windows 信号量使用

#include<iostream>

#include <Windows.h>

using namespace std;

const int MAX_SEM_COUNT = 5;//信号量数量

const int THREAD_COUNT = 10;//线程数量

HANDLE g_sem;//全局信号量对象句柄

DWORD WINAPI threadFunc(LPVOID);//线程函数前向声明

int main()

{

    HANDLE arrThread[THREAD_COUNT];

    g_sem = CreateSemaphore(NULL,MAX_SEM_COUNT,MAX_SEM_COUNT,NULL);

    if (!g_sem)

    {

        cout<<"call CreateSemaphore() failed!"<<endl;

        return -1;

    }

    DWORD threadID = -1;

    for (int i = 0; i < THREAD_COUNT; ++i)

    {

        arrThread[i] = CreateThread(NULL, 0, threadFunc, NULL, 0, &threadID);

        if (!arrThread[i])

        {

            cout<<"call CreateThread() failed!"<<endl;

            return -2;

        }

    }

    WaitForMultipleObjects(THREAD_COUNT, arrThread, true, INFINITE);

    for (int i = 0; i < THREAD_COUNT; ++i)

    {

        CloseHandle(arrThread[i]);

    }

    CloseHandle(g_sem);

    system("pause");

    return 0;

}

//线程函数，使用信号量的例子

DWORD WINAPI threadFunc(LPVOID)

{

    DWORD waitResult;

    bool bContinue = true;

    while (bContinue)

    {

        waitResult = WaitForSingleObject(g_sem,0);

        switch (waitResult)

        {

        case WAIT_OBJECT_0:

            cout << GetCurrentThreadId()<< " wait sem succeed!"<< endl;

            bContinue = false;

            Sleep(5);

            if (!ReleaseSemaphore(g_sem, 1, NULL))

            {

                cout<<"call ReleaseSemaphore() failed!"<<endl;

                return GetLastError();

            }

        break;

        case WAIT_TIMEOUT:

            cout << GetCurrentThreadId()<< " wait sem timeout!"<< endl;

            break;

        }

    }

}