1 ! Copyright (C) 2005, 2008 Chris Double, Slava Pestov.
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2 ! See http://factorcode.org/license.txt for BSD license.
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3 USING: concurrency.messaging kernel arrays
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4 continuations help.markup help.syntax quotations calendar ;
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5 IN: concurrency.promises
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8 { $class-description "The class of write-once promises." } ;
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11 { $values { "promise" promise } }
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12 { $description "Creates a new promise which may be fulfilled by calling " { $link fulfill } "." } ;
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14 HELP: promise-fulfilled?
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15 { $values { "promise" promise } { "?" "a boolean" } }
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16 { $description "Tests if " { $link fulfill } " has previously been called on the promise, in which case " { $link ?promise } " will return immediately without blocking." } ;
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18 HELP: ?promise-timeout
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19 { $values { "promise" promise } { "timeout" { $maybe duration } } { "result" object } }
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20 { $description "Waits for another thread to fulfill a promise, returning immediately if the promise has already been fulfilled. A timeout of " { $link f } " indicates that the thread may block indefinitely, otherwise it will wait up to the " { $snippet "timeout" } " before throwing an error." }
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21 { $errors "Throws an error if the timeout expires before the promise has been fulfilled." } ;
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24 { $values { "promise" promise } { "result" object } }
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25 { $description "Waits for another thread to fulfill a promise, returning immediately if the promise has already been fulfilled." } ;
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28 { $values { "value" object } { "promise" promise } }
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29 { $description "Fulfills a promise by writing a value to it. Any threads waiting for the value are notified." }
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30 { $errors "Throws an error if the promise has already been fulfilled." } ;
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32 ARTICLE: "concurrency.promises" "Promises"
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33 "The " { $vocab-link "concurrency.promises" } " vocabulary implements " { $emphasis "promises" } ", which are thread-safe write-once variables. Once a promise is created, threads may block waiting for it to be " { $emphasis "fulfilled" } "; at some point in the future, another thread may provide a value at which point all waiting threads are notified."
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34 { $subsection promise }
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35 { $subsection <promise> }
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36 { $subsection fulfill }
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37 { $subsection ?promise }
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38 { $subsection ?promise-timeout } ;
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40 ABOUT: "concurrency.promises"
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