MPI communication

gistfile1.txt

#include <cstdlib>
#include <cstdio>
#include <cmath>

#include <iostream>

#include "mpi.h"

using namespace std;

void master(MPI_Status status, int size) {
  MPI_Request sendRequest;
  
  int n = 20;
  
  int numbers[20] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 };
  int numbersSent = 0;
  int numbersReceived = 0;
  
  for(int i = 1; i < size; i++) {
    MPI_Isend( &numbers[i - 1], sizeof(int), MPI_INT, i, 5, MPI_COMM_WORLD, &sendRequest);
    numbersSent++;
  }
  
  while(numbersReceived < n) {
    int buf[3];
    MPI_Recv( buf, sizeof(int) * 3, MPI_INT, MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &status);
    if(buf[0] > 0) cout << buf[2] << ": pierwsza" << endl;
    else cout << buf[2] << ": zlozona" << endl;
    numbersReceived++;
    if(numbersSent < n) {
      MPI_Isend( &numbers[numbersSent], sizeof(int), MPI_INT, buf[1], 5, MPI_COMM_WORLD, &sendRequest);
      numbersSent++;
    }
  }
  // Terminate listeners
  int terminator = -1;
  for(int i = 1; i < size; i++) {
    MPI_Send( &terminator, sizeof(int), MPI_INT, i, 5, MPI_COMM_WORLD);
  }
  
}

void slave(MPI_Status status, int rank) {
  int number = 0;
  while(number != -1) {
    MPI_Recv( &number, sizeof(int), MPI_INT, MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &status);
    if(number == -1) break; // Terminate if -1 received
    int buf[3];
    buf[0] = 0;
    buf[1] = rank;
    buf[2] = number;
    MPI_Send( buf, sizeof(int) * 3, MPI_INT, 0, 5, MPI_COMM_WORLD);
  }
}

int main( int argc, char** argv ){ 
  
  MPI_Status status;
  int rank, size;
  
  MPI_Init( &argc, &argv );
  MPI_Comm_rank( MPI_COMM_WORLD, &rank ); 
  MPI_Comm_size( MPI_COMM_WORLD, &size );

  switch(rank) {
    case 0:
      master(status, size);
      break;
    default:
      slave(status, rank);
      break;
  }

  MPI_Finalize(); 
  return(0);

}