/* StarPU --- Runtime system for heterogeneous multicore architectures.
 *
 * Copyright (C) 2009, 2010  Université de Bordeaux 1
 * Copyright (C) 2010, 2011, 2012, 2013  Centre National de la Recherche Scientifique
 *
 * StarPU is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at
 * your option) any later version.
 *
 * StarPU is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * See the GNU Lesser General Public License in COPYING.LGPL for more details.
 */

#include <starpu_mpi.h>
#include "helper.h"
#include <unistd.h>

//#define NB 1000
#define NB 10

int main(int argc, char **argv)
{
	int ret, rank, size, i, nb_requests;
	starpu_data_handle_t tab_handle[NB];
	starpu_mpi_req request[NB];

	MPI_Init(NULL, NULL);
	MPI_Comm_rank(MPI_COMM_WORLD, &rank);
	MPI_Comm_size(MPI_COMM_WORLD, &size);

	if (size%2 != 0)
	{
		if (rank == 0)
			FPRINTF(stderr, "We need a even number of processes.\n");

		MPI_Finalize();
		return STARPU_TEST_SKIPPED;
	}

	ret = starpu_init(NULL);
	STARPU_CHECK_RETURN_VALUE(ret, "starpu_init");
	ret = starpu_mpi_init(NULL, NULL, 0);
	STARPU_CHECK_RETURN_VALUE(ret, "starpu_mpi_init");

	for(i=0 ; i<NB ; i++)
	{
		starpu_variable_data_register(&tab_handle[i], 0, (uintptr_t)&rank, sizeof(int));
		starpu_data_set_tag(tab_handle[i], i);
		request[i] = NULL;
	}

	int other_rank = rank%2 == 0 ? rank+1 : rank-1;

	fprintf(stderr, "rank %d exchanging with rank %d\n", rank, other_rank);

	if (rank%2)
	{
		starpu_mpi_isend(tab_handle[0], &request[0], other_rank, 0, MPI_COMM_WORLD);
		starpu_mpi_recv(tab_handle[2], other_rank, 2, MPI_COMM_WORLD, NULL);
		starpu_mpi_isend(tab_handle[1], &request[1], other_rank, 1, MPI_COMM_WORLD);
		nb_requests = 2;
	}
	else
	{
		starpu_mpi_irecv(tab_handle[0], &request[0], other_rank, 0, MPI_COMM_WORLD);
		starpu_mpi_irecv(tab_handle[1], &request[1], other_rank, 1, MPI_COMM_WORLD);
		starpu_mpi_isend(tab_handle[2], &request[2], other_rank, 2, MPI_COMM_WORLD);
		nb_requests = 3;
	}

	int finished=0;
	while (!finished)
	{
		for(i=0 ; i<nb_requests ; i++)
		{
			if (request[i])
			{
				int flag;
				MPI_Status status;
				starpu_mpi_test(&request[i], &flag, &status);
				if (flag)
					fprintf(stderr, "request[%d] = %d %p\n", i, flag, request[i]);
			}
		}
		finished = request[0] == NULL;
		for(i=1 ; i<nb_requests ; i++) finished = finished && request[i] == NULL;
	}

	for(i=0 ; i<NB ; i++)
		starpu_data_unregister(tab_handle[i]);

	starpu_mpi_shutdown();
	starpu_shutdown();

	MPI_Finalize();

	return 0;
}