《Windows核心编程》第十一章——线程池

• 隐式使用工作项

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

int g_nCount = 0;
VOID NTAPI SimpleCallback(PTP_CALLBACK_INSTANCE pInstance, PVOID pvContext)
{
    g_nCount++;
    printf("test:%d\n", g_nCount);
}

void main()
{
    int nCount = 500;
    PTP_SIMPLE_CALLBACK pFunc = SimpleCallback;
    while (0 != nCount)
    {
        TrySubmitThreadpoolCallback(pFunc, NULL, NULL);

        nCount--;
    }
    getchar();
}

通过结果观察发现，利用了线程池，输出并非有序：

显式地控制工作项

void main()
{
    g_pWorkItem = CreateThreadpoolWork(TaskHandler, NULL, NULL);
    if (NULL == g_pWorkItem)
    {
        return;
    }
    int nCount = 5000;
    while (nCount)
    {
        SubmitThreadpoolWork(g_pWorkItem);
        nCount--;
    }
    WaitForThreadpoolWorkCallbacks(g_pWorkItem, FALSE);
    CloseThreadpoolWork(g_pWorkItem);
    getchar();
}

如果改为下面这样，则会报错：

int g_nCount = 0;
PTP_WORK g_pWorkItem = NULL;

void NTAPI TaskHandler(PTP_CALLBACK_INSTANCE Instance, PVOID Context, PTP_WORK work)
{
    g_nCount++;
    printf("test:%d..\n", g_nCount);
}

unsigned int _stdcall testthread(PVOID pParam)
{
    int nCount = 500;
    while (nCount)
    {
        SubmitThreadpoolWork(g_pWorkItem);
        nCount--;
    }

    return 0;
}

void main()
{
    g_pWorkItem = CreateThreadpoolWork(TaskHandler, NULL, NULL);
    if (NULL == g_pWorkItem)
    {
        return;
    }
　　_beginthreadex(NULL, 0, testthread, NULL, 0, NULL);
    WaitForThreadpoolWorkCallbacks(g_pWorkItem, FALSE);
    CloseThreadpoolWork(g_pWorkItem);
    getchar();
}

因为据书上说，只能取消或等待本线程中的工作项。