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;;;; "process.scm", Multi-Processing for Scheme
;;; Copyright (C) 1992, 1993 Aubrey Jaffer.
;
;Permission to copy this software, to redistribute it, and to use it
;for any purpose is granted, subject to the following restrictions and
;understandings.
;
;1. Any copy made of this software must include this copyright notice
;in full.
;
;2. I have made no warrantee or representation that the operation of
;this software will be error-free, and I am under no obligation to
;provide any services, by way of maintenance, update, or otherwise.
;
;3. In conjunction with products arising from the use of this
;material, there shall be no use of my name in any advertising,
;promotional, or sales literature without prior written consent in
;each case.
(require 'full-continuation)
(require 'queue)
(define (add-process! thunk1)
(cond ((procedure? thunk1)
(defer-ints)
(enqueue! process:queue thunk1)
(allow-ints))
(else (slib:error "add-process!: wrong type argument " thunk1))))
(define (process:schedule!)
(defer-ints)
(cond ((queue-empty? process:queue) (allow-ints)
'still-running)
(else (call-with-current-continuation
(lambda (cont)
(enqueue! process:queue cont)
(let ((proc (dequeue! process:queue)))
(allow-ints)
(proc 'run))
(kill-process!))))))
(define (kill-process!)
(defer-ints)
(cond ((queue-empty? process:queue) (allow-ints)
(slib:exit))
(else (let ((proc (dequeue! process:queue)))
(allow-ints)
(proc 'run))
(kill-process!))))
(define ints-disabled #f)
(define alarm-deferred #f)
(define (defer-ints) (set! ints-disabled #t))
(define (allow-ints)
(set! ints-disabled #f)
(cond (alarm-deferred
(set! alarm-deferred #f)
(alarm-interrupt))))
;;; Make THE process queue.
(define process:queue (make-queue))
(define (alarm-interrupt)
(alarm 1)
(if ints-disabled (set! alarm-deferred #t)
(process:schedule!)))
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