-(use-modules (srfi srfi-9)
- (srfi srfi-9 gnu)
- (ice-9 q)
- (ice-9 match))
+(define-module (loopy agenda)
+ #:use-module (srfi srfi-9)
+ #:use-module (srfi srfi-9 gnu)
+ #:use-module (ice-9 q)
+ #:use-module (ice-9 match)
+ #:export (make-agenda
+ agenda?
+ agenda-queue agenda-prompt-tag
+ agenda-port-pmapping agenda-schedule
+
+ make-async-prompt-tag
+
+ make-time-segment
+ time-segment?
+ time-segment-time time-segment-queue
+
+ time-< time-= time-<=
+
+ make-schedule
+ schedule-add! schedule-empty?
+ schedule-segments
+
+ make-port-mapping
+ port-mapping-set! port-mapping-remove!
+ port-mapping-empty? port-mapping-non-empty?
+
+ %current-agenda
+ start-agenda agenda-run-once))
;; @@: Using immutable agendas here, so wouldn't it make sense to
;; replace this queue stuff with using pfds based immutable queues?
+\f
+;;; Agenda definition
+;;; =================
+
+;;; The agenda consists of:
+;;; - a queue of immediate items to handle
+;;; - sheduled future events to be added to a future queue
+;;; - a tag by which running processes can escape for some asynchronous
+;;; operation (from which they can be returned later)
+;;; - a mapping of ports to various handler procedures
+;;;
+;;; The goal, eventually, is for this all to be immutable and functional.
+;;; However, we aren't there yet. Some tricky things:
+;;; - The schedule needs to be immutable, yet reasonably efficient.
+;;; - Need to use immutable queues (ijp's pfds library?)
+;;; - Modeling reading from ports as something repeatable,
+;;; and with reasonable separation from functional components?
+
(define-immutable-record-type <agenda>
- (make-agenda-intern queue prompt-tag port-mapping)
+ (make-agenda-intern queue prompt-tag port-mapping schedule)
agenda?
(queue agenda-queue)
(prompt-tag agenda-prompt-tag)
- (port-mapping agenda-port-mapping))
+ (port-mapping agenda-port-mapping)
+ (schedule agenda-schedule))
(define (make-async-prompt-tag)
(make-prompt-tag "prompt"))
(define* (make-agenda #:key
(queue (make-q))
(prompt (make-prompt-tag))
- (port-mapping (make-port-mapping)))
- (make-agenda-intern queue prompt port-mapping))
+ (port-mapping (make-port-mapping))
+ (schedule (make-schedule)))
+ (make-agenda-intern queue prompt port-mapping schedule))
+
+
+\f
+;;; Schedule
+;;; ========
+
+;;; This is where we handle timed events for the future
+
+;; This section totally borrows from SICP
+;; <3 <3 <3
+
+;; NOTE: time is a cons of (seconds . microseconds)
+
+(define-record-type <time-segment>
+ (make-time-segment-intern time queue)
+ time-segment?
+ (time time-segment-time)
+ (queue time-segment-queue))
+
+(define (time-segment-right-format time)
+ (match time
+ ;; time is already a cons of second and microsecnd
+ (((? integer? s) . (? integer? u)) time)
+ ;; time was just an integer (just the second)
+ ((? integer? _) (cons time 0))
+ (_ (throw 'invalid-time "Invalid time" time))))
+
+(define* (make-time-segment time #:optional (queue (make-q)))
+ (make-time-segment-intern time queue))
+
+(define (time-< time1 time2)
+ (cond ((< (car time1)
+ (car time2))
+ #t)
+ ((and (= (car time1)
+ (car time2))
+ (< (cdr time1)
+ (cdr time2)))
+ #t)
+ (else #f)))
+
+(define (time-= time1 time2)
+ (and (= (car time1) (car time2))
+ (= (cdr time1) (cdr time2))))
+
+(define (time-<= time1 time2)
+ (or (time-< time1 time2)
+ (time-= time1 time2)))
+
+(define-record-type <schedule>
+ (make-schedule-intern segments)
+ schedule?
+ (segments schedule-segments set-schedule-segments!))
+
+(define* (make-schedule #:optional segments)
+ (make-schedule-intern (or segments '())))
+
+;; TODO: This code is reasonably easy to read but it
+;; mutates AND is worst case of O(n) in both space and time :(
+;; but at least it'll be reasonably easy to refactor to
+;; a more functional setup?
+(define (schedule-add! time proc schedule)
+ (let ((time (time-segment-right-format time)))
+ (define (new-time-segment)
+ (let ((new-segment
+ (make-time-segment time)))
+ (enq! (time-segment-queue new-segment) proc)
+ new-segment))
+ (define (loop segments)
+ (define (segment-equals-time? segment)
+ (time-= time (time-segment-time segment)))
+
+ (define (segment-more-than-time? segment)
+ (time-< time (time-segment-time segment)))
+
+ ;; We could switch this out to be more mutate'y
+ ;; and avoid the O(n) of space... is that over-optimizing?
+ (match segments
+ ;; If we're at the end of the list, time to make a new
+ ;; segment...
+ ('() (cons (make-time-segment time) '()))
+ ;; If the segment's time is exactly our time, good news
+ ;; everyone! Let's append our stuff to its queue
+ (((? segment-equals-time? first) rest ...)
+ (enq! (time-segment-queue first) proc)
+ segments)
+ ;; If the first segment is more than our time,
+ ;; ours belongs before this one, so add it and
+ ;; start consing our way back
+ (((? segment-more-than-time? first) rest ...)
+ (cons (new-time-segment) segments))
+ ;; Otherwise, build up recursive result
+ ((first rest ... )
+ (cons first (loop rest)))))
+ (set-schedule-segments!
+ schedule
+ (loop (schedule-segments schedule)))))
+
+(define (schedule-empty? schedule)
+ (eq? (schedule-segments schedule) '()))
+
+
+\f
+;;; Port handling
+;;; =============
(define (make-port-mapping)
(make-hash-table))
-(define (port-mapping-set! port-mapping port #:optional read write except)
+(define* (port-mapping-set! port-mapping port #:optional read write except)
"Sets port-mapping for reader / writer / exception handlers"
(if (not (or read write except))
(throw 'no-handlers-given "No handlers given for port" port))
"Whether this port-mapping contains any elements"
(not (port-mapping-empty? port-mapping)))
+
+\f
+;;; Execution of agenda, and current agenda
+;;; =======================================
+
(define %current-agenda (make-parameter #f))
(define* (start-agenda agenda #:optional stop-condition)