156 lines
4.9 KiB
Racket
156 lines
4.9 KiB
Racket
#lang racket
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(require math/base) ;; for random number generation
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;; globals
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;; must control access via semaphore as listener thread or broadcast thread
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;; might need to access it
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(define connections '()) ;; maintains a list of open ports
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;; ((in1, out1), (in2, out2), (in3, out3), (in4, out4) ...)
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;; lets keep thread descriptor values
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;
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(define fair (make-semaphore 1)) ;; managing connections above
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(define can-i-broadcast (make-semaphore 1))
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;;
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;; This is a relay server making two clients communicate
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;; Both `server' and `accept-and-handle' change
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;; to use a custodian.
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;; To start server
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;; (define stop (serve 8080))
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;; (stop) to close the server
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(define (serve port-no)
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(define main-cust (make-custodian))
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(parameterize ([current-custodian main-cust])
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(define listener (tcp-listen port-no 5 #t))
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(define (loop)
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(accept-and-handle listener)
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(loop))
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(thread loop))
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(lambda ()
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(displayln "\nGoodbye, shutting down all services\n")
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(custodian-shutdown-all main-cust)))
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(define (accept-and-handle listener)
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(define cust (make-custodian))
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(parameterize ([current-custodian cust])
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(define-values (in out) (tcp-accept listener))
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(semaphore-wait fair)
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;; keep track of open ports
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(append connections (list (list in out)))
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(semaphore-wait fiar)
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; thread will communicate to all clients at once in a broadcast
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; manner
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(thread (lambda ()
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(handle in out) ;; this handles connection with that specific client
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(close-input-port in)
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(close-output-port out)))
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)
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;; Watcher thread:
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;; kills current thread for waiting too long for connection from
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;; clients
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(thread (lambda ()
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(sleep 120)
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(custodian-shutdown-all cust))))
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; (define (handle connections)
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; ())
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;; each thread needs 2 new threads
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(define (handle in out)
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; define function to deal with in
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(define (something-to-say in)
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(sync/timeout 4 (read-line-evt in 'linefeed)))
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; define function to deal with out
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; thread them each
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; (server-loop in out)
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(sleep 5) ;; wait 5 seconds to guarantee client has already send message
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(define echo (read-line in)) ;; bind message to echo
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(displayln (string-append echo "\n"))
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; echo back the message, appending echo
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; could regex match the input to extract the name
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(writeln "Admin: Hello there" out) ;; append "echo " to echo and send back
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(flush-output out)
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)
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;; This is a single server communicating directly to the client
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; author: Ibrahim Mkusa
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;; about: print and read concurrently
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;; notes: output may need to be aligned and formatted nicely
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;; look into
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;; 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
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;; create custodian for managing all resources
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;; so we can shutdown everything at once
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;(define guard (make-custodian (current-custodian)))
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;(current-custodian guard)
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;; reads values continously from stdin and redisplays them
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(define (read-loop)
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(display (read-line))
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(display "\n")
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(read-loop)
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)
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(define input-prompt "input: ")
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(define output-prompt "output: ")
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;; prompt for username and bind to a variable username
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(display "What's your name?\n")
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(define username (read-line))
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(define usernamei (string-append username ": ")) ;; make username appear nicer in a prompt
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;; intelligent read, quits when user types in "quit"
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(define (read-loop-i)
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;(semaphore-wait fair)
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(display usernamei)
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(define input (read-line))
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;; do something over here with input maybe send it out
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;; Tests input if its a quit then kills all threads
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;; An if would be better here tbh
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(cond ((string=? input "quit") (begin (kill-thread a)
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(kill-thread t))))
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(display (string-append output-prompt input "\n"))
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;(semaphore-post fair)
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(read-loop-i)
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)
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;; print hello world continously
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;; "(hello-world)" can be executed as part of background thread
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;; that prints in the event there is something in the input port
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(define (hello-world)
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(sleep (random-integer 0 15)) ;; sleep between 0 and 15 seconds to simulate coms
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;; with server
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;(semaphore-wait fair)
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;; we will retrieve the line printed below from the server
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;; at this time we simulate the input from different users
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(define what-to-print (random-integer 0 2))
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(if (= what-to-print 0)
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(display "Doug: What's up, up?\n")
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(display "Fred: Looking good, good!\n"))
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;(semaphore-post fair)
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(hello-world))
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(define t (thread (lambda ()
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(read-loop-i))))
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(define a (thread (lambda ()
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(hello-world))))
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(thread-wait t) ;; returns prompt back to drracket
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;; below doesn't execute
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; (sleep 10)
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; (kill-thread t)
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; (define a (thread (display "hello world!\n")))
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; (display "John: hello soso\n")
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; (display "Emmanuel: cumbaya!!!!\n")
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