C++ 事件（event）使用总结

  事件最常用在多线程同步互斥机制。

 常用的函数有：

 1、CreateEvent 创建事件。

函数原型如下所示，一共四个参数：

HANDLE CreateEvent(

　LPSECURITY_ATTRIBUTES lpEventAttributes,　// SECURITY_ATTRIBUTES结构指针，可为NULL
　BOOL bManualReset,     // 手动/自动
　                                    // TRUE：表示手动，在WaitForSingleObject后必须手动调用ResetEvent清除信号
　                                   // FALSE：表示自动，在WaitForSingleObject后，系统自动清除事件信号
　BOOL bInitialState,        //初始状态，FALSE为无信号，TRUE为有信号
　LPCTSTR lpName         //事件的名称
    );

2、SetEvent：设置为激活触发状态。

3、ResetEvent：设置为未激活触发状态。

4、WaitForSingleObject：检测信号，如果未激活，代码就会处于挂起状态，不再往下执行。

下面是多线程同步的示例：

  

   

    

     

    
    

     

      #include <tchar.h> 
     
    
   

    

     

    
    

     

      #include <iostream>
     
    
   

    

     

    
    

     

      #include <wtypes.h>
     
    
   

    

     

    
    

     

      using namespace std;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      DWORD WINAPI ThreadProc(LPVOID lpParam);
     
    
   

    

     

    
    

     

      DWORD WINAPI ThreadProc2(LPVOID lpParam);
     
    
   

    

     

    
    

     

      DWORD g_dwThreadID;
     
    
   

    

     

    
    

     

      DWORD g_dwThreadID2;
     
    
   

    

     

    
    

     

      UINT g_nTickets = 300;  
     
    
   

    

     

    
    

     

      HANDLE g_hEvent1 = NULL;
     
    
   

    

     

    
    

     

      HANDLE g_hEvent2 = NULL;
     
    
   

    

     

    
    

     

      CRITICAL_SECTION g_cs;
     
    
   

    

     

    
    

     

      int ThreadCout = 0;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      int main(int argc, _TCHAR* argv[])
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

      	cout << "Main thread is running." << endl;
     
    
   

    

     

    
    

     
	InitializeCriticalSection(&g_cs);//初始化临界区
     
    
   

    

     

    
    

     

      	HANDLE hHandle = CreateThread(NULL, 0, ThreadProc, NULL, 0, &g_dwThreadID);
     
    
   

    

     

    
    

     

      	ThreadCout++;
     
    
   

    

     

    
    

     

      	HANDLE hHandle2 = CreateThread(NULL, 0, ThreadProc2, NULL, 0, &g_dwThreadID2);
     
    
   

    

     

    
    

     

      	ThreadCout++;
     
    
   

    

     

    
    

     

      	g_hEvent1 = CreateEvent(NULL, FALSE, TRUE, NULL);  //备注5:g_hEvent1 = CreateEvent(NULL, TRUE, TRUE, NULL);
     
    
   

    

     

    
    

     

      	g_hEvent2 = CreateEvent(NULL, FALSE, TRUE, NULL);  //备注5:g_hEvent2 = CreateEvent(NULL, TRUE, TRUE, NULL);
     
    
   

    

     

    
    

     
	ResetEvent(g_hEvent1);
     
    
   

    

     

    
    

     
	ResetEvent(g_hEvent2);
     
    
   

    

     

    
    

     
	SetEvent(g_hEvent1);
     
    
   

    

     

    
    

     
	while (TRUE)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		EnterCriticalSection(&g_cs);
     
    
   

    

     

    
    

     
		int nCount = ThreadCout;
     
    
   

    

     

    
    

     
		LeaveCriticalSection(&g_cs);
     
    
   

    

     

    
    

     
		if (nCount == 0)
     
    
   

    

     

    
    

     

      		{
     
    
   

    

     

    
    

     

      			cout << "Main break" << endl;
     
    
   

    

     

    
    

     
			break;
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
	Sleep(1000);    //备注4
     
    
   

    

     

    
    

     
	CloseHandle(hHandle);
     
    
   

    

     

    
    

     
	CloseHandle(hHandle2);
     
    
   

    

     

    
    

     
	DeleteCriticalSection(&g_cs);
     
    
   

    

     

    
    

     

      	cout << "Main End " << endl;
     
    
   

    

     

    
    

     
	system("pause");
     
    
   

    

     

    
    

     
	return 0;
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      DWORD WINAPI ThreadProc(LPVOID lpParam)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
	while (TRUE)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		WaitForSingleObject(g_hEvent1, INFINITE);
     
    
   

    

     

    
    

     

      		cout << "线程1：" << g_dwThreadID << " thread is running." << endl;
     
    
   

    

     

    
    

     
		EnterCriticalSection(&g_cs);
     
    
   

    

     

    
    

     
		int temp = g_nTickets;
     
    
   

    

     

    
    

     
		LeaveCriticalSection(&g_cs);
     
    
   

    

     

    
    

     

      		cout << "线程1：" << g_dwThreadID << " thread is temp." << endl;
     
    
   

    

     

    
    

     
		if (temp > 0)
     
    
   

    

     

    
    

     

      		{
     
    
   

    

     

    
    

     
			Sleep(100);  //Sleep(1000) 
     
    
   

    

     

    
    

     

      			cout << "线程1：" << g_dwThreadID << " sell ticket : " << temp << endl;
     
    
   

    

     

    
    

     
			EnterCriticalSection(&g_cs);
     
    
   

    

     

    
    

     

      			g_nTickets--;
     
    
   

    

     

    
    

     
			LeaveCriticalSection(&g_cs);
     
    
   

    

     

    
    

     
			SetEvent(g_hEvent2);
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     
		else
     
    
   

    

     

    
    

     

      		{
     
    
   

    

     

    
    

     

      			cout << "线程1 break" << endl;
     
    
   

    

     

    
    

     
			SetEvent(g_hEvent2);//没有这个ThreadProc2不能终止 
     
    
   

    

     

    
    

     
			break;
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
	EnterCriticalSection(&g_cs);
     
    
   

    

     

    
    

     

      	ThreadCout--;
     
    
   

    

     

    
    

     
	LeaveCriticalSection(&g_cs);
     
    
   

    

     

    
    

     

      	cout << "线程1 end" << endl;
     
    
   

    

     

    
    

     
	return 0;
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      DWORD WINAPI ThreadProc2(LPVOID lpParam)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
	while (TRUE)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		WaitForSingleObject(g_hEvent2, INFINITE);
     
    
   

    

     

    
    

     

      		cout << "线程2： " << g_dwThreadID2 << " thread is running." << endl;
     
    
   

    

     

    
    

     
		EnterCriticalSection(&g_cs);
     
    
   

    

     

    
    

     
		int temp = g_nTickets;
     
    
   

    

     

    
    

     
		LeaveCriticalSection(&g_cs);
     
    
   

    

     

    
    

     
		if (temp > 0)
     
    
   

    

     

    
    

     

      		{
     
    
   

    

     

    
    

     
			Sleep(100);  //Sleep(1000) //备注2
     
    
   

    

     

    
    

     

      			cout << "线程2：" << g_dwThreadID2 << " sell ticket : " << temp << endl;
     
    
   

    

     

    
    

     
			EnterCriticalSection(&g_cs);
     
    
   

    

     

    
    

     

      			g_nTickets--;
     
    
   

    

     

    
    

     
			LeaveCriticalSection(&g_cs);
     
    
   

    

     

    
    

     
			SetEvent(g_hEvent1);			
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     
		else
     
    
   

    

     

    
    

     

      		{
     
    
   

    

     

    
    

     

      			cout << "线程2 break" << endl;			
     
    
   

    

     

    
    

     
			SetEvent(g_hEvent1);//同样的问题，没有这个ThreadProc不能终止
     
    
   

    

     

    
    

     
			break;
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
	EnterCriticalSection(&g_cs);
     
    
   

    

     

    
    

     

      	ThreadCout--;
     
    
   

    

     

    
    

     
	LeaveCriticalSection(&g_cs);
     
    
   

    

     

    
    

     

      	cout << "线程2 end" << endl;
     
    
   

    

     

    
    

     
	return 0;
     
    
   

    

     

    
    

     

      }
     
    
  
 

执行结果如下图：

文章来源: wanghao.blog.csdn.net，作者：AI浩，版权归原作者所有，如需转载，请联系作者。

原文链接：wanghao.blog.csdn.net/article/details/108380956