timer.hpp

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#pragma once
 
#include <chrono>
#include <future>
#include <thread>
 
namespace bricks {
 
class timer {
 public:
  timer() noexcept {};  // NOLINT (can't use default, since std::promise does not have a noexcept
                        // ctor)
 
  timer(const timer&) = delete;
  auto operator=(const timer&) -> timer& = delete;
 
  timer(timer&&) = default;
  auto operator=(timer&&) -> timer& = default;
 
  ~timer() { abort(); };
 
  using completion_token = std::future<void>;
 
  template <typename Rep = int64_t, typename Period = std::ratio<1>>
  [[nodiscard]] auto start(const std::chrono::duration<Rep, Period>& duration =
                               std::chrono::duration<Rep, Period>{}) const noexcept
      -> completion_token
  {
    return std::async(std::launch::async, [abortion_future = abortion_future_, duration]() {
      abortion_future.wait_for(duration);
    });
  }
 
  inline auto abort() -> void
  {
    abortion_promise_.set_value();
    abortion_promise_ = {};
    abortion_future_ = abortion_promise_.get_future();
  }
 
 private:
  std::promise<void> abortion_promise_{};
  std::shared_future<void> abortion_future_{abortion_promise_.get_future()};
};
 
}  // namespace bricks