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make_shared alloc optimization

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Steven Dee (Jōshin) 2024-08-27 21:15:39 -07:00
parent 1c5401a141
commit d9b35fab19
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1 changed files with 40 additions and 4 deletions
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44
ctl/shared_ptr.h
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@ -80,7 +80,7 @@ class shared_ref
}
private:
virtual void dispose() = 0;
virtual void dispose() noexcept = 0;
size_t shared = 0;
size_t weak = 0;
@ -102,7 +102,7 @@ class shared_pointer : public shared_ref
{
}
void dispose() override
void dispose() noexcept override
{
move(d)(p);
}
@ -111,6 +111,35 @@ class shared_pointer : public shared_ref
[[no_unique_address]] D d;
};
template<typename T>
class shared_emplace : public shared_ref
{
public:
union
{
T t;
};
template<typename... Args>
void construct(Args&&... args)
{
::new (&t) T(forward<Args>(args)...);
}
static unique_ptr<shared_emplace> make()
{
return unique_ptr(new shared_emplace());
}
private:
explicit constexpr shared_emplace() noexcept = default;
void dispose() noexcept override
{
t.~T();
}
};
template<typename T, typename U>
concept shared_ptr_convertible = is_convertible_v<U, T> || is_void_v<T>;
@ -302,6 +331,9 @@ class shared_ptr
template<typename U>
friend class shared_ptr;
template<typename U, typename... Args>
friend shared_ptr<U> make_shared(Args&&... args);
element_type* p = nullptr;
__::shared_ref* rc = nullptr;
};
@ -385,8 +417,12 @@ template<typename T, typename... Args>
shared_ptr<T>
make_shared(Args&&... args)
{
// TODO(mrdomino): shared_emplace
return shared_ptr<T>(new T(forward<Args>(args)...));
auto rc = __::shared_emplace<T>::make();
rc->construct(forward<Args>(args)...);
shared_ptr<T> r;
r.p = &rc->t;
r.rc = rc.release();
return r;
}
} // namespace ctl