67 lines
2.6 KiB
Racket
67 lines
2.6 KiB
Racket
#lang racket/base
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;; Trivial example program demonstrating os2-tcp.rkt.
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(require racket/string)
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(require racket/set)
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(require racket/match)
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(require "os2.rkt")
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(require "os2-tcp.rkt")
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(define (send-to-all local-addr active-remotes speaker line)
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(define formatted-line (string->bytes/utf-8
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(format "~a: ~a~n" speaker (bytes->string/utf-8 line))))
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(for/list ([remote (in-set active-remotes)])
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(send-message (tcp-channel local-addr remote formatted-line))))
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(define (format-names active-remotes)
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(if (set-empty? active-remotes)
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#"No-one else is here right now.\r\n"
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(string->bytes/utf-8
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(string-append*
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"These connections are active:\r\n"
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(for/list ([remote (in-set active-remotes)]) (format " - ~a\r\n" remote))))))
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(define (connection-handler local-addr)
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(transition (set) ;; of remote TcpAddresses
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(role (topic-publisher (tcp-channel local-addr (wild) (wild))))
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(role (topic-subscriber (tcp-channel (wild) local-addr (wild)))
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#:state active-remotes
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#:topic t
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#:on-presence (match t
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[(topic 'publisher (tcp-channel (== local-addr) _ _) #f)
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;; Ignore loopback flow.
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(transition active-remotes)]
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[(topic 'publisher (tcp-channel remote-addr (== local-addr) _) #f)
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(write `(arrived ,remote-addr)) (newline)
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(transition (set-add active-remotes remote-addr)
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(send-message (tcp-channel local-addr remote-addr
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(format-names active-remotes)))
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(send-to-all local-addr active-remotes remote-addr #"<arrived>")
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(send-tcp-mode remote-addr local-addr 'lines)
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(send-tcp-credit remote-addr local-addr 1))])
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#:on-absence (match t
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[(topic 'publisher (tcp-channel (== local-addr) _ _) #f)
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;; Ignore loopback flow.
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(transition active-remotes)]
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[(topic 'publisher (tcp-channel remote-addr (== local-addr) _) #f)
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(write `(departed ,remote-addr)) (newline)
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(transition (set-remove active-remotes remote-addr))])
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[(tcp-channel remote-addr (== local-addr) (? eof-object?))
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(define new-active-remotes (set-remove active-remotes remote-addr))
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(transition new-active-remotes
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(send-message (tcp-channel local-addr remote-addr #"Goodbye!\r\n"))
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(send-to-all local-addr new-active-remotes remote-addr #"<departed>"))]
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[(tcp-channel remote-addr (== local-addr) (? bytes? bs))
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(transition active-remotes
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(send-tcp-credit remote-addr local-addr 1)
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(send-to-all local-addr active-remotes remote-addr bs))])))
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(define (main port)
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(ground-vm
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(transition 'none
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(spawn tcp-spy)
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(spawn tcp-driver)
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(spawn (connection-handler (tcp-listener port))))))
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(main 5999)
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