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/*********************************************************************
*
* Copyright (C) 2012, Northwestern University and Argonne National Laboratory
* See COPYRIGHT notice in top-level directory.
*
*********************************************************************/
/* $Id$ */
/* simple demonstration of pnetcdf
* text attribute on dataset
* write out rank into 1-d array collectively.
* This example demonstrates the non-blocking write interface */
/* This program creates a file, say named output.nc, with the following
contents, shown by running ncmpidump command .
% mpiexec -n 4 pnetcdf-write-nb /orangefs/wkliao/output.nc
% ncmpidump /orangefs/wkliao/output.nc
netcdf output {
// file format: CDF-2 (large file)
dimensions:
d1 = 4 ;
variables:
int v1(d1) ;
int v2(d1) ;
// global attributes:
:string = "Hello World\n",
"" ;
data:
v1 = 0, 1, 2, 3 ;
v2 = 0, 1, 2, 3 ;
}
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h> /* strncpy() */
#include <assert.h>
#include <mpi.h>
#include <pnetcdf.h>
static void handle_error(int status, int lineno)
{
fprintf(stderr, "Error at line %d: %s\n", lineno, ncmpi_strerror(status));
MPI_Abort(MPI_COMM_WORLD, 1);
}
int main(int argc, char **argv) {
int ret, ncfile, nprocs, rank, dimid, varid1, varid2, ndims=1;
char filename[256], buf[13] = "Hello World\n";
int data1, data2, requests[2], statuses[2];
MPI_Offset start, count=1;
MPI_Info info;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
if (argc > 2) {
if (rank == 0) printf("Usage: %s filename\n", argv[0]);
MPI_Finalize();
exit(-1);
}
if (argc > 1) snprintf(filename, 256, "%s", argv[1]);
else strcpy(filename, "testfile.nc");
MPI_Info_create(&info);
MPI_Info_set(info, "nc_var_align_size", "1");
ret = ncmpi_create(MPI_COMM_WORLD, filename,
NC_CLOBBER|NC_64BIT_OFFSET, info, &ncfile);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
MPI_Info_free(&info);
ret = ncmpi_def_dim(ncfile, "d1", nprocs, &dimid);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
ret = ncmpi_def_var(ncfile, "v1", NC_INT, ndims, &dimid, &varid1);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
ret = ncmpi_def_var(ncfile, "v2", NC_INT, ndims, &dimid, &varid2);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
ret = ncmpi_put_att_text(ncfile, NC_GLOBAL, "string", 13, buf);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
/* all processors defined the dimensions, attributes, and variables,
* but here in ncmpi_enddef is the one place where metadata I/O
* happens. Behind the scenes, rank 0 takes the information and writes
* the netcdf header. All processes communicate to ensure they have
* the same (cached) view of the dataset */
ret = ncmpi_enddef(ncfile);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
start=rank, count=1, data1=rank, data2=rank;
/* in this simple example every process writes its rank to two 1d variables */
/* we used a basic MPI_INT type to this flexible mode call, but could
* have used any derived MPI datatype that describes application data
* structures */
/* furthermore, we use the non-blocking interface to essentially
* schedule the two write operations. No i/o actually happens here,
* which is why these routines do not need to be collective. */
ret = ncmpi_iput_vara(ncfile, varid1, &start, &count, &data1, count,
MPI_INT, &requests[0]);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
ret = ncmpi_iput_vara(ncfile, varid2, &start, &count, &data2, count,
MPI_INT, &requests[1]);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
ret = ncmpi_wait_all(ncfile, 2, requests, statuses);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
/* check status of each nonblocking call */
if (statuses[0] != NC_NOERR) handle_error(statuses[0], __LINE__);
if (statuses[1] != NC_NOERR) handle_error(statuses[1], __LINE__);
ret = ncmpi_close(ncfile);
if (ret != NC_NOERR) handle_error(ret, __LINE__);
MPI_Finalize();
return 0;
}
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