相关疑难解决方法(0)

我GetSystemTimeAdjustment在Windows 7上使用该功能运行了一些测试,得到了一些我无法解释的有趣结果.正如我所理解的那样,如果系统时间定期同步,则该方法应该返回,如果是,则在哪个时间间隔以及更新它的增量(请参阅MSDN上的GetSystemTimeAdjustment函数).

从此我可以看出,如果我查询系统时间,例如GetSystemTimeAsFileTime重复使用,我应该不做任何更改(系统时钟尚未更新),或者是检索到的增量的倍数的更改GetSystemTimeAdjustment.问题一:这个假设是否正确？

现在考虑以下测试代码:

#include <windows.h>
#include <iostream>
#include <iomanip>

int main()
{
    FILETIME fileStart;
    GetSystemTimeAsFileTime(&fileStart);
    ULARGE_INTEGER start;
    start.HighPart = fileStart.dwHighDateTime;
    start.LowPart = fileStart.dwLowDateTime;

    for (int i=20; i>0; --i)
    {
        FILETIME timeStamp1;
        ULARGE_INTEGER ts1;

        GetSystemTimeAsFileTime(&timeStamp1);

        ts1.HighPart = timeStamp1.dwHighDateTime;
        ts1.LowPart  = timeStamp1.dwLowDateTime;

        std::cout << "Timestamp: " << std::setprecision(20) << (double)(ts1.QuadPart - start.QuadPart) / 10000000 << std::endl;

    }

    DWORD dwTimeAdjustment = 0, dwTimeIncrement = 0, dwClockTick;
    BOOL fAdjustmentDisabled = TRUE;
    GetSystemTimeAdjustment(&dwTimeAdjustment, &dwTimeIncrement, …

以下代码段

    [DllImport("winmm.dll", EntryPoint = "timeBeginPeriod")]
    public static extern uint TimeBeginPeriod(uint uMilliseconds);

    static void Main(string[] args)
    {
        if (TimeBeginPeriod(1) != 0)
            Console.WriteLine("TimeBeginPeriod failed!");

        Console.WriteLine("Sleep");
        Stopwatch sw = Stopwatch.StartNew();
        for (int i = 0; i < 10; i++)
        {
            Thread.Sleep(1);
            Console.WriteLine(sw.ElapsedTicks * 1000d / Stopwatch.Frequency);
            sw.Restart();
        }

        Console.WriteLine("Threading.Timer");
        sw = null;
        System.Threading.Timer t = null;
        int n = 0;

        t = new Timer(state =>
        {
            if (sw == null)
                sw = Stopwatch.StartNew();
            else
            {
                Console.WriteLine(sw.ElapsedTicks * 1000d / Stopwatch.Frequency);
                n++;
                sw.Restart();
            } …