Re: [Boost-users] [intrusive_ptr] Counting implementation

From: Gennadiy Rozental (rogeeff_at_[hidden])
Date: 2008-07-31 18:10:17

Alexander Gutenev <gutenev <at> gmail.com> writes:

> 
> Updated, after looking into other's implementation:

I would add IncrementPolicy with following default.

struct trivial_increment_policy {
    void inc( long& c ) { ++c; }
    bool dec( long& c ) { return --c == 0; }
}

> template<class Derived>
template<class Derived, template IncrementPolicy=trivial_increment_policy>
> class intrusive_pointee_base
> {
> private:
>   typedef intrusive_pointee_base self;
> 
> protected:
>   intrusive_pointee_base(void) : reference_counter_(0) {}
>   intrusive_pointee_base(self const&) : reference_counter_(0) {}
>   intrusive_pointee_base operator=(self const&) { return *this }
>   ~intrusive_pointee_base(void) {}
> 
> private:
>   friend void intrusive_ptr_add_ref(const Derived * p)
>   {
      IncrementPolicy::inc(&static_cast<self const 
> *>(p)->reference_counter_);
>   }
> 
>   friend void intrusive_ptr_release(const Derived * p)
>   {
      if(!IncrementPolicy::dec(
         &static_cast<self const>*>(p)->reference_counter_))
>       delete p;
>   }
> 
>   mutable volatile long reference_counter_;
> }; 
> 

Now you can add your own 

struct nt_mt_safe_increment {
    void inc( long& c ) { ::InterlockedIncrement(c); }
    bool dec( long& c ) { return ::InterlockedDecrement(--c) == 0; }
};

Gennadiy