How to use a timer in a win32 dll ?

[legrillon]

Hi,

I'm using a client/server application from a software company .
This software allows me to interact with it thanks to a user DLL that I have to implement on the NT side of the communication. This is what they call a "user exit".
So far so good : each time the software sends or receives a buffer, it fires my DLL, pass information to it , retrieves back updated data, and everything's fine.

I have an additional need : I would like to detect in my DLL if inactivity occurs for let's say 10 minutes so that I can take special action. Inactivity means my DLL hasn't been fired for 10 minutes.

I tried to use SetTimer (callback function) / KillTimer in my DLL but as you can imagine, when I call SetTimer in my DLL and then give control back to the main application, the callback application is never called in case of a time-out .

Is there a way to solve that issue ?

Thanks for reading and helping me on this topic.

Marc

[j0nas]

I think SetTimer is a bad idea due to the fact it requires pumping of window message etc...

It's kind of hard to give a general solution (don't know enough about the requirments), but I'll try anyway.

I see, at least, two solutions. The first one is easy.

Solution 1:
Compare the time each time you're called. If last time called is longer than the inactivity period, take actions...

Solution 2:
Create a thread that hangs a event object. Let the timeout value in the wait function (WaitForSingleObject or WaitForMulitpleObject) control the inactivity period. If the wait function is timed out, set a global flag. Reset the global flag when you're called.

[legrillon]

Jonas,
Thanks for your reply.

My problem is that I must detect the inactivity period outside my DLL.
As soon as the time-out is reached, I must shutdown the whole application. I cant' wait for my DLL to be called ...

I've read somewhere else (can't remember) that a possible solution could be to start a new thread dedicated to the timer management from within the DLL.
Do you think this is doable ?

Thanks
Marc

[j0nas]

Originally posted by legrillon
I've read somewhere else (can't remember) that a possible solution could be to start a new thread dedicated to the timer management from within the DLL.
Do you think this is doable ?

Yepp, that's basically what my second solution was.

The only problem with this solution, can be that you (your DLL) don't know the life-time etc... I mean, you need to start the thread at some point. The same goes with thread-cleanup. If the DLL interface (that you implement) specifies init/deinit functions, then it's easy and clean. You can of course always start and stop a thread from within DllMain (should work, but I'm more confident with the init/deinit approach).

How will you terminate the app?

[legrillon]

There is such a mess in my head... You're right Jonas, it was basically your 2nd solution. Sorry, I need some rest.

Regarding the shutdown of the app, in fact, I've just changed my mind and I will handle the time-out differently, I explain you how

Each time my DLL is called, I can look at the buffer to be sent to the host and I can determine if it is a logon request . Logon should be the first request transmitted to the host and then a normal client-server conversation can take place.

In case of time-out, I want to force the user to log again before resuming his conversation with the host.

I think I can do that with your solution:
- a thread taking care of any time-out
- a static global variable in my DLL that indicates if the next coming buffer should be a logon request ; this variable is set by the timer thread in case of a time-out
- if my DLL is not called with a logon request as expected, I set the DLL return code to FALSE, the buffer will not be sent by the application, this a capability given by the application and the user will get an error message. This way , I can force the user to submit a logon request again.

Jonas, thanks a lot!
I'll try to code that and I'll let you know.
Marc

[legrillon]

Jonas,

It works!

My DLL creates an Event Object and set it to Signaled each time it's called by the app.

I have a thread waiting on that Event object with a specific delay, in an infinite loop.
When the Event gets signaled, the thread determines if it's a time-out or if it was signaled by the parent DLL.
In the first case, it does a MessageBox and posts a flag to the DLL to force the user to call the logon screen .
In the second case, it simply resets the Event object and waits again.

Thanks a lot Jonas, I've really appreciated your help

Marc

[rfmobile]

Another option is to use the multimedia timer. At least you wouldn't need to create a separate thread.

The timer accepts a callback function.

#include <mmsystem.h>

MMRESULT timeSetEvent(
UINT uDelay,
UINT uResolution,
LPTIMECALLBACK lpTimeProc,
DWORD_PTR dwUser,
UINT fuEvent
);

-rick

[legrillon]

Due to PC problem, I've just read your answer today...
Thanks for your suggestion, rfmobile. Seems to be even simpler!
Bye
Marc

[vicodin451]

Don't forget about waitable timers (CreateWaitableTimer, etc)...