148 lines
4.6 KiB
Scheme
148 lines
4.6 KiB
Scheme
; Copyright (c) 1993-1999 by Richard Kelsey and Jonathan Rees. See file COPYING.
|
|
|
|
; The root scheduler.
|
|
;
|
|
; This uses RUN-THREADS-WITH-HOUSEKEEPER from the round-robin scheduler.
|
|
; The housekeeping thread flushes output buffers and wakes any sleeping
|
|
; threads whose time has come.
|
|
|
|
(define (root-scheduler thunk quantum housekeeping-quantum)
|
|
(let ((*result* 111))
|
|
(call-with-current-continuation
|
|
(lambda (abort)
|
|
(initialize-channel-i/o!)
|
|
(run-threads-with-housekeeper (make-root-event-handler
|
|
(lambda () (set! *result* (thunk)))
|
|
quantum
|
|
abort)
|
|
(lambda ()
|
|
(spawn-output-forcers #t)
|
|
(wake-some-threads))
|
|
housekeeping-quantum)
|
|
*result*))))
|
|
|
|
; Returns a handler and a procedure for adding new threads. No events
|
|
; are handled specially. The only upcall is for aborting execution.
|
|
|
|
(define (make-root-event-handler thunk quantum abort)
|
|
(let ((runnable (make-thread-queue))
|
|
(thread-count (make-counter))
|
|
(safe-dynamic-env (with-handler root-handler get-dynamic-env))
|
|
(thread (make-thread thunk
|
|
(get-dynamic-env)
|
|
'scheduler-initial-thread)))
|
|
(increment-counter! thread-count)
|
|
(enqueue-thread! runnable thread)
|
|
(round-robin-event-handler
|
|
runnable quantum safe-dynamic-env thread-count
|
|
(lambda args #f) ; we handle no events
|
|
(lambda (thread token args) ; upcall handler
|
|
(if (eq? token abort-token)
|
|
(abort (car args))
|
|
(propogate-upcall thread token args)))
|
|
root-wait)))
|
|
|
|
; Let the user know if anything goes wrong while running a root thread.
|
|
; Errors kill the offending thread, warnings allow it to proceed.
|
|
|
|
(define (root-handler condition next-handler)
|
|
(let ((out (current-error-port)))
|
|
(cond ((error? condition)
|
|
(display "Error while running root thread, thread killed: " out)
|
|
(display (current-thread) out)
|
|
(newline out)
|
|
(cheap-display-condition condition out)
|
|
(terminate-current-thread))
|
|
((warning? condition)
|
|
(cheap-display-condition condition out)
|
|
(unspecific)) ;proceed
|
|
(else
|
|
(next-handler)))))
|
|
|
|
(define (cheap-display-condition condition out)
|
|
(display (case (car condition)
|
|
((error) "Error")
|
|
((exception) "Exception")
|
|
((warning) "Warning")
|
|
(else (car condition)))
|
|
out)
|
|
(display ": " out)
|
|
(display (cadr condition) out)
|
|
(newline out)
|
|
(for-each (lambda (irritant)
|
|
(display " " out)
|
|
(display irritant out)
|
|
(newline out))
|
|
(cddr condition)))
|
|
|
|
; Upcall token
|
|
|
|
(define abort-token (list 'abort-token))
|
|
|
|
(define scheme-exit-now
|
|
(lambda (status)
|
|
(upcall abort-token status)))
|
|
|
|
; Getting around to calling the VM's WAIT procedure. We disable interrupts
|
|
; to keep things from happening behind our back, and then see if there is
|
|
; any thread to run or any event pending, or if work may appear in the future.
|
|
|
|
(define (root-wait)
|
|
(set-enabled-interrupts! 0)
|
|
(let ((forcers? (spawn-output-forcers #f)))
|
|
(call-with-values
|
|
wake-some-threads
|
|
(lambda (woke-some? time-until-wakeup)
|
|
(cond ((or forcers? woke-some? (event-pending?))
|
|
(set-enabled-interrupts! all-interrupts)
|
|
#t)
|
|
((or time-until-wakeup
|
|
(waiting-for-i/o?))
|
|
(do-some-waiting time-until-wakeup)
|
|
(set-enabled-interrupts! all-interrupts)
|
|
(root-wait))
|
|
((session-data-ref deadlock-handler)
|
|
=> (lambda (handler)
|
|
(handler)
|
|
(set-enabled-interrupts! all-interrupts)
|
|
#t))
|
|
(else
|
|
(set-enabled-interrupts! all-interrupts)
|
|
#f))))))
|
|
|
|
(define one-day-of-milliseconds (* (* 1000 60) (* 60 24)))
|
|
|
|
; A mess because a fixnum's worth of milliseconds is only a few days.
|
|
; The VM's WAIT procedure takes its maximum-wait argument in either
|
|
; milliseconds or minutes.
|
|
|
|
(define (do-some-waiting time-until-wakeup)
|
|
(call-with-values
|
|
(lambda ()
|
|
(cond ((not time-until-wakeup)
|
|
(values -1 #f))
|
|
((< time-until-wakeup one-day-of-milliseconds)
|
|
(values time-until-wakeup #f))
|
|
(else
|
|
(values (quotient time-until-wakeup 60000)
|
|
#t))))
|
|
(structure-ref primitives wait)))
|
|
|
|
(define deadlock-handler (make-session-data-slot! #f))
|
|
|
|
(define (call-when-deadlocked! thunk)
|
|
(session-data-set! deadlock-handler thunk))
|
|
|
|
; Find any ports that need to be flushed. We get both a thunk to flush the
|
|
; port and the port itself; the port is only used for reporting problems.
|
|
|
|
(define (spawn-output-forcers others-waiting?)
|
|
(let ((thunks (output-port-forcers others-waiting?)))
|
|
(cond ((null? thunks)
|
|
#f)
|
|
(else
|
|
(for-each spawn-on-root thunks)
|
|
#t))))
|
|
|
|
(define unspecific (structure-ref primitives unspecific))
|