[usocket-devel] Fwd: Detecting whether the other end has closed my socket stream

[Roger Sen Montero]

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 at 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 at 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 at 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 at 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 at gmail.com
>>
>> _______________________________________________
>> usocket-devel mailing list
>> usocket-devel at common-lisp.net
>> http://lists.common-lisp.net/cgi-bin/mailman/listinfo/usocket-devel
>>
>>
>
> --
> Roger Sen Montero
> roger.sen at gmail.com
>



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



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