The first 32 months of 30 days runloop block the thread timeout

1. runloop block the thread timeout

bool CvCaptureCAM::grabFrame(double timeOut) {

    NSAutoreleasePool* localpool = [[NSAutoreleasePool alloc] init];
    double sleepTime = 0.005;
    double total = 0;

    // If the capture is launched in a separate thread, then
    // [NSRunLoop currentRunLoop] is not the same as in the main thread, and has no timer.
    //see https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/nsrunloop_Class/Reference/Reference.html
    // "If no input sources or timers are attached to the run loop, this
    // method exits immediately"
    // using usleep() is not a good alternative, because it may block the GUI.
    // Create a dummy timer so that runUntilDate does not exit immediately:
    [NSTimer scheduledTimerWithTimeInterval:100 target:nil selector:@selector(doFireTimer:) userInfo:nil repeats:YES];
    while (![capture updateImage] && (total += sleepTime)<=timeOut) {
        [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:sleepTime]];
    }

    [localpool drain];

    return total <= timeOut;
}