tmp/tmpvjwkaq_6/{from.md → to.md}
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| 1 |
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##### General <a id="util.smartptr.atomic.general">[[util.smartptr.atomic.general]]</a>
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The library provides partial specializations of the `atomic` template
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for shared-ownership smart pointers [[util.sharedptr]].
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[*Note 1*: The partial specializations are declared in header
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`<memory>`. — *end note*]
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The behavior of all operations is as specified in
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[[atomics.types.generic]], unless specified otherwise. The template
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parameter `T` of these partial specializations may be an incomplete
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type.
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All changes to an atomic smart pointer in [[util.smartptr.atomic]], and
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all associated `use_count` increments, are guaranteed to be performed
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atomically. Associated `use_count` decrements are sequenced after the
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atomic operation, but are not required to be part of it. Any associated
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deletion and deallocation are sequenced after the atomic update step and
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are not part of the atomic operation.
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[*Note 2*: If the atomic operation uses locks, locks acquired by the
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implementation will be held when any `use_count` adjustments are
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performed, and will not be held when any destruction or deallocation
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resulting from this is performed. — *end note*]
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[*Example 1*:
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``` cpp
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template<typename T> class atomic_list {
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struct node {
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T t;
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shared_ptr<node> next;
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};
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atomic<shared_ptr<node>> head;
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public:
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shared_ptr<node> find(T t) const {
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auto p = head.load();
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while (p && p->t != t)
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p = p->next;
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return p;
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}
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void push_front(T t) {
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auto p = make_shared<node>();
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p->t = t;
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p->next = head;
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while (!head.compare_exchange_weak(p->next, p)) {}
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}
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};
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```
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— *end example*]
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