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|
#lang racket
(require math/base) ;; for random number generation
;; globals
;; must control access via semaphore as listener thread or broadcast thread
;; might need to access it
(define connections '())
;; This is a single server communicating directly to the client
;;;;;;;;;;;;;;;;;;;;;;Server Client communication;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (serve in-port out-port)
(let loop []
(define evt (sync/timeout 2
(read-line-evt in-port 'any)
(thread-receive-evt)))
(cond
[(not evt)
(displayln "Timed out, exiting")
(tcp-abandon-port in-port)
(tcp-abandon-port out-port)]
[(string? evt)
(fprintf out-port "~a~n" evt) ;; echoes back received string
(flush-output out-port) ;; flushes the buffer
(loop)] ;; iterates again
[else
(printf "Received a message in mailbox: ~a~n"
(thread-receive))
(loop)])))
(define port-num 4322)
(define (start-server)
(define listener (tcp-listen port-num))
(thread
(lambda ()
(let loop () ;; the server now loops continously listening in for connections
(define-values [in-port out-port] (tcp-accept listener))
;; lets add this open ports to global list of connections
(semaphore-wait fair)
(append connections (list (list in-port out-port)))
(semaphore-post fair)
(serve in-port out-port) ; could be do the greeting in here
(loop)))))
(start-server)
(define client-thread
(thread
(lambda ()
(define-values [in-port out-port] (tcp-connect "localhost" port-num))
(display "first\nsecond\nthird\n" out-port)
(flush-output out-port)
; copy-port will block until EOF is read from in-port
(copy-port in-port (current-output-port)))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; author: Ibrahim Mkusa
;; about: print and read concurrently
;; notes: output may need to be aligned and formatted nicely
;; look into
;; https://docs.racket-lang.org/gui/text-field_.html#%28meth._%28%28%28lib._mred%2Fmain..rkt%29._text-field~25%29._get-editor%29%29
;; create custodian for managing all resources
;; so we can shutdown everything at once
;(define guard (make-custodian (current-custodian)))
;(current-custodian guard)
;; reads values continously from stdin and redisplays them
(define (read-loop)
(display (read-line))
(display "\n")
(read-loop)
)
(define input-prompt "input: ")
(define output-prompt "output: ")
;; prompt for username and bind to a variable username
(display "What's your name?\n")
(define username (read-line))
(define usernamei (string-append username ": ")) ;; make username appear nicer in a prompt
(define fair (make-semaphore 1))
;; intelligent read, quits when user types in "quit"
(define (read-loop-i)
;(semaphore-wait fair)
(display usernamei)
(define input (read-line))
;; do something over here with input maybe send it out
;; Tests input if its a quit then kills all threads
;; An if would be better here tbh
(cond ((string=? input "quit") (begin (kill-thread a)
(kill-thread t))))
(display (string-append output-prompt input "\n"))
;(semaphore-post fair)
(read-loop-i)
)
;; print hello world continously
;; "(hello-world)" can be executed as part of background thread
;; that prints in the event there is something in the input port
(define (hello-world)
(sleep (random-integer 0 15)) ;; sleep between 0 and 15 seconds to simulate coms
;; with server
;(semaphore-wait fair)
;; we will retrieve the line printed below from the server
;; at this time we simulate the input from different users
(define what-to-print (random-integer 0 2))
(if (= what-to-print 0)
(display "Doug: What's up, up?\n")
(display "Fred: Looking good, good!\n"))
;(semaphore-post fair)
(hello-world))
(define t (thread (lambda ()
(read-loop-i))))
(define a (thread (lambda ()
(hello-world))))
(thread-wait t) ;; returns prompt back to drracket
;; below doesn't execute
; (sleep 10)
; (kill-thread t)
; (define a (thread (display "hello world!\n")))
; (display "John: hello soso\n")
; (display "Emmanuel: cumbaya!!!!\n")
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