c – 如何使用互斥锁严格交替使用两个线程？

发布时间：2020-12-16 10:20:32 所属栏目：百科来源：网络整理

导读：我需要创建两个严格交替的线程.这是我使用的示例代码： #include Windows.h#include iostreamusing std::cout;using std::endl;HANDLE g_hMutex1;HANDLE g_hMutex2;DWORD WINAPI ThreadFunc1(LPVOID lpParam);DWORD WINAPI ThreadFunc2(LPVOID lpParam);int

我需要创建两个严格交替的线程.这是我使用的示例代码：

#include <Windows.h>
#include <iostream>
using std::cout;
using std::endl;

HANDLE g_hMutex1;
HANDLE g_hMutex2;

DWORD WINAPI ThreadFunc1(LPVOID lpParam);
DWORD WINAPI ThreadFunc2(LPVOID lpParam);

int main(void)
{
    int nCalcNumber = 10;
    DWORD dwThreadId;
    HANDLE pThreadHandles[2];

    g_hMutex1 = CreateMutex(NULL,FALSE,NULL);
    g_hMutex1 = CreateMutex(NULL,NULL);

    pThreadHandles[0] = CreateThread(
        NULL,ThreadFunc1,static_cast<void*>(&nCalcNumber),&dwThreadId);

    pThreadHandles[1] = CreateThread(
        NULL,ThreadFunc2,&dwThreadId);

    WaitForMultipleObjects(2,pThreadHandles,TRUE,INFINITE);

    CloseHandle(pThreadHandles[0]);
    CloseHandle(pThreadHandles[1]);
    CloseHandle(g_hMutex1);
    CloseHandle(g_hMutex2);

    return 0;
}

DWORD WINAPI ThreadFunc1(LPVOID lpParam)
{
    int* nCalcNumber = static_cast<int*>(lpParam);

    for (int i = 0; i < *nCalcNumber; i++)
    {
        WaitForSingleObject(g_hMutex1,INFINITE);

        cout << "Func 1" << endl;

        ReleaseMutex(g_hMutex1);
    }

    return 0;
}

DWORD WINAPI ThreadFunc2(LPVOID lpParam)
{
    int* nCalcNumber = static_cast<int*>(lpParam);

    for (int i = 0; i < *nCalcNumber; i++)
    {
        WaitForSingleObject(g_hMutex1,INFINITE);

        cout << "Func 2" << endl;

        ReleaseMutex(g_hMutex1);
    }

    return 0;
}

结果,我希望收到：

Func 1
 Func 2
 Func 1
 Func 2
 Func 1
 Func 2
 ...and so one

应该添加什么来获得所需的结果.我可以使用第二个互斥锁吗？

解决方法

如果你可以使用信号量：你可以使用信号量而不是互斥量,它很容易使用相同的互斥量.

这段代码工作正常：

#include <windows.h>
#include <iostream>
using std::cout;
using std::endl;

PHANDLE sem1;
PHANDLE sem2;

DWORD WINAPI ThreadFunc1(LPVOID lpParam);
DWORD WINAPI ThreadFunc2(LPVOID lpParam);

int main(void)
{
    int nCalcNumber = 10;
    DWORD dwThreadId;
    HANDLE pThreadHandles[2];

    sem1 = (PHANDLE) CreateSemaphore(NULL,1,NULL);
    sem2 = (PHANDLE) CreateSemaphore(NULL,NULL);


    pThreadHandles[0] = CreateThread(
                                     NULL,static_cast<void*> (&nCalcNumber),&dwThreadId);

    pThreadHandles[1] = CreateThread(
                                     NULL,INFINITE);

    CloseHandle(pThreadHandles[0]);
    CloseHandle(pThreadHandles[1]);
    CloseHandle(sem1);
    CloseHandle(sem2);

    return 0;
}

DWORD WINAPI ThreadFunc1(LPVOID lpParam)
{
    int* nCalcNumber = static_cast<int*> (lpParam);

    for (int i = 0; i < *nCalcNumber; i++)
    {
        WaitForSingleObject(sem1,INFINITE);

        cout << "Func 1" << endl;

        ReleaseSemaphore(sem2,NULL);
    }

    return 0;
}

DWORD WINAPI ThreadFunc2(LPVOID lpParam)
{
    int* nCalcNumber = static_cast<int*> (lpParam);

    for (int i = 0; i < *nCalcNumber; i++)
    {

        WaitForSingleObject(sem2,INFINITE);

        cout << "Func 2" << endl;

        ReleaseSemaphore(sem1,NULL);
    }

    return 0;
}

（编辑：李大同）

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