1 (import srfi-69 matchable)
3 (define trace-enabled #f)
9 (define actor-table (make-hash-table))
11 (define (make-actor-with-address address behaviour)
13 (print "Making actor with address " address))
14 (hash-table-set! actor-table address behaviour)
17 (define next-actor-address 1)
19 (define (make-actor behaviour)
20 (make-actor-with-address next-actor-address behaviour)
21 (let ((address next-actor-address))
22 (set! next-actor-address (+ next-actor-address 1))
29 (define (dispatch-message address message)
31 (print "Dispatching message " message " to " address))
32 (let ((behaviour (hash-table-ref/default actor-table address '())))
34 (print "Warning: discarded message " message " to unknown actor " address)
35 (let ((value (apply behaviour (cons address message))))
40 (print "Deleting actor " address))
41 (hash-table-delete! actor-table address))
44 (print "Updating behaviour of " address))
45 (hash-table-set! actor-table address value)))))))
48 ;;; FIFO queue implementation
52 (define (cell val prev next)
55 (define cell-prev cadr)
56 (define cell-next caddr)
57 (define (set-cell-prev! cell prev-cell)
58 (set-car! (cdr cell) prev-cell))
59 (define (set-cell-next! cell next-cell)
60 (set-car! (cddr cell) next-cell))
66 ((empty?) (null? head))
67 ((push) (if (not (= (length args) 1))
68 (error "Wrong number of arguments to push.")
69 (if (not (null? head))
70 (let ((old-head head))
71 (set! head (cell (car args) '() old-head))
72 (set-cell-prev! old-head head))
75 (set! head (cell (car args) '() '()))
77 ((pop) (if (not (= (length args) 0))
78 (error "Wrong number of arguments to pop.")
81 (let ((old-tail tail))
82 (set! tail (cell-prev old-tail))
85 (set-cell-next! tail '()))
86 (cell-val old-tail)))))))))
88 (define (fifo-push fifo x)
91 (define (fifo-pop fifo)
94 (define (fifo-empty? fifo)
102 (define message-queue (make-fifo))
104 (define (next-addressed-msg)
105 (if (fifo-empty? message-queue)
107 (fifo-pop message-queue)))
109 (define (send-message actor . message)
111 (print "Queued message " message " to " actor))
112 (fifo-push message-queue (cons actor message)))
114 (define (process-next-message)
115 (let ((addressed-msg (next-addressed-msg)))
116 (if (null? addressed-msg)
118 (let ((address (car addressed-msg))
119 (message (cdr addressed-msg)))
120 (dispatch-message address message)))))
123 (unless (null? (process-next-message))
126 (define (send-and-run actor . message)
127 (apply send-message (cons actor message))