On Sat, 12 Aug 2017 16:17:21 -0700 (PDT), Zelphir Kaltstahl
<zelphirkaltst...@gmail.com> wrote:
>Is it in general not possible to use a place more than once?
No problem. A very simple example is shown below.
This example only demonstrates that places can remain running and
responding to new requests. Real interaction between the coordinator
[main program] and the places [threads] is left as an exercise.
George
##################################################
#lang racket
;==================================
(define place-body
(let [
(output (? (fmt . whatever)
(apply eprintf fmt whatever)
(flush-output (current-error-port))
))
(id #f)
]
(lambda (ch)
(output "place starting~n")
(let/ec done
(let loop [
(msg (place-channel-get ch))
]
(match msg
([list 'init val]
(set! id val)
)
('terminate
(done)
)
(else
(output "place ~s: ~s~n" id msg)
))
(loop (place-channel-get ch))
))
(output "place ~s stopping~n" id)
)))
;==================================
(define my-places (list))
(define (start-places how-many)
(for/list [(i how-many)]
(let [
(p #f)
(_i #f)(_o #f)(_e #f)
]
(set!-values (p _i _o _e)
(place* #:err (current-error-port)
ch
(place-body ch)))
(printf "created place ~s~n" i)
(place-channel-put p (list 'init i ))
p
)))
(define (stop-places lst)
(for [(p lst)]
(place-channel-put p 'terminate)
(place-wait p)
))
;==================================
(define (main)
(set! my-places (start-places 3))
(sleep 1)
(let loop [
(msg (list 'the 'quick 'brown 'fox 'jumped 'over 'the
'lazy 'dogs))
(index 0)
]
(cond
([null? msg])
(else
(place-channel-put (list-ref my-places index) (car msg))
(loop (cdr msg) (remainder (+ index 1) (length my-places)))
))
)
(sleep 1)
(stop-places my-places)
)
##################################################
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