Timeouts in a thread?

[danielmashman]

Hi All,

I have a borland c++ builder application where I am lauching a thread to manage USB HID communications with an external device. I want to wait a specified amount of time at a point within this thread for the device to be attached. Is there an easy way of setting up a timeout to do this? I could have a for loop with a counter and use Sleep() routine but not sure if this is the best way of doing it.

I apologize in advance for the lack of information but not really sure what extra info to provide. Please ask if neccessary.

 

[ArkM]

If you want to suspend unconditionally, the Sleep function (w/o any loop counters) is the best way to go (it's exactly what this function is intendened for).

For more advanced HID programming stuff look at

http://www.lvr.com/hidpage.htm

 

[Prattaratt]

I have not tried anything like this myself before, but have you tried creating a timer object and then using WaitForEvent? Like I said, I have not done this so I do not have any sample code, but I would look at Windows System calls of CreateWaitableTimer, SetWaitableTimer and OpenWaitableTimer, as well as WaitForSingleObject. Alternatively, you could investigate CreateEvent, and set the timeout parameter of the WaitForSingleObject. Just a couple of approaches to try.

 

[danielmashman]

Thanks for the responses. Here's a more detailed description of what I am trying to do:
The particular part in the code is attempting to put the USB HID device into a boot loader mode by sending a USB command. Once the device receives this command I know it will disconnect and reconnect from the USB as it enters the bootloader mode. I have a rough idea of how long this will take (something in the order of 300ms). I have registered for device events in my application so I know when a USB device is attached/detached so what I want is a loop that continuously poles a flag for the device to be attached for a maximum time of (say 500ms).

I think the easiest way would be to do something like this:

for(timout = 50; ((timeout > 0) && !DeviceAttached); timeout--)
    sleep(10);    //suspend for 10ms

if(!DeviceAttached)
    return -1;    //error

//check this is the correct device (PID, VID)

Not sure how long do get the thread to sleep for between checking the DeviceAttached flag though. I think 10ms should be fine.