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Waiting for a thread to terminate

, 5 Sep 2002
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How to pause the main thread until a secondary thread is finished
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Introduction

A few weeks ago, I had to program a custom dialog-box as part of a MSI-Setup. The code for this has to be distributed as a Regular-DLL. This dialog-box makes some actions during the initialisation and depending of the result, I had to show or not this box. The actions made were done with others threads. The problem was to wait these actions to be terminated, to first analyse the result, and then display or not the box.

The first method I've found was very simple and worked very well, but only when this DLL was used from another "normal" application. When this DLL was called from a MSI-Setup, everything went wrong.

Then I requested some help from Microsoft which gave me a few days later a solution that didn't work too!! But it gave me a good idea, and finally I found the right solution, which works on every OS and regardless which kind of application calls this DLL. It works also on multiprocessor machines.

The solution

You've to write two functions. The first one, void CMyTestDialog::PeekMessageLoop() will acquire the messages from the message queue:
void CMyTestDialog::PeekMessageLoop()
{
    MSG msg;
    while (PeekMessage(&msg, NULL, NULL, NULL, PM_REMOVE))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
}

The second one, void CMyTestDialog::WaitForThreadToTerminate(HANDLE hThread) will take the handle of the thread we are waiting for:

<PRE lang=c++>void CMyTestDialog::WaitForThreadToTerminate(HANDLE hThread)
{
    DWORD dwRet;
    do
    {
        dwRet = ::MsgWaitForMultipleObjects(1, &hThread, FALSE, 
            INFINITE, QS_ALLINPUT);
        if (dwRet != WAIT_OBJECT_0)
        {
            PeekMessageLoop();
        }
    } while ((dwRet != WAIT_OBJECT_0) && (dwRet != WAIT_FAILED));
}

Sample code

Suppose you have a dialog-box with a button. When you click on it, your DLL launches an action in a secondary thread, and have to wait until this action is done. The only thing you have to do is:
void CMyTestDialog::OnButton1() 
{
    m_pUpdateThread = AfxBeginThread(UpdateDeviceContent, 
        (LPVOID)this/*, THREAD_PRIORITY_BELOW_NORMAL*/);
    if (m_pUpdateThread)
    {
        WaitForThreadToTerminate(m_pUpdateThread->m_hThread);
    }
//Do whatever you want after the action is finished
}

So I hope this article will help someone. The sample code in the zip-file is not very clean, but I think it's quite simple and everyone can understand it.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Ybbozman
Web Developer
Germany Germany
No Biography provided

Comments and Discussions

 
Generaljust wanna say thanks! Pinmembersprikitik17-Feb-09 21:03 
Generalgo what i wanted PinmemberBalkrishna Talele24-Jan-06 19:06 
Generalexcellent articles Pinmemberspring12-Aug-05 15:39 
GeneralThanks, bro PinmemberMingming Lu10-Jan-04 19:02 
QuestionHow do I revise the sample code for waiting multiple threads Pinmemberjordan_chuang10-Mar-03 20:32 
AnswerRe: How do I revise the sample code for waiting multiple threads PinmemberYbbozman31-Mar-03 23:19 
GeneralThe thread handle should be copied PinmemberSheng-hung8-Dec-02 19:43 
GeneralRe: The thread handle should be copied PinmemberYbbozman31-Mar-03 23:19 
GeneralRe: The thread handle should be copied PinmemberckTan8124-Mar-05 15:42 
GeneralRe: The thread handle should be copied PinmemberSheng-hung1-Apr-05 14:11 
GeneralRe: The thread handle should be copied PinmemberckTan813-Apr-05 14:39 
Generalthanks PinmemberShouFeng Qi7-Oct-02 23:34 
GeneralAtlWaitWithMessageLoop PinmemberAriel Rocholl13-Sep-02 6:33 
GeneralRe: AtlWaitWithMessageLoop PinmemberYbbozman17-Sep-02 19:36 
GeneralRe: AtlWaitWithMessageLoop PinmemberAriel Rocholl23-Sep-02 6:38 
GeneralRe: AtlWaitWithMessageLoop PinmemberAriel Rocholl23-Sep-02 6:39 
GeneralRe: AtlWaitWithMessageLoop PinmemberYbbozman9-Oct-02 20:54 
QuestionWhat was the solution proposed my MS? PinmemberErnesto Perales Soto9-Sep-02 11:14 
AnswerRe: What was the solution proposed my MS? PinmemberYbbozman10-Sep-02 3:23 
GeneralMSI setup DLL sample... PinmemberMario M.7-Sep-02 15:29 
GeneralRe: MSI setup DLL sample... PinmemberYbbozman10-Sep-02 3:19 
Generalthanx PinsussAnonymous6-Sep-02 20:49 
GeneralIt looks good! PinmemberLeafdown6-Sep-02 3:56 

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