#include <stdio.h>
#include <mpi.h>
#include <stdlib.h>
#include <unistd.h>
// 16 КБайт
#define MESSAGE_SIZE (16*1024)
#define IDX0 0
#define IDX1 1

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

        double start_time, end_time;
        double start_send, end_send;
        int my_rank, commsize;
        char *data;

        MPI_Init(&argc, &argv);
        MPI_Comm_size(MPI_COMM_WORLD, &commsize);
        MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);

        if ((my_rank == 0) || (my_rank ==1)) {
                data = (char *)malloc(sizeof(char) * MESSAGE_SIZE);
                start_time = MPI_Wtime();

                if (my_rank == 0) {
                        start_send = MPI_Wtime();
                        MPI_Rsend(data, MESSAGE_SIZE, MPI_CHAR, IDX1, 0, MPI_COMM_WORLD);
                        end_send = MPI_Wtime();

                        sleep(2);

                        MPI_Recv(data, MESSAGE_SIZE, MPI_CHAR, IDX1, 0, MPI_COMM_WORLD, NULL);
                }
                else {
                        MPI_Recv(data, MESSAGE_SIZE, MPI_CHAR, IDX0, 0, MPI_COMM_WORLD, NULL);

                        start_send = MPI_Wtime();
                        MPI_Rsend(data, MESSAGE_SIZE, MPI_CHAR, IDX0, 0, MPI_COMM_WORLD);
                        end_send = MPI_Wtime();
                }
                end_time = MPI_Wtime();
                printf("[%d]Execution time (MPI_Rsend): %f; Send time: %f\n", my_rank, end_time - start_time, end_send - start_send);
                free(data);
	}

	MPI_Finalize();
}