3 make-actor-with-address
14 (define trace-enabled #f) ;used for debugging
21 (define actor-table (make-hash-table))
23 (define (make-actor-with-address address behaviour)
25 (print "Making actor with address " address))
26 (hash-table-set! actor-table address behaviour)
29 (define next-actor-address 1)
31 (define (make-actor behaviour)
32 (make-actor-with-address next-actor-address behaviour)
33 (let ((address next-actor-address))
34 (set! next-actor-address (+ next-actor-address 1))
42 (define (dispatch-message address message)
44 (print "Dispatching message " message " to " address))
45 (let ((behaviour (hash-table-ref/default actor-table address '())))
47 (print "Warning: discarded message " message " to unknown actor " address)
48 (let ((value (apply behaviour (cons address message))))
53 (print "Deleting actor " address))
54 (hash-table-delete! actor-table address))
57 (print "Updating behaviour of " address))
58 (hash-table-set! actor-table address value)))))))
62 ;;; FIFO queue implementation
66 (define (cell val prev next)
69 (define cell-prev cadr)
70 (define cell-next caddr)
71 (define (set-cell-prev! cell prev-cell)
72 (set-car! (cdr cell) prev-cell))
73 (define (set-cell-next! cell next-cell)
74 (set-car! (cddr cell) next-cell))
80 ((empty?) (null? head))
81 ((push) (if (not (= (length args) 1))
82 (error "Wrong number of arguments to push.")
83 (if (not (null? head))
84 (let ((old-head head))
85 (set! head (cell (car args) '() old-head))
86 (set-cell-prev! old-head head))
89 (set! head (cell (car args) '() '()))
91 ((pop) (if (not (= (length args) 0))
92 (error "Wrong number of arguments to pop.")
95 (let ((old-tail tail))
96 (set! tail (cell-prev old-tail))
99 (set-cell-next! tail '()))
100 (cell-val old-tail)))))))))
102 (define (fifo-push fifo x)
105 (define (fifo-pop fifo)
108 (define (fifo-empty? fifo)
116 (define message-queue (make-fifo))
118 (define (next-addressed-msg)
119 (if (fifo-empty? message-queue)
121 (fifo-pop message-queue)))
123 (define (send-message actor . message)
125 (print "Queued message " message " to " actor))
126 (fifo-push message-queue (cons actor message)))
128 (define (process-next-message)
129 (let ((addressed-msg (next-addressed-msg)))
130 (if (null? addressed-msg)
132 (let ((address (car addressed-msg))
133 (message (cdr addressed-msg)))
134 (dispatch-message address message)))))
137 (unless (null? (process-next-message))
140 (define (send-and-run actor . message)
141 (apply send-message (cons actor message))