116 lines
4.2 KiB
Markdown
116 lines
4.2 KiB
Markdown
[stopsource]
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# 32 Concurrency support library [[thread]](./#thread)
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## 32.3 Stop tokens [[thread.stoptoken]](thread.stoptoken#stopsource)
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### 32.3.5 Class stop_source [stopsource]
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#### [32.3.5.1](#general) General [[stopsource.general]](stopsource.general)
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namespace std {class stop_source {public:// [[stopsource.cons]](#cons "32.3.5.2 Constructors, copy, and assignment"), constructors, copy, and assignment stop_source(); explicit stop_source(nostopstate_t) noexcept {}// [[stopsource.mem]](#mem "32.3.5.3 Member functions"), member functionsvoid swap(stop_source&) noexcept;
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stop_token get_token() const noexcept; bool stop_possible() const noexcept; bool stop_requested() const noexcept; bool request_stop() noexcept; bool operator==(const stop_source& rhs) noexcept = default; private: shared_ptr<*unspecified*> *stop-state*; // *exposition only*};}
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[1](#general-1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L935)
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*stop-state* refers to the stop_source's associated stop state[.](#general-1.sentence-1)
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A stop_source object is disengaged when *stop-state* is empty[.](#general-1.sentence-2)
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[2](#general-2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L939)
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stop_source models[*stoppable-source*](stoptoken.concepts#concept:stoppable-source "32.3.3 Stop token concepts [stoptoken.concepts]"),[copyable](concepts.object#concept:copyable "18.6 Object concepts [concepts.object]"),[equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_comparable [concept.equalitycomparable]"), and[swappable](concept.swappable#concept:swappable "18.4.9 Concept swappable [concept.swappable]")[.](#general-2.sentence-1)
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#### [32.3.5.2](#cons) Constructors, copy, and assignment [[stopsource.cons]](stopsource.cons)
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[ð](#lib:stop_source,constructor)
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`stop_source();
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`
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[1](#cons-1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L954)
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*Effects*: Initializes *stop-state* with a pointer to a new stop state[.](#cons-1.sentence-1)
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[2](#cons-2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L958)
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*Postconditions*: stop_possible() is true and stop_requested() is false[.](#cons-2.sentence-1)
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[3](#cons-3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L963)
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*Throws*: bad_alloc if memory cannot be allocated for the stop state[.](#cons-3.sentence-1)
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#### [32.3.5.3](#mem) Member functions [[stopsource.mem]](stopsource.mem)
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[ð](#lib:swap,stop_source)
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`void swap(stop_source& rhs) noexcept;
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`
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[1](#mem-1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L976)
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*Effects*: Equivalent to:*stop-state*.swap(rhs.*stop-state*);
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[ð](#lib:get_token,stop_source)
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`stop_token get_token() const noexcept;
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`
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[2](#mem-2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L990)
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*Returns*: stop_token() if stop_possible() is false;
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otherwise a new associated stop_token object;
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i.e., its *stop-state* member is equal to
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the *stop-state* member of *this[.](#mem-2.sentence-1)
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[ð](#lib:stop_possible,stop_source)
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`bool stop_possible() const noexcept;
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`
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[3](#mem-3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L1004)
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*Returns*: *stop-state* != nullptr[.](#mem-3.sentence-1)
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[ð](#lib:stop_requested,stop_source)
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`bool stop_requested() const noexcept;
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`
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[4](#mem-4)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L1015)
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*Returns*: true if *stop-state* refers to a stop state
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that has received a stop request;
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otherwise, false[.](#mem-4.sentence-1)
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[ð](#lib:request_stop,stop_source)
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`bool request_stop() noexcept;
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`
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[5](#mem-5)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L1028)
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*Effects*: Executes a stop request operation ([[stoptoken.concepts]](stoptoken.concepts "32.3.3 Stop token concepts")) on
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the associated stop state, if any[.](#mem-5.sentence-1)
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