c++ - WaitForSingleObject 不起作用

Question

请看下面的代码:

#include <windows.h>
int main(int argc, char* argv[])
{
    HANDLE _mutex = ::CreateMutex(NULL, FALSE, "abc");
    if (!_mutex)
        throw std::runtime_error("CreateMutex failed");

    if (::WaitForSingleObject(_mutex, INFINITE) != WAIT_OBJECT_0)
        throw std::runtime_error("WaitForSingleObject failed");

    printf("Must lock here\n");

    if (::WaitForSingleObject(_mutex, INFINITE) != WAIT_OBJECT_0)
        throw std::runtime_error("WaitForSingleObject failed");

    printf("Why come here????\n");
    return 0;
}

我不知道为什么控制台打印出来:

Must lock here
Why come here???

互斥锁不起作用吗？我只想显示结果

Must lock here

并在打印上面的文本后阻塞。

Answer 1

如果您想要一个像您描述的那样运行的同步原语，您可以改用自动重置事件。

 #include <windows.h>
 #include <stdexcept>
 #include <stdio.h>
 int main(int argc, char* argv[])
 {
     HANDLE _mutex = ::CreateEvent(NULL, FALSE,         TRUE, NULL);
                                         // auto reset  // initially signalled
     if (!_mutex)
         throw std::runtime_error("CreateEvent failed");

     if (::WaitForSingleObject(_mutex, INFINITE) != WAIT_OBJECT_0) 
         throw std::runtime_error("WaitForSingleObject failed");
     // unsignalled now

     printf("Must lock here\n");

     // will block forever until someone calls SetEvent
     if (::WaitForSingleObject(_mutex, INFINITE) != WAIT_OBJECT_0)
         throw std::runtime_error("WaitForSingleObject failed");

     printf("Why come here????\n");
     return 0;
 }