[99s-extend] timeout in cowboy loop handler
Loïc Hoguin
essen at ninenines.eu
Wed Oct 16 06:35:43 CEST 2013
Loop handlers are designed to wait for a long time with the socket
*idle* and then eventually send one response then close the socket.
Things like long-polling.
What you are doing is just streaming, for which you do not need a
timeout because the socket isn't idle. You are just sending a large
response, and normal handlers are perfectly capable of doing that.
On 10/16/2013 06:12 AM, akonsu wrote:
> thanks. one more question if you do not mind. you say that we need
> timeouts when the client does not notify us when it dies. but then you
> say that if the client dies then the socket write will fail. to me this
> sounds like a contradiction. would you please clarify?
>
> (I assume that this is the problem that we are discussing:
> http://stackoverflow.com/questions/283375/detecting-tcp-client-disconnect,
> right?)
>
>
> 2013/10/16 Loïc Hoguin <essen at ninenines.eu <mailto:essen at ninenines.eu>>
>
> On 10/16/2013 05:48 AM, akonsu wrote:
>
> 1. do you mean that there is no way on the server side to tell
> if the
> client has disconnected?
>
>
> There are ways, and Cowboy will happily detect them. There's also
> the problem that a side may be closed without the other side knowing
> about it, which is why you need timeouts.
>
>
> 2. if I use a normal handler, I will still run into the same
> problem, it
> does not matter which handler I use, from the standpoint of deciding
> whether the client is still there, right?
>
>
> If the client is gone, the send will fail. Normal handlers are
> pretty much the same except they don't have a timeout, because your
> code has an explicit end.
>
> I am confused as to how I can implement my streaming and not
> drop the
> connection on each client and yet make sure I do close the
> connections
> when the clients disconnect...
>
>
> 2013/10/15 Loïc Hoguin <essen at ninenines.eu
> <mailto:essen at ninenines.eu> <mailto:essen at ninenines.eu
> <mailto:essen at ninenines.eu>>>
>
>
> Infinite is bad practice, yes. Infinite means some
> connections will
> *never* be closed, eating FDs and memory for nothing.
>
> I'm not sure why you want to receive messages, you could
> just use a
> normal handler that asks for more data, sends it, ask for
> more data,
> sends it, etc.
>
>
>
> --
> Loïc Hoguin
> Erlang Cowboy
> Nine Nines
> http://ninenines.eu
>
>
--
Loïc Hoguin
Erlang Cowboy
Nine Nines
http://ninenines.eu
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