/*=========================================================================

  Program:   ParaView
  Module:    $RCSfile: vtkSubGroup.h,v $

  Copyright (c) Kitware, Inc.
  All rights reserved.
  See Copyright.txt or http://www.paraview.org/HTML/Copyright.html for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
/*----------------------------------------------------------------------------
 Copyright (c) Sandia Corporation
 See Copyright.txt or http://www.paraview.org/HTML/Copyright.html for details.
----------------------------------------------------------------------------*/

// .NAME vtkSubGroup - scalable collective communication for a
//      subset of members of a parallel VTK application
//
// .SECTION Description
//     This class provides scalable broadcast, reduce, etc. using
//     only a vtkMultiProcessController. It does not require MPI.
//     Users are vtkPKdTree and vtkDistributedDataFilter.
//
// .SECTION See Also
//      vtkPKdTree vtkDistributedDataFilter

#ifndef __vtkSubGroup_h
#define __vtkSubGroup_h

#include "vtkObject.h"

class vtkMultiProcessController;
class vtkCommunicator;

class VTK_PARALLEL_EXPORT vtkSubGroup : public vtkObject 
{
public:
  vtkTypeRevisionMacro(vtkSubGroup, vtkObject);
  virtual void PrintSelf(ostream &os, vtkIndent indent);
  static vtkSubGroup *New();

//BTX
  // The wrapper gets confused here and falls down.
  enum {MINOP = 1, MAXOP = 2, SUMOP = 3};
//ETX
  // Description:
  //    Initialize a communication subgroup for the processes
  //    with rank p0 through p1 of the given communicator.  (So
  //    vtkSubGroup is limited to working with subgroups that
  //    are identified by a contiguous set of rank IDs.)
  //    The third argument is the callers rank, which must
  //    in the range from p0 through p1.
  
  int Initialize(int p0, int p1, int me, int tag, vtkCommunicator *c);
  
  int Gather(int *data, int *to, int length, int root);
  int Gather(char *data, char *to, int length, int root);
  int Gather(float *data, float *to, int length, int root);
  int Broadcast(float *data, int length, int root);
  int Broadcast(double *data, int length, int root);
  int Broadcast(int *data, int length, int root);
  int Broadcast(char *data, int length, int root);
  int ReduceSum(int *data, int *to, int length, int root);
  int ReduceMax(float *data, float *to, int length, int root);
  int ReduceMax(double *data, double *to, int length, int root);
  int ReduceMax(int *data, int *to, int length, int root);
  int ReduceMin(float *data, float *to, int length, int root);
  int ReduceMin(double *data, double *to, int length, int root);
  int ReduceMin(int *data, int *to, int length, int root);
  
  int AllReduceUniqueList(int *list, int len, int **newList);
  int MergeSortedUnique(int *list1, int len1, int *list2, int len2, int **newList);
  
  void setGatherPattern(int root, int length);
  int getLocalRank(int processID);
  
  int Barrier();
  
  void PrintSubGroup() const;

  static int MakeSortedUnique(int *list, int len, int **newList);
  
  int tag;

protected:
  vtkSubGroup();
  ~vtkSubGroup();

private:
  int computeFanInTargets();
  void restoreRoot(int rootLoc);
  void moveRoot(int rootLoc);
  void setUpRoot(int root);

  int nFrom;
  int nTo; 
  
  int sendId;                // gather
  int sendOffset;
  int sendLength;

  int recvId[20];
  int recvOffset[20];
  int recvLength[20];
  int fanInFrom[20];         // reduce, broadcast

  int fanInTo;
  int nSend;
  int nRecv;
  int gatherRoot;
  int gatherLength;
  
  int *members;
  int nmembers;
  int myLocalRank;
  
  vtkCommunicator *comm;

  vtkSubGroup(const vtkSubGroup&); // Not implemented
  void operator=(const vtkSubGroup&); // Not implemented
};
#endif
