text: //  Copyright (c)      2019 Mikael Simberg
  //  Copyright (c) 2007-2017 Hartmut Kaiser
  //
  //  SPDX-License-Identifier: BSL-1.0
  //  Distributed under the Boost Software License, Version 1.0. (See accompanying
  //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  
  // The parallel_executor has a constructor that takes a thread_pool_base as an
  // argument and executes all its work on that thread pool. This checks that the
  // usual functions of an executor work with this executor when used *without the
  // HPX runtime*. This test fails if thread pools, schedulers etc. assume that
  // the global runtime (configuration, thread manager, etc.) always exists.
  
  #include <hpx/local/execution.hpp>
  #include <hpx/local/future.hpp>
  #include <hpx/local/thread.hpp>
  #include <hpx/modules/schedulers.hpp>
  #include <hpx/modules/testing.hpp>
  #include <hpx/modules/thread_pools.hpp>
  
  #include <algorithm>
  #include <cstddef>
  #include <cstdint>
  #include <cstdlib>
  #include <iterator>
  #include <memory>
  #include <numeric>
  #include <string>
  #include <utility>
  #include <vector>
  
  ///////////////////////////////////////////////////////////////////////////////
  hpx::thread::id test(int passed_through)
  {
      HPX_TEST_EQ(passed_through, 42);
      return hpx::this_thread::get_id();
  }
  
  template <typename Executor>
  void test_sync(Executor& exec)
  {
      HPX_TEST(hpx::parallel::execution::sync_execute(exec, &test, 42) ==
          hpx::this_thread::get_id());
  }
  
  template <typename Executor>
  void test_async(Executor& exec)
  {
      HPX_TEST(hpx::parallel::execution::async_execute(exec, &test, 42).get() !=
          hpx::this_thread::get_id());
  }
  
  ///////////////////////////////////////////////////////////////////////////////
  hpx::thread::id test_f(hpx::future<void> f, int passed_through)
  {
      HPX_TEST(f.is_ready());    // make sure, future is ready
  
      f.get();    // propagate exceptions
  
      HPX_TEST_EQ(passed_through, 42);
      return hpx::this_thread::get_id();
  }
  
  template <typename Executor>
  void test_then(Executor& exec)
  {
      hpx::future<void> f = hpx::make_ready_future();
  
      HPX_TEST(
          hpx::parallel::execution::then_execute(exec, &test_f, f, 42).get() !=
          hpx::this_thread::get_id());
  }
  
  ///////////////////////////////////////////////////////////////////////////////
  void bulk_test(int, hpx::thread::id tid, int passed_through)    //-V813
  {
      HPX_TEST_NEQ(tid, hpx::this_thread::get_id());
      HPX_TEST_EQ(passed_through, 42);
  }
  
  template <typename Executor>
  void test_bulk_sync(Executor& exec)
  {
      hpx::thread::id tid = hpx::this_thread::get_id();
  
      std::vector<int> v(107);
      std::iota(std::begin(v), std::end(v), std::rand());
  
      using hpx::placeholders::_1;
      using hpx::placeholders::_2;
  
      hpx::parallel::execution::bulk_sync_execute(
          exec, hpx::bind(&bulk_test, _1, tid, _2), v, 42);
      hpx::parallel::execution::bulk_sync_execute(exec, &bulk_test, v, tid, 42);
  }
  
  template <typename Executor>
  void test_bulk_async(Executor& exec)
  {
      hpx::thread::id tid = hpx::this_thread::get_id();
  
      std::vector<int> v(107);
      std::iota(std::begin(v), std::end(v), std::rand());
  
      using hpx::placeholders::_1;
      using hpx::placeholders::_2;
  
      hpx::when_all(hpx::parallel::execution::bulk_async_execute(
                        exec, hpx::bind(&bulk_test, _1, tid, _2), v, 42))
          .get();
      hpx::when_all(hpx::parallel::execution::bulk_async_execute(
                        exec, &bulk_test, v, tid, 42))
          .get();
  }
  
  ///////////////////////////////////////////////////////////////////////////////
  void bulk_test_f(int, hpx::shared_future<void> f, hpx::thread::id tid,
      int passed_through)    //-V813
  {
      HPX_TEST(f.is_ready());    // make sure, future is ready
  
      f.get();    // propagate exceptions
  
      HPX_TEST_NEQ(tid, hpx::this_thread::get_id());
      HPX_TEST_EQ(passed_through, 42);
  }
  
  template <typename Executor>
  void test_bulk_then(Executor& exec)
  {
      hpx::thread::id tid = hpx::this_thread::get_id();
  
      std::vector<int> v(107);
      std::iota(std::begin(v), std::end(v), std::rand());
  
      using hpx::placeholders::_1;
      using hpx::placeholders::_2;
      using hpx::placeholders::_3;
  
      hpx::shared_future<void> f = hpx::make_ready_future();
  
      hpx::parallel::execution::bulk_then_execute(
          exec, hpx::bind(&bulk_test_f, _1, _2, tid, _3), v, f, 42)
          .get();
      hpx::parallel::execution::bulk_then_execute(
          exec, &bulk_test_f, v, f, tid, 42)
          .get();
  }
  
  ///////////////////////////////////////////////////////////////////////////////
  void test_thread_pool_os_executor(hpx::execution::parallel_executor exec)
  {
      test_sync(exec);
      test_async(exec);
      test_then(exec);
      test_bulk_sync(exec);
      test_bulk_async(exec);
      test_bulk_then(exec);
  }
  
  int main()
  {
      {
          // Choose a scheduler.
          using sched_type =
              hpx::threads::policies::local_priority_queue_scheduler<>;
  
          // Choose all the parameters for the thread pool and scheduler.
          std::size_t const num_threads = (std::min)(
              std::size_t(4), std::size_t(hpx::threads::hardware_concurrency()));
          std::size_t const max_cores = num_threads;
          hpx::threads::policies::detail::affinity_data ad{};
          ad.init(num_threads, max_cores, 0, 1, 0, "core", "balanced", true);
          hpx::threads::policies::callback_notifier notifier{};
          hpx::threads::policies::thread_queue_init_parameters
              thread_queue_init{};
          sched_type::init_parameter_type scheduler_init(
              num_threads, ad, num_threads, thread_queue_init, "my_scheduler");
          hpx::threads::detail::network_background_callback_type
              network_callback{};
          hpx::threads::thread_pool_init_parameters thread_pool_init("my_pool", 0,
              hpx::threads::policies::scheduler_mode::default_, num_threads, 0,
              notifier, ad, network_callback, 0,
              (std::numeric_limits<std::int64_t>::max)(),
              (std::numeric_limits<std::int64_t>::max)());
  
          // Create the scheduler, thread pool, and associated executor.
          std::unique_ptr<sched_type> scheduler{new sched_type(scheduler_init)};
          hpx::threads::detail::scheduled_thread_pool<sched_type> pool{
              std::move(scheduler), thread_pool_init};
          hpx::execution::parallel_executor exec{&pool};
  
          // Run the pool.
          std::mutex m;
          std::unique_lock<std::mutex> l(m);
          pool.run(l, num_threads);
  
          // We can't wait for futures on the main thread, so we spawn a thread to
          // run the tests for us.
          hpx::apply(exec, &test_thread_pool_os_executor, exec);
  
          // Stop the pool.
          pool.stop(l, true);
      }
  
      return hpx::util::report_errors();
  }
  