Great, I just had a go with your changes and it now works for me. There are a couple of typos, you don't pass in the max-buffer-size keyword arg and you forgot to rename my variable from "usocket" to "socket" (diff attached). 

With those changes I think I'm happy. Thanks again for looking into this for me.
Frank,



On 27 May 2015 at 19:09, Chun Tian (binghe) <binghe.lisp@gmail.com> wrote:
Hi Frank,

Thank you very much!  Now I understand the issue, and I think your patch is correct.  The function RECEIVE-MESSAGE was directly from my early work (the LispWorks-UDP [1] package), in which there’s no WAIT-FOR-INPUT yet, and raw socket fd is the user-level socket object.  If RECEIVE-MESSAGE starts to touch the other slots in the usocket object, we should move all its code back to the SOCKET-RECEIVE method.

Any way, I have committed a fix with your idea to latest Github master [2], but when I ran your test code, I get following results in both Windows and Mac:

0s 0 Waiting state NIL
5s 1 Waiting state NIL
10s 2 Waiting state NIL
15s 3 Waiting state NIL

I think that’s because WAIT-FOR-INPUT always returns NIL (nothing can be read from the UDP server socket), therefore your other code (using SOCKET-RECEIVE and SOCKET-SEND) never get a chance to be called…  do you think this is reasonable?

Regards,

Chun

[1] https://common-lisp.net/project/cl-net-snmp/lispworks.html
[2] https://github.com/usocket/usocket/commit/8763542e354af85989678188898af57e50fc0fbb

Il giorno 26/mag/2015, alle ore 17:30, Frank James <frank.a.james@gmail.com> ha scritto:

> Hi Chun,
>
> I've had a bit more time to look into this and I think I've got a better idea of what's going on.
>
> Firstly, I had a really obvious typo above (doh!) which caused the error I saw in socket-send (2, above). Putting in the count parameter and the socket-send succeeds, as expected.
>
> Replacing the handler-case with handler-bind and dropping into the debugger, I identified where the strange error I was seeing with socket-receive comes from (4, above). It seems the recvfrom is returning an error code of 10035, (WSAEWOULDBLOCK), which you are signalling with a condition. But the ns-try-again-condition only has a :HOST-OR-IP initarg, not a :SOCKET initarg. So I commented out that bit of code and the condition is signalled ok (although I'm not handling it, but that's fine).
>
> So my test function is
>
> (defun usocket-test ()
>   (let ((s (usocket:socket-connect nil nil
>                                    :protocol :datagram
>                                    :element-type '(unsigned-byte 8)
>                                    :local-port 8001)))
>     (unwind-protect
>         (do ((i 0 (1+ i))
>              (buffer (make-array 1024 :element-type '(unsigned-byte 8)
>                                  :initial-element 0))
>              (now (get-universal-time))
>              (done nil))
>             ((or done (= i 4))
>              nil)
>           (format t "~Ds ~D Waiting state ~S~%" (- (get-universal-time) now) i (usocket::state s))
>           (when (usocket:wait-for-input s :ready-only t :timeout 5)
>             (format t "~D state ~S~%" i (usocket::state s))
>             (handler-bind
>                 ((error (lambda (c)
>                           (format t "socket-receive error: ~A~%" c)
>                           (break)
>                           nil)))
>               (multiple-value-bind (buffer count remote-host remote-port)
>
>                   (usocket:socket-receive s buffer 1024)
>                 (handler-bind
>                     ((error (lambda (c)
>                                (format t "socket-send error: ~A~%" c)
>                                (break))))
>                   (when buffer
>                     (usocket:socket-send s (subseq buffer 0 count) count
>                                          :host remote-host
>                                          :port remote-port)))))))
>       (usocket:socket-close s))))
>
>
>
> My output is now:
>
> 0s 0 Waiting state NIL
> 0 state :READ
> 2s 1 Waiting state :READ
> 1 state :READ
> 2s 2 Waiting state :READ
> 2 state :READ
> 2s 3 Waiting state :READ
> 3 state :READ
> NIL
>
>
> We are getting closer. The read state is still staying in :READ even after a successful socket-receive call, so the loop is still spinning. I can fix this easily by passing in the socket instance directly to the receive-message function and manually setting the %ready-p flag to nil. This gives me the correct behaviour:
>
> 0s 0 Waiting state NIL
> 0 state :READ
> 4s 1 Waiting state :READ
> 9s 2 Waiting state NIL
> 14s 3 Waiting state NIL
> NIL
>
> I've attached a diff of backend/lispworks.lisp showing what I describe above, feel free to use/ignore it.
>
>
> Frank.
>
>
>
> On 24 May 2015 at 20:57, Frank James <frank.a.james@gmail.com> wrote:
> Hi Chun,
>
> Thanks for looking into this. I've just pulled the most recent codes from github and have had a little play with them. I now get an error signalled on the socket-receive when I expect an error (rather than a simple -1 count as before). This is good.
>
> However, I am still seeing the socket-state behaviour I described before, along with a new bug that has probably been introduced by the recent changes.
>
> Consider the following simple function which listens for UDP port 8001 for up to 4 iterations:
>
> (defun usocket-test ()
>  (let ((s (usocket:socket-connect nil nil
>                          :protocol :datagram
>                                 :element-type '(unsigned-byte 8)
>                                 :local-port 8001)))
>    (unwind-protect
>        (do ((i 0 (1+ i))
>             (buffer (make-array 1024 :element-type '(unsigned-byte 8) :initial-element 0))
>             (done nil))
>            ((or done (= i 4))
>             nil)
>          (when (usocket:wait-for-input s :ready-only t :timeout 10)
>            (format t "~D state ~S~%" i (usocket::state s))
>            (handler-case
>                (multiple-value-bind (buffer count remote-host remote-port)
>                    (usocket:socket-receive s buffer 1024)
>                  (handler-case
>                      (usocket:socket-send s (subseq buffer 0 count)
>                                           :host remote-host
>                                           :port remote-port)
>                    (error (c)
>                      (format t "socket-send error: ~A~%" c))))
>              (error (c)
>                (format t "socket-receive error: ~A~%" c)))))
>      (usocket:socket-close s))))
>
>
> after calling this from your repl, from another process send a UDP packet to port 8001 to get things going. I get the following output:
>
> 0 state :READ
> socket-send error: #<STANDARD-GENERIC-FUNCTION USOCKET:SOCKET-SEND 21CADCFA> is called with unpaired keyword in (2130706433 :PORT 58279).
> 1 state :READ
> socket-receive error: MAKE-INSTANCE is called with keyword :SOCKET among the arguments (USOCKET:NS-TRY-AGAIN-CONDITION :SOCKET 2604) which is not one of (:HOST-OR-IP).
> 2 state :READ
> socket-receive error: MAKE-INSTANCE is called with keyword :SOCKET among the arguments (USOCKET:NS-TRY-AGAIN-CONDITION :SOCKET 2604) which is not one of (:HOST-OR-IP).
> 3 state :READ
> socket-receive error: MAKE-INSTANCE is called with keyword :SOCKET among the arguments (USOCKET:NS-TRY-AGAIN-CONDITION :SOCKET 2604) which is not one of (:HOST-OR-IP).
> NIL
>
> My observations:
> 1. The initial socket-receive succeeds (as expected).
> 2. The initial socket-send fails with an error I've not seen before and can't diagnose...
> 3. Subsequent calls to wait-for-input return immediately because the socket is still in a :READ state, even though I already successfully called socket-receive in the first iteration.
> 4. Subsequent calls to socket-receive now fail with a different error I can't diagnose.
>
> If I didn't have the max iteration cap, this would spin using 100% of a CPU core and adding around 2MB to the heap per second (on my machine), maxing out the 1GB personal edition heap limit in a short space of time. So I think it's a pretty serious issue. I mainly use SBCL, I use LispWorks occasionally to make sure my codes work on at least 1 other implementation, so I'm not exactly a LispWorks expert.
>
> If you want any more explanations, clarifications or examples I'll be happy to do my best to help.
>
> As before, I'm using LispWorks personal edition 6.1.1 on Windows 8.1.
>
> Frank.
>
>
>
> On 22 May 2015 at 09:24, Chun Tian (binghe) <binghe.lisp@gmail.com> wrote:
> Hi Frank,
>
> Today I have modified SOCKET-SEND and SOCKET-RECEIVE for LispWorks, to be able to detect and report socket errors.  I think in this way, these APIs on LispWorks could behavior closer to other platforms.
>
> Now on Windows, your test code should return a USOCKET:CONNECTION-RESET-ERROR condition, which equals to WSA error ECONNRESET.  However, when I test the same code on Mac OS X, it instead returns USOCKET:CONNECTION-REFUSED-ERROR, I think this is a behavior of BSD sockets.
>
> I hope you can try latest usocket code from Git [1], to see if it works better for your case now. My code changes commit can be seen here [2].
>
> For wait-for-input, I can’t see what you see (the socket object remains in a :READ state), if you still think this is an issue, I hope you can create another test code to demonstrate this issue.
>
> Regards,
>
> Chun
>
> [1] https://github.com/usocket/usocket
> [2] https://github.com/usocket/usocket/commit/13386639889fa812540fc4f77824c47e7616db37
>
> Il giorno 10/apr/2015, alle ore 23:00, Frank James <frank.a.james@gmail.com> ha scritto:
>
> > I've been testing some UDP codes on Lispworks (personal 32bit Windows version) and have encountered some undocumented behaviour, I think it's a matter of opinion whether it's a bug or not but it should probably have a sentence or two documenting it somewhere.
> >
> > Basically I'm sending a UDP packet to a host and listening for a reply, using socket-send and socket-receive. If the host in question is not listening for UDP traffic on that particular port, the Windows socket API says it should return an ECONNRESET error immediately on the socket-receive call, this is indicated by a -1 return value from the underlying recvfrom call.
> >
> > When this happens the Lispworks backend code returns a length of -1 (and buffer nil). This is perfectly acceptable behaviour I think (although it'd be somewhat nicer to signal an error, but that's a matter of taste). But it should be documented that checking the length here is the correct way to detect an error occurred.
> >
> > Example code would be something like:
> >
> > (let ((sock (usocket:socket-connect "localhost" 1234 :protocol :datagram :element-type '(unsigned-byte 8))))
> >   (unwind-protect
> >     (progn
> >       (usocket:socket-send sock (make-array 16 :element-type '(unsigned-byte 8) :initial-element 0) 16)
> >       (let ((buffer (make-array 16 :element-type '(unsigned-byte 8) :initial-element 0)))
> >         (usocket:socket-receive sock buffer 16)))
> >     (usocket:socket-close sock)))
> >
> >
> > What is somewhat more annoying is that the socket object remains in a :READ state. This means that a polling loop using wait-for-input spins continuously, with each socket-receive returning -1 (as explained above). Probably the socket state should be cleared if a socket-receive fails.
> >
> > Apologies if this is all well-known to those reading this list, but it caused me 10 minutes of head scratching earlier today and thought it was worth mentioning.
> >
> > Frank.
> >
>
>
>
> <diff.lisp>