X-Git-Url: https://jxself.org/git/?a=blobdiff_plain;f=loopy.scm;h=1c26a2f3b211a31d48c4746e70edd6901c31b4de;hb=ceed07c211d0ca9812bf36eff48a2692edc7b5eb;hp=a77b7927d835886527c999168a6d5dfd1b87a195;hpb=54436fdab23d09ee5e0c8976e584a32a3c0eca34;p=8sync.git

diff --git a/loopy.scm b/loopy.scm
index a77b792..1c26a2f 100644
--- a/loopy.scm
+++ b/loopy.scm
@@ -1,30 +1,441 @@
-(use-modules (srfi srfi-9)
-             (srfi srfi-9 gnu)
-             (ice-9 q)
-             (ice-9 match))
+(define-module (loopy agenda)
+  #:use-module (srfi srfi-1)
+  #: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 (<agenda>
+            make-agenda agenda?
+            agenda-queue agenda-prompt-tag
+            agenda-read-port-map agenda-write-port-map agenda-except-port-map
+            agenda-schedule
+            
+            make-async-prompt-tag
+
+            <time-segment>
+            make-time-segment time-segment?
+            time-segment-time time-segment-queue
+
+            time< time= time<= time-delta+
+            time-minus time-plus
+
+            <time-delta>
+            make-time-delta tdelta time-delta?
+            time-delta-sec time-delta-usec
+
+            <schedule>
+            make-schedule schedule?
+            schedule-add! schedule-empty?
+            schedule-segments
+            schedule-soonest-time
+
+            schedule-segments-split schedule-extract-until!
+            add-segments-contents-to-queue!
+
+            <run-request>
+            make-run-request run-request?
+            run-request-proc run-request-when
+
+            run-it wrap run run-at delay
+
+            %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)
+  (make-agenda-intern queue prompt-tag
+                      read-port-map write-port-map except-port-map
+                      schedule time)
   agenda?
   (queue agenda-queue)
-  (prompt-tag agenda-prompt-tag))
+  (prompt-tag agenda-prompt-tag)
+  (read-port-map agenda-read-port-map)
+  (write-port-map agenda-write-port-map)
+  (except-port-map agenda-except-port-map)
+  (schedule agenda-schedule)
+  (time agenda-time))
 
 (define (make-async-prompt-tag)
   (make-prompt-tag "prompt"))
 
 (define* (make-agenda #:key
                       (queue (make-q))
-                      (prompt (make-prompt-tag)))
-  (make-agenda-intern queue prompt))
+                      (prompt (make-prompt-tag))
+                      (read-port-map (make-hash-table))
+                      (write-port-map (make-hash-table))
+                      (except-port-map (make-hash-table))
+                      (schedule (make-schedule))
+                      (time (gettimeofday)))
+  ;; TODO: document arguments
+  "Make a fresh agenda."
+  (make-agenda-intern queue prompt
+                      read-port-map write-port-map except-port-map
+                      schedule time))
+
+
+
+;;; Schedule
+;;; ========
+
+;;; This is where we handle timed events for the future
+
+;; This section totally borrows from the ideas in 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)
+  "Ensure TIME is in the right format.
+
+The right format means (second . microsecond).
+If an integer, will convert appropriately."
+  ;; TODO: add floating point / rational number support.
+  (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 a time segment of TIME and QUEUE
+
+No automatic conversion is done, so you might have to
+run (time-segment-right-format) first."
+  (make-time-segment-intern time queue))
+
+(define (time< time1 time2)
+  "Check if TIME1 is less than TIME2"
+  (cond ((< (car time1)
+            (car time2))
+         #t)
+        ((and (= (car time1)
+                 (car time2))
+              (< (cdr time1)
+                 (cdr time2)))
+         #t)
+        (else #f)))
+
+(define (time= time1 time2)
+  "Check whether TIME1 and TIME2 are equivalent"
+  (and (= (car time1) (car time2))
+       (= (cdr time1) (cdr time2))))
+
+(define (time<= time1 time2)
+  "Check if TIME1 is less than or equal to TIME2"
+  (or (time< time1 time2)
+      (time= time1 time2)))
+
+
+(define-record-type <time-delta>
+  (make-time-delta-intern sec usec)
+  time-delta?
+  (sec time-delta-sec)
+  (usec time-delta-usec))
+
+(define* (make-time-delta sec #:optional (usec 0))
+  "Make a <time-delta> of SEC seconds and USEC microseconds.
+
+This is used primarily so the agenda can recognize RUN-REQUEST objects
+which are meant "
+  (make-time-delta-intern sec usec))
+
+(define tdelta make-time-delta)
+
+(define (time-carry-correct time)
+  "Corrects/handles time microsecond carry.
+Will produce (0 . 0) instead of a negative number, if needed."
+  (cond ((>= (cdr time) 1000000)
+         (cons
+          (+ (car time) 1)
+          (- (cdr time) 1000000)))
+        ((< (cdr time) 0)
+         (if (= (car time) 0)
+             '(0 0)
+             (cons
+              (- (car time) 1)
+              (+ (cdr time) 1000000))))
+        (else time)))
+
+(define (time-delta+ time time-delta)
+  "Increment a TIME by the value of TIME-DELTA"
+  (time-carry-correct
+   (cons (+ (car time) (time-delta-sec time-delta))
+         (+ (cdr time) (time-delta-usec time-delta)))))
+
+(define (time-minus time1 time2)
+  "Subtract TIME2 from TIME1"
+  (time-carry-correct
+   (cons (- (car time1) (car time2))
+         (- (cdr time2) (cdr time2)))))
+
+(define (time-plus time1 time2)
+  "Add TIME1 and TIME2"
+  (time-carry-correct
+   (cons (+ (car time1) (car time2))
+         (+ (cdr time2) (cdr time2)))))
+
+
+(define-record-type <schedule>
+  (make-schedule-intern segments)
+  schedule?
+  (segments schedule-segments set-schedule-segments!))
+
+(define* (make-schedule #:optional segments)
+  "Make a schedule, optionally pre-composed of SEGMENTS"
+  (make-schedule-intern (or segments '())))
+
+(define (schedule-soonest-time schedule)
+  "Return a cons of (sec . usec) for next time segement, or #f if none"
+  (let ((segments (schedule-segments schedule)))
+    (if (eq? segments '())
+        #f
+        (time-segment-time (car 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! schedule time proc)
+  "Mutate SCHEDULE, adding PROC at an appropriate time segment for TIME"
+  (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)
+  "Check if the SCHEDULE is currently empty"
+  (eq? (schedule-segments schedule) '()))
+
+(define (schedule-segments-split 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-segments-split schedule time)
+    (set-schedule-segments! schedule segments-after)
+    segments-before))
+
+(define (add-segments-contents-to-queue! segments queue)
+  (for-each
+   (lambda (segment)
+     (let ((seg-queue (time-segment-queue segment)))
+       (while (not (q-empty? seg-queue))
+         (enq! queue (deq! seg-queue)))))
+   segments))
+
+
+
+;;; Request to run stuff
+;;; ====================
+
+(define-immutable-record-type <run-request>
+  (make-run-request proc when)
+  run-request?
+  (proc run-request-proc)
+  (when run-request-when))
+
+(define* (run-it proc #:optional when)
+  "Make a request to run PROC (possibly at WHEN)"
+  (make-run-request proc when))
+
+(define-syntax-rule (wrap body ...)
+  "Wrap contents in a procedure"
+  (lambda ()
+    body ...))
+
+(define-syntax-rule (run body ...)
+  "Run everything in BODY but wrap in a convenient procedure"
+  (make-run-request (wrap body ...) #f))
+
+(define-syntax-rule (run-at body ... when)
+  "Run BODY at WHEN"
+  (make-run-request (wrap body ...) when))
+
+(define-syntax-rule (run-delay body ... delay-time)
+  "Run BODY at DELAY-TIME time from now"
+  (make-run-request (wrap body ...) (tdelta delay-time)))
+
+(define (delay run-request delay-time)
+  "Delay a RUN-REQUEST by DELAY-TIME"
+  (set-field run-request
+             (run-request-when)
+             (tdelta delay-time)))
+
+
+;;; Execution of agenda, and current agenda
+;;; =======================================
 
 (define %current-agenda (make-parameter #f))
 
-(define* (start-agenda agenda #:optional stop-condition)
+(define (update-agenda-from-select! agenda)
+  "Potentially (select) on ports specified in agenda, adding items to queue"
+  (define (hash-keys hash)
+    (hash-map->list (lambda (k v) k) hash))
+  (define (get-wait-time)
+    ;; TODO: we need to figure this out based on whether there's anything
+    ;;   in the queue, and if not, how long till the next scheduled item
+    (let ((soonest-time (schedule-soonest-time (agenda-schedule agenda))))
+      (cond 
+       ((not (q-empty? (agenda-queue agenda)))
+        (cons 0 0))
+       (soonest-time    ; ie, the agenda is non-empty
+        (let* ((current-time (agenda-time agenda)))
+          (if (time<= soonest-time current-time)
+              ;; Well there's something due so let's select
+              ;; (this avoids a (possible?) race condition chance)
+              (cons 0 0)
+              (time-minus soonest-time current-time))))
+       (else
+        (cons #f #f)))))
+  (define (do-select)
+    ;; TODO: support usecond wait time too
+    (match (get-wait-time)
+      ((sec . usec)
+       (select (hash-keys (agenda-read-port-map agenda))
+               (hash-keys (agenda-write-port-map agenda))
+               (hash-keys (agenda-except-port-map agenda))
+               sec usec))))
+  (define (get-procs-to-run)
+    (define (ports->procs ports port-map)
+      (lambda (initial-procs)
+        (fold
+         (lambda (port prev)
+           (cons (lambda ()
+                   ((hash-ref port-map port) port))
+                 prev))
+         initial-procs
+         ports)))
+    (match (do-select)
+      ((read-ports write-ports except-ports)
+       ;; @@: Come on, we can do better than append ;P
+       ((compose (ports->procs
+                  read-ports
+                  (agenda-read-port-map agenda))
+                 (ports->procs
+                  write-ports
+                  (agenda-write-port-map agenda))
+                 (ports->procs
+                  except-ports
+                  (agenda-except-port-map agenda)))
+        '()))))
+  (define (update-agenda)
+    (let ((procs-to-run (get-procs-to-run))
+          (q (agenda-queue agenda)))
+      (for-each
+       (lambda (proc)
+         (enq! q proc))
+       procs-to-run))
+    agenda)
+  (define (ports-to-select?)
+    (define (has-items? selector)
+      ;; @@: O(n)
+      ;;    ... we could use hash-for-each and a continuation to jump
+      ;;    out with a #t at first indication of an item
+      (not (= (hash-count (const #t)
+                          (selector agenda))
+              0)))
+    (or (has-items? agenda-read-port-map)
+        (has-items? agenda-write-port-map)
+        (has-items? agenda-except-port-map)))
+
+  (if (ports-to-select?)
+      (update-agenda)
+      agenda))
+
+
+(define* (start-agenda agenda
+                       #:key stop-condition
+                       (get-time gettimeofday)
+                       (handle-ports update-agenda-from-select!))
+  ;; TODO: Document fields
+  "Start up the AGENDA"
   (let loop ((agenda agenda))
-    (let ((new-agenda   
+    (let ((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
@@ -32,7 +443,22 @@
              (agenda-run-once agenda))))
       (if (and stop-condition (stop-condition agenda))
           'done
-          (loop new-agenda)))))
+          (let* ((agenda
+                  ;; We have to update the time after ports handled, too
+                  ;; because it may have changed after a select
+                  (set-field
+                   (handle-ports
+                    ;; Adjust the agenda's time just in time
+                    ;; We do this here rather than in agenda-run-once to make
+                    ;; agenda-run-once's behavior fairly predictable
+                    (set-field agenda (agenda-time) (get-time)))
+                   (agenda-time) (get-time))))
+            ;; Update the agenda's current queue based on
+            ;; currently applicable time segments
+            (add-segments-contents-to-queue!
+             (schedule-extract-until! (agenda-schedule agenda) (agenda-time agenda))
+             (agenda-queue agenda))
+            (loop agenda))))))
 
 (define (agenda-run-once agenda)
   "Run once through the agenda, and produce a new agenda
@@ -51,17 +477,36 @@ based on the results"
       (let* ((proc (q-pop! queue))
              (proc-result (call-proc proc))
              (enqueue
-              (lambda (new-proc)
-                (enq! next-queue new-proc))))
+              (lambda (run-request)
+                (define (schedule-at! time proc)
+                  (schedule-add! (agenda-schedule agenda) time proc))
+                (let ((request-time (run-request-when run-request)))
+                  (match request-time
+                    ((? time-delta? time-delta)
+                     (let ((time (time-delta+ (agenda-time agenda)
+                                              time-delta)))
+                       (schedule-at! time (run-request-proc run-request))))
+                    ((? integer? sec)
+                     (let ((time (cons sec 0)))
+                       (schedule-at! time (run-request-proc run-request))))
+                    (((? integer? sec) . (? integer? usec))
+                     (schedule-at! request-time (run-request-proc run-request)))
+                    (#f
+                     (enq! next-queue (run-request-proc run-request))))))))
         ;; @@: We might support delay-wrapped procedures here
         (match proc-result
-          ((? procedure? new-proc)
+          ;; TODO: replace procedure with something that indicates
+          ;;   intent to run.  Use a (run foo) procedure
+          ((? run-request? new-proc)
            (enqueue new-proc))
-          (((? procedure? new-procs) ...)
+          (((? run-request? new-procs) ...)
            (for-each
             (lambda (new-proc)
               (enqueue new-proc))
-            new-procs)))))
-    ;; TODO: Selecting on ports would happen here?
+            new-procs))
+          ;; do nothing
+          (_ #f))))
+    ;; TODO: Alternately, we could return the next-queue
+    ;;   along with changes to be added to the schedule here?
     ;; Return new agenda, with next queue set
     (set-field agenda (agenda-queue) next-queue)))