/*
* Copyright 2021 Jeisson Hidalgo-Cespedes - Universidad de Costa Rica
* Creates a secondary thread that greets in the standard output
*/
#include <mpi.h>
#include <cstdint>
#include <iostream>
#include <random>
int random(std::mt19937& randomEngine, int min, int max) {
// Produce random values with uniform discrete distribution
std::uniform_int_distribution<int> randomDistribution(min, max - 1);
// Generate and return a random number using the uniform distribution
return randomDistribution(randomEngine);
}
int main(int argc, char* argv[]) {
if (MPI_Init(&argc, &argv) == MPI_SUCCESS) {
int my_rank = -1;
MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
int process_count = -1;
MPI_Comm_size(MPI_COMM_WORLD, &process_count);
char hostname[MPI_MAX_PROCESSOR_NAME];
int hostname_len = -1;
MPI_Get_processor_name(hostname, &hostname_len);
// Try to get a seed from hardware, if available
std::random_device::result_type seed = std::random_device()();
// This object generates randon numbers using the Mersenne-Twister algoritym
std::mt19937 randomEngine(seed + my_rank);
// srand(MPI_Wtime() * 1e9 + my_rank);
int my_lucky_number = random(randomEngine, 0, 100);
const int32_t previous = (process_count + my_rank - 1) % process_count;
const int32_t next = (my_rank + 1) % process_count;
int32_t can_print = 1;
if (my_rank != 0) {
MPI_Recv(&can_print, /*capacity*/ 1, MPI_INT32_T, /*source*/previous
, /*tag*/ 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
}
std::cout << "Process " << my_rank << "/" << process_count
<< ": my lucky number is " << my_lucky_number << std::endl;
if (my_rank < process_count - 1) {
MPI_Send(&can_print, /*count*/ 1, MPI_INT32_T, /*dest*/ next, /*tag*/ 0
, MPI_COMM_WORLD);
}
int global_min = -1;
int global_sum = -1;
int global_max = -1;
MPI_Reduce(&my_lucky_number, &global_min, /*count*/ 1,
MPI_INT, MPI_MIN, /*root*/ 0, MPI_COMM_WORLD);
MPI_Reduce(&my_lucky_number, &global_sum, /*count*/ 1,
MPI_INT, MPI_SUM, /*root*/ 0, MPI_COMM_WORLD);
MPI_Reduce(&my_lucky_number, &global_max, /*count*/ 1,
MPI_INT, MPI_MAX, /*root*/ 0, MPI_COMM_WORLD);
if (my_rank == 0) {
std::cout << "Process " << my_rank << "/" << process_count
<< ": all minimum " << global_min << std::endl;
const double average = double(global_sum) / process_count;
std::cout << "Process " << my_rank << "/" << process_count
<< ": all average " << average << std::endl;
std::cout << "Process " << my_rank << "/" << process_count
<< ": all maximum " << global_max << std::endl;
}
MPI_Finalize();
} else {
std::cout << "Error: could not init MPI environment" << std::endl;
}
return 0;
}