Cwinthread::CreateThread中的event是做什么用的 啊

[baitiane7100]

问题1：

在学win32多线程的时候，2个线程互斥，一般会用全局Event, 注意是全局。

mfc比较诡异，封装的一个CWinThread类，然后在这个线程类内部自己搞了个Event，奇怪。

它弄一个Event予以何为？？？ 和谁同步，和谁互斥？？？

自己的内部 啊

BOOL CWinThread::CreateThread(DWORD dwCreateFlags, UINT nStackSize,
	LPSECURITY_ATTRIBUTES lpSecurityAttrs)
{
#ifndef _MT
	dwCreateFlags;
	nStackSize;
	lpSecurityAttrs;

	return FALSE;
#else
	ASSERT(m_hThread == NULL);  // already created?

	// setup startup structure for thread initialization
	_AFX_THREAD_STARTUP startup; memset(&startup, 0, sizeof(startup));
	startup.pThreadState = AfxGetThreadState();
	startup.pThread = this;
	startup.hEvent = ::CreateEvent(NULL, TRUE, FALSE, NULL);   //这里创建了一个
	startup.hEvent2 = ::CreateEvent(NULL, TRUE, FALSE, NULL);   //创建了第二个
	startup.dwCreateFlags = dwCreateFlags;
	if (startup.hEvent == NULL || startup.hEvent2 == NULL)
	{
		TRACE0("Warning: CreateEvent failed in CWinThread::CreateThread.\n");
		if (startup.hEvent != NULL)
			::CloseHandle(startup.hEvent);
		if (startup.hEvent2 != NULL)
			::CloseHandle(startup.hEvent2);
		return FALSE;
	}

	// create the thread (it may or may not start to run)
	m_hThread = (HANDLE)_beginthreadex(lpSecurityAttrs, nStackSize,
		&_AfxThreadEntry, &startup, dwCreateFlags | CREATE_SUSPENDED, (UINT*)&m_nThreadID);
	if (m_hThread == NULL)
		return FALSE;

	// start the thread just for MFC initialization
	VERIFY(ResumeThread() != (DWORD)-1);
	VERIFY(::WaitForSingleObject(startup.hEvent, INFINITE) == WAIT_OBJECT_0);
	::CloseHandle(startup.hEvent);

	// if created suspended, suspend it until resume thread wakes it up
	if (dwCreateFlags & CREATE_SUSPENDED)
		VERIFY(::SuspendThread(m_hThread) != (DWORD)-1);

	// if error during startup, shut things down
	if (startup.bError)
	{
		VERIFY(::WaitForSingleObject(m_hThread, INFINITE) == WAIT_OBJECT_0);
		::CloseHandle(m_hThread);
		m_hThread = NULL;
		::CloseHandle(startup.hEvent2);
		return FALSE;
	}

	// allow thread to continue, once resumed (it may already be resumed)
	::SetEvent(startup.hEvent2);
	return TRUE;
#endif //!_MT
}

问题2：

::WaitForSingleObject(startup.hEvent, INFINITE);
表示无穷的时间内，等到 这个事件被激发，然后返回？？

[Eleven]

// start the thread just for MFC initialization
VERIFY(ResumeThread() != (DWORD)-1);
VERIFY(::WaitForSingleObject(startup.hEvent, INFINITE) == WAIT_OBJECT_0);
::CloseHandle(startup.hEvent);
---------
看这里的注释，第一个EVENT用作启动线程为MFC的初始化使用。

// allow thread to continue, once resumed (it may already be resumed)
::SetEvent(startup.hEvent2);
-------------
第二个EVENT用作恢复线程运行，因为创建线程的时候指定的参数是CREATE_SUSPENDED。
调用CWinThread::RusmeThread()的时候使EVENT为signal状态。

[Eleven]

::WaitForSingleObject(startup.hEvent, INFINITE);
表示无穷的时间内，等到 这个事件被激发，然后返回？？
--------------
是的，直到EVENT事件对象为signal状态，WaitFor函数返回。

[baitiane7100]

这么说，event这玩意的功能不仅仅是用来互斥？？

[Quote=引用 1 楼 的回复:]

// start the thread just for MFC initialization
VERIFY(ResumeThread() != (DWORD)-1);
VERIFY(::WaitForSingleObject(startup.hEvent, INFINITE) == WAIT_OBJECT_0);
::CloseHandle(startup.hEv……
[/Quote]

[baitiane7100]

ResumeThread不对吧，你看代码，仅仅是回复线程，并没有对事件对象进行恢复。使其具有信号啊。。

但是按你所说的，理解下去却是对的。




[Quote=引用 1 楼 的回复:]

// start the thread just for MFC initialization
VERIFY(ResumeThread() != (DWORD)-1);
VERIFY(::WaitForSingleObject(startup.hEvent, INFINITE) == WAIT_OBJECT_0);
::CloseHandle(startup.hEv……
[/Quote]