Re: [boost] portable precise garbage collector for C++

From: Larry Evans (cppljevans_at_[hidden])
Date: 2007-09-21 07:26:44

On 09/21/07 04:14, Achilleas Margaritis wrote:
> O/H Kim Barrett έγραψε:
>> At 2:06 AM +0300 9/21/07, Achilleas Margaritis wrote:
>>> I thought std containers use the allocator::pointer type for their pointers.
>> Unfortunately, not necessarily. They're permitted to bypass that and use
>> T* directly. Ion Gaztañaga ran into this when trying to put containers
>> into shared memory for boost.interprocess.
>> _______________________________________________
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> 
> The collector offers the possibility of customizing the scanning 
> procedure (the procedure which scans a block for pointers) through the 
> class gc_traits<T>. So if there is a data structure where gc_ptr<T> can 
> not be used, a custom scan routine especially coded for the data 
> structure in question can solve the problem.

Given the following:

   std::list<gc_ptr<Node> > node_list;

where Node is defined in cppgc/src/main.cpp,
then no gc_ptr's within node_list would be
registered as root pointers; so, wouldn't
any Nodes of the gc_ptr's pushed into node_list be
collected?  I guess I don't understand how a customized
scanner would help.  Sure, once it's known that
node_list contains gc_ptr's, the scanner could be
called, but the collector first needs to be notified
of that fact.

Am I missing something.