1 ;;; 8sync --- Asynchronous programming for Guile
2 ;;; Copyright (C) 2015, 2016 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!
57 make-run-request run-request?
58 run-request-proc run-request-when
61 make-port-request port-request port-request?
63 port-request-read port-request-write port-request-except
66 make-port-remove-request port-remove-request port-remove-request?
67 port-remove-request-port
69 run-it wrap wrap-apply run run-at run-delay
72 8sync-run 8sync-run-at 8sync-run-delay
73 8sync-port 8sync-port-remove
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 print-error-and-continue))
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-abort-to-prompt async-request)
477 (abort-to-prompt (current-agenda-prompt)
480 ;; Async port request and run-request meta-requests
481 (define (make-async-request proc)
482 "Wrap PROC in an async-request
484 The purpose of this is to make sure that users don't accidentally
485 return the wrong thing via (8sync) and trip themselves up."
486 (cons '*async-request* proc))
488 (define (setup-async-request resume-kont async-request)
489 "Complete an async request for agenda-run-once's continuation handling"
491 (('*async-request* . async-setup-proc)
492 (async-setup-proc resume-kont))
493 ;; TODO: deliver more helpful errors depending on what the user
495 (_ (throw 'invalid-async-request
496 "Invalid request passed back via an (8sync) procedure."
499 (define-record-type <wrapped-exception>
500 (make-wrapped-exception key args stacks)
502 (key wrapped-exception-key)
503 (args wrapped-exception-args)
504 (stacks wrapped-exception-stacks))
506 (define-syntax-rule (propagate-%async-exceptions body)
507 (let ((body-result body))
508 (if (wrapped-exception? body-result)
509 (throw '8sync-caught-error
510 (wrapped-exception-key body-result)
511 (wrapped-exception-args body-result)
512 (wrapped-exception-stacks body-result))
517 "Run BODY asynchronously (8synchronously?) at a prompt, then return.
519 Possibly specify WHEN as the second argument."
523 (8sync-run-at body when))))
525 (define-syntax-rule (8sync-run body ...)
526 (8sync-run-at body ... #f))
528 (define-syntax-rule (8sync-run-at body ... when)
529 (propagate-%async-exceptions
530 (8sync-abort-to-prompt
531 ;; Send an asynchronous request to apply a continuation to the
532 ;; following function, then handle that as a request to the agenda
535 ;; We're making a run request
537 ;; Wrapping the following execution to run...
539 ;; Once we get the result from the inner part, we'll resume
540 ;; this continuation, but first
541 ;; @@: Is this running immediately, or queueing the result
542 ;; after evaluation for the next agenda tick? It looks
543 ;; like evaluating immediately. Is that what we want?
545 ;; Any unhandled errors are caught
546 (let ((exception-stack #f))
548 ;; Run the actual code the user requested
551 ;; If something bad happened and we didn't catch it,
552 ;; we'll wrap it up in such a way that the continuation
556 ((eq? key '8sync-caught-error)
558 ((orig-key orig-args orig-stacks)
559 (make-wrapped-exception
561 (cons exception-stack orig-stacks)))))
563 (make-wrapped-exception key args
564 (list exception-stack)))))
566 (set! exception-stack (make-stack #t 1 0)))))))
569 (define-syntax-rule (8sync-run-delay body ... delay-time)
570 (8sync-run-at body ... (tdelta delay-time)))
572 (define-syntax-rule (8sync-delay args ...)
573 (8sync-run-delay args ...))
575 (define-syntax-rule (8sync-port port port-request-args ...)
576 (8sync-abort-to-prompt
579 (list (make-port-request port port-request-args ...)
581 ;; What's with returning #f to kont?
582 ;; Otherwise we sometimes get errors like
583 ;; "Zero values returned to single-valued continuation""
584 (wrap (kont #f)) #f))))))
586 (define-syntax-rule (8sync-port-remove port)
587 (8sync-abort-to-prompt
590 (list (make-port-remove-request port)
592 ;; See comment in 8sync-port
593 (wrap (kont #f)) #f))))))
596 ;; TODO: Write (%run-immediately)
598 (define-syntax-rule (8sync-nowait body)
599 "Run body asynchronously but ignore its result...
600 forge ahead in our current function!"
601 (8sync-abort-to-prompt
604 (list (make-run-request
605 ;; See comment in 8sync-port
607 (make-run-request (lambda () body) #f))))))
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))))))
621 ;; This is sugar... and could probably be considerably
622 ;; simplified and optimized. But whatever.
623 (define-syntax-rule (8sleep time)
624 (8sync-delay 'no-op time))
628 ;;; Execution of agenda, and current agenda
629 ;;; =======================================
631 (define %current-agenda (make-parameter #f))
633 (define (update-agenda-from-select! agenda)
634 "Potentially (select) on ports specified in agenda, adding items to queue.
636 Also handles sleeping when all we have to do is wait on the schedule."
637 (define (hash-keys hash)
638 (hash-map->list (lambda (k v) k) hash))
639 (define (get-wait-time)
640 ;; TODO: we need to figure this out based on whether there's anything
641 ;; in the queue, and if not, how long till the next scheduled item
642 (let ((soonest-time (schedule-soonest-time (agenda-schedule agenda))))
644 ((not (q-empty? (agenda-queue agenda)))
646 (soonest-time ; ie, the agenda is non-empty
647 (let* ((current-time (agenda-time agenda)))
648 (if (time<= soonest-time current-time)
649 ;; Well there's something due so let's select
650 ;; (this avoids a (possible?) race condition chance)
652 (time-minus soonest-time current-time))))
656 ;; TODO: support usecond wait time too
657 (match (get-wait-time)
661 (select (hash-keys (agenda-read-port-map agenda))
662 (hash-keys (agenda-write-port-map agenda))
663 (hash-keys (agenda-except-port-map agenda))
665 (lambda (key . rest-args)
669 (_ (error "Unhandled error in select!" key rest-args))))))))
670 (define (get-procs-to-run)
671 (define (ports->procs ports port-map)
672 (lambda (initial-procs)
676 ((hash-ref port-map port) port))
681 ((read-ports write-ports except-ports)
682 ;; @@: Come on, we can do better than append ;P
683 ((compose (ports->procs
685 (agenda-read-port-map agenda))
688 (agenda-write-port-map agenda))
691 (agenda-except-port-map agenda)))
693 (define (update-agenda)
694 (let ((procs-to-run (get-procs-to-run))
695 (q (agenda-queue agenda)))
701 (define (ports-to-select?)
702 (define (has-items? selector)
704 ;; ... we could use hash-for-each and a continuation to jump
705 ;; out with a #t at first indication of an item
706 (not (= (hash-count (const #t)
709 (or (has-items? agenda-read-port-map)
710 (has-items? agenda-write-port-map)
711 (has-items? agenda-except-port-map)))
713 (if (or (ports-to-select?)
714 ;; select doubles as sleep...
715 (not (schedule-empty? (agenda-schedule agenda))))
719 (define (agenda-handle-port-request! agenda port-request)
720 "Update an agenda for a port-request"
721 (define (handle-selector request-selector port-map-selector)
722 (if (request-selector port-request)
723 ;; @@: Should we remove if #f?
724 (hash-set! (port-map-selector agenda)
725 (port-request-port port-request)
726 (request-selector port-request))))
727 (handle-selector port-request-read agenda-read-port-map)
728 (handle-selector port-request-write agenda-write-port-map)
729 (handle-selector port-request-except agenda-except-port-map))
732 (define (agenda-handle-port-remove-request! agenda port-remove-request)
733 "Update an agenda for a port-remove-request"
734 (let ((port (port-remove-request-port port-remove-request)))
735 (hash-remove! (agenda-read-port-map agenda) port)
736 (hash-remove! (agenda-write-port-map agenda) port)
737 (hash-remove! (agenda-except-port-map agenda) port)))
740 (define (stop-on-nothing-to-do agenda)
741 (and (q-empty? (agenda-queue agenda))
742 (schedule-empty? (agenda-schedule agenda))
743 (= 0 (hash-count (const #t) (agenda-read-port-map agenda)))
744 (= 0 (hash-count (const #t) (agenda-write-port-map agenda)))
745 (= 0 (hash-count (const #t) (agenda-except-port-map agenda)))))
748 (define* (start-agenda agenda
750 ;; @@: Should we make stop-on-nothing-to-do
751 ;; the default stop-condition?
752 (stop-condition stop-on-nothing-to-do)
753 (get-time gettimeofday)
754 (handle-ports update-agenda-from-select!)
755 ;; For live hacking madness, etc
757 ;; TODO: Document fields
758 "Start up the AGENDA"
759 (let loop ((agenda agenda))
761 ;; @@: Hm, maybe here would be a great place to handle
762 ;; select'ing on ports.
763 ;; We could compose over agenda-run-once and agenda-read-ports
764 (agenda-run-once agenda)))
765 ;; @@: This relies on mutation at present on the queue, in the rare
766 ;; event it's used. If we ever switch to something more immutable,
767 ;; it should return a new modified agenda instead.
769 (post-run-hook agenda))
770 (if (and stop-condition (stop-condition agenda))
773 ;; We have to update the time after ports handled, too
774 ;; because it may have changed after a select
777 ;; Adjust the agenda's time just in time
778 ;; We do this here rather than in agenda-run-once to make
779 ;; agenda-run-once's behavior fairly predictable
780 (set-field agenda (agenda-time) (get-time)))
781 (agenda-time) (get-time))))
782 ;; Update the agenda's current queue based on
783 ;; currently applicable time segments
784 (add-segments-contents-to-queue!
785 (schedule-extract-until! (agenda-schedule agenda) (agenda-time agenda))
786 (agenda-queue agenda))
790 (define (print-error-and-continue key . args)
791 "Frequently used as pre-unwind-handler for agenda"
793 ((eq? key '8sync-caught-error)
795 ((orig-key orig-args stacks)
796 (display "\n*** Caught async exception. ***\n")
797 (format (current-error-port)
798 "* Original key '~s and arguments: ~s *\n"
800 (display "* Caught stacks below (ending with original) *\n\n")
803 (display-backtrace s (current-error-port))
804 (newline (current-error-port)))
807 (format (current-error-port)
808 "\n*** Caught exception with key '~s and arguments: ~s ***\n"
810 (display-backtrace (make-stack #t 1 0)
811 (current-error-port))
812 (newline (current-error-port)))))
814 (define-syntax-rule (maybe-catch-all (catch-handler pre-unwind-handler)
816 (if (or catch-handler pre-unwind-handler)
821 (or catch-handler (lambda _ #f))
822 (or pre-unwind-handler (lambda _ #f)))
825 (define (agenda-run-once agenda)
826 "Run once through the agenda, and produce a new agenda
827 based on the results"
828 (define (call-proc proc)
830 (agenda-prompt-tag agenda)
832 (parameterize ((%current-agenda agenda))
834 ((agenda-catch-handler agenda)
835 (agenda-pre-unwind-handler agenda))
837 (lambda (kont async-request)
838 (setup-async-request kont async-request))))
840 (let ((queue (agenda-queue agenda))
841 (next-queue (make-q)))
842 (while (not (q-empty? queue))
843 (let* ((proc (q-pop! queue))
844 (proc-result (call-proc proc))
846 (lambda (run-request)
847 (define (schedule-at! time proc)
848 (schedule-add! (agenda-schedule agenda) time proc))
849 (let ((request-time (run-request-when run-request)))
851 ((? time-delta? time-delta)
852 (let ((time (time-delta+ (agenda-time agenda)
854 (schedule-at! time (run-request-proc run-request))))
856 (let ((time (cons sec 0)))
857 (schedule-at! time (run-request-proc run-request))))
858 (((? integer? sec) . (? integer? usec))
859 (schedule-at! request-time (run-request-proc run-request)))
861 (enq! next-queue (run-request-proc run-request))))))))
862 (define (handle-individual result)
863 ;; @@: Could maybe optimize by switching to an explicit cond...
865 ((? run-request? new-proc)
867 ((? port-request? port-request)
868 (agenda-handle-port-request! agenda port-request))
869 ((? port-remove-request? port-remove-request)
870 (agenda-handle-port-remove-request! agenda port-remove-request))
873 ;; @@: We might support delay-wrapped procedures here
876 (for-each handle-individual results))
877 (one-result (handle-individual one-result)))))
878 ;; TODO: Alternately, we could return the next-queue
879 ;; along with changes to be added to the schedule here?
880 ;; Return new agenda, with next queue set
881 (set-field agenda (agenda-queue) next-queue)))