Semaphore小测试程序

通过等待函数和ReleaseSemaphore可以确保同一时刻有有限个线程访问指定的资源。

以下是一个测试小程序

#include "stdafx.h"
#include <windows.h>
#include <stdio.h>

HANDLE hSemaphore;

typedef struct _ThreadParam{
    char name[100];
}ThreadParam;

DWORD WINAPI ThreadProc(LPVOID lpParam)
{
    ThreadParam *pTp = (ThreadParam*)lpParam;

    printf("thread %s waiting...\n", pTp->name);
    WaitForSingleObject(hSemaphore, INFINITE);
    printf("thread %s entering thread..\n", pTp->name);

    for (volatile int i = 0; i < 65535; i++)
    {
        for (volatile int j = 0; j < 100; j++)
        {
            int k = i * j;
        }
    }

    printf("thread %s leaving thread..\n", pTp->name);
    ReleaseSemaphore(hSemaphore, 1, NULL);
    return 0;
}

int main(int argc, char* argv[])
{
    const int threadCount = 10;
    HANDLE hThread[threadCount];
    DWORD dwTemp;
    ThreadParam *tp[threadCount];

    hSemaphore = CreateSemaphore(NULL, 2, 2, NULL);

    for (int i = 0; i < threadCount; i++)
    {
        tp[i] = new ThreadParam;
        wsprintf(tp[i]->name, "%d", i);
        hThread[i] = CreateThread(NULL, 0, ThreadProc, tp[i], NULL, &dwTemp);
    }

    WaitForMultipleObjects(10, hThread, TRUE, INFINITE);

    for (int i = 0; i < threadCount; i++)
    {
        delete tp[i];
    }
    return 0;
}