X-Git-Url: https://jxself.org/git/?a=blobdiff_plain;f=loopy.scm;h=96d6a9044a1138ad622aade1c71887638c1639d5;hb=4e11c23676cb1d82d01c4609bdf7639a268da3ce;hp=0f6edc569d5f3a02768096ab05c666816815d4d2;hpb=8ef593dc9802e11f3222ab81e021e8807fd8bdb9;p=8sync.git

diff --git a/loopy.scm b/loopy.scm
index 0f6edc5..96d6a90 100644
--- a/loopy.scm
+++ b/loopy.scm
@@ -1,38 +1,236 @@
-(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
+;;   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)
+  (make-agenda-intern queue prompt-tag port-mapping schedule)
   agenda?
-  (queue agenda-queue))
+  (queue agenda-queue)
+  (prompt-tag agenda-prompt-tag)
+  (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))
+                      (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* (make-agenda #:key (queue (make-q)))
-  (make-agenda-intern queue))
+(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) '()))
+
+
+
+;;; Port handling
+;;; =============
+
+(define (make-port-mapping)
+  (make-hash-table))
+
+(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))
+  (hashq-set! port-mapping port
+              `#(,read ,write ,except)))
+
+(define (port-mapping-remove! port-mapping port)
+  (hashq-remove! port-mapping port))
+
+;; TODO: This is O(n), I'm pretty sure :\
+;; ... it might be worthwhile for us to have a
+;;   port-mapping record that keeps a count of how many
+;;   handlers (maybe via a promise?)
+(define (port-mapping-empty? port-mapping)
+  "Is this port mapping empty?"
+  (eq? (hash-count (const #t) port-mapping) 0))
+
+(define (port-mapping-non-empty? port-mapping)
+  "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)
   (let loop ((agenda agenda))
-    (let ((new-agenda
+    (let ((new-agenda   
+           ;; @@: Hm, maybe here would be a great place to handle
+           ;;   select'ing on ports.
+           ;;   We could compose over agenda-run-once and agenda-read-ports
            (parameterize ((%current-agenda agenda))
              (agenda-run-once agenda))))
-      (if (and stop-condition (stop-condition))
+      (if (and stop-condition (stop-condition agenda))
           'done
           (loop new-agenda)))))
 
 (define (agenda-run-once agenda)
   "Run once through the agenda, and produce a new agenda
 based on the results"
+  (define (call-proc proc)
+    (call-with-prompt
+        (agenda-prompt-tag agenda)
+      (lambda ()
+        (proc))
+      ;; TODO
+      (lambda (k) k)))
+
   (let ((queue (agenda-queue agenda))
         (next-queue (make-q)))
     (while (not (q-empty? queue))
       (let* ((proc (q-pop! queue))
-             (proc-result (proc))
+             (proc-result (call-proc proc))
              (enqueue
               (lambda (new-proc)
                 (enq! next-queue new-proc))))
@@ -44,7 +242,9 @@ based on the results"
            (for-each
             (lambda (new-proc)
               (enqueue new-proc))
-            new-procs)))))
+            new-procs))
+          ;; do nothing
+          (_ #f))))
     ;; TODO: Selecting on ports would happen here?
     ;; Return new agenda, with next queue set
     (set-field agenda (agenda-queue) next-queue)))