1 ;; Simple Actor Machine
3 ;; Houses a population of actors which can communicate using messages
4 ;; with actors on the same machine or other machines via the network.
19 (define this-host "localhost")
20 (define this-port 8000)
22 (define (make-address host port id)
23 (make-uri #:scheme "actor"
28 (define (make-local-address . args)
29 (make-address this-host
35 (define (address-id address) (cadr (uri-path address)))
37 (define (address-local? address)
38 (and (equal? (uri-host address) this-host)
39 (equal? (uri-port address) this-port)))
41 (define actor-table (make-hash-table))
43 (define (make-actor beh)
44 (let* ((address (make-local-address))
45 (id (address-id address)))
46 (hash-table-set! actor-table id beh)
49 (define (deliver-message address . message)
50 (let ((id (address-id address)))
51 (let ((behaviour (hash-table-ref/default actor-table id '())))
53 (print "Warning: discarded message" message " to unknown actor " address)
54 (match (apply (hash-table-ref actor-table id) (cons address message))
55 ('done (hash-table-delete! actor-table id))
57 (new-beh (hash-table-set! actor-table id new-beh)))))))
61 (define local-queue-mutex (make-mutex "message queue"))
62 (define message-available-mutex (make-mutex "message available"))
63 (mutex-lock! message-available-mutex #f #f)
64 (define local-queue (make-fifo))
66 (define (send-message address . message)
67 (apply (if (address-local? address)
70 (cons address message)))
72 (define (send-local-message address . message)
73 (mutex-lock! local-queue-mutex)
74 (fifo-push local-queue (cons address message))
75 (mutex-unlock! message-available-mutex)
76 (mutex-unlock! local-queue-mutex))
78 (define (send-network-message address . message)
79 (let ((s (udp-open-socket))
80 (machine (address-machine address)))
83 (machine-host machine)
84 (machine-port machine))
86 (udp-close-socket s)))
88 (define (next-local-message)
90 (mutex-lock! message-available-mutex #f #f)
91 (mutex-lock! local-queue-mutex)
92 (set! res (fifo-pop local-queue))
93 (if (not (fifo-empty? local-queue))
94 (mutex-unlock! message-available-mutex))
95 (mutex-unlock! local-queue-mutex)
98 (define (start-scheduler)
102 (apply deliver-message (next-local-message))
107 (define reader-queue-mutex (make-mutex "reader queue"))
108 (define reader-available-mutex (make-mutex "reader available"))
109 (mutex-lock! reader-available-mutex #f #f)
110 (define reader-queue (make-fifo))
113 (make-actor (lambda (self . message)
114 (mutex-lock! reader-queue-mutex)
115 (fifo-push reader-queue (car message))
116 (mutex-unlock! reader-available-mutex)
117 (mutex-unlock! reader-queue-mutex)
120 (define (next-reader)
122 (mutex-lock! reader-available-mutex #f #f)
123 (mutex-lock! reader-queue-mutex)
124 (set! res (fifo-pop reader-queue))
125 (if (not (fifo-empty? reader-queue))
126 (mutex-unlock! reader-available-mutex))
127 (mutex-unlock! reader-queue-mutex)
130 (define (start-console)
132 (let ((reader (next-reader)))
133 (##sys#thread-block-for-i/o! (current-thread) 0 #t)
135 (send-message reader (read-line)))
141 (define (start-network-listener)
144 (let ((s (udp-open-socket*)))
145 (udp-bind! s #f this-port)
147 (let-values (((n str) (udp-recv s 1024)))
148 (print "Received " n " bytes over network: " str)
149 (match (with-input-from-string str read)
150 ((uri-str message ...)
151 (apply send-message (cons (uri-reference uri-str) message)))
153 (print "Warning: received badly formatted message string '" str "'"))))
159 (make-actor (lambda (self . message)
162 (print "## System actor received shutdown message.")
165 (('println strings ...)
166 (apply print strings)
172 (send-message system 'println "Hello, what is your name?")
173 (send-message console
174 (make-actor (lambda (self . message)
177 (send-message system 'println "Hello, " name "!")
183 (send-message system 'shutdown)))
185 (print (uri->string system))
188 (start-network-listener)
191 ;; (thread-join! scheduler-thread)