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Stepper fix for possible race condition

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Uses queue-callback to avoid a possible race condition in updating of editor
on non-eventspace thread.

Fixes PR 12217
This commit is contained in:
John Clements 2011-09-21 22:42:20 -07:00
parent 048fa1d7b8
commit c8a15f7013
1 changed files with 11 additions and 13 deletions
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24
collects/stepper/private/view-controller.rkt
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@ -67,13 +67,15 @@
(thread
(lambda ()
(let loop ()
(let* ([new-result (async-channel-get view-channel)]
[new-step (format-result new-result)])
(set! view-history (append view-history (list new-step)))
(set! num-steps-available (length view-history))
;; this is only necessary the first time, but it's cheap:
(semaphore-post first-step-sema))
(update-status-bar)
(define new-result (async-channel-get view-channel))
(define new-step (format-result new-result))
(queue-callback
(lambda ()
(set! view-history (append view-history (list new-step)))
(set! num-steps-available (length view-history))
;; this is only necessary the first time, but it's cheap:
(semaphore-post first-step-sema)
(update-status-bar)))
(loop)))))
@ -263,17 +265,13 @@
(send e begin-edit-sequence)
(send canvas set-editor e)
(send e reset-width canvas)
;; why set the position within the step? I'm confused by this.--JBC
(send e set-position (send e last-position))
(send e end-edit-sequence))
(update-status-bar))
;; update the X/Y display in the upper right corner of the stepper;
;; this should be one-at-a-time.
;; set the status bar to the correct m/n text.
(define (update-status-bar)
(call-with-semaphore update-status-bar-semaphore update-status-bar/inner))
(define (update-status-bar/inner)
(send status-text begin-edit-sequence)
(send status-text lock #f)
(send status-text delete 0 (send status-text last-position))