Re: [boost] reflection for smart_ptr cycles?

From: Peter Dimov (pdimov_at_[hidden])
Date: 2004-11-11 14:40:12

Rene Rivera wrote:
> A "faster" way to infer cycles for pointers could be done with a bit
> more information on the shared_ptr. If you keep a set of object memory
> spans (heap address, and class sizeof) for all shared instances you
> can find all shared_ptrs that fall within those shared instances.

See sp_collector.cpp.

> With that you can build the reference graph to detect the cycles.

Except that you can't. :-)

struct X
{
    std::vector<Y> v_;
};

If Y has shared_ptr instances that refer back to X, this is untraceable, 
because the tracer doesn't know that it should follow the pointer inside the 
std::vector.