Mutex Next

mutex.hpp

		// CLASS mutex
class mutex
	{	// class for mutual exclusion
public:
	constexpr mutex() _NOEXCEPT
		: _Data()
		{	// construct std::mutex
		}

	mutex(const mutex&) = delete;
	mutex& operator=(const mutex&) = delete;

#if _STD_MUTEX_LEVEL >= 1
	// Vista+ uses SRWLOCK, which provides trivial destruction and never fails

	~mutex() _NOEXCEPT = default;

	void lock() _NOEXCEPT // Strengthened
		{	// lock the mutex
		__std_mutex_lock_vista(&_Data._Data);
		}

	bool try_lock() _NOEXCEPT // Strengthened
		{	// try to lock the mutex
		return (__std_mutex_try_lock_vista(&_Data._Data) != 0);
		}

	void unlock() _NOEXCEPT // Strengthened
		{	// unlock the mutex
		__std_mutex_unlock_vista(&_Data._Data);
		}
#else /* ^^^ _STD_MUTEX_LEVEL >= 1 ^^^ // vvv _STD_MUTEX_LEVEL == 0 vvv */
	// Windows XP mode tries SRWLOCK, falls back to separately allocated
	// CRITICAL_SECTION (allocated on first lock() or try_lock() attempt)
	~mutex() _NOEXCEPT
		{	// destroy std::mutex
		__std_mutex_destroy_xp(&_Data);
		}

	void lock()
		{	// lock the mutex
		if (__std_mutex_lock_xp(&_Data) != __std_win32_success)
			{	// failed to allocate CRITICAL_SECTION
			_THROW(system_error, _STD make_error_code(errc::resource_unavailable_try_again));
			}
		}

	bool try_lock()
		{	// try to lock the mutex
		bool _Result;
		if (__std_mutex_try_lock_xp(&_Data, &_Result) != __std_win32_success)
			{	// failed to allocate CRITICAL_SECTION
			_THROW(system_error, _STD make_error_code(errc::resource_unavailable_try_again));
			}

		return (_Result);
		}

	void unlock() _NOEXCEPT // Strengthened
		{	// unlock the mutex
		__std_mutex_unlock_xp(&_Data);
		}
#endif /* _STD_MUTEX_LEVEL */

private:
	friend condition_variable;
	friend _STDEXT condition_variable_light;
	__std_mutex_data _Data;
	};