[bpt/guile.git] / ice-9 / occam-channel.scm

;;;; Occam-like channels

;;; Copyright (C) 2003, 2006 Free Software Foundation, Inc.
;;;
;; This library is free software; you can redistribute it and/or
;; modify it under the terms of the GNU Lesser General Public
;; License as published by the Free Software Foundation; either
;; version 2.1 of the License, or (at your option) any later version.
;; 
;; This library is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;; Lesser General Public License for more details.
;; 
;; You should have received a copy of the GNU Lesser General Public
;; License along with this library; if not, write to the Free Software
;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

(define-module (ice-9 occam-channel)
  #:use-syntax (ice-9 syncase)
  #:use-module (oop goops)
  #:use-module (ice-9 threads)
  #:export-syntax (alt
		   ;; macro use:
		   oc:lock oc:unlock oc:consequence
		   oc:immediate-dispatch oc:late-dispatch oc:first-channel
		   oc:set-handshake-channel oc:unset-handshake-channel)
  #:export (make-channel
	    ?
	    !
	    make-timer
	    ;; macro use:
	    handshake-channel mutex
	    sender-waiting?
	    immediate-receive late-receive
	    )
  )

(define no-data '(no-data))
(define receiver-waiting '(receiver-waiting))

(define-class <channel> ())

(define-class <data-channel> (<channel>)
  (handshake-channel #:accessor handshake-channel)
  (data #:accessor data #:init-value no-data)
  (cv #:accessor cv #:init-form (make-condition-variable))
  (mutex #:accessor mutex #:init-form (make-mutex)))

(define-method (initialize (ch <data-channel>) initargs)
  (next-method)
  (set! (handshake-channel ch) ch))

(define-method (make-channel)
  (make <data-channel>))

(define-method (sender-waiting? (ch <data-channel>))
  (not (eq? (data ch) no-data)))

(define-method (receiver-waiting? (ch <data-channel>))
  (eq? (data ch) receiver-waiting))

(define-method (immediate-receive (ch <data-channel>))
  (signal-condition-variable (cv ch))
  (let ((res (data ch)))
    (set! (data ch) no-data)
    res))

(define-method (late-receive (ch <data-channel>))
  (let ((res (data ch)))
    (set! (data ch) no-data)
    res))

(define-method (? (ch <data-channel>))
  (lock-mutex (mutex ch))
  (let ((res (cond ((receiver-waiting? ch)
		    (unlock-mutex (mutex ch))
		    (scm-error 'misc-error '?
			       "another process is already receiving on ~A"
			       (list ch) #f))
		   ((sender-waiting? ch)
		    (immediate-receive ch))
		   (else
		    (set! (data ch) receiver-waiting)
		    (wait-condition-variable (cv ch) (mutex ch))
		    (late-receive ch)))))
    (unlock-mutex (mutex ch))
    res))

(define-method (! (ch <data-channel>))
  (! ch *unspecified*))

(define-method (! (ch <data-channel>) (x <top>))
  (lock-mutex (mutex (handshake-channel ch)))
  (cond ((receiver-waiting? ch)
	 (set! (data ch) x)
	 (signal-condition-variable (cv (handshake-channel ch))))
	((sender-waiting? ch)
	 (unlock-mutex (mutex (handshake-channel ch)))
	 (scm-error 'misc-error '! "another process is already sending on ~A"
		    (list ch) #f))
	(else
	 (set! (data ch) x)
	 (wait-condition-variable (cv ch) (mutex ch))))
  (unlock-mutex (mutex (handshake-channel ch))))

;;; Add protocols?

(define-class <port-channel> (<channel>)
  (port #:accessor port #:init-keyword #:port))

(define-method (make-channel (port <port>))
  (make <port-channel> #:port port))

(define-method (? (ch <port-channel>))
  (read (port ch)))

(define-method (! (ch <port-channel>))
  (write (port ch)))

(define-class <timer-channel> (<channel>))

(define the-timer (make <timer-channel>))

(define timer-cv (make-condition-variable))
(define timer-mutex (make-mutex))

(define (make-timer)
  the-timer)

(define (timeofday->us t)
  (+ (* 1000000 (car t)) (cdr t)))

(define (us->timeofday n)
  (cons (quotient n 1000000)
	(remainder n 1000000)))

(define-method (? (ch <timer-channel>))
  (timeofday->us (gettimeofday)))

(define-method (? (ch <timer-channel>) (t <integer>))
  (lock-mutex timer-mutex)
  (wait-condition-variable timer-cv timer-mutex (us->timeofday t))
  (unlock-mutex timer-mutex))

;;; (alt CLAUSE ...)
;;;
;;; CLAUSE ::= ((? CH) FORM ...)
;;;            | (EXP (? CH) FORM ...)
;;;            | (EXP FORM ...)
;;;
;;; where FORM ... can be => (lambda (x) ...)
;;;
;;; *fixme* Currently only handles <data-channel>:s
;;;

(define-syntax oc:lock
  (syntax-rules (?)
    ((_ ((? ch) form ...)) (lock-mutex (mutex ch)))
    ((_ (exp (? ch) form ...)) (lock-mutex (mutex ch)))
    ((_ (exp form ...)) #f)))

(define-syntax oc:unlock
  (syntax-rules (?)
    ((_ ((? ch) form ...)) (unlock-mutex (mutex ch)))
    ((_ (exp (? ch) form ...)) (unlock-mutex (mutex ch)))
    ((_ (exp form ...)) #f)))

(define-syntax oc:consequence
  (syntax-rules (=>)
    ((_ data) data)
    ((_ data => (lambda (x) e1 e2 ...))
     (let ((x data)) e1 e2 ...))
    ((_ data e1 e2 ...)
     (begin data e1 e2 ...))))

(define-syntax oc:immediate-dispatch
  (syntax-rules (?)
    ((_ ((? ch) e1 ...))
     ((sender-waiting? ch)
      (oc:consequence (immediate-receive ch) e1 ...)))
    ((_ (exp (? ch) e1 ...))
     ((and exp (sender-waiting? ch))
      (oc:consequence (immediate-receive ch) e1 ...)))
    ((_ (exp e1 ...))
     (exp e1 ...))))

(define-syntax oc:late-dispatch
  (syntax-rules (?)
    ((_ ((? ch) e1 ...))
     ((sender-waiting? ch)
      (oc:consequence (late-receive ch) e1 ...)))
    ((_ (exp (? ch) e1 ...))
     ((and exp (sender-waiting? ch))
      (oc:consequence (late-receive ch) e1 ...)))
    ((_ (exp e1 ...))
     (#f))))

(define-syntax oc:first-channel
  (syntax-rules (?)
    ((_ ((? ch) e1 ...) c2 ...)
     ch)
    ((_ (exp (? ch) e1 ...) c2 ...)
     ch)
    ((_ c1 c2 ...)
     (first-channel c2 ...))))

(define-syntax oc:set-handshake-channel
  (syntax-rules (?)
    ((_ ((? ch) e1 ...) handshake)
     (set! (handshake-channel ch) handshake))
    ((_ (exp (? ch) e1 ...) handshake)
     (and exp (set! (handshake-channel ch) handshake)))
    ((_ (exp e1 ...) handshake)
     #f)))

(define-syntax oc:unset-handshake-channel
  (syntax-rules (?)
    ((_ ((? ch) e1 ...))
     (set! (handshake-channel ch) ch))
    ((_ (exp (? ch) e1 ...))
     (and exp (set! (handshake-channel ch) ch)))
    ((_ (exp e1 ...))
     #f)))

(define-syntax alt
  (lambda (x)
    (define (else-clause? x)
      (syntax-case x (else)
	((_) #f)
	((_ (else e1 e2 ...)) #t)
	((_ c1 c2 ...) (else-clause? (syntax (_ c2 ...))))))
    
    (syntax-case x (else)
      ((_ c1 c2 ...)
       (else-clause? x)
       (syntax (begin
		 (oc:lock c1)
		 (oc:lock c2) ...
		 (let ((res (cond (oc:immediate-dispatch c1)
				  (oc:immediate-dispatch c2) ...)))
		   (oc:unlock c1)
		   (oc:unlock c2) ...
		   res))))
      ((_ c1 c2 ...)
       (syntax (begin
		 (oc:lock c1)
		 (oc:lock c2) ...
		 (let ((res (cond (oc:immediate-dispatch c1)
				  (oc:immediate-dispatch c2) ...
				  (else (let ((ch (oc:first-channel c1 c2 ...)))
					  (oc:set-handshake-channel c1 ch)
					  (oc:set-handshake-channel c2 ch) ...
					  (wait-condition-variable (cv ch)
								   (mutex ch))
					  (oc:unset-handshake-channel c1)
					  (oc:unset-handshake-channel c2) ...
					  (cond (oc:late-dispatch c1)
						(oc:late-dispatch c2) ...))))))
		   (oc:unlock c1)
		   (oc:unlock c2) ...
		   res)))))))
Commit	Line	Data
60eefd9c MD	1	;;;; Occam-like channels
60eefd9c MD	2
cd5fea8d	3	;;; Copyright (C) 2003, 2006 Free Software Foundation, Inc.
60eefd9c	4	;;;
73be1d9e MV	5	;; This library is free software; you can redistribute it and/or
	6	;; modify it under the terms of the GNU Lesser General Public
	7	;; License as published by the Free Software Foundation; either
	8	;; version 2.1 of the License, or (at your option) any later version.
	9	;;
	10	;; This library is distributed in the hope that it will be useful,
	11	;; but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	13	;; Lesser General Public License for more details.
	14	;;
	15	;; You should have received a copy of the GNU Lesser General Public
	16	;; License along with this library; if not, write to the Free Software
92205699	17	;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
60eefd9c MD	18
60eefd9c MD	19	(define-module (ice-9 occam-channel)
51407fa0	20	#:use-syntax (ice-9 syncase)
60eefd9c MD	21	#:use-module (oop goops)
60eefd9c MD	22	#:use-module (ice-9 threads)
51407fa0 MD	23	#:export-syntax (alt
	24	;; macro use:
	25	oc:lock oc:unlock oc:consequence
	26	oc:immediate-dispatch oc:late-dispatch oc:first-channel
	27	oc:set-handshake-channel oc:unset-handshake-channel)
fb831451 MD	28	#:export (make-channel
	29	?
	30	!
	31	make-timer
51407fa0 MD	32	;; macro use:
	33	handshake-channel mutex
	34	sender-waiting?
	35	immediate-receive late-receive
fb831451 MD	36	)
fb831451 MD	37	)
60eefd9c MD	38
	39	(define no-data '(no-data))
	40	(define receiver-waiting '(receiver-waiting))
	41
fb831451 MD	42	(define-class <channel> ())
	43
	44	(define-class <data-channel> (<channel>)
51407fa0	45	(handshake-channel #:accessor handshake-channel)
60eefd9c MD	46	(data #:accessor data #:init-value no-data)
	47	(cv #:accessor cv #:init-form (make-condition-variable))
	48	(mutex #:accessor mutex #:init-form (make-mutex)))
	49
51407fa0 MD	50	(define-method (initialize (ch <data-channel>) initargs)
	51	(next-method)
	52	(set! (handshake-channel ch) ch))
	53
8411a446	54	(define-method (make-channel)
fb831451	55	(make <data-channel>))
60eefd9c	56
51407fa0 MD	57	(define-method (sender-waiting? (ch <data-channel>))
	58	(not (eq? (data ch) no-data)))
	59
	60	(define-method (receiver-waiting? (ch <data-channel>))
	61	(eq? (data ch) receiver-waiting))
	62
	63	(define-method (immediate-receive (ch <data-channel>))
	64	(signal-condition-variable (cv ch))
60eefd9c MD	65	(let ((res (data ch)))
60eefd9c MD	66	(set! (data ch) no-data)
51407fa0 MD	67	res))
	68
	69	(define-method (late-receive (ch <data-channel>))
	70	(let ((res (data ch)))
	71	(set! (data ch) no-data)
	72	res))
	73
	74	(define-method (? (ch <data-channel>))
	75	(lock-mutex (mutex ch))
	76	(let ((res (cond ((receiver-waiting? ch)
	77	(unlock-mutex (mutex ch))
	78	(scm-error 'misc-error '?
	79	"another process is already receiving on ~A"
	80	(list ch) #f))
	81	((sender-waiting? ch)
	82	(immediate-receive ch))
	83	(else
	84	(set! (data ch) receiver-waiting)
	85	(wait-condition-variable (cv ch) (mutex ch))
	86	(late-receive ch)))))
60eefd9c MD	87	(unlock-mutex (mutex ch))
	88	res))
	89
fb831451 MD	90	(define-method (! (ch <data-channel>))
	91	(! ch unspecified))
	92
	93	(define-method (! (ch <data-channel>) (x <top>))
51407fa0 MD	94	(lock-mutex (mutex (handshake-channel ch)))
51407fa0 MD	95	(cond ((receiver-waiting? ch)
60eefd9c	96	(set! (data ch) x)
51407fa0 MD	97	(signal-condition-variable (cv (handshake-channel ch))))
	98	((sender-waiting? ch)
	99	(unlock-mutex (mutex (handshake-channel ch)))
60eefd9c	100	(scm-error 'misc-error '! "another process is already sending on ~A"
51407fa0 MD	101	(list ch) #f))
	102	(else
	103	(set! (data ch) x)
	104	(wait-condition-variable (cv ch) (mutex ch))))
	105	(unlock-mutex (mutex (handshake-channel ch))))
fb831451 MD	106
	107	;;; Add protocols?
	108
	109	(define-class <port-channel> (<channel>)
	110	(port #:accessor port #:init-keyword #:port))
	111
	112	(define-method (make-channel (port <port>))
	113	(make <port-channel> #:port port))
	114
	115	(define-method (? (ch <port-channel>))
	116	(read (port ch)))
	117
	118	(define-method (! (ch <port-channel>))
	119	(write (port ch)))
	120
	121	(define-class <timer-channel> (<channel>))
	122
	123	(define the-timer (make <timer-channel>))
	124
	125	(define timer-cv (make-condition-variable))
	126	(define timer-mutex (make-mutex))
	127
	128	(define (make-timer)
	129	the-timer)
	130
	131	(define (timeofday->us t)
	132	(+ (* 1000000 (car t)) (cdr t)))
	133
	134	(define (us->timeofday n)
	135	(cons (quotient n 1000000)
	136	(remainder n 1000000)))
	137
	138	(define-method (? (ch <timer-channel>))
	139	(timeofday->us (gettimeofday)))
	140
	141	(define-method (? (ch <timer-channel>) (t <integer>))
	142	(lock-mutex timer-mutex)
	143	(wait-condition-variable timer-cv timer-mutex (us->timeofday t))
	144	(unlock-mutex timer-mutex))
	145
51407fa0 MD	146	;;; (alt CLAUSE ...)
	147	;;;
	148	;;; CLAUSE ::= ((? CH) FORM ...)
	149	;;; \| (EXP (? CH) FORM ...)
	150	;;; \| (EXP FORM ...)
	151	;;;
	152	;;; where FORM ... can be => (lambda (x) ...)
	153	;;;
	154	;;; fixme Currently only handles <data-channel>:s
	155	;;;
	156
	157	(define-syntax oc:lock
	158	(syntax-rules (?)
	159	((_ ((? ch) form ...)) (lock-mutex (mutex ch)))
	160	((_ (exp (? ch) form ...)) (lock-mutex (mutex ch)))
	161	((_ (exp form ...)) #f)))
	162
	163	(define-syntax oc:unlock
	164	(syntax-rules (?)
	165	((_ ((? ch) form ...)) (unlock-mutex (mutex ch)))
	166	((_ (exp (? ch) form ...)) (unlock-mutex (mutex ch)))
	167	((_ (exp form ...)) #f)))
	168
	169	(define-syntax oc:consequence
	170	(syntax-rules (=>)
	171	((_ data) data)
	172	((_ data => (lambda (x) e1 e2 ...))
	173	(let ((x data)) e1 e2 ...))
	174	((_ data e1 e2 ...)
	175	(begin data e1 e2 ...))))
	176
	177	(define-syntax oc:immediate-dispatch
	178	(syntax-rules (?)
	179	((_ ((? ch) e1 ...))
	180	((sender-waiting? ch)
	181	(oc:consequence (immediate-receive ch) e1 ...)))
	182	((_ (exp (? ch) e1 ...))
	183	((and exp (sender-waiting? ch))
	184	(oc:consequence (immediate-receive ch) e1 ...)))
	185	((_ (exp e1 ...))
	186	(exp e1 ...))))
	187
	188	(define-syntax oc:late-dispatch
	189	(syntax-rules (?)
	190	((_ ((? ch) e1 ...))
	191	((sender-waiting? ch)
	192	(oc:consequence (late-receive ch) e1 ...)))
	193	((_ (exp (? ch) e1 ...))
	194	((and exp (sender-waiting? ch))
	195	(oc:consequence (late-receive ch) e1 ...)))
	196	((_ (exp e1 ...))
	197	(#f))))
	198
	199	(define-syntax oc:first-channel
	200	(syntax-rules (?)
	201	((_ ((? ch) e1 ...) c2 ...)
	202	ch)
	203	((_ (exp (? ch) e1 ...) c2 ...)
	204	ch)
	205	((_ c1 c2 ...)
	206	(first-channel c2 ...))))
	207
	208	(define-syntax oc:set-handshake-channel
	209	(syntax-rules (?)
210	((_ ((? ch) e1 ...) handshake)
211	(set! (handshake-channel ch) handshake))
212	((_ (exp (? ch) e1 ...) handshake)
213	(and exp (set! (handshake-channel ch) handshake)))
214	((_ (exp e1 ...) handshake)
215	#f)))
216
217	(define-syntax oc:unset-handshake-channel
218	(syntax-rules (?)
219	((_ ((? ch) e1 ...))
220	(set! (handshake-channel ch) ch))
221	((_ (exp (? ch) e1 ...))
222	(and exp (set! (handshake-channel ch) ch)))
223	((_ (exp e1 ...))
224	#f)))
225
226	(define-syntax alt
227	(lambda (x)
228	(define (else-clause? x)
229	(syntax-case x (else)
230	((_) #f)
231	((_ (else e1 e2 ...)) #t)
232	((_ c1 c2 ...) (else-clause? (syntax (_ c2 ...))))))
233
234	(syntax-case x (else)
235	((_ c1 c2 ...)
236	(else-clause? x)
237	(syntax (begin
238	(oc:lock c1)
239	(oc:lock c2) ...
240	(let ((res (cond (oc:immediate-dispatch c1)
241	(oc:immediate-dispatch c2) ...)))
242	(oc:unlock c1)
243	(oc:unlock c2) ...
244	res))))
245	((_ c1 c2 ...)
246	(syntax (begin
247	(oc:lock c1)
248	(oc:lock c2) ...
249	(let ((res (cond (oc:immediate-dispatch c1)
250	(oc:immediate-dispatch c2) ...
251	(else (let ((ch (oc:first-channel c1 c2 ...)))
252	(oc:set-handshake-channel c1 ch)
253	(oc:set-handshake-channel c2 ch) ...
254	(wait-condition-variable (cv ch)
255	(mutex ch))
256	(oc:unset-handshake-channel c1)
257	(oc:unset-handshake-channel c2) ...
258	(cond (oc:late-dispatch c1)
259	(oc:late-dispatch c2) ...))))))
260	(oc:unlock c1)
261	(oc:unlock c2) ...
262	res)))))))