stopToken.hpp

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#ifndef RAD_STOP_TOKEN_HPP
#define RAD_STOP_TOKEN_HPP
 
#include <atomic>
#include <memory>
 
namespace rad {
 
namespace detail {

struct StopState {
    StopState() noexcept = default;
 
    void IncSources() noexcept;
    void DecSources() noexcept;
 
    void IncTokens() noexcept;
    void DecTokens() noexcept;
 
    unsigned GetNumSources() const noexcept;
    unsigned GetNumTokens() const noexcept;
 
    [[nodiscard]] bool StopRequested() const noexcept;
    bool RequestStop() noexcept;
 
  private:
    std::atomic<unsigned> m_num_sources;
    std::atomic<unsigned> m_num_tokens;
 
    std::atomic<bool> m_stop_requested;
};
 
}  // namespace detail
 
class StopSource;

class StopToken {
  public:
    StopToken() noexcept = default;
    StopToken(StopToken const&) noexcept;
    StopToken(StopToken&&) noexcept = default;
    StopToken& operator=(StopToken const&);
    ~StopToken();

    void Swap(StopToken& other) noexcept;

    [[nodiscard]] bool StopRequested() const noexcept;

    [[nodiscard]] bool StopPossible() const noexcept;

    bool operator==(StopToken const& rhs) const noexcept;
    bool operator!=(StopToken const& rhs) const noexcept;
 
  private:
    friend class StopSource;

    explicit StopToken(std::shared_ptr<detail::StopState> state) noexcept;
 
    std::shared_ptr<::rad::detail::StopState> m_state;
};

class StopSource {
  public:
    StopSource() noexcept;
    StopSource(StopSource const&) noexcept;
    StopSource& operator=(StopSource const&);
    StopSource(StopSource&&) noexcept = default;
    ~StopSource();

    bool operator==(StopSource const& rhs) const noexcept;
    bool operator!=(StopSource const& rhs) const noexcept;

    [[nodiscard]] bool StopRequested() const noexcept;

    [[nodiscard]] bool StopPossible() const noexcept;

    [[nodiscard]] StopToken GetToken() const noexcept;

    void Swap(StopSource& other) noexcept;

    bool RequestStop() noexcept;
 
  private:
    std::shared_ptr<::rad::detail::StopState> m_state;
};
 
}  // namespace rad
 
#endif  // #define RAD_STOP_TOKEN_HPP