Re: Using CreateTimerQueueTimer

"Tom Widmer [VC++ MVP]" <>
Wed, 17 Jan 2007 15:10:40 +0000
sandy84 wrote:

Hello all,
I want to create a Windows NT Service which will delete records on
timely interval. So I am using ATL wizard generated code by using
windows services option. In Run() function I want to call the function
which will delete the record on timely interval. So for that the code
is as follows:

HANDLE m_hStop;
m_hStop = ::CreateEvent(0, TRUE, FALSE, 0);

HANDLE hTimerQTimer;
CreateTimerQueueTimer(&hTimerQTimer, NULL, DeleteRecords, NULL, 1000,

if (::WaitForSingleObject (m_hStop, INFINITE) == WAIT_OBJECT_0)
    DeleteTimerQueueTimer(NULL, hTimerQTimer, NULL);

I'd pass INVALID_HANDLE_VALUE as the third parameter, to ensure your
callback has finished before you return.


where DeleteRecords is the function which is callback function. I am
setting event m_hStop in Handler() function for stop and shutdown. Is
this the right implementation or a better mechanism is possible to
achieve this same thing?

It would be simpler just to use a loop with
WaitForSingleObject(m_hStop, 60000)
and do away with the timer entirely.

  Also is it possible that the function

DeleteRecords is member function of some class?

No. The best you can do is pass a static member function, and then pass
"this" as the callback parameter (arg 4 I think). Then the static member
can either call a non-static member, or just do the work itself,
accessing member variables through the parameter (cast to a pointer to
your class's type of course).

  Because when I make it

a member function of some class then I get following error:

error C2664: 'CreateTimerQueueTimer' : cannot convert parameter 3 from
'void (void *,unsigned char)' to 'void (__stdcall *)(void *,unsigned
char)' None of the functions with this name in scope match the target

Curretly DeleteRecords is defined as:

VOID CALLBACK DeleteRecords(PVOID pvContext, BOOLEAN fTimeout)

Change that to:
static VOID CALLBACK DeleteRecords(PVOID pvContext, BOOLEAN fTimeout)
   MyClass* pMyClass = static_cast<MyClass*>(pvContext);


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