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/*
* Distributed under the OSI-approved Apache License, Version 2.0. See
* accompanying file Copyright.txt for details.
*
* Write single values to a file. There are four different cases:
* 1. Global constant - same on all processes, constant over time
* 2. Global value - same on all processes, may change over time
* 3. Local constants - different across processes, constant over time
* 4. Local value - different across processes, may change over time
*
* Constants are not handled separately from time-varying values in ADIOS.
* Simply write them only in the first step.
*
* Writing a global value from multiple processes does not hurt but it is
* useless.
*
* Created on: Jun 2, 2017
* Author: pnorbert
*/
#include <iostream>
#include <string>
#include <vector>
#include <adios2.h>
#if ADIOS2_USE_MPI
#include <mpi.h>
#endif
int main(int argc, char *argv[])
{
int rank = 0, nproc = 1;
#if ADIOS2_USE_MPI
int provided;
// MPI_THREAD_MULTIPLE is only required if you enable the SST MPI_DP
MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &nproc);
#endif
const int NSTEPS = 5;
// generate different random numbers on each process,
// but always the same sequence at each run
srand(rank * 32767);
#if ADIOS2_USE_MPI
adios2::ADIOS adios(MPI_COMM_WORLD);
#else
adios2::ADIOS adios;
#endif
// Application variables for output
// 1. Global value, constant across processes, constant over time
// This is 'nproc'
// 2. Global value, constant across processes, varying value over time
// This is 'step'
// 3. Local value, varying across processes, constant over time
// It will appear in reading as a 1D array of nproc elements.
// This is 'rank'
// 4. Local value, varying across processes, varying over time
unsigned int Nparts; // random size per process, 5..10 each
try
{
// Get io settings from the config file or
// create one with default settings here
adios2::IO io = adios.DeclareIO("Output");
io.SetEngine("BPFile");
io.SetParameters({{"verbose", "4"}});
/*
* Define variables
*/
// 1. Global constant, same value across processes, constant over time
adios2::Variable<int> varNproc = io.DefineVariable<int>("Nproc");
(void)varNproc; // For the sake of the example we create an unused
// variable
// 2. Global value, same value across processes, varying value over time
adios2::Variable<int> varStep = io.DefineVariable<int>("Step");
adios2::Variable<std::string> varGlobalString =
io.DefineVariable<std::string>("GlobalString");
// 3. Local value, varying across processes, constant over time
adios2::Variable<int> varProcessID =
io.DefineVariable<int>("ProcessID", {adios2::LocalValueDim});
// 4. Local value, varying across processes, varying over time
adios2::Variable<unsigned int> varNparts =
io.DefineVariable<unsigned int>("Nparts", {adios2::LocalValueDim});
// Open file. "w" means we overwrite any existing file on disk,
// but Advance() will append steps to the same file.
adios2::Engine writer = io.Open("values.bp", adios2::Mode::Write);
for (int step = 0; step < NSTEPS; step++)
{
writer.BeginStep();
// random size per process, 5..10 each
Nparts = rand() % 6 + 5;
// 1. and 2. Writing a global value from only one process
if (rank == 0)
{
// 1. Writing a global constant value only once
if (step == 0)
{
adios2::Variable<int> varNproc = io.InquireVariable<int>("Nproc");
writer.Put<int>(varNproc, nproc);
}
writer.Put<int>(varStep, step);
std::string str = "This is step " + std::to_string(step);
// str will go out of scope before EndStep(), so we must use
// Sync mode in Put()
writer.Put<std::string>(varGlobalString, str, adios2::Mode::Sync);
}
// 3. and 4. Writing a local value on every process. Will be shown
// at reading as a 1D array
if (step == 0)
{
writer.Put<int>(varProcessID, rank);
}
writer.Put<unsigned int>(varNparts, Nparts);
// Indicate we are done for this step.
// Disk I/O will be performed during this call unless
// time aggregation postpones all of that to some later step
writer.EndStep();
}
// Called once: indicate that we are done with this output for the run
writer.Close();
}
catch (std::invalid_argument &e)
{
if (rank == 0)
{
std::cout << "Invalid argument exception, STOPPING PROGRAM\n";
std::cout << e.what() << "\n";
}
}
catch (std::ios_base::failure &e)
{
if (rank == 0)
{
std::cout << "System exception, STOPPING PROGRAM\n";
std::cout << e.what() << "\n";
}
}
catch (std::exception &e)
{
if (rank == 0)
{
std::cout << "Exception, STOPPING PROGRAM\n";
std::cout << e.what() << "\n";
}
}
#if ADIOS2_USE_MPI
MPI_Finalize();
#endif
return 0;
}
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