//********************************************************************

//

// Xinyi Wang

// Advanced Operating Systems

// Programming Project #2: Programming using MPI and RPC

// Project 2_2: the client/server model

// Date Assigned: Thursday, March 7, 2013

// Due Date: Tuesday, March 26, 2013 by 9:30 a.m.

// Instructor: Dr. Ajay K. Katangur

//

//********************************************************************

//*************************************************************************

//

// main Function

// -------------

// This function is to simulate the token ring, and send two tokens in

// the clock-wise and counter clock-wise directions. Finally, it will

// print out the information to the screen.

//

//

// Return Value

// ------------

// int 0 if program works good

//

//

// Value Parameters

// ----------------

// argc int count of command

// argv character array pointer content of command

//

//

// Reference Parameters

// --------------------

// None

//

//

// Local Variables

// ---------------

// rank int processes ranks

// nprocs int how many processes

// i int loop count for rounds

// token1 int token for the clock-wise direction

// token2 int token for the counter clock-wise direction

// tag1 int tag for the clock-wise communication

// tag2 int tag for the counter clock-wise communication

// rounds int number of rounds

// flag1 int flag for the clock-wise communication completion

// flag2 int flag for the counter clock-wise communication completion

// left int the left handside rank

// right int the right handside rank

//

//************************************************************************

#include <stdio.h>

#include <unistd.h>

#include <mpi.h>

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

{

int rank, nprocs;

int i, token1, token2, tag1 = 11, tag2 = 22, rounds, flag1, flag2;

int left, right;

MPI_Init(&argc, &argv);

MPI_Comm_size(MPI_COMM_WORLD, &nprocs);

MPI_Comm_rank(MPI_COMM_WORLD, &rank);

MPI_Status status1, status2;

MPI_Request reqs1[2], reqs2[2];

if ((rounds = atoi(argv[1])) <= 0) {

if (rank == 0)

fprintf(stderr, "invalid rounds: %s\n", argv[1]);

MPI_Finalize();

return 0;

}

token1 = 0;

token2 = nprocs * rounds;

right = (rank + 1) % nprocs;

left = (nprocs + rank - 1) % nprocs;

/* Process with rank 0 sends the first token */

if (rank == 0)

{

MPI_Isend(&token1, 1, MPI_INT, right, tag1, MPI_COMM_WORLD, &reqs1[1]);MPI_Wait(&reqs1[1],&status1);

MPI_Isend(&token2, 1, MPI_INT, left, tag2, MPI_COMM_WORLD, &reqs1[0]);MPI_Wait(&reqs1[0],&status2);

}

for (i= 0; i < rounds; i++)

{

MPI_Irecv(&token1, 1, MPI_INT, left, tag1, MPI_COMM_WORLD, &reqs2[1]);

MPI_Irecv(&token2, 1, MPI_INT, right, tag2, MPI_COMM_WORLD, &reqs2[0]);

MPI_Test(&reqs2[0], &flag2, &status2);

while (flag2 == 0) {

MPI_Test(&reqs2[0], &flag2, &status2);

}

printf("Rank %3d: received token1 %2d from rank %3d. (counter clock-wise)\n", rank, token2, right);

token2 = token2 - 1;

//sleep(1); /* To see the output printed one by one simulating message passing */

if (((rank != 0) || (i < (rounds - 1))) )

{

/* Only send it on if we are not rank 0, or therefsdf are more rounds to go */

MPI_Isend(&token2, 1, MPI_INT, left, tag2, MPI_COMM_WORLD, &reqs1[0]);MPI_Wait(&reqs1[0],&status2);

}

MPI_Test(&reqs2[1], &flag1, &status1);

while (flag1 == 0) {

MPI_Test(&reqs2[1], &flag1, &status1);

}

printf("Rank %3d: received token1 %2d from rank %3d. (clock-wise)\n", rank, token1, left);

token1 = token1 + 1;

//sleep(1); /* To see the output printed one by one simulating message passing */

if (((rank != 0) || (i < (rounds - 1))) )

{

/* Only send it on if we are not rank 0, or there are more rounds to go */

MPI_Isend(&token1, 1, MPI_INT, right, tag1, MPI_COMM_WORLD, &reqs1[1]);MPI_Wait(&reqs1[1],&status1);

}

}

MPI_Finalize();

return 0;

}