1 ;;; 8sync --- Asynchronous programming for Guile
2 ;;; Copyright (C) 2015 Christopher Allan Webber <cwebber@dustycloud.org>
4 ;;; This file is part of 8sync.
6 ;;; 8sync is free software: you can redistribute it and/or modify it
7 ;;; under the terms of the GNU Lesser General Public License as
8 ;;; published by the Free Software Foundation, either version 3 of the
9 ;;; License, or (at your option) any later version.
11 ;;; 8sync is distributed in the hope that it will be useful,
12 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
13 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 ;;; GNU Lesser General Public License for more details.
16 ;;; You should have received a copy of the GNU Lesser General Public
17 ;;; License along with 8sync. If not, see <http://www.gnu.org/licenses/>.
19 (define-module (8sync agenda)
20 #:use-module (srfi srfi-1)
21 #:use-module (srfi srfi-9)
22 #:use-module (srfi srfi-9 gnu)
23 #:use-module (ice-9 q)
24 #:use-module (ice-9 match)
25 #:use-module (ice-9 receive)
28 agenda-queue agenda-prompt-tag
29 agenda-read-port-map agenda-write-port-map agenda-except-port-map
37 make-time-segment time-segment?
38 time-segment-time time-segment-queue
40 time< time= time<= time-delta+
44 make-time-delta tdelta time-delta?
45 time-delta-sec time-delta-usec
48 make-schedule schedule?
49 schedule-add! schedule-empty?
53 schedule-segments-split schedule-extract-until!
54 add-segments-contents-to-queue!
59 make-run-request run-request?
60 run-request-proc run-request-when
63 make-port-request port-request port-request?
65 port-request-read port-request-write port-request-except
68 make-port-remove-request port-remove-request port-remove-request?
69 port-remove-request-port
71 run-it wrap wrap-apply run run-at run-delay
73 %run %run-at %run-delay %port-request %port-remove-request
74 %8sync-run %8sync-run-at %8sync-run-delay
75 %8sync-port %8sync-port-remove
77 catch-8sync catch-%8sync
79 ;; used for introspecting the error, but a method for making
82 wrapped-exception-key wrapped-exception-args
83 wrapped-exception-stacks
85 print-error-and-continue
90 start-agenda agenda-run-once))
92 ;; @@: Using immutable agendas here, so wouldn't it make sense to
93 ;; replace this queue stuff with using pfds based immutable queues?
99 ;;; The agenda consists of:
100 ;;; - a queue of immediate items to handle
101 ;;; - sheduled future events to be added to a future queue
102 ;;; - a tag by which running processes can escape for some asynchronous
103 ;;; operation (from which they can be returned later)
104 ;;; - a mapping of ports to various handler procedures
106 ;;; The goal, eventually, is for this all to be immutable and functional.
107 ;;; However, we aren't there yet. Some tricky things:
108 ;;; - The schedule needs to be immutable, yet reasonably efficient.
109 ;;; - Need to use immutable queues (ijp's pfds library?)
110 ;;; - Modeling reading from ports as something repeatable,
111 ;;; and with reasonable separation from functional components?
113 (define-immutable-record-type <agenda>
114 (make-agenda-intern queue prompt-tag
115 read-port-map write-port-map except-port-map
116 schedule time catch-handler pre-unwind-handler)
119 (prompt-tag agenda-prompt-tag)
120 (read-port-map agenda-read-port-map)
121 (write-port-map agenda-write-port-map)
122 (except-port-map agenda-except-port-map)
123 (schedule agenda-schedule)
125 (catch-handler agenda-catch-handler)
126 (pre-unwind-handler agenda-pre-unwind-handler))
128 (define (make-async-prompt-tag)
129 "Make an async prompt tag for an agenda.
131 Generally done automatically for the user through (make-agenda)."
132 (make-prompt-tag "prompt"))
134 (define* (make-agenda #:key
136 (prompt (make-prompt-tag))
137 (read-port-map (make-hash-table))
138 (write-port-map (make-hash-table))
139 (except-port-map (make-hash-table))
140 (schedule (make-schedule))
141 (time (gettimeofday))
143 (pre-unwind-handler #f))
144 ;; TODO: document arguments
145 "Make a fresh agenda."
146 (make-agenda-intern queue prompt
147 read-port-map write-port-map except-port-map
149 catch-handler pre-unwind-handler))
151 (define (current-agenda-prompt)
152 "Get the prompt for the current agenda; signal an error if there isn't one."
153 (let ((current-agenda (%current-agenda)))
154 (if (not current-agenda)
157 "Can't get current agenda prompt if there's no current agenda!")
158 (agenda-prompt-tag current-agenda))))
160 ;; helper for making queues for an agenda
161 (define (list->q lst)
162 "Makes a queue composed of LST items"
170 (define (make-q* . args)
171 "Makes a queue and populates it with this invocation's ARGS"
178 ;;; This is where we handle timed events for the future
180 ;; This section totally borrows from the ideas in SICP
183 ;; NOTE: time is a cons of (seconds . microseconds)
185 (define-record-type <time-segment>
186 (make-time-segment-intern time queue)
188 (time time-segment-time)
189 (queue time-segment-queue))
191 ;; @@: This seems to be the same as srfi-18's seconds->time procedure?
192 ;; Maybe double check and switch to that? (Thanks amz3!)
194 (define (time-from-float-or-fraction time)
195 "Produce a (sec . usec) pair from TIME, a float or fraction"
196 (let* ((mixed-whole (floor time))
197 (mixed-rest (- time mixed-whole)) ; float or fraction component
199 (usec (floor (* 1000000 mixed-rest))))
200 (cons (inexact->exact sec) (inexact->exact usec))))
202 (define (time-segment-right-format time)
203 "Ensure TIME is in the right format.
205 The right format means (second . microsecond).
206 If an integer, will convert appropriately."
207 ;; TODO: add floating point / rational number support.
209 ;; time is already a cons of second and microsecnd
210 (((? integer? s) . (? integer? u)) time)
211 ;; time was just an integer (just the second)
212 ((? integer? _) (cons time 0))
213 ((or (? rational? _) (? inexact? _))
214 (time-from-float-or-fraction time))
215 (_ (throw 'invalid-time "Invalid time" time))))
217 (define* (make-time-segment time #:optional (queue (make-q)))
218 "Make a time segment of TIME and QUEUE
220 No automatic conversion is done, so you might have to
221 run (time-segment-right-format) first."
222 (make-time-segment-intern time queue))
224 (define (time< time1 time2)
225 "Check if TIME1 is less than TIME2"
226 (cond ((< (car time1)
236 (define (time= time1 time2)
237 "Check whether TIME1 and TIME2 are equivalent"
238 (and (= (car time1) (car time2))
239 (= (cdr time1) (cdr time2))))
241 (define (time<= time1 time2)
242 "Check if TIME1 is less than or equal to TIME2"
243 (or (time< time1 time2)
244 (time= time1 time2)))
247 (define-record-type <time-delta>
248 (make-time-delta-intern sec usec)
251 (usec time-delta-usec))
253 (define* (make-time-delta time)
254 "Make a <time-delta> of SEC seconds and USEC microseconds.
256 This is used primarily so the agenda can recognize RUN-REQUEST objects
257 which are meant to delay computation"
258 (match (time-segment-right-format time)
260 (make-time-delta-intern sec usec))))
262 (define tdelta make-time-delta)
264 (define (time-carry-correct time)
265 "Corrects/handles time microsecond carry.
266 Will produce (0 . 0) instead of a negative number, if needed."
267 (cond ((>= (cdr time) 1000000)
270 (- (cdr time) 1000000)))
276 (+ (cdr time) 1000000))))
279 (define (time-delta+ time time-delta)
280 "Increment a TIME by the value of TIME-DELTA"
282 (cons (+ (car time) (time-delta-sec time-delta))
283 (+ (cdr time) (time-delta-usec time-delta)))))
285 (define (time-minus time1 time2)
286 "Subtract TIME2 from TIME1"
288 (cons (- (car time1) (car time2))
289 (- (cdr time1) (cdr time2)))))
291 (define (time-plus time1 time2)
292 "Add TIME1 and TIME2"
294 (cons (+ (car time1) (car time2))
295 (+ (cdr time1) (cdr time2)))))
298 (define-record-type <schedule>
299 (make-schedule-intern segments)
301 (segments schedule-segments set-schedule-segments!))
303 (define* (make-schedule #:optional segments)
304 "Make a schedule, optionally pre-composed of SEGMENTS"
305 (make-schedule-intern (or segments '())))
307 (define (schedule-soonest-time schedule)
308 "Return a cons of (sec . usec) for next time segement, or #f if none"
309 (let ((segments (schedule-segments schedule)))
310 (if (eq? segments '())
312 (time-segment-time (car segments)))))
314 ;; TODO: This code is reasonably easy to read but it
315 ;; mutates AND is worst case of O(n) in both space and time :(
316 ;; but at least it'll be reasonably easy to refactor to
317 ;; a more functional setup?
318 (define (schedule-add! schedule time proc)
319 "Mutate SCHEDULE, adding PROC at an appropriate time segment for TIME"
320 (let ((time (time-segment-right-format time)))
321 (define (new-time-segment)
323 (make-time-segment time)))
324 (enq! (time-segment-queue new-segment) proc)
326 (define (loop segments)
327 (define (segment-equals-time? segment)
328 (time= time (time-segment-time segment)))
330 (define (segment-more-than-time? segment)
331 (time< time (time-segment-time segment)))
333 ;; We could switch this out to be more mutate'y
334 ;; and avoid the O(n) of space... is that over-optimizing?
336 ;; If we're at the end of the list, time to make a new
338 ('() (cons (new-time-segment) '()))
339 ;; If the segment's time is exactly our time, good news
340 ;; everyone! Let's append our stuff to its queue
341 (((? segment-equals-time? first) rest ...)
342 (enq! (time-segment-queue first) proc)
344 ;; If the first segment is more than our time,
345 ;; ours belongs before this one, so add it and
346 ;; start consing our way back
347 (((? segment-more-than-time? first) rest ...)
348 (cons (new-time-segment) segments))
349 ;; Otherwise, build up recursive result
351 (cons first (loop rest)))))
352 (set-schedule-segments!
354 (loop (schedule-segments schedule)))))
356 (define (schedule-empty? schedule)
357 "Check if the SCHEDULE is currently empty"
358 (eq? (schedule-segments schedule) '()))
360 (define (schedule-segments-split schedule time)
361 "Does a multiple value return of time segments before/at and after TIME"
362 (let ((time (time-segment-right-format time)))
363 (define (segment-is-now? segment)
364 (time= (time-segment-time segment) time))
365 (define (segment-is-before-now? segment)
366 (time< (time-segment-time segment) time))
368 (let loop ((segments-before '())
369 (segments-left (schedule-segments schedule)))
371 ;; end of the line, return
373 (values (reverse segments-before) '()))
375 ;; It's right now, so time to stop, but include this one in before
376 ;; but otherwise return
377 (((? segment-is-now? first) rest ...)
378 (values (reverse (cons first segments-before)) rest))
380 ;; This is prior or at now, so add it and keep going
381 (((? segment-is-before-now? first) rest ...)
382 (loop (cons first segments-before) rest))
384 ;; Otherwise it's past now, just return what we have
386 (values segments-before segments-after))))))
388 (define (schedule-extract-until! schedule time)
389 "Extract all segments until TIME from SCHEDULE, and pop old segments off"
390 (receive (segments-before segments-after)
391 (schedule-segments-split schedule time)
392 (set-schedule-segments! schedule segments-after)
395 (define (add-segments-contents-to-queue! segments queue)
398 (let ((seg-queue (time-segment-queue segment)))
399 (while (not (q-empty? seg-queue))
400 (enq! queue (deq! seg-queue)))))
405 ;;; Request to run stuff
406 ;;; ====================
408 (define-record-type <run-request>
409 (make-run-request proc when)
411 (proc run-request-proc)
412 (when run-request-when))
414 (define* (run-it proc #:optional when)
415 "Make a request to run PROC (possibly at WHEN)"
416 (make-run-request proc when))
418 (define-syntax-rule (wrap body ...)
419 "Wrap contents in a procedure"
423 (define-syntax-rule (wrap-apply body)
424 "Wrap possibly multi-value function in a procedure, applies all arguments"
429 ;; @@: Do we really want `body ...' here?
430 ;; what about just `body'?
431 (define-syntax-rule (run body ...)
432 "Run everything in BODY but wrap in a convenient procedure"
433 (make-run-request (wrap body ...) #f))
435 (define-syntax-rule (run-at body ... when)
437 (make-run-request (wrap body ...) when))
439 ;; @@: Is it okay to overload the term "delay" like this?
440 ;; Would `run-in' be better?
441 (define-syntax-rule (run-delay body ... delay-time)
442 "Run BODY at DELAY-TIME time from now"
443 (make-run-request (wrap body ...) (tdelta delay-time)))
446 ;; A request to set up a port with at least one of read, write, except
447 ;; handling processes
449 (define-record-type <port-request>
450 (make-port-request-intern port read write except)
452 (port port-request-port)
453 (read port-request-read)
454 (write port-request-write)
455 (except port-request-except))
457 (define* (make-port-request port #:key read write except)
458 (if (not (or read write except))
459 (throw 'no-port-handler-given "No port handler given.\n"))
460 (make-port-request-intern port read write except))
462 (define port-request make-port-request)
464 (define-record-type <port-remove-request>
465 (make-port-remove-request port)
467 (port port-remove-request-port))
469 (define port-remove-request make-port-remove-request)
473 ;;; Asynchronous escape to run things
474 ;;; =================================
476 (define-syntax-rule (%8sync async-request)
477 "Run BODY asynchronously at a prompt, passing args to make-future.
479 Runs things asynchronously (8synchronously?)"
480 (propagate-%async-exceptions
481 (abort-to-prompt (current-agenda-prompt)
484 ;; Async port request and run-request meta-requests
485 (define (make-async-request proc)
486 "Wrap PROC in an async-request
488 The purpose of this is to make sure that users don't accidentally
489 return the wrong thing via (%8sync) and trip themselves up."
490 (cons '*async-request* proc))
492 (define (setup-async-request resume-kont async-request)
493 "Complete an async request for agenda-run-once's continuation handling"
495 (('*async-request* . async-setup-proc)
496 (async-setup-proc resume-kont))
497 ;; TODO: deliver more helpful errors depending on what the user
499 (_ (throw 'invalid-async-request
500 "Invalid request passed back via an (%8sync) procedure."
503 (define-record-type <wrapped-exception>
504 (make-wrapped-exception key args stacks)
506 (key wrapped-exception-key)
507 (args wrapped-exception-args)
508 (stacks wrapped-exception-stacks))
510 (define-syntax-rule (propagate-%async-exceptions body)
511 (let ((body-result body))
512 (if (wrapped-exception? body-result)
513 (throw '8sync-caught-error
514 (wrapped-exception-key body-result)
515 (wrapped-exception-args body-result)
516 (wrapped-exception-stacks body-result))
519 (define-syntax-rule (%run body ...)
520 (%run-at body ... #f))
522 (define-syntax-rule (%run-at body ... when)
523 ;; Send an asynchronous request to apply a continuation to the
524 ;; following function, then handle that as a request to the agenda
527 ;; We're making a run request
529 ;; Wrapping the following execution to run...
531 ;; Once we get the result from the inner part, we'll resume
532 ;; this continuation, but first
533 ;; @@: Is this running immediately, or queueing the result
534 ;; after evaluation for the next agenda tick? It looks
535 ;; like evaluating immediately. Is that what we want?
537 ;; Any unhandled errors are caught
538 (let ((exception-stack #f))
540 ;; Run the actual code the user requested
543 ;; If something bad happened and we didn't catch it,
544 ;; we'll wrap it up in such a way that the continuation
548 ((eq? key '8sync-caught-error)
550 ((orig-key orig-args orig-stacks)
551 (make-wrapped-exception
553 (cons exception-stack orig-stacks)))))
555 (make-wrapped-exception key args
556 (list exception-stack)))))
558 (set! exception-stack (make-stack #t 1 0)))))))
561 (define-syntax-rule (%run-delay body ... delay-time)
562 (%run-at body ... (tdelta delay-time)))
564 (define-syntax-rule (%port-request port port-request-args ...)
567 (list (make-port-request port port-request-args ...)
568 (make-run-request (wrap kont) #f)))))
570 (define-syntax-rule (%port-remove-request port)
573 (list (make-port-remove-request port)
574 (make-run-request (wrap kont) #f)))))
578 (define-syntax-rule (%8sync-run rest ...)
579 "Sugar for (%8sync (%run ...))"
580 (%8sync (%run rest ...)))
582 (define-syntax-rule (%8sync-run-at rest ...)
583 "Sugar for (%8sync (%run-at ...))"
584 (%8sync (%run-at rest ...)))
586 (define-syntax-rule (%8sync-run-delay rest ...)
587 "Sugar for (%8sync (%run-delay ...))"
588 (%8sync (%run-delay rest ...)))
590 (define-syntax-rule (%8sync-port rest ...)
591 "Sugar for (%8sync (%port-request ...))"
592 (%8sync (%port-request rest ...)))
594 (define-syntax-rule (%8sync-port-remove rest ...)
595 "Sugar for (%8sync (%port-remove-request ...))"
596 (%8sync (%port-remove-request rest ...)))
599 ;; TODO: Write (%run-immediately)
602 (define-syntax-rule (%run-with-return return body ...)
609 (define-syntax-rule (catch-8sync exp (handler-key handler) ...)
610 (catch '8sync-caught-error
613 (lambda (_ orig-key orig-args orig-stacks)
615 ((or (eq? handler-key #t)
616 (eq? orig-key handler-key))
617 (apply handler orig-stacks orig-args)) ...
618 (else (raise '8sync-caught-error
619 orig-key orig-args orig-stacks))))))
622 (define-syntax-rule (catch-%8sync rest ...)
623 (catch-8sync rest ...))
627 ;;; Execution of agenda, and current agenda
628 ;;; =======================================
630 (define %current-agenda (make-parameter #f))
632 (define (update-agenda-from-select! agenda)
633 "Potentially (select) on ports specified in agenda, adding items to queue.
635 Also handles sleeping when all we have to do is wait on the schedule."
636 (define (hash-keys hash)
637 (hash-map->list (lambda (k v) k) hash))
638 (define (get-wait-time)
639 ;; TODO: we need to figure this out based on whether there's anything
640 ;; in the queue, and if not, how long till the next scheduled item
641 (let ((soonest-time (schedule-soonest-time (agenda-schedule agenda))))
643 ((not (q-empty? (agenda-queue agenda)))
645 (soonest-time ; ie, the agenda is non-empty
646 (let* ((current-time (agenda-time agenda)))
647 (if (time<= soonest-time current-time)
648 ;; Well there's something due so let's select
649 ;; (this avoids a (possible?) race condition chance)
651 (time-minus soonest-time current-time))))
655 ;; TODO: support usecond wait time too
656 (match (get-wait-time)
660 (select (hash-keys (agenda-read-port-map agenda))
661 (hash-keys (agenda-write-port-map agenda))
662 (hash-keys (agenda-except-port-map agenda))
664 (lambda (key . rest-args)
668 (_ (error "Unhandled error in select!" key rest-args))))))))
669 (define (get-procs-to-run)
670 (define (ports->procs ports port-map)
671 (lambda (initial-procs)
675 ((hash-ref port-map port) port))
680 ((read-ports write-ports except-ports)
681 ;; @@: Come on, we can do better than append ;P
682 ((compose (ports->procs
684 (agenda-read-port-map agenda))
687 (agenda-write-port-map agenda))
690 (agenda-except-port-map agenda)))
692 (define (update-agenda)
693 (let ((procs-to-run (get-procs-to-run))
694 (q (agenda-queue agenda)))
700 (define (ports-to-select?)
701 (define (has-items? selector)
703 ;; ... we could use hash-for-each and a continuation to jump
704 ;; out with a #t at first indication of an item
705 (not (= (hash-count (const #t)
708 (or (has-items? agenda-read-port-map)
709 (has-items? agenda-write-port-map)
710 (has-items? agenda-except-port-map)))
712 (if (or (ports-to-select?)
713 ;; select doubles as sleep...
714 (not (schedule-empty? (agenda-schedule agenda))))
718 (define (agenda-handle-port-request! agenda port-request)
719 "Update an agenda for a port-request"
720 (define (handle-selector request-selector port-map-selector)
721 (if (request-selector port-request)
722 ;; @@: Should we remove if #f?
723 (hash-set! (port-map-selector agenda)
724 (port-request-port port-request)
725 (request-selector port-request))))
726 (handle-selector port-request-read agenda-read-port-map)
727 (handle-selector port-request-write agenda-write-port-map)
728 (handle-selector port-request-except agenda-except-port-map))
731 (define (agenda-handle-port-remove-request! agenda port-remove-request)
732 "Update an agenda for a port-remove-request"
733 (let ((port (port-remove-request-port port-remove-request)))
734 (hash-remove! (agenda-read-port-map agenda) port)
735 (hash-remove! (agenda-write-port-map agenda) port)
736 (hash-remove! (agenda-except-port-map agenda) port)))
739 (define (stop-on-nothing-to-do agenda)
740 (and (q-empty? (agenda-queue agenda))
741 (schedule-empty? (agenda-schedule agenda))
742 (= 0 (hash-count (const #t) (agenda-read-port-map agenda)))
743 (= 0 (hash-count (const #t) (agenda-write-port-map agenda)))
744 (= 0 (hash-count (const #t) (agenda-except-port-map agenda)))))
747 (define* (start-agenda agenda
749 ;; @@: Should we make stop-on-nothing-to-do
750 ;; the default stop-condition?
752 (get-time gettimeofday)
753 (handle-ports update-agenda-from-select!))
754 ;; TODO: Document fields
755 "Start up the AGENDA"
756 (let loop ((agenda agenda))
758 ;; @@: Hm, maybe here would be a great place to handle
759 ;; select'ing on ports.
760 ;; We could compose over agenda-run-once and agenda-read-ports
761 (agenda-run-once agenda)))
762 (if (and stop-condition (stop-condition agenda))
765 ;; We have to update the time after ports handled, too
766 ;; because it may have changed after a select
769 ;; Adjust the agenda's time just in time
770 ;; We do this here rather than in agenda-run-once to make
771 ;; agenda-run-once's behavior fairly predictable
772 (set-field agenda (agenda-time) (get-time)))
773 (agenda-time) (get-time))))
774 ;; Update the agenda's current queue based on
775 ;; currently applicable time segments
776 (add-segments-contents-to-queue!
777 (schedule-extract-until! (agenda-schedule agenda) (agenda-time agenda))
778 (agenda-queue agenda))
782 (define (print-error-and-continue key . args)
783 "Frequently used as pre-unwind-handler for agenda"
785 ((eq? key '8sync-caught-error)
787 ((orig-key orig-args stacks)
788 (display "\n*** Caught async exception. ***\n")
789 (format (current-error-port)
790 "* Original key '~s and arguments: ~s *\n"
792 (display "* Caught stacks below (ending with original) *\n\n")
795 (display-backtrace s (current-error-port))
796 (newline (current-error-port)))
799 (format (current-error-port)
800 "\n*** Caught exception with key '~s and arguments: ~s ***\n"
802 (display-backtrace (make-stack #t 1 0)
803 (current-error-port))
804 (newline (current-error-port)))))
806 (define-syntax-rule (maybe-catch-all (catch-handler pre-unwind-handler)
808 (if (or catch-handler pre-unwind-handler)
813 (or catch-handler (lambda _ #f))
814 (or pre-unwind-handler (lambda _ #f)))
817 (define (agenda-run-once agenda)
818 "Run once through the agenda, and produce a new agenda
819 based on the results"
820 (define (call-proc proc)
822 (agenda-prompt-tag agenda)
824 (parameterize ((%current-agenda agenda))
826 ((agenda-catch-handler agenda)
827 (agenda-pre-unwind-handler agenda))
829 (lambda (kont async-request)
830 (setup-async-request kont async-request))))
832 (let ((queue (agenda-queue agenda))
833 (next-queue (make-q)))
834 (while (not (q-empty? queue))
835 (let* ((proc (q-pop! queue))
836 (proc-result (call-proc proc))
838 (lambda (run-request)
839 (define (schedule-at! time proc)
840 (schedule-add! (agenda-schedule agenda) time proc))
841 (let ((request-time (run-request-when run-request)))
843 ((? time-delta? time-delta)
844 (let ((time (time-delta+ (agenda-time agenda)
846 (schedule-at! time (run-request-proc run-request))))
848 (let ((time (cons sec 0)))
849 (schedule-at! time (run-request-proc run-request))))
850 (((? integer? sec) . (? integer? usec))
851 (schedule-at! request-time (run-request-proc run-request)))
853 (enq! next-queue (run-request-proc run-request))))))))
854 (define (handle-individual result)
855 ;; @@: Could maybe optimize by switching to an explicit cond...
857 ((? run-request? new-proc)
859 ((? port-request? port-request)
860 (agenda-handle-port-request! agenda port-request))
861 ((? port-remove-request? port-remove-request)
862 (agenda-handle-port-remove-request! agenda port-remove-request))
865 ;; @@: We might support delay-wrapped procedures here
868 (for-each handle-individual results))
869 (one-result (handle-individual one-result)))))
870 ;; TODO: Alternately, we could return the next-queue
871 ;; along with changes to be added to the schedule here?
872 ;; Return new agenda, with next queue set
873 (set-field agenda (agenda-queue) next-queue)))