concrt.h

C语言库函数的原型,有用的拿去

            return _Rhs;
        }

        _Ty _CompareAndSwap(_Ty _NewValue, _Ty _Comperand) {
            return _Subatomic_impl<sizeof(_Ty)>::_CompareAndSwap(_M_value, _NewValue, _Comperand);
        }

        _Ty _FetchAndAdd(_Ty _Addend) {
            return _Subatomic_impl<sizeof(_Ty)>::_FetchAndAdd(_M_value, _Addend);
        }

        _Ty operator++() {
            return _Subatomic_impl<sizeof(_Ty)>::_Increment(_M_value);
        }

        _Ty operator++(int) {
            return _Subatomic_impl<sizeof(_Ty)>::_Increment(_M_value) - 1;
        }

        _Ty operator--() {
            return _Subatomic_impl<sizeof(_Ty)>::_Decrement(_M_value);
        }

        _Ty operator--(int) {
            return _Subatomic_impl<sizeof(_Ty)>::_Decrement(_M_value) + 1;
        }

        _Ty operator+=(_Ty _Addend) {
            return _FetchAndAdd(_Addend) + _Addend;
        }
    };

    //
    // An RAII class that spin-waits on a "rented" flag.
    //
    class _SpinLock
    {
    private:
        volatile long& _M_flag;

    public:
        _CRTIMP _SpinLock(volatile long& _Flag);
        _CRTIMP ~_SpinLock();

    private:
        _SpinLock(const _SpinLock&);
        void operator=(const _SpinLock&);
    };

    //
    // A class that holds the count used for spinning and is dependent
    // on the number of hardware threads
    //
    struct _SpinCount
    {
        // Initializes the spinCount to either 0 or SPIN_COUNT, depending on
        // the number of hardware threads.
        static void __cdecl _Initialize();

        // Returns the current value of s_spinCount
        _CRTIMP static unsigned int __cdecl _Value();

        // The number of iterations used for spinning
        static unsigned int _S_spinCount;
    };

    /// <summary>
    ///     Default method for yielding during a spin wait
    /// </summary>
    /**/
    void _CRTIMP __cdecl _UnderlyingYield();

    /// <summary>
    ///     Implements busy wait with no backoff
    /// </summary>
    /**/
    template<unsigned int _YieldCount = 1>
    class _CRTIMP _SpinWait
    {
    public:

        typedef void (__cdecl *_YieldFunction)();

        /// <summary>
        ///     Construct a spin wait object
        /// </summary>
        /**/
        _SpinWait(_YieldFunction _YieldMethod = _UnderlyingYield)
            : _M_yieldFunction(_YieldMethod), _M_state(_StateInitial)
        {
            // Defer initialization of other fields to _SpinOnce().
        }

        /// <summary>
        ///     Set a dynamic spin count.
        /// </summary>
        /**/
        void _SetSpinCount(unsigned int _Count)
        {
            _ASSERTE(_M_state == _StateInitial);
            if (_Count == 0)
            {
                // Specify a count of 0 if we are on a single proc.
                _M_state = _StateSingle;
            }
            else
            {
                _M_currentSpin = _Count;
                _M_currentYield = _YieldCount;
                _M_state = _StateSpin;
            }
        }

        /// <summary>
        ///     Spins for one time quantum,until a maximum spin is reached.
        /// </summary>
        /// <returns>
        ///     false if spin count has reached steady state, true otherwise.
        /// </returns>
        /// <remarks>
        ///     If the spin count is not changing that means that it is probably not a good idea to spin again
        ///     because there is either only one processor, or maximum spin has been reached and blocking is
        ///     probably a better solution. However, if called again, SpinOnce will spin for a maximum spin count.
        /// </remarks>
        /**/
        bool _SpinOnce()
        {
            switch (_M_state)
            {
            case _StateSpin:
            {
                unsigned long _Count = _NumberOfSpins();

                for (unsigned long _I = 0; _I < _Count; _I++)
                {
                    _YieldProcessor();
                }

                if (!_ShouldSpinAgain())
                {
                    _M_state = (_M_currentYield == 0) ? _StateBlock : _StateYield;
                }

                return true;
            }

            case _StateYield:
                _ASSERTE(_M_currentYield > 0);
                if (--_M_currentYield == 0)
                {
                    _M_state = _StateBlock;
                }

                // Execute the yield
                _DoYield();
                return true;

            case _StateBlock:
                // Reset to defaults if client does not block
                _Reset();
                return false;

            case _StateSingle:
                // No need to spin on a single processor: just execute the yield
                _DoYield();
                return false;

            case _StateInitial:
                // Reset counters to their default value and Spin once.
                _Reset();
                return _SpinOnce();
            default:
                // Unreached
                return false;
            };
        }

    protected:

        /// <summary>
        ///     State of the spin wait class.
        /// </summary>
        /**/
        enum _SpinState
        {
            _StateInitial,
            _StateSpin,
            _StateYield,
            _StateBlock,
            _StateSingle
        };

        /// <summary>
        ///     Yields its time slice using the specified yieldFunciton
        /// </summary>
        /**/
        void _DoYield()
        {
            bool _ShouldYield = (_YieldCount != 0);
            if (_ShouldYield)
            {
                _ASSERTE(_M_yieldFunction != NULL);
                _M_yieldFunction();
            }
            else
            {
                _YieldProcessor();
            }
        }

        /// <summary>
        ///     Resets the counts and state to the default.
        /// </summary>
        /**/
        void _Reset()
        {
            _M_state = _StateInitial;

            // Reset to the default spin value. The value specified
            // by the client is ignored on a reset.
            _SetSpinCount(_SpinCount::_Value());

            _ASSERTE(_M_state != _StateInitial);
        }

        /// <summary>
        ///     Determines the current spin count
        /// </summary>
        /// <returns>
        ///     The number of spins to execute for this iteration
        /// </returns>
        /**/
        unsigned long _NumberOfSpins()
        {
            return 1;
        }

        /// <summary>
        ///     Determines whether maximum spin has been reached
        /// </summary>
        /// <returns>
        ///     false if spin count has reached steady state, true otherwise.
        /// </returns>
        /**/
        bool _ShouldSpinAgain()
        {
            return (--_M_currentSpin > 0);
        }

        unsigned long  _M_currentSpin;
        unsigned long  _M_currentYield;
        _SpinState     _M_state;
        _YieldFunction _M_yieldFunction;
    };

    typedef _SpinWait<>   _SpinWaitBackoffNone;
    typedef _SpinWait<0>  _SpinWaitNoYield;

    //
    // This reentrant lock uses CRITICAL_SECTION and is intended for use when kernel blocking
    // is desirable and where it is either known that the lock will be taken recursively in
    // the same thread, or when it is just not known that a non-reentrant lock can be used safely.
    //
    class _ReentrantBlockingLock
    {
    public:
        // Constructor for _ReentrantBlockingLock
        _CRTIMP _ReentrantBlockingLock();

        // Destructor for _ReentrantBlockingLock
        _CRTIMP ~_ReentrantBlockingLock();

        // Acquire the lock, spin if necessary
        _CRTIMP void _Acquire();

        // Tries to acquire the lock, does not spin.
        // Returns true if the acquisition worked, false otherwise
        _CRTIMP bool _TryAcquire();

        // Releases the lock
        _CRTIMP void _Release();


        // An exception safe RAII wrapper.
        class _Scoped_lock
        {
        public:
            // Constructs a holder and acquires the specified lock
            explicit _Scoped_lock(_ReentrantBlockingLock& _Lock) : _M_lock(_Lock)
            {
                _M_lock._Acquire();
            }

            // Destroys the holder and releases the lock
            ~_Scoped_lock()
            {
                _M_lock._Release();
            }
        private:
            _ReentrantBlockingLock& _M_lock;

            _Scoped_lock(const _Scoped_lock&);                    // no copy constructor
            _Scoped_lock const & operator=(const _Scoped_lock&);  // no assignment operator
        };

    private:
        // Critical section requires windows.h. Hide the implementation so that
        // user code need not include windows.
        _CONCRT_BUFFER _M_criticalSection[(4 * sizeof(void *) + 2 * sizeof(long) + sizeof(_CONCRT_BUFFER) - 1) / sizeof(_CONCRT_BUFFER)];
    };

    //
    // This reentrant lock is a pure spin lock and is intended for use when kernel blocking
    // is desirable and where it is either known that the lock will be taken recursively in
    // the same thread, or when it is just not known that a non-reentrant lock can be used safely.
    //
    class _ReentrantLock
    {
    public:
        // Constructor for _ReentrantLock
        _CRTIMP _ReentrantLock();

        // Acquire the lock, spin if necessary
        _CRTIMP void _Acquire();

        // Tries to acquire the lock, does not spin
        // Returns true if the acquisition worked, false otherwise
        _CRTIMP bool _TryAcquire();

        // Releases the lock
        _CRTIMP void _Release();

        // An exception safe RAII wrapper.
        class _Scoped_lock
        {
        public:
            // Constructs a holder and acquires the specified lock
            explicit _Scoped_lock(_ReentrantLock& _Lock) : _M_lock(_Lock)
            {
                _M_lock._Acquire();
            }

            // Destroys the holder and releases the lock
            ~_Scoped_lock()
            {
                _M_lock._Release();
            }
        private:
            _ReentrantLock& _M_lock;

            _Scoped_lock(const _Scoped_lock&);                    // no copy constructor
            _Scoped_lock const & operator=(const _Scoped_lock&);  // no assignment operator
        };

    private:
        long _M_recursionCount;
        volatile long _M_owner;