[racket-dev] Implementation question

From: nicolas carraggi (nicocarraggi at hotmail.com)
Date: Sun Apr 20 10:41:18 EDT 2014

Hey guys,
Thanks a lot for your quick answers!
My ping method now:
(define (ping hostname port-no personalip)  (define t (thread             (lambda ()               (with-handlers ((exn:fail:network? (lambda (x) (begin (displayln (string-append hostname ":" (number->string port-no) " NOOOOOOOOOO")) #f))));(displayln (exn-message x)))))                 (define-values (in out) (tcp-connect hostname port-no))                 (write "'ping" out)                 (write personalip out)                 (flush-output out)                 (display (string-append hostname ":" (number->string port-no) " "))                 (displayln (read in))                 (close-input-port in)                 (close-output-port out)                 #t))))  (sync/timeout 0.01 t)  (kill-thread t))
This is the result when I do a multicast from to ( a lot of these don't exist and that's why tcp-connect was taking ages to throw an error.) Those returning a NOOOOO are existing network nodes where no server is running. Pong is the answer from the server running on my laptop.
> (multicast-ping "" 8080 0 200) NOOOOOOOOOO192.168.1.105:8080 NOOOOOOOOOO192.168.1.108:8080 pong-------------------Multicast finished!

It's still test-code but it's working fine now, maybe the timout time is too small but now it works well!
Subject: Re: [racket-dev] Implementation question
From: matthias at ccs.neu.edu
Date: Sat, 19 Apr 2014 09:25:27 -0400
CC: nicocarraggi at hotmail.com; dev at racket-lang.org
To: laurent.orseau at gmail.com

Let me recommend events instead: 
#lang racket
;; Nat -> Void ;; wait for t seconds before connecting to google.com, then stop(define (do-work t)  (thread   (lambda ()     (with-handlers ((exn:fail:network? (lambda (x) (displayln (exn-message x)))))       (sleep t)       (define-values (in out) (tcp-connect "google.com" 80))        'done))))
;; returns #f if 3 seconds pass w/o the thread shutting down (sync/timeout 3 (do-work (random 6)))

On Apr 19, 2014, at 8:34 AM, Laurent wrote:One simpler possibility is to use `tcp-connect/enable-break` and run a timer in parallel to break it after a shorter delay.
For example:

(define-values (in out) (values #f #f))

(define connect-thread
   (λ()(set!-values (in out) 
                    (tcp-connect "www.google.com" 80)))))

(sleep 3)
(unless in
  (displayln "Connection not established. Breaking thread.")

  (break-thread connect-thread))

The timer can also be place into its own thread if you need to set up several connections in parallel.

Hope this helps,Laurent

On Thu, Apr 17, 2014 at 6:48 PM, nicolas carraggi <nicocarraggi at hotmail.com> wrote:

I am actually using "Racket/tcp" for a project in Racket.I'm creating a peer-to-peer network but now I encountered a small problem.For a multicast I want to connect with each server on the same network. 

For this I use "tcp-connect", but when i try to connect to an ip address which is not hosting a server, throwing the error only happens after more than 1 minute. So I would like to use a modified "tcp-connect" with a smaller time-out.

Where can I find the implementation of "tcp-connect"?
I already found "tcp.rkt" but there it gets the "tcp-connect" method from "'#%network" but I can't find this one...



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