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// SPDX-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
#include <algorithm>
#include <functional>
#include <iostream>
#include <numeric>
#include <vector>
#include <dune/common/dynvector.hh>
#include <dune/common/typetraits.hh>
#include <dune/common/parallel/mpidata.hh>
#include <dune/common/parallel/mpifuture.hh>
#include <dune/common/parallel/mpihelper.hh>
namespace Dune {
template<class Dummy>
struct MPIData<const int&, Dummy>
{
static_assert(Dune::AlwaysFalse<Dummy>::value, "MPIData of reference type should not be used!");
// MPIData of reference type should not be used!
// This struct should never be used it just
// exists to generate a compiler error
};
}
int main(int argc, char** argv){
auto& mpihelper = Dune::MPIHelper::instance(argc, argv);
auto cc = mpihelper.getCommunication();
// p2p
if(mpihelper.size() > 1){
if(mpihelper.rank() == 0){
Dune::Future<int> f = cc.isend(42, 1, 0);
f.wait();
int i = 42;
Dune::Future<const int&> f2 = cc.isend<const int&>(i, 1, 0);
f2.wait();
}else if(mpihelper.rank() == 1){
Dune::Future<int> f = cc.irecv(41, 0, 0);
std::cout << "Rank 1 received " << f.get() << std::endl;
int j = 41;
Dune::Future<int&> f2 = cc.irecv<int&>(j, 0, 0);
std::cout << "Rank 1 received " << f2.get() << std::endl;
}
}
int answer;
if(mpihelper.rank() == 0){
std::cout << "Broadcast lvalue-reference" << std::endl;
answer = 42;
}
Dune::Future<int> f = cc.ibroadcast(answer, 0);
f.wait();
std::cout << "Rank " << mpihelper.rank() << " knows: The answer is " << answer << std::endl;
if(mpihelper.rank() == 0)
std::cout << "Broadcast value" << std::endl;
Dune::Future<int> f2 = cc.ibroadcast(int(answer), 0);
std::cout << "Rank " << mpihelper.rank() << " knows: The answer is " << f2.get() << std::endl;
Dune::DynamicVector<double> vec(3);
if(mpihelper.rank() == 0){
std::cout << "Broadcast vector" << std::endl;
std::iota(vec.begin(), vec.end(), 41);
}
Dune::Future<Dune::DynamicVector<double>> f3 = cc.ibroadcast(vec, 0);
f3.wait();
std::cout << "Rank " << mpihelper.rank() << " received vector: " << vec << std::endl;
if(mpihelper.rank() == 0)
std::cout << "nonb Barrier ==========================" << std::endl;
Dune::Future<void> f4 = cc.ibarrier();
f4.wait();
if(mpihelper.rank() == 0){
std::cout << "nonb gather ===========================" << std::endl;
Dune::Future<Dune::DynamicVector<int>> f = cc.igather(mpihelper.rank() + 42, Dune::DynamicVector<int>(mpihelper.size()), 0);
std::cout << "Gather result: " << f.get() << std::endl;
}else{
cc.igather(mpihelper.rank(), {}, 0).wait();
}
if(mpihelper.rank() == 0){
std::cout << "nonb scatter ===========================" << std::endl;
std::vector<int> my_buddies(mpihelper.size());
std::iota(my_buddies.begin(), my_buddies.end(), 42);
Dune::Future<int> f = cc.iscatter(my_buddies, 0, 0);
std::cout << "Scatter result (Rank " << mpihelper.rank() << "): " << f.get() << std::endl;
}else{
Dune::Future<int> f = cc.iscatter(std::vector<int>(0), 0, 0);
std::cout << "Scatter result (Rank " << mpihelper.rank() << "): " << f.get() << std::endl;
}
{
if(mpihelper.rank() == 0)
std::cout << "nonb allreduce ===========================" << std::endl;
Dune::Future<int> f = cc.iallreduce<std::plus<int>>(mpihelper.rank()+4, 0);
std::cout << "Allreduce result on rank " << mpihelper.rank() <<": " << f.get() << std::endl;
}
{
if(mpihelper.rank() == 0)
std::cout << "nonb allreduce inplace ===========================" << std::endl;
Dune::Future<Dune::DynamicVector<int>> f = cc.iallreduce<std::plus<int>>(Dune::DynamicVector<int>{42, 3+mpihelper.rank()});
std::cout << "Allreduce result on rank " << mpihelper.rank() <<": " << f.get() << std::endl;
}
{
if(mpihelper.rank() == 0)
std::cout << "check for MPI_SUM with double& ===========================" << std::endl;
double answer = 42;
auto f = cc.iallreduce<std::plus<double>>(answer);
std::cout << "Allreduce result on rank " << mpihelper.rank() <<": " << f.get() << std::endl;
}
// that's wrong, MPIFuture will hold a dangeling reference:
// Dune::MPIFuture<int&> g;
// {
// int i = 42;
// g = cc.iallreduce<std::plus<int>>(i);
// }
// g.wait();
return 0;
}
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