to simplify communication between the processes
  // that are aggregating data
  vtkSmartPointer<vtkMultiProcessController> subController = nullptr;
  if (this->NumberOfTargetProcesses == 1)
  {
    subController = controller;
  }
  else
  {
    int localProcessId = controller->GetLocalProcessId();
    int numberOfProcessesPerGroup = numberOfProcesses / this->NumberOfTargetProcesses;
    int localColor = localProcessId / numberOfProcessesPerGroup;
    if (numberOfProcesses % this->NumberOfTargetProcesses)
    {
      double d = 1. * numberOfProcesses / this->NumberOfTargetProcesses;
      localColor = int(localProcessId / d);
    }
    subController.TakeReference(controller->PartitionController(localColor, 0));
  }

  int subNumProcs = subController->GetNumberOfProcesses();
  int subRank = subController->GetLocalProcessId();

  std::vector<vtkIdType> pointCount(subNumProcs, 0);
  vtkIdType numPoints = input->GetNumberOfPoints();
  subController->AllGather(&numPoints, pointCount.data(), 1);