[boost] Re: operator new (size_t, ...)

From: Philippe A. Bouchard (philippeb_at_[hidden])
Date: 2003-01-15 09:36:20

"Peter Dimov" <pdimov_at_[hidden]> wrote in message
news:00bc01c2bc89$d77fe5e0$1d00a8c0_at_pdimov2...
> From: "Philippe A. Bouchard" <philippeb_at_[hidden]>
> > Greeting everyone,
> >
> >     It seems placement operator new (size_t, ...) would extend a lot
> garbage
> > collection possibilities.  Why don't we define a set of rules for each
tag
> > this overloaded placed operator would use:
> >
> > shared_ptr<int>(new int());
> >
> > GC type defined at run-time:
> > shared_ptr<int>(new (gc) int());  // Add pointer to a list
> > shared_ptr<int>(new (rc) int());  // Add counter + pointer to a list
> > shared_ptr<int>(new (os) int());  // Add owner to a list
>
> I am not sure how these are intended to work, and in particular, how is
> shared_ptr<> supposed to handle the different variations, given that it
gets
> a plain "int *" in all cases.

- ownership is similar to weak_ptr.
- agreeing with M. Colvin on operator new (size_t, gc) thought.

Define only 2 allocators then:

// Standard allocator version
void * operator new (size_t);

// GC allocator version
void * operator new (size_t s, gc const &)
{
    // Simple list version
    static list<void *> garbage_collection;

    // Pointers with stack depth version
    static map<int, void *> garbage_collection;

    // Add memory swapping
    static ...;
    static list< pair<void *, void *> > swapped_memory;

    void * p = malloc(s);

    if (p)
    {
        // Add pointer to the appropriate list
        garbage_collection.push_back(p);
        ...;
    }
    else
    {
        // Swap memory if needed
        ...;
    }

    return p;
}

    I've examined other possibilities but I think this one is more
interesting... other one mostly helped to warm up.  operator new (size_t,
rc/os) would require yet another distinct smart pointer.

Philippe A. Bouchard