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<H1>[99s-extend] timeout in cowboy loop handler</H1>
<B>Loïc Hoguin</B>
<A HREF="mailto:extend%40lists.ninenines.eu?Subject=Re%3A%20%5B99s-extend%5D%20timeout%20in%20cowboy%20loop%20handler&In-Reply-To=%3C525E179F.2010200%40ninenines.eu%3E"
TITLE="[99s-extend] timeout in cowboy loop handler">essen at ninenines.eu
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<I>Wed Oct 16 06:35:43 CEST 2013</I>
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<PRE>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:
><i> thanks. one more question if you do not mind. you say that we need
</I>><i> timeouts when the client does not notify us when it dies. but then you
</I>><i> say that if the client dies then the socket write will fail. to me this
</I>><i> sounds like a contradiction. would you please clarify?
</I>><i>
</I>><i> (I assume that this is the problem that we are discussing:
</I>><i> <A HREF="http://stackoverflow.com/questions/283375/detecting-tcp-client-disconnect,">http://stackoverflow.com/questions/283375/detecting-tcp-client-disconnect,</A>
</I>><i> right?)
</I>><i>
</I>><i>
</I>><i> 2013/10/16 Loïc Hoguin <<A HREF="https://lists.ninenines.eu/listinfo/extend">essen at ninenines.eu</A> <mailto:<A HREF="https://lists.ninenines.eu/listinfo/extend">essen at ninenines.eu</A>>>
</I>><i>
</I>><i> On 10/16/2013 05:48 AM, akonsu wrote:
</I>><i>
</I>><i> 1. do you mean that there is no way on the server side to tell
</I>><i> if the
</I>><i> client has disconnected?
</I>><i>
</I>><i>
</I>><i> There are ways, and Cowboy will happily detect them. There's also
</I>><i> the problem that a side may be closed without the other side knowing
</I>><i> about it, which is why you need timeouts.
</I>><i>
</I>><i>
</I>><i> 2. if I use a normal handler, I will still run into the same
</I>><i> problem, it
</I>><i> does not matter which handler I use, from the standpoint of deciding
</I>><i> whether the client is still there, right?
</I>><i>
</I>><i>
</I>><i> If the client is gone, the send will fail. Normal handlers are
</I>><i> pretty much the same except they don't have a timeout, because your
</I>><i> code has an explicit end.
</I>><i>
</I>><i> I am confused as to how I can implement my streaming and not
</I>><i> drop the
</I>><i> connection on each client and yet make sure I do close the
</I>><i> connections
</I>><i> when the clients disconnect...
</I>><i>
</I>><i>
</I>><i> 2013/10/15 Loïc Hoguin <<A HREF="https://lists.ninenines.eu/listinfo/extend">essen at ninenines.eu</A>
</I>><i> <mailto:<A HREF="https://lists.ninenines.eu/listinfo/extend">essen at ninenines.eu</A>> <mailto:<A HREF="https://lists.ninenines.eu/listinfo/extend">essen at ninenines.eu</A>
</I>><i> <mailto:<A HREF="https://lists.ninenines.eu/listinfo/extend">essen at ninenines.eu</A>>>>
</I>><i>
</I>><i>
</I>><i> Infinite is bad practice, yes. Infinite means some
</I>><i> connections will
</I>><i> *never* be closed, eating FDs and memory for nothing.
</I>><i>
</I>><i> I'm not sure why you want to receive messages, you could
</I>><i> just use a
</I>><i> normal handler that asks for more data, sends it, ask for
</I>><i> more data,
</I>><i> sends it, etc.
</I>><i>
</I>><i>
</I>><i>
</I>><i> --
</I>><i> Loïc Hoguin
</I>><i> Erlang Cowboy
</I>><i> Nine Nines
</I>><i> <A HREF="http://ninenines.eu">http://ninenines.eu</A>
</I>><i>
</I>><i>
</I>
--
Loïc Hoguin
Erlang Cowboy
Nine Nines
<A HREF="http://ninenines.eu">http://ninenines.eu</A>
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