[erlang-questions] Best way to kill an async thread in a linked in driver?

Steve Vinoski <>
Fri Aug 13 05:43:33 CEST 2010


On Thu, Aug 12, 2010 at 6:14 PM, Mazen Harake
<> wrote:
> On 12/08/2010 14:42, Kresten Krab Thorup wrote:
>>
>> I'd write the driver using select and non-blocking reads; that way you
>> would not need async threads at all.
>
>  Hmm... I'm not sure what you mean but the part I do understand is that
> select() blocks... right? I can't have anything that blocks in the driver
> since I must be able to interact with it as I'm waiting for input. E.g. I
> need to update a certain part of the screen even if the user is not pressing
> any buttons.
>
> I don't see how select() would make any difference? Perhaps I misunderstood
> you, could you explain a bit more on how that would work? Or perhaps point
> me to some direction?

What Kresten is essentially recommending is that you make the file
descriptor from which you're reading characters non-blocking and then
register it into the emulator's event loop via driver_select(). Once
your file descriptor has something to read, the emulator will call
your code via your driver's ready_input callback. At that point you
can read your character(s) from your fd and process them pretty much
like you're doing now. You can read the fd until you get EAGAIN or
EWOULDBLOCK, at which point there's nothing left to read, and you can
then return from your ready_input callback. The emulator will call you
every time there's something to read until you unregister the fd.

As Kresten said, no async thread required.

--steve


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