Class thread_executor

example/cpp14/executors/pipeline.cpp:19–75

An executor that launches a new thread for each function submitted to it. This class satisfies the executor requirements.

// An executor that launches a new thread for each function submitted to it.
// This class satisfies the executor requirements.
class thread_executor
{
private:
  // Singleton execution context that manages threads launched by the new_thread_executor.
  class thread_bag
  {
    friend class thread_executor;

    void add_thread(std::thread&& t)
    {
      std::unique_lock<std::mutex> lock(mutex_);
      threads_.push_back(std::move(t));
    }

    thread_bag() = default;

    ~thread_bag()
    {
      for (auto& t : threads_)
        t.join();
    }

    std::mutex mutex_;
    std::vector<std::thread> threads_;
  };

public:
  static thread_bag& query(execution::context_t)
  {
    static thread_bag threads;
    return threads;
  }

  static constexpr auto query(execution::blocking_t)
  {
    return execution::blocking.never;
  }

  template <class Func>
  void execute(Func f) const
  {
    thread_bag& bag = query(execution::context);
    bag.add_thread(std::thread(std::move(f)));
  }

  friend bool operator==(const thread_executor&,
      const thread_executor&) noexcept
  {
    return true;
  }

  friend bool operator!=(const thread_executor&,
      const thread_executor&) noexcept
  {
    return false;
  }
};