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#include "orte_config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <mpi.h>
/*
LOGIC:
- the 'server' opens a port and write the info to a file
- the 'clients' open the file and connect to the port
- after each accept, the server and client do a merge to
convert the intercomm to an intracomm
DETAIL STEPS:
- server open port
- server does accept
- client #1 does connect
- server and client #1 do merge
- server does accept
- client #2 does connect
- server, client #1 and client #2 do merge
- server does accept
- client #3 does connect
- server, client #1, client #2 and client #3 do merge
*/
#define TAG 0
#define CHK(code) do \
{ \
int retval = code ; \
if (retval != MPI_SUCCESS) \
{ \
fprintf(stderr, "Error: " #code "\n") ; \
exit(1) ; \
} \
} while(0)
int main(int argc, char *argv[])
{
char hostname[OPAL_MAXHOSTNAMELEN] ;
char buff[255] ;
int role ;
int num_clients ;
int size, rank ;
FILE *fp ;
char server_port_name[MPI_MAX_PORT_NAME] ;
MPI_Comm intercomm, intracomm ;
MPI_Status status ;
int msg_count ;
int i ;
/* sanity check the args */
if(argc != 3)
{
fprintf(stderr, "usage %s <num clients> <1:server | 0:client>\n", argv[0]) ;
exit(1) ;
}
num_clients = atoi(argv[1]) ;
role = atoi(argv[2]) ;
if (num_clients <= 0 || (role != 0 && role != 1))
{
fprintf(stderr, "usage %s <num clients> <1:server | 0:client>\n", argv[0]) ;
exit(1) ;
}
/* initialize MPI */
CHK(MPI_Init(&argc, &argv)) ;
/* get the node name */
{
int retval = gethostname(hostname, sizeof(hostname));
if(retval == -1)
{
fprintf(stderr, "gethostname failed: %s\n", strerror(errno)) ;
exit(1) ;
}
}
/* server */
if(role == 1)
{
printf("SERVER: on node '%s'\n", hostname) ;
/* open port to establish connections */
CHK(MPI_Open_port(MPI_INFO_NULL, server_port_name)) ;
printf("SERVER: opened port=%s\n", server_port_name) ;
/* store the port name */
fp = fopen("server_port_name.txt", "w") ;
if(fp == NULL)
{
fprintf(stderr, "fopen failed: %s\n", strerror(errno)) ;
exit(1) ;
}
fprintf(fp, "%s", server_port_name) ;
fclose(fp) ;
/* the server accepts connections from all the clients */
for(i = 0 ; i < num_clients ; i++ )
{
/* accept connections at this port */
CHK(MPI_Comm_accept(server_port_name, MPI_INFO_NULL, 0,
i == 0 ? MPI_COMM_WORLD : intracomm,
&intercomm)) ;
printf("SERVER: accepted connection from client %d\n", i+1) ;
/* merge, to form one intra communicator */
CHK(MPI_Intercomm_merge(intercomm, 0, &intracomm)) ;
printf("SERVER: merged with client %d\n", i+1) ;
CHK(MPI_Comm_size(intracomm, &size)) ;
CHK(MPI_Comm_rank(intracomm, &rank)) ;
printf("SERVER: after merging with client %d: size=%d rank=%d\n", i+1, size, rank) ;
}
} /* end server */
/* client */
if(role == 0)
{
printf("CLIENT: on node '%s'\n", hostname) ;
fp = fopen("server_port_name.txt", "r") ;
if(fp == NULL)
{
fprintf(stderr, "fopen failed: %s\n", strerror(errno)) ;
exit(1) ;
}
fscanf(fp, "%s", server_port_name) ;
fclose(fp) ;
printf("CLIENT: attempting to connect to server on port=%s\n", server_port_name) ;
/* connect to the server */
CHK(MPI_Comm_connect (server_port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD, &intercomm)) ;
printf("CLIENT: connected to server on port\n") ;
/* merge the server and client to one intra communicator */
CHK(MPI_Intercomm_merge(intercomm, 1, &intracomm)) ;
printf("CLIENT: merged with existing intracomm\n") ;
CHK(MPI_Comm_size(intracomm, &size)) ;
CHK(MPI_Comm_rank(intracomm, &rank)) ;
printf("CLIENT: after merging, new comm: size=%d rank=%d\n", size, rank) ;
for (i = rank ; i < num_clients ; i++)
{
/* client performs a collective accept */
CHK(MPI_Comm_accept(server_port_name, MPI_INFO_NULL, 0, intracomm, &intercomm)) ;
printf("CLIENT: connected to server on port\n") ;
/* merge the two intra comms back to one communicator */
CHK(MPI_Intercomm_merge(intercomm, 0, &intracomm)) ;
printf("CLIENT: merged with existing members\n") ;
CHK(MPI_Comm_size(intracomm, &size)) ;
CHK(MPI_Comm_rank(intracomm, &rank)) ;
printf("CLIENT: new size after merging with existing members: size=%d rank=%d\n", size, rank) ;
}
} /* end client */
CHK(MPI_Comm_size(intracomm, &size)) ;
CHK(MPI_Comm_rank(intracomm, &rank)) ;
printf("After fusion: size=%d rank=%d\n", size, rank) ;
if(rank == 0)
{
msg_count = num_clients ;
while(msg_count)
{
CHK(MPI_Recv(buff, 255, MPI_CHAR, MPI_ANY_SOURCE,
MPI_ANY_TAG, intracomm, &status)) ;
printf("Received hello msg from '%s'\n", buff) ;
msg_count-- ;
}
}
else
{
/* all ranks > 0 */
CHK(MPI_Send(hostname, strlen(hostname) + 1, MPI_CHAR, 0, TAG, intracomm)) ;
}
CHK(MPI_Finalize()) ;
fprintf(stderr, "Rank %d is exiting\n", rank);
return 0 ;
}
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