Im looking for some advice regarding creating an
std::vector<hpx::future<std::vector <int> > > where the elements of the
innermost vector use a random number generator.
Typically, if I were to use to generate this vector of random integers, Id
use either boost or standard library random functions (or possibly Intel MKL
/ VSL); however, all of these RNGs have a state. As I understand, a naïve
implementation, just passing a reference to the RNG state would lead to race
conditions and will result in the RNG state ending up in some
undefined-state. If I understand correctly, that would be the reason that
an action cannot have a non-const reference parameter.
In light of this, how could I use a future to represent this vector of
future integer-vectors? Is there any way to make this code concurrent?
As a rough reference:
#include <random>
#include <vector>
#include <hpx/hpx.hpp>
#include <hpx/include/future.hpp>
#include <hpx/include/async.hpp>
#include <hpx/hpx_main.hpp>
using random_vec_t = std::vector<int>;
constexpr int random_vec_size = 8;
constexpr int vec_random_size = 30;
//template <typename RNG>
std::vector<random_vec_t> Generate_Random_Vector(std::mt19937_64 &rng) {
std::vector<random_vec_t> random_vector_set;
static const int range_ = 100;
std::uniform_int_distribution<int> dist_(0, range_);
random_vector_set.resize(vec_random_size);
for (auto &vec : random_vector_set) {
vec.reserve(random_vec_size);
for (int i = 0; i < random_vec_size; ++i)
vec.push_back(dist_(rng));
}
return random_vector_set;
}
HPX_PLAIN_ACTION(Generate_Random_Vector, generate_random_vector_action); //
<= this line fails with message: static_assert failed "Using non-const
references as arguments for actions is not supported."
int main(int argc, char *argv[]) {
std::mt19937_64 rng_;
hpx::future<std::vector<random_vec_t>> future_vectors_ =
hpx::async(generate_random_vector_action, rng_);
auto vecs_ = future_vectors_.get();
for (auto outer_vec : vecs_) {
for (auto inner_vec : outer_vec)
std::cout << inner_vec << "\t";
std::cout << std::endl;
}
return 0;
}
Thanks and regards,
Shmuel
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