Re: [Libevent-users] detection of TCP disconnection

[Dan Kegel <dank@xxxxxxxxx>]

On Tue, Nov 22, 2011 at 4:18 PM,  <Ivan.Novick@xxxxxxx> wrote:
> In order to detect a "disconnection" by the client i look for a return
> value of 0 from read() in the callback function.
>
> This seems to work correctly when i do a kill -INT on the client or a kill
> -9 on the client: the callback is triggered on the server and the return
> from read() is 0.
>
> However if i a do hard reset(power off) of the machine running the client,
> it does not seem to work and I believe I am not getting a callback
> function for the event on the server.

This is normal and expected.  TCP doesn't really have a good way to detect this.
You can use SO_KEEPALIVE to ask the OS to do its own keepalives;
then it'll probably detect dead connections within a couple hours.
- Dan
***********************************************************************
To unsubscribe, send an e-mail to majordomo@xxxxxxxxxxxxx with
unsubscribe libevent-users    in the body.