32 Concurrency support library [thread]

32.11 Safe reclamation [saferecl]

32.11.2 Read-copy update (RCU) [saferecl.rcu]

32.11.2.3 Class template rcu_obj_base [saferecl.rcu.base]

1
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Objects of type T to be protected by RCU inherit from a specialization rcu_obj_base<T, D> for some D.
namespace std { template<class T, class D = default_delete<T>> class rcu_obj_base { public: void retire(D d = D(), rcu_domain& dom = rcu_default_domain()) noexcept; protected: rcu_obj_base() = default; rcu_obj_base(const rcu_obj_base&) = default; rcu_obj_base(rcu_obj_base&&) = default; rcu_obj_base& operator=(const rcu_obj_base&) = default; rcu_obj_base& operator=(rcu_obj_base&&) = default; ~rcu_obj_base() = default; private: D deleter; // exposition only }; }
2
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The behavior of a program that adds specializations for rcu_obj_base is undefined.
3
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T may be an incomplete type.
It shall be complete before any member of the resulting specialization of rcu_obj_base is referenced.
4
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D shall be a function object type ([function.objects]) for which, given a value d of type D and a value ptr of type T*, the expression d(ptr) is valid.
5
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D shall meet the requirements for Cpp17DefaultConstructible and Cpp17MoveAssignable.
6
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If D is trivially copyable, all specializations of rcu_obj_base<T, D> are trivially copyable.
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void retire(D d = D(), rcu_domain& dom = rcu_default_domain()) noexcept;
7
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Mandates: T is an rcu-protectable type.
8
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Preconditions: *this is a base class subobject of an object x of type T.
The member function rcu_obj_base<T, D>​::​retire was not invoked on x before.
The assignment to deleter does not exit via an exception.
9
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Effects: Evaluates deleter = std​::​move(d) and schedules the evaluation of the expression deleter(
addressof(x)) in the domain dom; the behavior is undefined if that evaluation exits via an exception.
May invoke scheduled evaluations in dom.
[Note 1: 
If such evaluations acquire resources held across any invocation of retire on dom, deadlock can occur.
— end note]