Re: [Boost-users] [multi_index] Problem of scope with the replace in static data structure

Subject: Re: [Boost-users] [multi_index] Problem of scope with the replace in static data structure
From: Rodrigo Dias Ferreira (rodrigodias_at_[hidden])
Date: 2009-02-12 06:27:08

Hi Joaquim,

I saw what you meant, and I have changed...
But still if I use the same graph_h, still I got the same problem:
Here it is my solution for the Graph constructor:
        Graph(const Graph &g) : _rangeBegin(g._rangeBegin), _rangeEnd(g._rangeEnd),
                _nodeRep(g._nodeRep), _nodeNameRep(g._nodeNameRep), _localPropRep(g._localPropRep),
                _globalPropRep(g._globalPropRep){
                //_nodeRep::_uniqueName* Initialization
                pair<nodeMapIt,nodeMapIt> rangeNodeIt;
                nodeMapIt tmpNodeIt;
                rangeNodeIt.first = g._nodeRep.begin();
                rangeNodeIt.second = g._nodeRep.end();

                while (rangeNodeIt.first != rangeNodeIt.second){
                        _nodeRep.insert(nodeMap( &*(_nodeNameRep.find(rangeNodeIt.first->_uniqueName->_name)),
                                        rangeNodeIt.first->_timestamp, rangeNodeIt.first->_node));
                        ++rangeNodeIt.first;
                }

        }

I've debugged, but I didn't see anything suspicious anymore...
Did you see something else?

thanks,

                       Rodrigo

-------- Original-Nachricht --------
> Datum: Wed, 11 Feb 2009 18:26:33 +0100
> Von: joaquin_at_[hidden]
> An: Rodrigo Dias Ferreira <rodrigodias_at_[hidden]>
> Betreff: Re: [multi_index] Problem of scope with the replace in static data structure

> Rodrigo Dias Ferreira escribió:
> > Hi Joaquim,
> >
> >
> >   
> >> Can you please test the following? In your //Test of the
> >> commit section, rather than  reuse graph_h please use a different
> >> variable to do the after-commitChanges check:
> >>
> >> [...]
> >>
> >> Does this make any difference?
> >>     
> > Yes, it worked, if I instantiate another object (like graph_h2). 
> > After that I have done some more Debug to try to find the reason,
> > but I still don't understand, because inside the constructor it
> > finds the Nodes, when I use the same object (graph_h)...
> > Inside the overloaded operator-> does not work anymore, even I
> > am using the _localGraph in both stretch of codes.
> > So if it was the assignment of the _localGraph, it should not
> > work with the constructor also, isn't true?
> >   
> 
> What happens when you do *not* use graph_h2 is that, upon reassigning
> graph_h in
> 
>   graph_h = Graph_h(it);
> 
> the previous value of graph_h is destroyed, and presumably this leaves
> some dangling pointer/iterator when it shouldn't.
> 
> I've examined your code in search for candidates to potential dangling
> pointers/iterators and found something a little suspicious: Graph contains
> the following two member variables:
>  
>   uniqueNameTable _nodeNameRep;
>   nodeIndex            _nodeRep;
> 
> where uniqueNameTable is a container of uniqueNodeNameStruct's and
> nodeIndex is a container of nodeMaps pointing to
> uniqueNodeNameStruct's in _nodeRep, right? If so, default copy semantics
> of Graph is flawed; consider:
> 
>   Graph g2;
>   {
>     Graph g1; // g1._nodeRep elements point into g1._nodeNameRep
>     g2=g1; // g2._nodeRep elements point into g1._nodeNameRep
>   } // g1 is destroyed
>   // g2._nodeRep elements point to destroyed objects
> 
> See what I mean? Pointers inside _nodeRep are not reassigned on
> copy. Does the copy constructor of Graph take this issue into
> account?
> 
> If this leads nowhere, you can always try setting up Boost.MultiIndex
> safe mode:
> 
> http://boost.org/libs/multi_index/doc/tutorial/debug.html#safe_mode
> 
> and see if some safe mode assertion is triggered.
> 
> Joaquín M López Muñoz
> Telefónica, Investigación y Desarrollo

-- 
*************************************************
Rodrigo Dias Ferreira
Master Student of Computational Engineering
Technische Universität Dresden - Germany
E-mail: rodrigodias_at_[hidden]
*************************************************
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