Non-blocking SCTP connect [Was: [erlang-patches] SCTP improvements]

[Simon Cornish]

Hi Raimo,

I'm taking this as a separate thread for each topic.

On Wed, Dec 16, 2009 at 4:42 AM, Raimo Niskanen
raimo+erlang-patches-at-erix.ericsson.se wrote:
[...]
> http://github.com/erlang/otp/commit/92f3ceea0fa51df308f6f2689ff82857b6442c30
> Implement a non-blocking gen_sctp:connect

I think there are plenty of examples in OTP where library functions
return a different type based on the argument(s). But, subjective
comments on style aside (since I have no style :-) I had not
considered that this was changing existing interface semantics in a
service release.

I'm happy to rewrite it as new connect_nowait functions as you
suggest. What's the best way to do this? Amended commit? New commit?
New branch? Maybe Björn has an opinion since he has to do the messy
part...

Regards,
 Simon

>
> lib/kernel/src/inet_sctp.erl: 74/82
>  Comparision Timeout /= 0 should have been Timeout =/= 0
>  just to be certain...
>
>  To compare Timeout =/= 0 is unfortunately also wrong since
>  time may have elapsed since inet:start_timer/1 was
>  called and inet:timeout/1 may return 0 when the original
>  Timeout actually was nonzero.
>
> And, furthermore; having gen_sctp:connect/4,5 to return a
> different type for some value (i.e 0) of an argument
> (i.e Timeout) is considered ugly. And introducing such
> a change in a service release is out of the question.
>
> Therefore; can you rewrite your patch to introduce a new
> function gen_sctp:connect_nowait/4 that does exactly
> what your gen_sctp:connect(S, Add, Port, Opts, 0) did?
>
> There will be some code duplication, but you can maybe
> also avoid creating a timer alltogether and perhaps
> use a special value (e.g 0) to inet_sctp:connect/5,
> last argument, to not have to duplicate everything.
> inet_sctp is a non-public interface so it can be altered.
> Doing it this way also avoids fixing inet6_sctp.erl.
>