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lammps/examples/COUPLE/library/send2one.cpp
775e8f3cc8f5lammm-master-deprecated

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send2one.cpp
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#include "mpi.h"
#include "stdlib.h"
#include "stdio.h"
#include "send2one.h"
#include "memory.h"
#include "error.h"
/* ---------------------------------------------------------------------- */
Send2One::Send2One(MPI_Comm caller_comm)
{
comm = caller_comm;
MPI_Comm_rank(comm,&me);
MPI_Comm_size(comm,&nprocs);
memory = new Memory(comm);
error = new Error(comm);
buf = NULL;
maxbuf = 0;
}
/* ---------------------------------------------------------------------- */
Send2One::~Send2One()
{
delete memory;
delete error;
memory->sfree(buf);
}
/* ---------------------------------------------------------------------- */
void Send2One::execute()
{
int nme,nmax,nsize,ping;
MPI_Status status;
MPI_Request request;
// pre-processing before ping loop
pre();
// nme = size of data I contribute, in bytes
// nmax = max size of data on any proc, in bytes
// reallocate buf if necessary
nme = size();
MPI_Allreduce(&nme,&nmax,1,MPI_INT,MPI_MAX,comm);
if (nmax > maxbuf) {
maxbuf = nmax;
memory->sfree(buf);
buf = (char *) memory->smalloc(maxbuf,"foo:buf");
}
// pack my data into buf
pack(buf);
// proc 0 pings each proc, receives its data
// all other procs wait for ping, send their data to proc 0
// invoke process() to work with data
if (me == 0) {
for (int iproc = 0; iproc < nprocs; iproc++) {
if (iproc) {
MPI_Irecv(buf,maxbuf,MPI_CHAR,iproc,0,comm,&request);
MPI_Send(&ping,0,MPI_INT,iproc,0,comm);
MPI_Wait(&request,&status);
MPI_Get_count(&status,MPI_CHAR,&nsize);
} else nsize = nme;
process(nsize,buf);
}
} else {
MPI_Recv(&ping,0,MPI_INT,0,0,comm,&status);
MPI_Rsend(buf,nme,MPI_CHAR,0,0,comm);
}
post();
}
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