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/*
* Copyright 2019 Patrick Stotko
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef TEST_UTILS_H
#define TEST_UTILS_H
#include <chrono>
#include <cmath>
#include <cstddef>
#include <limits>
#include <random>
#include <stdexcept>
#include <string>
#include <thread>
#include <utility>
#include <vector>
#include <stdgpu/cstddef.h>
namespace test_utils
{
/**
* \brief Returns a seed chosen "truly" at random
* \return The randomly chosen seed
*/
inline std::size_t
random_seed()
{
try
{
std::random_device rd("/dev/urandom");
// rd.entropy() != 0.0
if (std::abs(rd.entropy()) >= std::numeric_limits<double>::min())
{
return rd();
}
throw std::runtime_error("Entropy is 0.0");
}
// For some reason, the following code fails to compile with NVCC+MSVC using the CUDA backend:
// [[maybe_unused]] const std::exception& e
// Thus, use the version below to fix unused parameter warnings
catch (const std::exception&)
{
}
return static_cast<std::size_t>(std::chrono::system_clock::now().time_since_epoch().count());
}
/**
* \brief Returns a seed chosen "truly" at random for the this local thread
* \return The randomly chosen thread-local seed
*/
inline std::size_t
random_thread_seed()
{
return random_seed() + std::hash<std::thread::id>()(std::this_thread::get_id());
}
/**
* \brief Runs the given function in N threads where N is the number of available concurrent threads the CPU can handle
* \param[in] f A function
* \param[in] args The arguments passed to f
*/
template <typename F, typename... Args>
inline void
for_each_concurrent_thread(F&& f, Args&&... args)
{
const stdgpu::index_t concurrent_threads =
std::max<stdgpu::index_t>(1, static_cast<stdgpu::index_t>(std::thread::hardware_concurrency()));
std::vector<std::thread> threads;
threads.reserve(static_cast<std::size_t>(concurrent_threads));
for (stdgpu::index_t i = 0; i < concurrent_threads; ++i)
{
threads.emplace_back(std::forward<F>(f), std::forward<Args>(args)...);
}
for (stdgpu::index_t i = 0; i < concurrent_threads; ++i)
{
if (threads[static_cast<std::size_t>(i)].joinable())
{
threads[static_cast<std::size_t>(i)].join();
}
}
}
} // namespace test_utils
#endif // TEST_UTILS_H
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