[bpt/guile.git] / module / 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 3 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-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	;;;
53befeb7 NJ	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 3 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
	17	;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
60eefd9c MD	18
	19	(define-module (ice-9 occam-channel)
	20	#:use-module (oop goops)
	21	#:use-module (ice-9 threads)
51407fa0 MD	22	#:export-syntax (alt
	23	;; macro use:
	24	oc:lock oc:unlock oc:consequence
	25	oc:immediate-dispatch oc:late-dispatch oc:first-channel
	26	oc:set-handshake-channel oc:unset-handshake-channel)
fb831451 MD	27	#:export (make-channel
	28	?
	29	!
	30	make-timer
51407fa0 MD	31	;; macro use:
	32	handshake-channel mutex
	33	sender-waiting?
	34	immediate-receive late-receive
fb831451 MD	35	)
fb831451 MD	36	)
60eefd9c MD	37
	38	(define no-data '(no-data))
	39	(define receiver-waiting '(receiver-waiting))
	40
fb831451 MD	41	(define-class <channel> ())
	42
	43	(define-class <data-channel> (<channel>)
51407fa0	44	(handshake-channel #:accessor handshake-channel)
60eefd9c MD	45	(data #:accessor data #:init-value no-data)
	46	(cv #:accessor cv #:init-form (make-condition-variable))
	47	(mutex #:accessor mutex #:init-form (make-mutex)))
	48
51407fa0 MD	49	(define-method (initialize (ch <data-channel>) initargs)
	50	(next-method)
	51	(set! (handshake-channel ch) ch))
	52
8411a446	53	(define-method (make-channel)
fb831451	54	(make <data-channel>))
60eefd9c	55
51407fa0 MD	56	(define-method (sender-waiting? (ch <data-channel>))
	57	(not (eq? (data ch) no-data)))
	58
	59	(define-method (receiver-waiting? (ch <data-channel>))
	60	(eq? (data ch) receiver-waiting))
	61
	62	(define-method (immediate-receive (ch <data-channel>))
	63	(signal-condition-variable (cv ch))
60eefd9c MD	64	(let ((res (data ch)))
60eefd9c MD	65	(set! (data ch) no-data)
51407fa0 MD	66	res))
	67
	68	(define-method (late-receive (ch <data-channel>))
	69	(let ((res (data ch)))
	70	(set! (data ch) no-data)
	71	res))
	72
	73	(define-method (? (ch <data-channel>))
	74	(lock-mutex (mutex ch))
	75	(let ((res (cond ((receiver-waiting? ch)
	76	(unlock-mutex (mutex ch))
	77	(scm-error 'misc-error '?
	78	"another process is already receiving on ~A"
	79	(list ch) #f))
	80	((sender-waiting? ch)
	81	(immediate-receive ch))
	82	(else
	83	(set! (data ch) receiver-waiting)
	84	(wait-condition-variable (cv ch) (mutex ch))
	85	(late-receive ch)))))
60eefd9c MD	86	(unlock-mutex (mutex ch))
	87	res))
	88
fb831451 MD	89	(define-method (! (ch <data-channel>))
	90	(! ch unspecified))
	91
	92	(define-method (! (ch <data-channel>) (x <top>))
51407fa0 MD	93	(lock-mutex (mutex (handshake-channel ch)))
51407fa0 MD	94	(cond ((receiver-waiting? ch)
60eefd9c	95	(set! (data ch) x)
51407fa0 MD	96	(signal-condition-variable (cv (handshake-channel ch))))
	97	((sender-waiting? ch)
	98	(unlock-mutex (mutex (handshake-channel ch)))
60eefd9c	99	(scm-error 'misc-error '! "another process is already sending on ~A"
51407fa0 MD	100	(list ch) #f))
	101	(else
	102	(set! (data ch) x)
	103	(wait-condition-variable (cv ch) (mutex ch))))
	104	(unlock-mutex (mutex (handshake-channel ch))))
fb831451 MD	105
	106	;;; Add protocols?
	107
	108	(define-class <port-channel> (<channel>)
	109	(port #:accessor port #:init-keyword #:port))
	110
	111	(define-method (make-channel (port <port>))
	112	(make <port-channel> #:port port))
	113
	114	(define-method (? (ch <port-channel>))
	115	(read (port ch)))
	116
	117	(define-method (! (ch <port-channel>))
	118	(write (port ch)))
	119
	120	(define-class <timer-channel> (<channel>))
	121
	122	(define the-timer (make <timer-channel>))
	123
	124	(define timer-cv (make-condition-variable))
	125	(define timer-mutex (make-mutex))
	126
	127	(define (make-timer)
	128	the-timer)
	129
	130	(define (timeofday->us t)
	131	(+ (* 1000000 (car t)) (cdr t)))
	132
	133	(define (us->timeofday n)
	134	(cons (quotient n 1000000)
	135	(remainder n 1000000)))
	136
	137	(define-method (? (ch <timer-channel>))
	138	(timeofday->us (gettimeofday)))
	139
	140	(define-method (? (ch <timer-channel>) (t <integer>))
	141	(lock-mutex timer-mutex)
	142	(wait-condition-variable timer-cv timer-mutex (us->timeofday t))
	143	(unlock-mutex timer-mutex))
	144
51407fa0 MD	145	;;; (alt CLAUSE ...)
	146	;;;
	147	;;; CLAUSE ::= ((? CH) FORM ...)
	148	;;; \| (EXP (? CH) FORM ...)
	149	;;; \| (EXP FORM ...)
	150	;;;
	151	;;; where FORM ... can be => (lambda (x) ...)
	152	;;;
	153	;;; fixme Currently only handles <data-channel>:s
	154	;;;
	155
	156	(define-syntax oc:lock
	157	(syntax-rules (?)
	158	((_ ((? ch) form ...)) (lock-mutex (mutex ch)))
	159	((_ (exp (? ch) form ...)) (lock-mutex (mutex ch)))
	160	((_ (exp form ...)) #f)))
	161
	162	(define-syntax oc:unlock
	163	(syntax-rules (?)
	164	((_ ((? ch) form ...)) (unlock-mutex (mutex ch)))
	165	((_ (exp (? ch) form ...)) (unlock-mutex (mutex ch)))
	166	((_ (exp form ...)) #f)))
	167
	168	(define-syntax oc:consequence
	169	(syntax-rules (=>)
	170	((_ data) data)
	171	((_ data => (lambda (x) e1 e2 ...))
	172	(let ((x data)) e1 e2 ...))
	173	((_ data e1 e2 ...)
	174	(begin data e1 e2 ...))))
	175
	176	(define-syntax oc:immediate-dispatch
	177	(syntax-rules (?)
	178	((_ ((? ch) e1 ...))
	179	((sender-waiting? ch)
	180	(oc:consequence (immediate-receive ch) e1 ...)))
	181	((_ (exp (? ch) e1 ...))
	182	((and exp (sender-waiting? ch))
	183	(oc:consequence (immediate-receive ch) e1 ...)))
	184	((_ (exp e1 ...))
	185	(exp e1 ...))))
	186
	187	(define-syntax oc:late-dispatch
	188	(syntax-rules (?)
	189	((_ ((? ch) e1 ...))
	190	((sender-waiting? ch)
	191	(oc:consequence (late-receive ch) e1 ...)))
	192	((_ (exp (? ch) e1 ...))
	193	((and exp (sender-waiting? ch))
	194	(oc:consequence (late-receive ch) e1 ...)))
	195	((_ (exp e1 ...))
	196	(#f))))
	197
	198	(define-syntax oc:first-channel
	199	(syntax-rules (?)
	200	((_ ((? ch) e1 ...) c2 ...)
	201	ch)
	202	((_ (exp (? ch) e1 ...) c2 ...)
	203	ch)
	204	((_ c1 c2 ...)
	205	(first-channel c2 ...))))
	206
	207	(define-syntax oc:set-handshake-channel
	208	(syntax-rules (?)
209	((_ ((? ch) e1 ...) handshake)
210	(set! (handshake-channel ch) handshake))
211	((_ (exp (? ch) e1 ...) handshake)
212	(and exp (set! (handshake-channel ch) handshake)))
213	((_ (exp e1 ...) handshake)
214	#f)))
215
216	(define-syntax oc:unset-handshake-channel
217	(syntax-rules (?)
218	((_ ((? ch) e1 ...))
219	(set! (handshake-channel ch) ch))
220	((_ (exp (? ch) e1 ...))
221	(and exp (set! (handshake-channel ch) ch)))
222	((_ (exp e1 ...))
223	#f)))
224
225	(define-syntax alt
226	(lambda (x)
227	(define (else-clause? x)
228	(syntax-case x (else)
229	((_) #f)
230	((_ (else e1 e2 ...)) #t)
231	((_ c1 c2 ...) (else-clause? (syntax (_ c2 ...))))))
232
233	(syntax-case x (else)
234	((_ c1 c2 ...)
235	(else-clause? x)
236	(syntax (begin
237	(oc:lock c1)
238	(oc:lock c2) ...
239	(let ((res (cond (oc:immediate-dispatch c1)
240	(oc:immediate-dispatch c2) ...)))
241	(oc:unlock c1)
242	(oc:unlock c2) ...
243	res))))
244	((_ c1 c2 ...)
245	(syntax (begin
246	(oc:lock c1)
247	(oc:lock c2) ...
248	(let ((res (cond (oc:immediate-dispatch c1)
249	(oc:immediate-dispatch c2) ...
250	(else (let ((ch (oc:first-channel c1 c2 ...)))
251	(oc:set-handshake-channel c1 ch)
252	(oc:set-handshake-channel c2 ch) ...
253	(wait-condition-variable (cv ch)
254	(mutex ch))
255	(oc:unset-handshake-channel c1)
256	(oc:unset-handshake-channel c2) ...
257	(cond (oc:late-dispatch c1)
258	(oc:late-dispatch c2) ...))))))
259	(oc:unlock c1)
260	(oc:unlock c2) ...
261	res)))))))