X-Git-Url: https://jxself.org/git/?a=blobdiff_plain;f=loopy.scm;h=7172e9b57b3a6d7cefcaad6fe29c00248f3c6bd1;hb=7ff622de68d583e0dccc400aa887b8f52c7c592e;hp=0a2cc44820c165ad000406417528fbd1231b35ae;hpb=d8527313ec9a47476020db8e82451746483492ee;p=8sync.git

diff --git a/loopy.scm b/loopy.scm
index 0a2cc44..7172e9b 100644
--- a/loopy.scm
+++ b/loopy.scm
@@ -1,17 +1,63 @@
-(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)
+  #:use-module (ice-9 receive)
+  #: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
+
+            schedule-segments-until schedule-extract-until!
+
+            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?
 
+
+;;; 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"))
@@ -19,13 +65,154 @@
 (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))
+
+
+
+;;; 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 (new-time-segment) '()))
+        ;; 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) '()))
+
+(define (schedule-segments-until schedule time)
+  "Does a multiple value return of time segments before/at and after TIME"
+  (let ((time (time-segment-right-format time)))
+    (define (segment-is-now? segment)
+      (time-= (time-segment-time segment) time))
+    (define (segment-is-before-now? segment)
+      (time-< (time-segment-time segment) time))
+
+    (let loop ((segments-before '())
+               (segments-left (schedule-segments schedule)))
+      (match segments-left
+        ;; end of the line, return
+        ('()
+         (values (reverse segments-before) '()))
+
+        ;; It's right now, so time to stop, but include this one in before
+        ;; but otherwise return
+        (((? segment-is-now? first) rest ...)
+         (values (reverse (cons first segments-before)) rest))
+
+        ;; This is prior or at now, so add it and keep going
+        (((? segment-is-before-now? first) rest ...)
+         (loop (cons first segments-before) rest))
+
+        ;; Otherwise it's past now, just return what we have
+        (segments-after
+         (values segments-before segments-after))))))
+
+(define (schedule-extract-until! schedule time)
+  "Extract all segments until TIME from SCHEDULE, and pop old segments off"
+  (receive (segments-before segments-after)
+      (schedule-split-segments-until schedule time)
+    (set-schedule-segments! schedule segments-after)
+    segments-before))
+
+
+
+;;; 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))
@@ -47,6 +234,11 @@
   "Whether this port-mapping contains any elements"
   (not (port-mapping-empty? port-mapping)))
 
+
+
+;;; Execution of agenda, and current agenda
+;;; =======================================
+
 (define %current-agenda (make-parameter #f))
 
 (define* (start-agenda agenda #:optional stop-condition)