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

  Program:   Visualization Toolkit
  Module:    TestNonBlockingCommunication.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm 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.

=========================================================================*/
// .NAME TestNonBlockingCommunication.cxx -- Tests non-blocking MPI comm.
//
// .SECTION Description
//  This test performs a non-blocking communication between 2 processes using
//  the following pattern where:
//  (1) Each process posts its receives
//  (2) The posts its sends
//  (3) Does a wait-all

// VTK includes
#include "vtkMPIController.h"
#include "vtkMathUtilities.h"

// C++ includes
#include <cassert>

// MPI
#include <vtk_mpi.h>

void FillArray(const int rank, const int size, double array[])
{
  for (int i = 0; i < size; ++i)
  {
    array[i] = (rank + 1) * (i + 1);
  } // END for
}

//------------------------------------------------------------------------------
int TestNonBlockingCommunication(int argc, char* argv[])
{
  vtkMPIController* myController = vtkMPIController::New();
  myController->Initialize(&argc, &argv, 0);

  double sndarray[10];
  double rcvarray[10];
  double expected[10];

  vtkMPICommunicator::Request requests[2];

  int N = myController->GetNumberOfProcesses();
  int Rank = myController->GetLocalProcessId();
  int SendRank = (Rank == 0) ? 1 : 0;
  if (N != 2)
  {
    cerr << "This test must be run with 2 MPI processes!\n";
    myController->Finalize();
    myController->Delete();
    return (-1);
  }
  assert("pre: N must be 2" && (N == 2));
  assert("pre: Rank is out-of-bounds" && (Rank >= 0) && (Rank < N));

  cout << "Filling arrays...";
  cout.flush();
  FillArray(Rank, 10, sndarray);
  FillArray(SendRank, 10, expected);
  cout << "[DONE]\n";
  cout.flush();

  // Post receives
  cout << "Posting receives....\n";
  cout.flush();
  myController->NoBlockReceive(rcvarray, 10, SendRank, 0, requests[0]);

  // Post sends
  cout << "Posting sends...\n";
  cout.flush();
  myController->NoBlockSend(sndarray, 10, SendRank, 0, requests[1]);

  // Wait all
  cout << "Do a wait all!\n";
  cout.flush();
  myController->WaitAll(2, requests);

  bool arraysMatch = true;
  for (int i = 0; i < 10; ++i)
  {
    if (!vtkMathUtilities::FuzzyCompare(rcvarray[i], expected[i]))
    {
      arraysMatch = false;
      break;
    }
  }
  if (arraysMatch)
  {
    cout << "RcvArray matches expected data!\n";
    cout.flush();
  }
  else
  {
    cout << "ERROR: rcvarray does not match expected data!\n";
    cout.flush();
  }
  myController->Barrier();

  myController->Finalize();
  myController->Delete();

  return 0;
}