racket/collects/frtime/core/frp.rkt
2010-08-26 12:11:00 -04:00

731 lines
26 KiB
Racket

#lang scheme
(require (only-in mzlib/etc
identity nor)
"contract.ss"
"erl.ss"
"heap.ss")
;;;;;;;;;;;;;
;; Globals ;;
;;;;;;;;;;;;;
;; the current logical time step
(define logical-time (box 0))
(define (current-logical-time)
(unbox logical-time))
(define frtime-inspector (make-inspector))
(print-struct #t)
(define snap? (make-parameter #f))
(define named-dependents (make-hash))
(define (compose-continuation-mark-sets2 s1 s2)
s2)
(define (my-ccm)
(current-continuation-marks)
; XXX What is this?
#;(continuation-mark-set->list (current-continuation-marks) 'drscheme-debug-continuation-mark-key))
;;;;;;;;;;;;;;;;
;; Structures ;;
;;;;;;;;;;;;;;;;
; also models events, where 'value' is all the events that
; haven't yet occurred (more specifically, an event-cons cell whose
; tail is *undefined*)
(define-struct signal ([value #:mutable]
[dependents #:mutable]
[stale? #:mutable]
[thunk #:mutable]
[depth #:mutable]
[continuation-marks #:mutable]
parameterization
[producers #:mutable])
#:inspector frtime-inspector
#:property prop:procedure
(lambda (fn . args)
(unregister #f fn) ; clear out stale dependencies from previous apps
(let* (; revisit error-reporting for switched behaviors
[ccm (my-ccm)]
[app-fun (lambda (cur-fn)
(let ([res (apply cur-fn args)])
(when (signal? res)
(set-signal-continuation-marks! res ccm))
res))])
(super-lift app-fun fn))))
; XXX Remove
#;(define (signal-custodian sig)
(call-with-parameterization
(signal-parameterization sig)
current-cust))
(define-struct ft-cust (signal constructed-sigs children) #:mutable)
(define make-non-scheduled identity)
(define (non-scheduled? x) #f)
(define (non-scheduled-signal x)
(error 'non-scheduled-signal "should never be called"))
(define current-cust
(make-parameter #f))
(define-struct multiple (values)
#:inspector frtime-inspector)
(define-struct event-set (time events))
(define (make-events-now events)
(make-event-set (current-logical-time) events))
(define-struct (signal:unchanged signal) ()
#:inspector frtime-inspector)
(define-struct (signal:compound signal:unchanged) (content copy)
#:inspector frtime-inspector)
(define-struct (signal:switching signal:unchanged) (current trigger)
#:inspector frtime-inspector)
(define-struct (signal:event signal) ()
#:inspector frtime-inspector)
; an external event; contains a list of pairs
; (recip val), where val is passed to recip's thunk
(define-struct external-event (recip-val-pairs))
; update the given signal at the given time
(define-struct alarm (time signal))
(define extra-cont-marks (make-parameter #f))
(define (effective-continuation-marks)
(if (extra-cont-marks)
(begin
; XXX Remove
#;(thread (lambda () (raise (make-exn:fail
"extra marks present!" (extra-cont-marks)))))
(compose-continuation-mark-sets2
(my-ccm)
(extra-cont-marks)
))
(my-ccm)))
;; Simple Structure Combinators
(define (event-receiver)
(event-producer2
(lambda (emit)
(lambda the-args
(if (cons? the-args)
(emit (first the-args))
(make-events-now empty))))))
(define (event-producer2 proc . deps)
(let* ([result (apply proc->signal (lambda args (make-events-now empty)) deps)]
[proc/emit (proc
(lambda (val)
(let ([old-value (signal-value result)])
(make-events-now
(if (and (event-set? old-value)
(= (current-logical-time) (event-set-time old-value)))
(append (event-set-events old-value) (list val))
(list val))))))])
(set-signal-thunk! result proc/emit)
result))
(define (build-signal ctor thunk producers)
(let ([ccm (effective-continuation-marks)])
(do-in-manager
(let* ([cust (current-cust)]
[cust-sig (and cust (ft-cust-signal cust))]
[sig (ctor
undefined empty #t thunk
(add1 (apply max 0 (cons (safe-signal-depth cust-sig) (map safe-signal-depth producers))))
ccm
(parameterize ([uncaught-exception-handler
(lambda (exn) (exn-handler exn))]
[extra-cont-marks ccm])
(current-parameterization))
(if cust-sig (append producers (list cust-sig)) producers))])
(when (cons? producers)
(register sig producers))
(when cust-sig
(register (make-non-scheduled sig) cust-sig))
(when cust
(set-ft-cust-constructed-sigs! cust (cons (make-weak-box sig) (ft-cust-constructed-sigs cust))))
(iq-enqueue sig)
sig))))
(define (proc->signal:switching thunk current-box trigger . producers)
(let ([ccm (effective-continuation-marks)])
(do-in-manager
(let* ([cust (current-cust)]
[cust-sig (and cust (ft-cust-signal cust))]
[sig (make-signal:switching
undefined empty #t thunk
(add1 (apply max 0 (cons (safe-signal-depth cust-sig) (map safe-signal-depth producers))))
ccm
(parameterize ([uncaught-exception-handler
(lambda (exn) (exn-handler exn))]
[extra-cont-marks ccm])
(current-parameterization))
(if cust-sig (cons cust-sig producers) producers)
current-box
trigger)])
(when (cons? producers)
(register sig producers))
(when cust-sig
(register (make-non-scheduled sig) cust-sig))
(when cust
(set-ft-cust-constructed-sigs!
cust (cons (make-weak-box sig) (ft-cust-constructed-sigs cust))))
(iq-enqueue sig)
sig))))
(define (proc->signal thunk . producers)
(build-signal make-signal thunk producers))
; XXX Remove
#;(define ht (make-hash))
#;(define (proc->signal/dont-gc-unless other-val thunk . producers)
(let ([result (build-signal make-signal thunk producers)])
(hash-set! ht other-val result)
result))
(define (proc->signal:unchanged thunk . producers)
(build-signal make-signal:unchanged thunk producers))
;;;;;;;;;;;;;;;;;;;;;;;;;
;; Simple Signal Tools ;;
;;;;;;;;;;;;;;;;;;;;;;;;;
(define (send-event rcvr val)
(! man (make-external-event (list (list rcvr val)))))
; XXX move man check into contract
(define (send-synchronous-event rcvr val)
(when (man?)
(error 'send-synchronous-event "already in frtime engine (would deadlock)"))
(! man (make-external-event (list (list rcvr val))))
(do-in-manager '()))
; XXX move man check into contract
(define (send-synchronous-events rcvr-val-pairs)
(when (man?)
(error 'send-synchronous-events "already in frtime engine (would deadlock)"))
(! man (make-external-event rcvr-val-pairs))
(do-in-manager '()))
; set-cell! : cell[a] a -> void
(define (set-cell! ref beh)
(if (man?)
(iq-enqueue (list ((signal-thunk ref) #t) beh))
(! man (make-external-event (list (list ((signal-thunk ref) #t) beh))))))
(define-values (undefined undefined?)
(let ()
(define-struct undefined ()
#:inspector frtime-inspector
#:property prop:procedure (lambda (fn . args) fn))
(values (make-undefined) undefined?)))
(define (behavior? v)
(and (signal? v) (not (event-set? (signal-value v)))))
(define (undef b)
(match b
[(and (? signal?)
(app signal-value value))
(set-signal-stale?! b #f)
(when (not (undefined? value))
(set-signal-value! b undefined)
(propagate b))]
[_ (void)]))
(define (multiple->values v)
(if (multiple? v)
(apply values (multiple-values v))
v))
(define (values->multiple proc)
(call-with-values
proc
(case-lambda
[(v) v]
[vals (make-multiple vals)])))
; value-now : signal[a] -> a
(define (value-now val)
;(multiple->values
(cond
[(signal:compound? val) ((signal:compound-copy val))]
[(signal:switching? val) (value-now (unbox (signal:switching-current val)))]
[(signal? val) (signal-value val)]
[else val]));)
(define (value-now/no-copy val)
;(multiple->values
(cond
[(signal:switching? val) (value-now/no-copy (unbox (signal:switching-current val)))]
[(signal? val) (signal-value val)]
[else val]));)
;; given a list, will return a list of their value-nows that will agree
(define (value-now/sync . sigs)
(do-in-manager-after
(apply values (map value-now sigs))))
(define (kill-signal sig)
(for-each
(lambda (prod)
(unregister sig prod))
(signal-producers sig))
(set-signal-thunk! sig (lambda _ 'really-dead))
(set-signal-value! sig 'dead)
(set-signal-dependents! sig empty)
(set-signal-producers! sig empty))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Dataflow Graph Maintenance ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (safe-signal-depth v)
(cond
[(signal? v) (signal-depth v)]
[(non-scheduled? v) (signal-depth (non-scheduled-signal v))]
[else 0]))
(define fix-depths
(lambda (inf sup [mem empty])
(if (memq sup mem)
(send-event exceptions (list (make-exn:fail "tight cycle in dataflow graph" (signal-continuation-marks sup))
sup))
(when (<= (safe-signal-depth inf)
(safe-signal-depth sup))
(set-signal-depth! inf (add1 (safe-signal-depth sup)))
(for-each
(lambda (dep) (fix-depths dep inf (cons sup mem)))
(foldl (lambda (wb acc)
(match (weak-box-value wb)
[(and sig (? signal?)) (cons sig acc)]
[(and (? non-scheduled?) (app non-scheduled-signal sig)) (cons sig acc)]
[_ acc]))
empty (signal-dependents inf)))))))
(define-values (iq-enqueue iq-dequeue iq-empty? iq-resort)
(let* ([depth
(lambda (msg)
(let ([msg (if (weak-box? msg) (weak-box-value msg) msg)])
(cond
[(cons? msg) (signal-depth (first msg))]
[(signal? msg) (signal-depth msg)]
[else 0])))]
[heap (make-heap
(lambda (b1 b2) (< (depth b1) (depth b2)))
eq?)])
(values
(lambda (b) (heap-insert heap b))
(lambda () (let ([v (heap-pop heap)])
(if (weak-box? v)
(weak-box-value v)
v)))
(lambda () (heap-empty? heap))
(lambda () (let loop ([elts empty])
(if (heap-empty? heap)
(let loop ([elts elts])
(when (cons? elts)
(heap-insert heap (first elts))
(loop (rest elts))))
(loop (cons (heap-pop heap) elts))))))))
(define-values (alarms-enqueue alarms-dequeue-beh alarms-peak-ms alarms-empty?)
(let ([heap (make-heap (lambda (a b) (< (first a) (first b))) eq?)])
(values (lambda (ms beh) (heap-insert heap (list ms (make-weak-box beh))))
(lambda () (match (heap-pop heap) [(list _ beh) (weak-box-value beh)]))
(lambda () (match (heap-peak heap) [(list ms _) ms]))
(lambda () (heap-empty? heap)))))
(define (schedule-alarm ms beh)
(if (eq? (self) man)
(alarms-enqueue ms beh)
(! man (make-alarm ms beh))))
;;;;;;;;;;;;;;;;;;;;;
;; Manager Helpers ;;
;;;;;;;;;;;;;;;;;;;;;
(define man?
(lambda ([v (self)])
(eq? v man)))
(define-syntax do-in-manager
(syntax-rules ()
[(_ expr ...)
(if (man?)
(begin expr ...)
(begin
(! man (list 'run-thunk (self)
(let ([params (current-parameterization)])
(lambda ()
(call-with-parameterization
params
(lambda () expr ...))))))
(receive [(list-rest 'vals vs) (apply values vs)]
[(list 'exn e) (raise e)])))]))
(define-syntax do-in-manager-after
(syntax-rules ()
[(_ expr ...)
(if (man?)
(begin expr ...)
(begin
(! man (list 'run-thunk/stabilized (self)
(let ([params (current-parameterization)])
(lambda ()
(call-with-parameterization
params
(lambda () expr ...))))))
(receive [(list-rest 'vals vs) (apply values vs)]
[(list 'exn e) (raise e)])))]))
(define (register inf sup)
(do-in-manager
(match sup
[(and (? signal?)
(app signal-dependents dependents))
(set-signal-dependents!
sup
(cons (make-weak-box inf) dependents))
(fix-depths inf sup)]
[(? list?) (for-each (lambda (sup1) (register inf sup1)) sup)]
[_ (void)])
inf))
(define (unregister inf sup)
(do-in-manager
(match sup
[(and (? signal?)
(app signal-dependents dependents))
(set-signal-dependents!
sup
(filter (lambda (a)
(let ([v (weak-box-value a)])
(nor (eq? v inf)
(eq? v #f))))
dependents))]
[_ (void)])))
(define (cust-killall! cust)
(let loop ([sigs (ft-cust-constructed-sigs cust)])
(when (cons? sigs)
(cond
[(weak-box-value (first sigs)) => kill-signal]
[else (void)])
(loop (rest sigs))))
(for-each cust-killall! (ft-cust-children cust)))
(define (super-lift fun bhvr)
(if (behavior? bhvr)
(parameterize ([extra-cont-marks
(effective-continuation-marks)])
(do-in-manager
(let* ([cust (make-ft-cust (void) empty empty)]
[_ (cond
[(current-cust)
=> (lambda (c) (set-ft-cust-children! c (cons cust (ft-cust-children c))))]
[else (void)])]
[pfun (lambda (b)
(parameterize ([current-cust cust])
(fun b)))]
[current (box undefined)])
(letrec ([custodian-signal
(proc->signal:unchanged
(lambda ()
(cust-killall! cust)
(set-ft-cust-constructed-sigs! cust empty)
(set-ft-cust-children! cust empty)
(unregister rtn (unbox current))
(set-box! current (pfun (value-now/no-copy bhvr)))
(register rtn (unbox current))
;; keep rtn's producers up-to-date
(set-signal-producers! rtn (cons (unbox current)
(cdr (signal-producers rtn))))
(iq-resort)
'custodian)
bhvr)]
[rtn (proc->signal:switching
(lambda () custodian-signal (value-now/no-copy (unbox current)))
current custodian-signal undefined bhvr custodian-signal)])
(set-ft-cust-signal! cust custodian-signal)
rtn))))
(fun bhvr)))
(define (propagate b)
(let ([empty-boxes 0]
[dependents (signal-dependents b)]
[depth (signal-depth b)])
(for-each
(lambda (wb)
(match (weak-box-value wb)
[(and dep (? signal?) (app signal-stale? #f))
(set-signal-stale?! dep #t)
; If I'm crossing a "back" edge (one potentially causing a cycle),
; then I send a message. Otherwise, I add to the internal
; priority queue.
(if (< depth (signal-depth dep))
(iq-enqueue wb)
(! man dep))]
[_
(set! empty-boxes (add1 empty-boxes))]))
dependents)
(when (> empty-boxes 9)
(set-signal-dependents!
b
(filter weak-box-value dependents)))))
(define (update0 b)
(match b
[(and (? signal?)
(app signal-value value)
(app signal-thunk thunk)
(app signal-parameterization params))
(set-signal-stale?! b #f)
(let ([new-value (call-with-parameterization
params
thunk)])
(when (or (signal:unchanged? b)
(and (not (eq? value new-value))
(or (not (event-set? new-value)) (cons? (event-set-events new-value))
(not (event-set? value)))))
(begin
(set-signal-value! b new-value)
(propagate b))))]
[_ (void)]))
(define (update1 b a)
(match b
[(and (? signal?)
(app signal-value value)
(app signal-thunk thunk))
(set-signal-stale?! b #f)
(let ([new-value (thunk a)])
(when (not (equal? value new-value))
(set-signal-value! b new-value)
(propagate b)))]
[_ (void)]))
(define (signal-count)
(! man `(stat ,(self)))
(receive [n n]))
(define (hash-table-size ht)
(let ([x 0])
(hash-for-each ht (lambda (k v)
(when k (set! x (add1 x)))))
x))
(define exn-handler (lambda (exn) (raise exn)))
;;;;;;;;;;;;;
;; Manager ;;
;;;;;;;;;;;;;
;; the manager of all signals
(define man
(spawn/name
'frtime-heart
(let* ([named-providers (make-hash)]
[cur-beh #f]
[signal-cache (make-weak-hash)]
[last-known-signal-count 50]
[notifications empty]
;; added for run-thunk/stablized
[thunks-to-run empty]
[do-and-queue (lambda (pid thnk)
(with-handlers
([exn:fail? (lambda (exn)
(set! notifications
(cons (list pid 'exn exn)
notifications)))])
(set! notifications
(cons (list* pid 'vals (call-with-values thnk list))
notifications))))])
(let outer ()
(with-handlers ([exn:fail?
(lambda (exn)
(when cur-beh
(set! exn (make-exn:fail
(exn-message exn)
(compose-continuation-mark-sets2
(signal-continuation-marks
cur-beh)
(exn-continuation-marks exn))));)
(iq-enqueue (list exceptions (list exn cur-beh)))
(when (behavior? cur-beh)
(undef cur-beh)))
(outer))])
(set! exn-handler (uncaught-exception-handler))
(let inner ()
;; process external messages until there is an internal update
;; or an expired alarm
(let loop ()
(receive [after (cond
[(not (iq-empty?)) 0]
[(not (alarms-empty?)) (- (alarms-peak-ms)
(current-inexact-milliseconds))]
[else #f])
(void)]
[(? signal? b)
(iq-enqueue b)
(loop)]
[(struct external-event (recip-val-pairs))
(for-each iq-enqueue recip-val-pairs)
(loop)]
[(struct alarm (ms beh))
(schedule-alarm ms beh)
(loop)]
[(list 'run-thunk rtn-pid thunk)
(begin
(do-and-queue rtn-pid thunk)
(loop))]
;; !Experimental!
;; queues thunks to be evaluated after this round of computation,
;; but before the next round
[(list 'run-thunk/stabilized rtn-pid thunk)
(begin
(set! thunks-to-run (cons (list rtn-pid thunk) thunks-to-run))
(loop))]
[(list 'stat rtn-pid)
(! rtn-pid (hash-table-size signal-cache))]
[(list 'remote-reg tid sym)
(let ([f+l (hash-ref named-providers sym)])
(when (not (member tid (mcdr f+l)))
(set-mcdr! f+l (cons tid (mcdr f+l)))))
(loop)]
[(list 'remote-evt sym val)
(iq-enqueue
(list (hash-ref named-dependents sym (lambda () dummy)) val))
(loop)]
[msg
(fprintf (current-error-port)
"frtime engine: msg not understood: ~a\n"
msg)
(loop)]))
;; enqueue expired timers for execution
(let loop ()
(unless (or (alarms-empty?)
(< (current-inexact-milliseconds)
(alarms-peak-ms)))
(let ([beh (alarms-dequeue-beh)])
(when (and beh (not (signal-stale? beh)))
(set-signal-stale?! beh #t)
(iq-enqueue beh)))
(loop)))
;; process internal updates
(let loop ()
(unless (iq-empty?)
(match (iq-dequeue)
[(list b val)
(set! cur-beh b)
(update1 b val)
(set! cur-beh #f)]
[b
(set! cur-beh b)
(update0 b)
(hash-ref signal-cache b (lambda () (hash-set! signal-cache b #t)))
(set! cur-beh #f)])
(loop)))
;; do the run-thunk/stabalized; use existing notification mechanism
(for-each (lambda (pair)
(do-and-queue (first pair) (second pair)))
thunks-to-run)
(for-each (lambda (lst)
(! (first lst) (rest lst)))
notifications)
(set! notifications empty)
(set! thunks-to-run empty)
(set-box! logical-time (add1 (unbox logical-time)))
(inner)))))))
(define exceptions (event-receiver))
(define dummy (proc->signal void))
(provide do-in-manager
do-in-manager-after)
(define thunk/c
(unconstrained-domain-> any/c)) ; XXX Not really thunk
(define producers/c
(listof any/c)) ; XXX bad
(define switching-current/c
(box/c any/c)) ; XXX
(define switching-trigger/c
any/c)
(provide/contract*
; Event Sets
[make-events-now ((listof any/c) . -> . event-set?)] ; XXX Ugly contract
[event-set? (any/c . -> . boolean?)]
[event-set-time (event-set? . -> . number?)]
[event-set-events (event-set? . -> . (listof any/c))] ; XXX Ugly contract
; Undefined
[undefined undefined?]
[undefined? (any/c . -> . boolean?)]
; Signals
[proc->signal ((thunk/c) () #:rest producers/c . ->* . signal?)]
[signal? (any/c . -> . boolean?)]
[signal-value (signal? . -> . any/c)]
[set-signal-value! (signal? any/c . -> . void)]
[signal-depth (signal? . -> . exact-nonnegative-integer?)]
[set-signal-depth! (signal? exact-nonnegative-integer? . -> . void)]
[set-signal-producers! (signal? producers/c . -> . void)]
[signal-thunk (signal? . -> . thunk/c)]
[set-signal-thunk! (signal? thunk/c . -> . void)]
[signal-count (-> exact-nonnegative-integer?)]
; Signal : Compound
[signal:compound? (any/c . -> . boolean?)]
[signal:compound-content (signal:compound? . -> . cons?)] ; XXX Ugly contract on codomain
; Signal : Switching
[proc->signal:switching ((thunk/c switching-current/c switching-trigger/c) () #:rest producers/c . ->* . signal:switching?)]
[signal:switching? (any/c . -> . boolean?)]
[signal:switching-current (signal:switching? . -> . switching-current/c)]
[signal:switching-trigger (signal:switching? . -> . switching-trigger/c)]
; Input queue
[iq-enqueue (any/c . -> . void)] ; XXX Not sure what any/c should be
[iq-resort (-> void)]
; Events
[send-event (signal? any/c . -> . void)]
[send-synchronous-event (signal? any/c . -> . void)]
[send-synchronous-events ((listof (cons/c signal? (listof any/c))) . -> . void)]
[event-receiver (-> signal?)]
[event-producer2 ((thunk/c) () #:rest producers/c . ->* . signal?)]
; Other
[register (signal? any/c . -> . void)] ; XXX Ugly contract
[unregister (signal? any/c . -> . void)] ; XXX Ugly contract
[current-logical-time (-> exact-nonnegative-integer?)]
[snap? (parameter/c boolean?)]
[super-lift ((any/c . -> . any/c) any/c . -> . any/c)] ; XXX Ugly contract
[behavior? (any/c . -> . boolean?)]
[value-now (any/c . -> . any/c)] ; XXX Should this return (not/c signal?) and why not take signal?
[value-now/sync (() () #:rest (listof any/c) . ->* . any)] ; XXX See above + not matching number of values returned with number of signals
[value-now/no-copy (any/c . -> . any/c)] ; XXX Should this return (not/c signal?) and why not take signal?
[safe-signal-depth (any/c . -> . exact-nonnegative-integer?)] ; XXX Ugly contract
[schedule-alarm (number? signal? . -> . void)]
[set-cell! (signal? any/c . -> . void)] ; XXX What is any/c?
[exceptions signal?])