Samuel,

(forwarded to the mailing list also)

Basically, as I understand the problem, is that lisp LISTEN does not notify end of file/connection and characters avaiable in the same manner READ-CHAR-NO-HANG (and the character stream system) does. LISTEN returns false on char not available and end-of-file. READ-CHAR-NO-HANG (as well as READLINE) uses conditions.

So, my question is, is there any different way (using usockets) of identifying when a non-char connection is closed?

Thanks!

---------- Forwarded message ----------
From: Roger Sen Montero <roger.sen@gmail.com>
Date: Thu, Mar 21, 2013 at 8:07 PM
Subject: Re: Detecting whether the other end has closed my socket stream
To: Samuel Edwin Ward <seward@cytochro.me>

Samuel,

I have identified the issue to a call to a listen when waiting to read the socket so I can multiplex multiple socket reading.

http://paste.lisp.org/display/136157

With the current code COLLECT-INPUT (listen stream) is not raising the end of file condition.

(defun collect-input (socket buffer &optional (end-char 13))
(loop :with stream = (usocket:socket-stream socket)
     :with byte
     :while (listen stream)
     :doing
     (setf byte (read-byte stream))
     (when (= byte end-char)
       (return t))
     (vector-push-extend byte buffer)))

Taking out the listen and changing it to

:while t

raises the condition correctly when the connection is closed from client side, but then I'm unable to multiplex.

On Thu, Mar 21, 2013 at 1:00 AM, Roger Sen Montero <roger.sen@gmail.com> wrote:

Samuel,

Let me create a simple test case from the current code and I'll post it here.

El miércoles, 13 de marzo de 2013, Samuel Edwin Ward escribió:

Hi Roger/all,

I wasn't able to reproduce this with my setup; I seem to get the end of file condition either way.

I'm using usocket 0.6.0.1 on sbcl 1.0.54.0-185b926 on Mac OS 10.7.5.

Can you provide your versions and/or a runnable test case?

On Mar 13, 2013, at 12:24, Roger Sen Montero <roger.sen@gmail.com> wrote:

Hi all!!

The FAQ states:

Reading from a stream which has been closed at the remote end signals an END-OF-FILE condition, meaning that reading from the stream and detecting that condition is the way to do it.

But when a create a server with:

:element-type 'character

I'm able to get an "Unexpected end of file" condition on the server side when the client disconnect.

Unfortunately, when I create the server with:

:element-type 'unsigned-byte

I do not get the condition, so I'm unable to detect when a client has disconnected.

Also, is there any plan to support utf8 streams directly without creating unsigned-byte sockets and converting from/to string to string-utf-8-bytes?

thanks!
--
Roger Sen Montero
roger.sen@gmail.com

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--
Roger Sen Montero
roger.sen@gmail.com

--
Roger Sen Montero
roger.sen@gmail.com