From: Christopher Allan Webber Date: Sun, 22 Nov 2015 17:33:22 +0000 (-0600) Subject: renamed 8sync directory to eightsync X-Git-Tag: v0.1.0~108 X-Git-Url: https://jxself.org/git/?a=commitdiff_plain;h=9b75050c50d072cc273861f5959c925eb1886ce4;p=8sync.git renamed 8sync directory to eightsync --- diff --git a/8sync/agenda.scm b/8sync/agenda.scm deleted file mode 100644 index 8ffe6f1..0000000 --- a/8sync/agenda.scm +++ /dev/null @@ -1,686 +0,0 @@ -;; Copyright (C) 2015 Christopher Allan Webber - -;; This library is free software; you can redistribute it and/or -;; modify it under the terms of the GNU Lesser General Public -;; License as published by the Free Software Foundation; either -;; version 3 of the License, or (at your option) any later version. -;; -;; This library is distributed in the hope that it will be useful, -;; but WITHOUT ANY WARRANTY; without even the implied warranty of -;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU -;; Lesser General Public License for more details. -;; -;; You should have received a copy of the GNU Lesser General Public -;; License along with this library; if not, write to the Free Software -;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA -;; 02110-1301 USA - -(define-module (eightsync 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 ( - 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 - - - make-time-segment time-segment? - time-segment-time time-segment-queue - - time< time= time<= time-delta+ - time-minus time-plus - - - make-time-delta tdelta time-delta? - time-delta-sec time-delta-usec - - - make-schedule schedule? - schedule-add! schedule-empty? - schedule-segments - schedule-soonest-time - - schedule-segments-split schedule-extract-until! - add-segments-contents-to-queue! - - %sync 8sync - - - make-run-request run-request? - run-request-proc run-request-when - - - make-port-request port-request port-request? - port-request-port - port-request-read port-request-write port-request-except - - run-it wrap run run-at run-delay - - %port-request %run %run-at %run-delay - 8port-request 8run 8run-at 8run-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 - (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) - (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 an async prompt tag for an agenda. - -Generally done automatically for the user through (make-agenda)." - (make-prompt-tag "prompt")) - -(define* (make-agenda #:key - (queue (make-q)) - (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)) - -(define (current-agenda-prompt) - "Get the prompt for the current agenda; signal an error if there isn't one." - (let ((current-agenda (%current-agenda))) - (if (not current-agenda) - (throw - 'no-current-agenda - "Can't get current agenda prompt if there's no current agenda!") - (agenda-prompt-tag current-agenda)))) - - - -;;; 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 - (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 - (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 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 - (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-record-type - (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 ...)) - -;; @@: Do we really want `body ...' here? -;; what about just `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)) - -;; @@: Is it okay to overload the term "delay" like this? -;; Would `run-in' be better? -(define-syntax-rule (run-delay body ... delay-time) - "Run BODY at DELAY-TIME time from now" - (make-run-request (wrap body ...) (tdelta delay-time))) - - -;; A request to set up a port with at least one of read, write, except -;; handling processes - -(define-record-type - (make-port-request-intern port read write except) - port-request? - (port port-request-port) - (read port-request-read) - (write port-request-write) - (except port-request-except)) - -(define* (make-port-request port #:key read write except) - (if (not (or read write except)) - (throw 'no-port-handler-given "No port handler given.\n")) - (make-port-request-intern port read write except)) - -(define port-request make-port-request) - - - -;;; Asynchronous escape to run things -;;; ================================= - -;; The future's in futures - -(define (make-future call-first on-success on-fail on-error) - ;; TODO: add error stuff here - (lambda () - (let ((call-result (call-first))) - ;; queue up calling the - (run (on-success call-result))))) - -(define (agenda-on-error agenda) - (const #f)) - -(define (agenda-on-fail agenda) - (const #f)) - -(define* (request-future call-first on-success - #:key - (agenda (%current-agenda)) - (on-fail (agenda-on-fail agenda)) - (on-error (agenda-on-error agenda)) - (when #f)) - ;; TODO: error handling - ;; do we need some distinction between expected, catchable errors, - ;; and unexpected, uncatchable ones? Probably...? - (make-run-request - (make-future call-first on-success on-fail on-error) - when)) - -(define-syntax-rule (%sync async-request) - "Run BODY asynchronously at a prompt, passing args to make-future. - -Pronounced `eight-sync' despite the spelling. - -%sync was chosen because (async) was already taken and could lead to -errors, and this version of asynchronous code uses a prompt, so the `a' -character becomes a `%' prompt! :) - -The % and 8 characters kind of look similar... hence this library's -name! (That, and the pun 'eight-synchronous' programming.) -There are 8sync aliases if you prefer that name." - (abort-to-prompt (current-agenda-prompt) - async-request)) - -(define-syntax-rule (8sync args ...) - "Alias for %sync" - (%sync args ...)) - -;; Async port request and run-request meta-requests -(define (make-async-request proc) - "Wrap PROC in an async-request - -The purpose of this is to make sure that users don't accidentally -return the wrong thing via (8sync) and trip themselves up." - (cons '*async-request* proc)) - -(define (setup-async-request resume-kont async-request) - "Complete an async request for agenda-run-once's continuation handling" - (match async-request - (('*async-request* . async-setup-proc) - (async-setup-proc resume-kont)) - ;; TODO: deliver more helpful errors depending on what the user - ;; returned - (_ (throw 'invalid-async-request - "Invalid request passed back via an (%sync) procedure." - async-request)))) - -(define-syntax-rule (%run body ...) - (%run-at body ... #f)) - -(define-syntax-rule (%run-at body ... when) - (make-async-request - (lambda (kont) - (make-run-request - (wrap - (kont - (begin body ...))) - when)))) - -(define-syntax-rule (%run-delay body ... delay-time) - (%run-at body ... (tdelta delay-time))) - -(define-syntax-rule (%port-request add-this-port port-request-args ...) - (make-async-request - (lambda (kont) - (list (make-port-request port-request-args ...) - (make-run-request kont))))) - -;; TODO -(define-syntax-rule (%run-with-return return body ...) - (make-async-request - (lambda (kont) - (let ((return kont)) - (lambda () - body ...))))) - -;; Aliases -(define-syntax-rule (8run args ...) (%run args ...)) -(define-syntax-rule (8run-at args ...) (%run-at args ...)) -(define-syntax-rule (8run-delay args ...) (%run-delay args ...)) -(define-syntax-rule (8port-request args ...) (%port-request args ...)) - - - -;;; Execution of agenda, and current agenda -;;; ======================================= - -(define %current-agenda (make-parameter #f)) - -(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 (agenda-handle-port-request! agenda port-request) - "Update an agenda for a port-request" - (define (handle-selector request-selector port-map-selector) - (if (request-selector port-request) - (hash-set! (port-map-selector agenda) - (port-request-port port-request) - (request-selector port-request)))) - (handle-selector port-request-read agenda-read-port-map) - (handle-selector port-request-write agenda-write-port-map) - (handle-selector port-request-except agenda-except-port-map)) - - -(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 ((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 - (agenda-run-once agenda))) - (if (and stop-condition (stop-condition agenda)) - 'done - (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 -based on the results" - (define (call-proc proc) - (call-with-prompt - (agenda-prompt-tag agenda) - (lambda () - (parameterize ((%current-agenda agenda)) - (proc))) - (lambda (kont async-request) - (setup-async-request kont async-request)))) - - (let ((queue (agenda-queue agenda)) - (next-queue (make-q))) - (while (not (q-empty? queue)) - (let* ((proc (q-pop! queue)) - (proc-result (call-proc proc)) - (enqueue - (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)))))))) - (define (handle-individual result) - (match result - ((? run-request? new-proc) - (enqueue new-proc)) - ((? port-request? port-request) - (agenda-handle-port-request! agenda port-request)) - ;; do nothing - (_ #f))) - ;; @@: We might support delay-wrapped procedures here - (match proc-result - ((results ...) - (for-each handle-individual results)) - (one-result (handle-individual one-result))))) - ;; 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))) diff --git a/Makefile.am b/Makefile.am index 4e4883b..c57bf73 100644 --- a/Makefile.am +++ b/Makefile.am @@ -45,7 +45,7 @@ moddir=$(prefix)/share/guile/site/2.0 godir=$(libdir)/guile/2.0/ccache SOURCES = \ - 8sync/agenda.scm + eightsync/agenda.scm TESTS = \ diff --git a/eightsync/agenda.scm b/eightsync/agenda.scm new file mode 100644 index 0000000..8ffe6f1 --- /dev/null +++ b/eightsync/agenda.scm @@ -0,0 +1,686 @@ +;; Copyright (C) 2015 Christopher Allan Webber + +;; This library is free software; you can redistribute it and/or +;; modify it under the terms of the GNU Lesser General Public +;; License as published by the Free Software Foundation; either +;; version 3 of the License, or (at your option) any later version. +;; +;; This library is distributed in the hope that it will be useful, +;; but WITHOUT ANY WARRANTY; without even the implied warranty of +;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +;; Lesser General Public License for more details. +;; +;; You should have received a copy of the GNU Lesser General Public +;; License along with this library; if not, write to the Free Software +;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +;; 02110-1301 USA + +(define-module (eightsync 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 ( + 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 + + + make-time-segment time-segment? + time-segment-time time-segment-queue + + time< time= time<= time-delta+ + time-minus time-plus + + + make-time-delta tdelta time-delta? + time-delta-sec time-delta-usec + + + make-schedule schedule? + schedule-add! schedule-empty? + schedule-segments + schedule-soonest-time + + schedule-segments-split schedule-extract-until! + add-segments-contents-to-queue! + + %sync 8sync + + + make-run-request run-request? + run-request-proc run-request-when + + + make-port-request port-request port-request? + port-request-port + port-request-read port-request-write port-request-except + + run-it wrap run run-at run-delay + + %port-request %run %run-at %run-delay + 8port-request 8run 8run-at 8run-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 + (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) + (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 an async prompt tag for an agenda. + +Generally done automatically for the user through (make-agenda)." + (make-prompt-tag "prompt")) + +(define* (make-agenda #:key + (queue (make-q)) + (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)) + +(define (current-agenda-prompt) + "Get the prompt for the current agenda; signal an error if there isn't one." + (let ((current-agenda (%current-agenda))) + (if (not current-agenda) + (throw + 'no-current-agenda + "Can't get current agenda prompt if there's no current agenda!") + (agenda-prompt-tag current-agenda)))) + + + +;;; 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 + (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 + (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 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 + (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-record-type + (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 ...)) + +;; @@: Do we really want `body ...' here? +;; what about just `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)) + +;; @@: Is it okay to overload the term "delay" like this? +;; Would `run-in' be better? +(define-syntax-rule (run-delay body ... delay-time) + "Run BODY at DELAY-TIME time from now" + (make-run-request (wrap body ...) (tdelta delay-time))) + + +;; A request to set up a port with at least one of read, write, except +;; handling processes + +(define-record-type + (make-port-request-intern port read write except) + port-request? + (port port-request-port) + (read port-request-read) + (write port-request-write) + (except port-request-except)) + +(define* (make-port-request port #:key read write except) + (if (not (or read write except)) + (throw 'no-port-handler-given "No port handler given.\n")) + (make-port-request-intern port read write except)) + +(define port-request make-port-request) + + + +;;; Asynchronous escape to run things +;;; ================================= + +;; The future's in futures + +(define (make-future call-first on-success on-fail on-error) + ;; TODO: add error stuff here + (lambda () + (let ((call-result (call-first))) + ;; queue up calling the + (run (on-success call-result))))) + +(define (agenda-on-error agenda) + (const #f)) + +(define (agenda-on-fail agenda) + (const #f)) + +(define* (request-future call-first on-success + #:key + (agenda (%current-agenda)) + (on-fail (agenda-on-fail agenda)) + (on-error (agenda-on-error agenda)) + (when #f)) + ;; TODO: error handling + ;; do we need some distinction between expected, catchable errors, + ;; and unexpected, uncatchable ones? Probably...? + (make-run-request + (make-future call-first on-success on-fail on-error) + when)) + +(define-syntax-rule (%sync async-request) + "Run BODY asynchronously at a prompt, passing args to make-future. + +Pronounced `eight-sync' despite the spelling. + +%sync was chosen because (async) was already taken and could lead to +errors, and this version of asynchronous code uses a prompt, so the `a' +character becomes a `%' prompt! :) + +The % and 8 characters kind of look similar... hence this library's +name! (That, and the pun 'eight-synchronous' programming.) +There are 8sync aliases if you prefer that name." + (abort-to-prompt (current-agenda-prompt) + async-request)) + +(define-syntax-rule (8sync args ...) + "Alias for %sync" + (%sync args ...)) + +;; Async port request and run-request meta-requests +(define (make-async-request proc) + "Wrap PROC in an async-request + +The purpose of this is to make sure that users don't accidentally +return the wrong thing via (8sync) and trip themselves up." + (cons '*async-request* proc)) + +(define (setup-async-request resume-kont async-request) + "Complete an async request for agenda-run-once's continuation handling" + (match async-request + (('*async-request* . async-setup-proc) + (async-setup-proc resume-kont)) + ;; TODO: deliver more helpful errors depending on what the user + ;; returned + (_ (throw 'invalid-async-request + "Invalid request passed back via an (%sync) procedure." + async-request)))) + +(define-syntax-rule (%run body ...) + (%run-at body ... #f)) + +(define-syntax-rule (%run-at body ... when) + (make-async-request + (lambda (kont) + (make-run-request + (wrap + (kont + (begin body ...))) + when)))) + +(define-syntax-rule (%run-delay body ... delay-time) + (%run-at body ... (tdelta delay-time))) + +(define-syntax-rule (%port-request add-this-port port-request-args ...) + (make-async-request + (lambda (kont) + (list (make-port-request port-request-args ...) + (make-run-request kont))))) + +;; TODO +(define-syntax-rule (%run-with-return return body ...) + (make-async-request + (lambda (kont) + (let ((return kont)) + (lambda () + body ...))))) + +;; Aliases +(define-syntax-rule (8run args ...) (%run args ...)) +(define-syntax-rule (8run-at args ...) (%run-at args ...)) +(define-syntax-rule (8run-delay args ...) (%run-delay args ...)) +(define-syntax-rule (8port-request args ...) (%port-request args ...)) + + + +;;; Execution of agenda, and current agenda +;;; ======================================= + +(define %current-agenda (make-parameter #f)) + +(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 (agenda-handle-port-request! agenda port-request) + "Update an agenda for a port-request" + (define (handle-selector request-selector port-map-selector) + (if (request-selector port-request) + (hash-set! (port-map-selector agenda) + (port-request-port port-request) + (request-selector port-request)))) + (handle-selector port-request-read agenda-read-port-map) + (handle-selector port-request-write agenda-write-port-map) + (handle-selector port-request-except agenda-except-port-map)) + + +(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 ((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 + (agenda-run-once agenda))) + (if (and stop-condition (stop-condition agenda)) + 'done + (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 +based on the results" + (define (call-proc proc) + (call-with-prompt + (agenda-prompt-tag agenda) + (lambda () + (parameterize ((%current-agenda agenda)) + (proc))) + (lambda (kont async-request) + (setup-async-request kont async-request)))) + + (let ((queue (agenda-queue agenda)) + (next-queue (make-q))) + (while (not (q-empty? queue)) + (let* ((proc (q-pop! queue)) + (proc-result (call-proc proc)) + (enqueue + (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)))))))) + (define (handle-individual result) + (match result + ((? run-request? new-proc) + (enqueue new-proc)) + ((? port-request? port-request) + (agenda-handle-port-request! agenda port-request)) + ;; do nothing + (_ #f))) + ;; @@: We might support delay-wrapped procedures here + (match proc-result + ((results ...) + (for-each handle-individual results)) + (one-result (handle-individual one-result))))) + ;; 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)))