28 lines
1.2 KiB
Racket
28 lines
1.2 KiB
Racket
#lang syndicate
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;; Toy file system, based on the example in the ESOP2016 submission.
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;; syndicate/actor implementation, without subconversation.
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(require/activate "fs-shell.rkt")
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(require/activate "fs-protocol.rkt")
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(require racket/set)
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(spawn (field [files (hash)] [monitored (set)])
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(on (asserted (observe (file $name _)))
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(printf "At least one reader exists for ~v\n" name)
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(assert! (file name (hash-ref (files) name #f)))
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(monitored (set-add (monitored) name)))
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(on (retracted (observe (file $name _)))
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(printf "No remaining readers exist for ~v\n" name)
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(retract! (file name (hash-ref (files) name #f)))
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(monitored (set-remove (monitored) name)))
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(on (message (save (file $name $content)))
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(when (set-member? (monitored) name)
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(retract! (file name (hash-ref (files) name #f)))
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(assert! (file name content)))
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(files (hash-set (files) name content)))
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(on (message (delete $name))
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(when (set-member? (monitored) name)
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(retract! (file name (hash-ref (files) name #f)))
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(assert! (file name #f)))
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(files (hash-remove (files) name))))
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