349 lines
12 KiB
Racket
349 lines
12 KiB
Racket
#lang racket/base
|
|
|
|
(require racket/set)
|
|
(require racket/match)
|
|
(require racket/list)
|
|
(require "route.rkt")
|
|
(require "gestalt.rkt")
|
|
(require "functional-queue.rkt")
|
|
(require (only-in web-server/private/util exn->string))
|
|
|
|
(provide (struct-out routing-update)
|
|
(struct-out message)
|
|
(struct-out quit)
|
|
(struct-out process)
|
|
(struct-out transition)
|
|
|
|
;; imported from route.rkt:
|
|
?
|
|
wildcard?
|
|
?!
|
|
(struct-out capture)
|
|
pretty-print-matcher
|
|
matcher-key-set
|
|
matcher-key-set/single
|
|
projection->pattern
|
|
|
|
sub
|
|
pub
|
|
gestalt-accepts?
|
|
|
|
spawn
|
|
send
|
|
feedback
|
|
spawn-world
|
|
deliver-event
|
|
transition-bind
|
|
sequence-transitions
|
|
log-events-and-actions?
|
|
routing-implementation)
|
|
|
|
(define pid-stack (make-parameter '()))
|
|
(define log-events-and-actions? (make-parameter #f))
|
|
|
|
;; TODO: support +Inf.0 as a level number
|
|
|
|
;; Events
|
|
(struct routing-update (gestalt) #:prefab)
|
|
(struct message (body meta-level feedback?) #:prefab)
|
|
|
|
;; Actions (in addition to Events)
|
|
;; (spawn is just process)
|
|
(struct quit () #:prefab)
|
|
|
|
;; Intra-world signalling
|
|
(struct pending-routing-update (aggregate affected-subgestalt known-target) #:prefab)
|
|
|
|
;; Actors and Configurations
|
|
(struct process (gestalt behavior state) #:transparent)
|
|
(struct world (next-pid ;; Natural, PID for next-spawned process
|
|
event-queue ;; Queue of Event
|
|
runnable-pids ;; Set of PIDs
|
|
partial-gestalt ;; Gestalt from local processes only; maps to PID
|
|
full-gestalt ;; Union of partial-gestalt and downward-gestalt
|
|
process-table ;; Hash from PID to Process
|
|
downward-gestalt ;; Gestalt representing interests of outside world
|
|
process-actions ;; Queue of (cons PID Action)
|
|
) #:transparent)
|
|
|
|
;; Behavior : maybe event * state -> transition
|
|
(struct transition (state actions) #:transparent)
|
|
|
|
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
|
;; Protocol and utilities
|
|
|
|
(define (sub p #:meta-level [ml 0] #:level [l 0]) (simple-gestalt #f p l ml))
|
|
(define (pub p #:meta-level [ml 0] #:level [l 0]) (simple-gestalt #t p l ml))
|
|
|
|
(define (gestalt-accepts? g m)
|
|
(match-define (message b ml f?) m)
|
|
(not (set-empty? (gestalt-match-value g b ml f?))))
|
|
|
|
(define (spawn behavior state [gestalt (gestalt-empty)]) (process gestalt behavior state))
|
|
(define (send body #:meta-level [ml 0]) (message body ml #f))
|
|
(define (feedback body #:meta-level [ml 0]) (message body ml #t))
|
|
|
|
(define (spawn-world . boot-actions)
|
|
(spawn world-handle-event
|
|
(enqueue-actions (world 0
|
|
(make-queue)
|
|
(set)
|
|
(gestalt-empty)
|
|
(gestalt-empty)
|
|
(hash)
|
|
(gestalt-empty)
|
|
(make-queue))
|
|
-1
|
|
boot-actions)))
|
|
|
|
(define (event? x) (or (routing-update? x) (message? x)))
|
|
(define (action? x) (or (event? x) (process? x) (quit? x)))
|
|
|
|
(define (transition-bind k t0)
|
|
(match-define (transition state0 actions0) t0)
|
|
(match (k state0)
|
|
[(transition state1 actions1) (transition state1 (cons actions0 actions1))]
|
|
[#f t0]))
|
|
|
|
(define (sequence-transitions t0 . steps)
|
|
(foldl transition-bind t0 steps))
|
|
|
|
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
|
;; Trigger guards
|
|
|
|
;; Trigger-guards only pass through routing updates if there has been
|
|
;; a change.
|
|
(struct trigger-guard (gestalt handler state) #:transparent)
|
|
|
|
(define (trigger-guard-handle e s0)
|
|
(match-define (trigger-guard old-gestalt handler old-state) s0)
|
|
(define (deliver s)
|
|
(match (handler e old-state)
|
|
[#f
|
|
(if (eq? s s0) #f (transition s '()))]
|
|
[(transition new-state actions)
|
|
(transition (struct-copy trigger-guard s [state new-state]) actions)]))
|
|
(match e
|
|
[(routing-update new-gestalt)
|
|
(if (equal? new-gestalt old-gestalt)
|
|
#f
|
|
(deliver (struct-copy trigger-guard s0 [gestalt new-gestalt])))]
|
|
[_ (deliver s0)]))
|
|
|
|
(define (trigger-guard-process p)
|
|
(match-define (process _ b s) p)
|
|
(struct-copy process p [behavior trigger-guard-handle] [state (trigger-guard #f b s)]))
|
|
|
|
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
|
;; World implementation
|
|
|
|
;; Each time a world is handed an event from its environment, it:
|
|
;; 1. dispatches events
|
|
;; a. removing them one-at-a-time from the queue
|
|
;; b. dispatching them to processes
|
|
;; c. updating process states and accumulating actions in the queue
|
|
;; d. any process that returned non-#f is considered "non-idle" for step 3.
|
|
;; 2. performs actions
|
|
;; a. removing them one-at-a-time from the queue
|
|
;; b. interpreting them
|
|
;; c. updating world state and accumulating events in the queue
|
|
;; 3. steps non-idle processes
|
|
;; a. runs through the set of processes accumulated in 1d. above
|
|
;; b. any process that returned non-#f is put in the "non-idle" set for next time
|
|
;; 4. yields updated world state and world actions to environment.
|
|
;;
|
|
;; Note that routing-update actions are queued internally as
|
|
;; pending-routing-update structures, in order to preserve and
|
|
;; communicate transient gestalt states to processes. In addition, the
|
|
;; known-target field of a pending-routing-update structure is used to
|
|
;; provide NC's initial gestalt signal to a newly-spawned process.
|
|
;;
|
|
;; TODO: should step 3 occur before step 1?
|
|
|
|
(define (enqueue-actions w pid actions)
|
|
(struct-copy world w
|
|
[process-actions (queue-append-list (world-process-actions w)
|
|
(filter-map (lambda (a) (and (action? a) (cons pid a)))
|
|
(flatten actions)))]))
|
|
|
|
;; The code is written to maintain the runnable-pids set carefully, to
|
|
;; ensure we can locally decide whether we're inert or not without
|
|
;; having to search the whole deep process tree.
|
|
(define (inert? w)
|
|
(and (queue-empty? (world-event-queue w))
|
|
(queue-empty? (world-process-actions w))
|
|
(set-empty? (world-runnable-pids w))))
|
|
|
|
(define (deliver-event e pid p)
|
|
(parameterize ((pid-stack (cons pid (pid-stack))))
|
|
(when (and (log-events-and-actions?) e)
|
|
(log-info "~a: ~v --> ~v ~v"
|
|
(reverse (pid-stack))
|
|
e
|
|
(process-behavior p)
|
|
(if (world? (process-state p))
|
|
"#<world>"
|
|
(process-state p))))
|
|
(with-handlers ([(lambda (exn) #t)
|
|
(lambda (exn)
|
|
(log-error "Process ~a died with exception:\n~a" pid (exn->string exn))
|
|
(transition (process-state p) (list (quit))))])
|
|
(match (with-continuation-mark 'minimart-process
|
|
pid ;; TODO: debug-name, other user annotation
|
|
((process-behavior p) e (process-state p)))
|
|
[#f #f] ;; inert.
|
|
[(? transition? t) t] ;; potentially runnable.
|
|
[x
|
|
(log-error "Process ~a returned non-#f, non-transition: ~v" pid x)
|
|
(transition (process-state p) (list (quit)))]))))
|
|
|
|
(define (mark-pid-runnable w pid)
|
|
(struct-copy world w [runnable-pids (set-add (world-runnable-pids w) pid)]))
|
|
|
|
(define (apply-transition pid t w)
|
|
(match t
|
|
[#f w]
|
|
[(transition new-state new-actions)
|
|
(let* ((w (transform-process pid w
|
|
(lambda (p)
|
|
(when (and (log-events-and-actions?)
|
|
(not (null? (flatten new-actions))))
|
|
(log-info "~a: ~v <-- ~v ~v"
|
|
(reverse (cons pid (pid-stack)))
|
|
new-actions
|
|
(process-behavior p)
|
|
(if (world? new-state)
|
|
"#<world>"
|
|
new-state)))
|
|
(struct-copy process p [state new-state])))))
|
|
(enqueue-actions (mark-pid-runnable w pid) pid new-actions))]))
|
|
|
|
(define (enqueue-event e w)
|
|
(struct-copy world w [event-queue (enqueue (world-event-queue w) e)]))
|
|
|
|
(define (perform-actions w)
|
|
(for/fold ([t (transition (struct-copy world w [process-actions (make-queue)]) '())])
|
|
((entry (in-list (queue->list (world-process-actions w)))))
|
|
(match-define (cons pid a) entry)
|
|
(transition-bind (perform-action pid a) t)))
|
|
|
|
(define (dispatch-events w)
|
|
(transition (for/fold ([w (struct-copy world w [event-queue (make-queue)])])
|
|
((e (in-list (queue->list (world-event-queue w)))))
|
|
(dispatch-event e w))
|
|
'()))
|
|
|
|
(define (transform-process pid w fp)
|
|
(define pt (world-process-table w))
|
|
(match (hash-ref pt pid)
|
|
[#f w]
|
|
[p (struct-copy world w [process-table (hash-set pt pid (fp p))])]))
|
|
|
|
(define (update-full-gestalt w)
|
|
(struct-copy world w [full-gestalt
|
|
(gestalt-union (world-partial-gestalt w) (world-downward-gestalt w))]))
|
|
|
|
(define (issue-local-routing-update w relevant-gestalt known-target)
|
|
(enqueue-event (pending-routing-update (world-full-gestalt w)
|
|
relevant-gestalt
|
|
known-target)
|
|
w))
|
|
|
|
(define (issue-routing-update w relevant-gestalt known-target)
|
|
(transition (issue-local-routing-update w relevant-gestalt known-target)
|
|
(routing-update (drop-gestalt (world-partial-gestalt w)))))
|
|
|
|
(define (apply-and-issue-routing-update w old-gestalt new-gestalt known-target)
|
|
(define new-partial
|
|
(gestalt-union (gestalt-erase-path (world-partial-gestalt w) old-gestalt) new-gestalt))
|
|
(issue-routing-update (update-full-gestalt (struct-copy world w [partial-gestalt new-partial]))
|
|
(gestalt-union old-gestalt new-gestalt)
|
|
known-target))
|
|
|
|
(define ((perform-action pid a) w)
|
|
(match a
|
|
[(? process? new-p)
|
|
(let* ((new-pid (world-next-pid w))
|
|
(new-p (trigger-guard-process new-p))
|
|
(new-gestalt (label-gestalt (process-gestalt new-p) new-pid))
|
|
(new-p (struct-copy process new-p [gestalt new-gestalt]))
|
|
(w (struct-copy world w
|
|
[next-pid (+ new-pid 1)]
|
|
[process-table (hash-set (world-process-table w) new-pid new-p)])))
|
|
(log-info "Spawned process ~a ~v ~v" new-pid (process-behavior new-p) (process-state new-p))
|
|
(apply-and-issue-routing-update w (gestalt-empty) new-gestalt new-pid))]
|
|
[(quit)
|
|
(define pt (world-process-table w))
|
|
(define p (hash-ref pt pid (lambda () #f)))
|
|
(if p
|
|
(let* ((w (struct-copy world w [process-table (hash-remove pt pid)])))
|
|
(log-info "Process ~a terminating; ~a processes remain"
|
|
pid
|
|
(hash-count (world-process-table w)))
|
|
(apply-and-issue-routing-update w (process-gestalt p) (gestalt-empty) pid))
|
|
(transition w '()))]
|
|
[(routing-update gestalt)
|
|
(define pt (world-process-table w))
|
|
(define p (hash-ref pt pid (lambda () #f)))
|
|
(if p
|
|
(let* ((old-gestalt (process-gestalt p))
|
|
(new-gestalt (label-gestalt gestalt pid))
|
|
(new-p (struct-copy process p [gestalt new-gestalt]))
|
|
(w (struct-copy world w [process-table (hash-set pt pid new-p)])))
|
|
(apply-and-issue-routing-update w old-gestalt new-gestalt #f))
|
|
(transition w '()))]
|
|
[(message body meta-level feedback?)
|
|
(if (zero? meta-level)
|
|
(transition (enqueue-event a w) '())
|
|
(transition w (message body (- meta-level 1) feedback?)))]))
|
|
|
|
(define (dispatch-event e w)
|
|
(match e
|
|
[(message body meta-level feedback?)
|
|
(define pids (gestalt-match-value (world-partial-gestalt w) body meta-level feedback?))
|
|
(define pt (world-process-table w))
|
|
(for/fold ([w w]) [(pid (in-set pids))]
|
|
(apply-transition pid (deliver-event e pid (hash-ref pt pid)) w))]
|
|
[(pending-routing-update g affected-subgestalt known-target)
|
|
(define affected-pids (gestalt-match affected-subgestalt g))
|
|
(define pt (world-process-table w))
|
|
(for/fold ([w w]) [(pid (in-set (set-add affected-pids known-target)))]
|
|
(match (hash-ref pt pid (lambda () #f))
|
|
[#f w]
|
|
[p (define g1 (gestalt-filter g (process-gestalt p)))
|
|
(apply-transition pid (deliver-event (routing-update g1) pid p) w)]))]))
|
|
|
|
;; This is roughly the "schedule" rule of the calculus.
|
|
(define (step-children w)
|
|
(define runnable-pids (world-runnable-pids w))
|
|
(if (set-empty? runnable-pids)
|
|
#f ;; world is inert.
|
|
(transition (for/fold ([w (struct-copy world w [runnable-pids (set)])])
|
|
[(pid (in-set runnable-pids))]
|
|
(define p (hash-ref (world-process-table w) pid (lambda () #f)))
|
|
(if (not p) w (apply-transition pid (deliver-event #f pid p) w)))
|
|
'()))) ;; world needs another check to see if more can happen.
|
|
|
|
(define (world-handle-event e w)
|
|
(if (or e (not (inert? w)))
|
|
(sequence-transitions (transition (inject-event e w) '())
|
|
dispatch-events
|
|
perform-actions
|
|
(lambda (w) (or (step-children w) (transition w '()))))
|
|
(step-children w)))
|
|
|
|
(define (inject-event e w)
|
|
(match e
|
|
[#f w]
|
|
[(routing-update g)
|
|
(define old-downward (world-downward-gestalt w))
|
|
(define new-downward (lift-gestalt (label-gestalt g 'out)))
|
|
(issue-local-routing-update (update-full-gestalt
|
|
(struct-copy world w [downward-gestalt new-downward]))
|
|
(gestalt-union old-downward new-downward)
|
|
#f)]
|
|
[(message body meta-level feedback?)
|
|
(enqueue-event (message body (+ meta-level 1) feedback?) w)]))
|
|
|
|
(define routing-implementation 'fastrouting)
|