Question

Question : How do you make a timer tick in the background? That is the thread that create the timer thread can still do something else while clock is ticking.

Attempt:
-Using _beginthreadex() –> It seems to have race condition

class Timer{
 ...
 static unsigned __stdcall tick(void *param){
    while(1){
        Timer::timer++;
        Sleep(Timer::timer*1000);
    }
    return 1;
}
}

.....
HANDLE time_thread = (HANDLE) _beginthreadex(0, 0, &Timer::tick,0,0,NULL);
...
//test for 20 seconds
//want to do something while the clock is not 20 seconds
//the mainthread here still has to receive input
//What is the proper way to do it?

while (Timer::getTime() != 20){
   cout << Timer::getTime()
}

CloseHandle(time_thread);
...

NOTE: Iam using Visual Studio 2008, not 11 so I do not have C++11 support.

Answer 1

I’m not sure what’s wrong with what you have here. You’ve created a thread that updates a member variable timer forever and your main use of it is a tight/fast loop that prints (presumably) that time until it reaches 20. What is it not doing? Technically there’s a race condition of incrementing that value versus checking it in another thread, but for the purposes of this example it should be fine…

EDIT: try this for non-blocking input with full input control:

HANDLE hStdIn = GetStdHandle( STD_INPUT_HANDLE );
while ( true ) {
    if ( WAIT_OBJECT_0 == WaitForSingleObject( hStdIn, 1000 ) ) {
        // read input
        INPUT_RECORD inputRecord;
        DWORD events;
        if ( ReadConsoleInput( hStdIn, &inputRecord, 1, &events ) ) {
            if ( inputRecord.EventType == KEY_EVENT ) {
                printf( "got char %c %s\n",
                    inputRecord.Event.KeyEvent.uChar.AsciiChar,
                    inputRecord.Event.KeyEvent.bKeyDown ? "down" : "up" );
            }
        }
    }
    printf( "update clock\n" );
}