28 lines
1.1 KiB
Racket
28 lines
1.1 KiB
Racket
#lang syndicate-monolithic
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;; Test case for a historical bug in Syndicate.
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;;
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;; When the bug existed, this program receiveed four SCN events in
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;; total, whereas it should receive only two.
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;;
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;; While metamessages were "echo cancelled", and receivers only ever
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;; got one copy of a sent metamessage no matter how many metas there
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;; were, state changes were not. Issuing a quick enough "pulse" of
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;; metaassertion while maintaining interest in it led to an "echo":
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;; multiple receipts of the pulse.
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;;
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;; The fix was to adjust the implementation of state change
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;; notifications to cancel the echo for metaassertions.
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(require syndicate/pretty)
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(spawn-dataspace
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(spawn (lambda (e counter)
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(and e
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(let ((new-counter (+ counter 1)))
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(printf "Received event ~a:\n~a\n" new-counter (syndicate-pretty-print->string e))
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(transition (+ counter 1) '()))))
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0
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(list (scn/union (assertion (at-meta 'x))
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(subscription 'x #:meta-level 1))
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(scn (subscription 'x #:meta-level 1)))))
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