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netcdf-c/nc_test4/tst_parallel3.c
Dennis Heimbigner 6723a38d90 remove some debug statements
2019-02-01 14:39:30 -07:00

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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/* This test of netCDF-4 parallel I/O was contributed by the HDF5
* team. */
#include <nc_tests.h>
#include "err_macros.h"
#define FILE_NAME "tst_parallel3.nc"
/*2,3,4 dimensional test, the first dimension is unlimited, time.
*/
#define NDIMS1 2
#define NDIMS2 4
#define DIMSIZE /*4 */ 768*2
#define DIMSIZE2 4
#define DIMSIZE3 4
#define TIMELEN 1
/*BIGFILE, >2G, >4G, >8G file
big file is created but no actually data is written
Dimensional size is defined inside the function
*/
#define ATTRNAME1 "valid_range"
#define ATTRNAME2 "scale_factor"
#define ATTRNAME3 "title"
/* The number of processors should be a good number for the
dimension to be divided evenly, the best set of number of processor
should be 2 power n. However, for NetCDF4 tests, the following numbers
are generally treated as good numbers:
1,2,3,4,6,8,12,16
The maximum number of processor is 16.*/
int test_pio(int);
int test_pio_attr(int);
int test_pio_big(int);
int test_pio_hyper(int);
int test_pio_extend(int);
char* getenv_all(MPI_Comm comm, int root, const char* name);
int facc_type;
int facc_type_open;
char file_name[NC_MAX_NAME + 1];
int main(int argc, char **argv)
{
int mpi_size, mpi_rank; /* mpi variables */
int i;
int NUMP[8] ={1,2,3,4,6,8,12,16};
int size_flag = 0;
/* Un-buffer the stdout and stderr */
setbuf(stderr, NULL);
setbuf(stdout, NULL);
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &mpi_size);
MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);
if (mpi_rank == 0)
printf("\n*** Testing more advanced parallel access.\n");
for (i = 0; i < 8; i++){
if(mpi_size == NUMP[i])
{
size_flag = 1;
break;
}
}
if(!size_flag){
printf("mpi_size is wrong\n");
printf(" The number of processor must be chosen from\n");
printf(" 1,2,3,4,6,8,12,16 \n");
return -1;
}
facc_type = NC_NETCDF4;
facc_type_open = 0;
/* Create file name. */
sprintf(file_name, "%s/%s", TEMP_LARGE, FILE_NAME);
/* Test NetCDF4 with MPI-IO driver */
if (mpi_rank == 0)
printf("*** Testing parallel IO for raw-data with MPI-IO (driver)...");
if(test_pio(NC_INDEPENDENT)!=0) ERR;
if(test_pio(NC_COLLECTIVE)!=0) ERR;
if (mpi_rank == 0)
SUMMARIZE_ERR;
if (mpi_rank == 0)
printf("*** Testing parallel IO for meta-data with MPI-IO (driver)...");
if(test_pio_attr(NC_INDEPENDENT)!=0) ERR;
if(test_pio_attr(NC_COLLECTIVE)!=0) ERR;
if (mpi_rank == 0)
SUMMARIZE_ERR;
if (mpi_rank == 0)
printf("*** Testing parallel IO for different hyperslab selections with MPI-IO (driver)...");
if(test_pio_hyper(NC_INDEPENDENT)!=0)ERR;
if(test_pio_hyper(NC_COLLECTIVE)!=0) ERR;
if (mpi_rank == 0)
SUMMARIZE_ERR;
if (mpi_rank == 0)
printf("*** Testing parallel IO for extending variables with MPI-IO (driver)...");
if(test_pio_extend(NC_COLLECTIVE)!=0) ERR;
if (mpi_rank == 0)
SUMMARIZE_ERR;
if (mpi_rank == 0)
printf("*** Testing parallel IO for raw-data with MPIPOSIX-IO (driver)...");
facc_type = NC_NETCDF4;
facc_type_open = 0;
if(test_pio(NC_INDEPENDENT)!=0) ERR;
if(test_pio(NC_COLLECTIVE)!=0) ERR;
if (mpi_rank == 0)
SUMMARIZE_ERR;
if (mpi_rank == 0)
printf("*** Testing parallel IO for meta-data with MPIPOSIX-IO (driver)...");
if(test_pio_attr(NC_INDEPENDENT)!=0) ERR;
if(test_pio_attr(NC_COLLECTIVE)!=0) ERR;
if (mpi_rank == 0)
SUMMARIZE_ERR;
if (mpi_rank == 0)
printf("*** Testing parallel IO for different hyperslab selections "
"with MPIPOSIX-IO (driver)...");
if(test_pio_hyper(NC_INDEPENDENT)!=0)ERR;
if(test_pio_hyper(NC_COLLECTIVE)!=0) ERR;
if (mpi_rank == 0)
SUMMARIZE_ERR;
if (mpi_rank == 0)
printf("*** Testing parallel IO for extending variables with MPIPOSIX-IO (driver)...");
if(test_pio_extend(NC_COLLECTIVE)!=0) ERR;
if (mpi_rank == 0)
SUMMARIZE_ERR;
/* if(!getenv_all(MPI_COMM_WORLD,0,"NETCDF4_NOCLEANUP")) */
remove(file_name);
MPI_Finalize();
if (mpi_rank == 0)
FINAL_RESULTS;
return 0;
}
/* Both read and write will be tested */
int test_pio(int flag)
{
/* MPI stuff. */
int mpi_size, mpi_rank;
MPI_Comm comm = MPI_COMM_WORLD;
MPI_Info info = MPI_INFO_NULL;
/* Netcdf-4 stuff. */
int ncid;
int nvid,uvid;
int rvid;
unsigned m,k,j,i;
/* two dimensional integer data test */
int dimids[NDIMS1];
size_t start[NDIMS1];
size_t count[NDIMS1];
int *data;
int *tempdata;
int *rdata;
int *temprdata;
/* four dimensional integer data test,
time dimension is unlimited.*/
int dimuids[NDIMS2];
size_t ustart[NDIMS2];
size_t ucount[NDIMS2];
int *udata;
int *tempudata;
int *rudata;
int *temprudata;
/* Initialize MPI. */
MPI_Comm_size(MPI_COMM_WORLD, &mpi_size);
MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);
/* Create a parallel netcdf-4 file. */
if (nc_create_par(file_name, facc_type, comm, info, &ncid)) ERR;
/* The first case is two dimensional variables, no unlimited dimension */
/* Create two dimensions. */
if (nc_def_dim(ncid, "d1", DIMSIZE2, dimids)) ERR;
if (nc_def_dim(ncid, "d2", DIMSIZE, &dimids[1])) ERR;
/* Create one var. */
if (nc_def_var(ncid, "v1", NC_INT, NDIMS1, dimids, &nvid)) ERR;
if (nc_enddef(ncid)) ERR;
/* Set up slab for this process. */
start[0] = 0;
start[1] = mpi_rank * DIMSIZE/mpi_size;
count[0] = DIMSIZE2;
count[1] = DIMSIZE/mpi_size;
/* start parallel netcdf4 */
if (nc_var_par_access(ncid, nvid, flag)) ERR;
if (!(data = malloc(sizeof(int)*count[1]*count[0]))) ERR;
tempdata = data;
for (j = 0; j < count[0]; j++){
for (i = 0; i < count[1]; i++)
{
*tempdata = mpi_rank * (j + 1);
tempdata++;
}
}
/* Write two dimensional integer data */
if (nc_put_vara_int(ncid, nvid, start, count, data)) ERR;
free(data);
/* Case 2: create four dimensional integer data,
one dimension is unlimited. */
/* Create four dimensions. */
if (nc_def_dim(ncid, "ud1", NC_UNLIMITED, dimuids)) ERR;
if (nc_def_dim(ncid, "ud2", DIMSIZE3, &dimuids[1])) ERR;
if (nc_def_dim(ncid, "ud3", DIMSIZE2, &dimuids[2])) ERR;
if (nc_def_dim(ncid, "ud4", DIMSIZE, &dimuids[3])) ERR;
/* Create one var. */
if (nc_def_var(ncid, "uv1", NC_INT, NDIMS2, dimuids, &uvid)) ERR;
if (nc_enddef(ncid)) ERR;
/* Set up selection parameters */
ustart[0] = 0;
ustart[1] = 0;
ustart[2] = 0;
ustart[3] = DIMSIZE*mpi_rank/mpi_size;
ucount[0] = TIMELEN;
ucount[1] = DIMSIZE3;
ucount[2] = DIMSIZE2;
ucount[3] = DIMSIZE/mpi_size;
/* Access parallel */
if (nc_var_par_access(ncid, uvid, flag)) ERR;
/* Create phony data. */
if (!(udata = malloc(ucount[0]*ucount[1]*ucount[2]*ucount[3]*sizeof(int)))) ERR;
tempudata = udata;
for( m=0; m<ucount[0];m++)
for( k=0; k<ucount[1];k++)
for (j=0; j<ucount[2];j++)
for (i=0; i<ucount[3]; i++)
{
*tempudata = (1+mpi_rank)*2*(j+1)*(k+1)*(m+1);
tempudata++;
}
/* Write slabs of phoney data. */
if (NC_INDEPENDENT == flag) {
int res;
res = nc_put_vara_int(ncid, uvid, ustart, ucount, udata);
if(res != NC_ECANTEXTEND) ERR;
}
else {
if (nc_put_vara_int(ncid, uvid, ustart, ucount, udata)) ERR;
}
free(udata);
/* Close the netcdf file. */
if (nc_close(ncid)) ERR;
if (nc_open_par(file_name, facc_type_open, comm, info, &ncid)) ERR;
/* Case 1: read two-dimensional variables, no unlimited dimension */
/* Set up slab for this process. */
start[0] = 0;
start[1] = mpi_rank * DIMSIZE/mpi_size;
count[0] = DIMSIZE2;
count[1] = DIMSIZE/mpi_size;
if (nc_inq_varid(ncid, "v1", &rvid)) ERR;
if (nc_var_par_access(ncid, rvid, flag)) ERR;
if (!(rdata = malloc(sizeof(int)*count[1]*count[0]))) ERR;
if (nc_get_vara_int(ncid, rvid, start, count, rdata)) ERR;
temprdata = rdata;
for (j=0; j<count[0];j++){
for (i=0; i<count[1]; i++){
if(*temprdata != mpi_rank*(j+1))
{
ERR_RET;
break;
}
temprdata++;
}
}
free(rdata);
/* Case 2: read four dimensional data, one dimension is unlimited. */
/* set up selection parameters */
ustart[0] = 0;
ustart[1] = 0;
ustart[2] = 0;
ustart[3] = DIMSIZE*mpi_rank/mpi_size;
ucount[0] = TIMELEN;
ucount[1] = DIMSIZE3;
ucount[2] = DIMSIZE2;
ucount[3] = DIMSIZE/mpi_size;
/* Inquiry the data */
/* (NOTE: This variable isn't written out, when access is independent) */
if (NC_INDEPENDENT != flag) {
if (nc_inq_varid(ncid, "uv1", &rvid)) ERR;
/* Access the parallel */
if (nc_var_par_access(ncid, rvid, flag)) ERR;
if (!(rudata = malloc(ucount[0]*ucount[1]*ucount[2]*ucount[3]*sizeof(int)))) ERR;
temprudata = rudata;
/* Read data */
if (nc_get_vara_int(ncid, rvid, ustart, ucount, rudata)) ERR;
for(m = 0; m < ucount[0]; m++)
for(k = 0; k < ucount[1]; k++)
for(j = 0; j < ucount[2]; j++)
for(i = 0; i < ucount[3]; i++)
{
if(*temprudata != (1+mpi_rank)*2*(j+1)*(k+1)*(m+1))
ERR_RET;
temprudata++;
}
free(rudata);
}
/* Close the netcdf file. */
if (nc_close(ncid)) ERR;
return 0;
}
/* Attributes: both read and write will be tested for parallel NetCDF*/
int test_pio_attr(int flag)
{
/* MPI stuff. */
int mpi_size, mpi_rank;
MPI_Comm comm = MPI_COMM_WORLD;
MPI_Info info = MPI_INFO_NULL;
/* Netcdf-4 stuff. */
int ncid;
int nvid;
int j, i;
double rh_range[2];
static char title[] = "parallel attr to netCDF";
nc_type st_type,vr_type;
size_t vr_len,st_len;
size_t orivr_len;
double *vr_val;
char *st_val;
/* two dimensional integer data*/
int dimids[NDIMS1];
size_t start[NDIMS1];
size_t count[NDIMS1];
int *data;
int *tempdata;
/* Initialize MPI. */
MPI_Comm_size(MPI_COMM_WORLD, &mpi_size);
MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);
/* Create a parallel netcdf-4 file. */
/* nc_set_log_level(NC_TURN_OFF_LOGGING); */
/* nc_set_log_level(3);*/
if (nc_create_par(file_name, facc_type, comm, info, &ncid)) ERR;
/* Create a 2-D variable so that an attribute can be added. */
if (nc_def_dim(ncid, "d1", DIMSIZE2, dimids)) ERR;
if (nc_def_dim(ncid, "d2", DIMSIZE, &dimids[1])) ERR;
/* Create one var. */
if (nc_def_var(ncid, "v1", NC_INT, NDIMS1, dimids, &nvid)) ERR;
orivr_len = 2;
rh_range[0] = 1.0;
rh_range[1] = 1000.0;
/* Write attributes of a variable */
if (nc_put_att_double (ncid, nvid, "valid_range", NC_DOUBLE,
orivr_len, rh_range)) ERR;
if (nc_put_att_text (ncid, nvid, "title", strlen(title),
title)) ERR;
/* Write global attributes */
if (nc_put_att_double (ncid, NC_GLOBAL, "g_valid_range", NC_DOUBLE,
orivr_len, rh_range)) ERR;
if (nc_put_att_text (ncid, NC_GLOBAL, "g_title", strlen(title), title)) ERR;
if (nc_enddef(ncid)) ERR;
/* Set up slab for this process. */
start[0] = 0;
start[1] = mpi_rank * DIMSIZE/mpi_size;
count[0] = DIMSIZE2;
count[1] = DIMSIZE/mpi_size;
/* Access parallel */
if (nc_var_par_access(ncid, nvid, flag)) ERR;
/* Allocating data */
data = malloc(sizeof(int)*count[1]*count[0]);
tempdata = data;
for(j = 0; j < count[0]; j++)
for (i = 0; i < count[1]; i++)
{
*tempdata = mpi_rank * (j + 1);
tempdata++;
}
if (nc_put_vara_int(ncid, nvid, start, count, data)) ERR;
free(data);
/* Close the netcdf file. */
if (nc_close(ncid)) ERR;
/* Read attributes */
if (nc_open_par(file_name, facc_type_open, comm, info, &ncid)) ERR;
/* Set up slab for this process. */
start[0] = 0;
start[1] = mpi_rank * DIMSIZE/mpi_size;
count[0] = DIMSIZE2;
count[1] = DIMSIZE/mpi_size;
/* Inquiry variable */
if (nc_inq_varid(ncid, "v1", &nvid)) ERR;
/* Access parallel */
if (nc_var_par_access(ncid, nvid, flag)) ERR;
/* Inquiry attribute */
if (nc_inq_att (ncid, nvid, "valid_range", &vr_type, &vr_len)) ERR;
/* check stuff */
if(vr_type != NC_DOUBLE || vr_len != orivr_len) ERR;
vr_val = (double *) malloc(vr_len * sizeof(double));
/* Get variable attribute values */
if (nc_get_att_double(ncid, nvid, "valid_range", vr_val)) ERR;
/* Check variable attribute value */
for(i = 0; i < vr_len; i++)
if (vr_val[i] != rh_range[i])
ERR_RET;
free(vr_val);
/* Inquiry global attribute */
if (nc_inq_att (ncid, NC_GLOBAL, "g_valid_range", &vr_type, &vr_len)) ERR;
/* Check stuff. */
if(vr_type != NC_DOUBLE || vr_len != orivr_len) ERR;
/* Obtain global attribute value */
vr_val = (double *) malloc(vr_len * sizeof(double));
if (nc_get_att_double(ncid, NC_GLOBAL, "g_valid_range", vr_val)) ERR;
/* Check global attribute value */
for(i = 0; i < vr_len; i++)
if (vr_val[i] != rh_range[i]) ERR_RET;
free(vr_val);
/* Inquiry string attribute of a variable */
if (nc_inq_att (ncid, nvid, "title", &st_type, &st_len)) ERR;
/* check string attribute length */
if(st_len != strlen(title)) ERR_RET;
/* Check string attribute type */
if(st_type != NC_CHAR) ERR_RET;
/* Allocate meory for string attribute */
st_val = (char *) malloc(st_len * (sizeof(char)));
/* Obtain variable string attribute value */
if (nc_get_att_text(ncid, nvid,"title", st_val)) ERR;
/*check string value */
if(strncmp(st_val,title,st_len)) {
free(st_val);
ERR_RET;
}
free(st_val);
/*Inquiry global attribute */
if (nc_inq_att (ncid, NC_GLOBAL, "g_title", &st_type, &st_len)) ERR;
/* check attribute length*/
if(st_len != strlen(title)) ERR_RET;
/*check attribute type*/
if(st_type != NC_CHAR) ERR_RET;
/* obtain global string attribute value */
st_val = (char*)malloc(st_len*sizeof(char));
if (nc_get_att_text(ncid, NC_GLOBAL,"g_title", st_val)) ERR;
/* check attribute value */
if(strncmp(st_val,title,st_len)){
free(st_val);
ERR_RET;
}
free(st_val);
/* Close the netcdf file. */
if (nc_close(ncid)) ERR;
return 0;
}
/* test different hyperslab settings */
int test_pio_hyper(int flag){
/* MPI stuff. */
int mpi_size, mpi_rank;
int res = NC_NOERR;
MPI_Comm comm = MPI_COMM_WORLD;
MPI_Info info = MPI_INFO_NULL;
/* Netcdf-4 stuff. */
int ncid;
int nvid;
int rvid;
int j, i;
/* two dimensional integer data test */
int dimids[NDIMS1];
size_t start[NDIMS1], count[NDIMS1];
int *data;
int *tempdata;
int *rdata;
int *temprdata;
int count_atom;
/* Initialize MPI. */
MPI_Comm_size(MPI_COMM_WORLD, &mpi_size);
MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);
if(mpi_size == 1) return 0;
/* Create a parallel netcdf-4 file. */
/* nc_set_log_level(NC_TURN_OFF_LOGGING); */
/* nc_set_log_level(4);*/
if (nc_create_par(file_name, facc_type, comm, info, &ncid)) ERR;
/* The case is two dimensional variables, no unlimited dimension */
/* Create two dimensions. */
if (nc_def_dim(ncid, "d1", DIMSIZE2, dimids)) ERR;
if (nc_def_dim(ncid, "d2", DIMSIZE, &dimids[1])) ERR;
/* Create one var. */
if (nc_def_var(ncid, "v1", NC_INT, NDIMS1, dimids, &nvid)) ERR;
if (nc_enddef(ncid)) ERR;
/* hyperslab illustration for 3-processor case
--------
|aaaacccc|
|aaaacccc|
|bbbb |
|bbbb |
--------
*/
/* odd number of processors should be treated differently */
if(mpi_size%2 != 0) {
count_atom = DIMSIZE*2/(mpi_size+1);
if(mpi_rank <= mpi_size/2) {
start[0] = 0;
start[1] = mpi_rank*count_atom;
count[0] = DIMSIZE2/2;
count[1] = count_atom;
}
else {
start[0] = DIMSIZE2/2;
start[1] = (mpi_rank-mpi_size/2-1)*count_atom;
count[0] = DIMSIZE2/2;
count[1] = count_atom;
}
}
else {
count_atom = DIMSIZE*2/mpi_size;
if(mpi_rank < mpi_size/2) {
start[0] = 0;
start[1] = mpi_rank*count_atom;
count[0] = DIMSIZE2/2;
count[1] = count_atom;
}
else {
start[0] = DIMSIZE2/2;
start[1] = (mpi_rank-mpi_size/2)*count_atom;
count[0] = DIMSIZE2/2;
count[1] = count_atom;
}
}
if (nc_var_par_access(ncid, nvid, flag)) ERR;
data = malloc(sizeof(int)*count[1]*count[0]);
tempdata = data;
for (j=0; j<count[0];j++){
for (i=0; i<count[1]; i++){
*tempdata = mpi_rank*(j+1);
tempdata ++;
}
}
if (nc_put_vara_int(ncid, nvid, start, count, data)) ERR;
free(data);
/* Close the netcdf file. */
if (nc_close(ncid)) ERR;
if (nc_open_par(file_name, facc_type_open, comm, info, &ncid)) ERR;
/* Inquiry the variable */
if (nc_inq_varid(ncid, "v1", &rvid)) ERR;
if (nc_var_par_access(ncid, rvid, flag)) ERR;
rdata = malloc(sizeof(int)*count[1]*count[0]);
/* Read the data with the same slab settings */
if (nc_get_vara_int(ncid, rvid, start, count, rdata)) ERR;
temprdata = rdata;
for (j=0; j<count[0];j++){
for (i=0; i<count[1]; i++){
if(*temprdata != mpi_rank*(j+1))
{
res = -1;
break;
}
temprdata++;
}
}
free(rdata);
if(res == -1) ERR_RET;
/* Close the netcdf file. */
if (nc_close(ncid)) ERR;
return 0;
}
/* test extending variables */
int test_pio_extend(int flag){
int rank, procs;
int ncFile;
int ncDimPart;
int ncDimVrtx;
int ncVarVrtx;
int dimsVrtx[2];
size_t start[2];
size_t count[2];
int vertices[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &procs);
/* Create netcdf file */
if (nc_create_par("test.nc", NC_NETCDF4, MPI_COMM_WORLD, MPI_INFO_NULL, &ncFile)) ERR;
/* Create netcdf dimensions */
if (nc_def_dim(ncFile, "partitions", procs, &ncDimPart)) ERR;
if (nc_def_dim(ncFile, "vertices", NC_UNLIMITED, &ncDimVrtx)) ERR;
/* Create netcdf variables */
dimsVrtx[0] = ncDimPart;
dimsVrtx[1] = ncDimVrtx;
if (nc_def_var(ncFile, "vertex", NC_INT, 2, dimsVrtx, &ncVarVrtx)) ERR;
/* Start writing data */
if (nc_enddef(ncFile)) ERR;
/* Set access mode */
if (nc_var_par_access(ncFile, ncVarVrtx, flag)) ERR;
/* Write vertices */
start[0] = rank;
start[1] = 0;
count[0] = 1;
count[1] = rank;
if (nc_put_vara_int(ncFile, ncVarVrtx, start, count, vertices)) ERR;
/* Close netcdf file */
if (nc_close(ncFile)) ERR;
return 0;
}
/*-------------------------------------------------------------------------
* Function: getenv_all
*
* Purpose: Used to get the environment that the root MPI task has.
* name specifies which environment variable to look for
* val is the string to which the value of that environment
* variable will be copied.
*
* NOTE: The pointer returned by this function is only
* valid until the next call to getenv_all and the data
* stored there must be copied somewhere else before any
* further calls to getenv_all take place.
*
* Return: pointer to a string containing the value of the environment variable
* NULL if the varialbe doesn't exist in task 'root's environment.
*
* Programmer: Leon Arber
* 4/4/05
*
* Modifications:
*
*-------------------------------------------------------------------------
*/
char* getenv_all(MPI_Comm comm, int root, const char* name)
{
int nID;
int len = -1;
static char* env = NULL;
assert(name);
MPI_Comm_rank(comm, &nID);
/* The root task does the getenv call
* and sends the result to the other tasks */
if(nID == root)
{
env = getenv(name);
if(env)
{
len = strlen(env);
MPI_Bcast(&len, 1, MPI_INT, root, comm);
MPI_Bcast(env, len, MPI_CHAR, root, comm);
}
/* len -1 indicates that the variable was not in the environment */
else
MPI_Bcast(&len, 1, MPI_INT, root, comm);
}
else
{
MPI_Bcast(&len, 1, MPI_INT, root, comm);
if(len >= 0)
{
if(env == NULL)
env = (char*) malloc(len+1);
else if(strlen(env) < len)
env = (char*) realloc(env, len+1);
MPI_Bcast(env, len, MPI_CHAR, root, comm);
env[len] = '\0';
}
else
{
if(env)
free(env);
env = NULL;
}
}
MPI_Barrier(comm);
return env;
}
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