[erlang-questions] Setting socket options on listen / accept

[Tianxiang Xiong]

Thanks Roger, that makes sense. And no, I'm not trying to build my own
socket acceptor pool; that's probably too ambitious. Just working through
Joe's book for now ��.

On Tue, Feb 6, 2018 at 3:51 AM, Roger Lipscombe <roger@REDACTED>
wrote:

> It's worth pointing out that certain 'raw' options only apply to the
> listening socket, and are not consistently inherited by (or
> transferred to) the accepting/connected socket. For example, on Linux,
> TCP keep-alive settings can be applied to the listening socket, and
> they'll be copied to the connected socket. On macOS, this (a) doesn't
> work, and (b) does other weird, unexpected things.
>
> Note also that you probably *don't* want to set {active, true} in
> listen/2 in a real application, because you're probably going to hand
> the socket off to another process (using
> gen_tcp:controlling_process/2), and this'll cause you to miss the
> occasional message during that window.
>
> And, frankly, if you're building your own socket acceptor pool,
> *don't*. Just use ranch (https://github.com/ninenines/ranch).
>
> On 6 February 2018 at 05:55, Tianxiang Xiong <tianxiang.xiong@REDACTED>
> wrote:
> > In Joe's Programming Erlang 2nd E, Chpt. 17, pg. 274, he says:
> >
> >> After we have accepted a connection, it’s a good idea to explicitly set
> >> the required socket options, like this:
> >
> >
> > {ok, Socket} = gen_tcp:accept(Listen),
> > inet:setopts(Socket, [{packet,4},binary,{nodelay,true},{active, true}]),
> > loop(Socket)
> >
> > Until then the book's been doing:
> >
> > {ok, Listen} = gen_tcp:listen(2345, [binary, {packet, 4}, {reuseaddr,
> true},
> > {active, true}])
> > {ok, Socket} = gen_tcp:accept(Listen),
> > ...
> > loop(Socket)
> >
> > Is there a reason we need to set the options after accept? Is it
> necessary
> > to set options on listen and accept?
> >
> >
> > _______________________________________________
> > erlang-questions mailing list
> > erlang-questions@REDACTED
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> >
>
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