[Boost-users] Problem with Iterator passing inside an index... a little complex...

6 Feb 2009

      Hi There,

I am using the Boost.MultiIndex and I am facing a problem that I am try
to resolving (debbuging) already about 20 hours...
I think I get the problem isolated, but I don't know how to solve,
and I don't know if this it is implemented.
So I decided to make a example, it is a little big, but I put it as resumed as I could and post here in order to know if anyone could help me out.

I will try to explain briefly here, I will copy the main() code right under the explanation, but the whole code of the example is in the end of the e-mail (with the classes and functions) If you want you could try to run too see what is the problem that I am talking about.)

When I try to access an pair of iterators pair<propIt,propIt> 
that I stored inside a class (propertystream_h),
somehow is changing to where the iterator points, I think it could 
be because the object which has originate (Graph) the index is created, stored in in a static index (which I call _graphRep) from the DynamicGraphs, passed to a handler (Graph_h), and then after the Graph goes out of scope it is destroyed. When the Graph_h._localGraph (copy of the iterator->Graph returned by the insertion in the _graphRep) access its member _globalProperties (which is an index containing the fields:
{string _key, string _value, propertystream_h _props} from the struct
globalPropSchema) through a iterator (let's call it: gpit), then it is fine. But then when I try to access through the gpit->_props._propRangeIt.first, the iterator of the propertystream_h (_propRangeIt.first), then the iterators, some how are messed up. ( -> in this example it points to last element, and then when I get next, never finds the end(). (sometimes it return some trash, sometimes I get segmentation fault).

So I would like to know why it is messing with the iterator? And how could I solve this problem?

that's it,
best regards,
                          Rodrigo

P.S.: I hope someone can help me...

copy of the main():

int main(){
	DynamicGraphs dg;
	Graph_h graph_h;
	propertystream_h propS;
	property_h prop_h;
	GlobalPropIterator gpit;
	GlobalProp_h gp_h;
	propertystream_h ps_h;
	property_h p_h;

	graph_h = dg.createGraph("COI:0351-123-4555");
	if (!graph_h)
		cout << "Unsuccessful creation!"<<endl;
	else
		cout << "Successful creation!" <<endl;

	//It works, because it takes from the _localPropRep, and it passes it as value!!!
	ps_h = graph_h->lookupLocalProp("name");
	while(!ps_h.end()){
		cout << "LocalProperties: ";
		p_h=ps_h.next();
		cout << "Key: " << p_h.key() << " Value: " << p_h.value() <<endl;
	}

	// It does not work, because is accessing the propertystream_h from
	// the _globalPropRep (index of the tuple
	// {string globalkey, string value, propertystream_h props}
	// the propertystream_h it has as member a pair of iterators for another index.
	// -> after a lot of debugging (about 16h) OI found out that
	// it seems that during the creation of a graph,
	// when it passes the graph to graph_h, and goes out of scope, it keep the
	// iterator reference to the first element, but just that... the next
	// gives me segmentation fault. Anyone knows how to pass the graph and the its members
	// the indexes-repositories as value, so it would not depend on the pointing to
	// the graph that was freed from the memory?
	gpit = graph_h->properties("*");
	if (!gpit)
		cout << "Not found any property in the globalProperties Repository."<<endl;
	else{
		int i=0;
		while (!gpit.end())
		{
			gp_h = gpit.next();
			cout << "While_1::Iteration_" << ++i << endl;
			cout << "GlobalProperty key: " << gp_h.key() << endl;
			cout << "GlobalProperty value: " << gp_h.value() << endl;
			ps_h = gp_h.propertyStreamHandler();
			int j = 0;
			while (!ps_h.end()){
				p_h = ps_h.next();
				cout << "While_2::Iteration" << ++j << endl;
				cout << "GlobalProperty::PropertyStream: key " << p_h.key() << endl;
				cout << "GlobalProperty::PropertyStream: value " << p_h.value() << endl;
			}
		}
	}
}

Here it is the code:

/*
 * IndexProblem.cpp
 *
 *  Created on: Feb 6, 2009
 *      Author: rodrigo
 */

#include <boost/multi_index_container.hpp>
#include <boost/multi_index/hashed_index.hpp>
#include <boost/multi_index/member.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include <boost/multi_index/composite_key.hpp>
#include <boost/tuple/tuple.hpp>
#include <boost/tokenizer.hpp>
#include <boost/lambda/lambda.hpp>
#include <climits>
#include <iomanip>
#include <iostream>

#include <ctime>
#include <string>

#if !defined(NDEBUG)
#define BOOST_MULTI_INDEX_ENABLE_INVARIANT_CHECKING
#define BOOST_MULTI_INDEX_ENABLE_SAFE_MODE
#endif

using std::string;
using std::pair;
using std::ostream;
using std::cout;
using std::endl;

using boost::multi_index_container;
using namespace boost::multi_index;

struct property {
	string _key;
	string _value;

	/// Default Constructor
	property(){}
	/// Constructor with parameters: initialize the name and graph
	property(string key, string value) : _key(key), _value(value) {}
	/// Copy Contructor
	property(const property &pm) : _key(pm._key), _value(pm._value) {}

	//For debugging TODO: delete later
	friend ostream& operator<<(ostream& os, const property &p){
		os << "Key: " << p._key << " value: " << p._value << endl;
		return os;
	}
};

/// Indexing in the data structure PropMap
typedef multi_index_container<
	property,
	indexed_by<
		hashed_non_unique<
			BOOST_MULTI_INDEX_MEMBER(property, string, _key)
		>
	>
...
propIndex;
typedef propIndex::iterator propIt;

class property_h {

private:
	/// Access to properties through the iterator
	propIt _pit;

public:
	/// Default Constructor
	property_h(){}
	/// Constructor with Parameters: for lookup of Nodes
	property_h (const propIt &it) : _pit(it){}
	/// Constructor with Parameters: for lookup of Nodes
	property_h (const property_h &h) : _pit(h._pit){}

		/// Returns the key from the property being handled
		string key() const {return _pit->_key;}
		/// Returns the value from the property being handled
		string value() const {return _pit->_value;}
};

class propertystream_h {

	/// _propRangeIt: for keeping a range in order to iterate over the graphs
	pair<propIt,propIt> _propRangeIt;
	/// _noMatches: true if there are no matches during the lookup function
	bool _noMatches;

public:
	/// Default Constructor
	propertystream_h() : _noMatches(true){}
	/// Constructor with parameters for local lookup
	propertystream_h(pair<propIt,propIt> rangeIt, bool noMatches) :
		_propRangeIt(rangeIt), _noMatches(noMatches){ }
	/// Default Constructor
	propertystream_h(const propertystream_h &ps) :
		_propRangeIt(ps._propRangeIt), _noMatches(ps._noMatches){}

	// returns null_h on end of stream ...
	property_h next(){
		return property_h(_propRangeIt.first++);
	}

	/// This function returns true whenever is the end of the stream
	bool end(){
		 return (_propRangeIt.first == _propRangeIt.second);
	}

	/// Overload operator!: shows if a creation was unsuccessful
	bool operator!(){ return _noMatches; }

};

struct globalPropSchema{
	string _key;
	string _value;
	propertystream_h _props;

	/// Default Constructor
	globalPropSchema() : _key(""), _value(""), _props(){}
	/// Parameter Constructor
	globalPropSchema(string k, string value,  propertystream_h props) : _key(k),
		_value(value),	_props(props){}
	/// Copy Constructor
	globalPropSchema(const globalPropSchema &gps) : _key(gps._key), _value(gps._value),
		_props(gps._props){}

	//TODO: Delete it: Debug
	friend ostream& operator<<(ostream &os, const globalPropSchema &gps){
		os << "Key: " << gps._key << " Value: "<< gps._value << " PropertyStreamAdress: "
		   << &gps._props <<endl;
		return os;
	}

};

typedef multi_index_container<
	globalPropSchema,
	indexed_by<
		ordered_non_unique<
			composite_key<
				globalPropSchema,
					BOOST_MULTI_INDEX_MEMBER(globalPropSchema, string, _key),
					BOOST_MULTI_INDEX_MEMBER(globalPropSchema, string, _value)
			>,
			composite_key_compare<
				std::greater<string>,
				std::less<string>
			  >
		>
	>
...
grobalProperties;
/// Iterator for the data structure of the global properties index
typedef grobalProperties::iterator globalPropIt;

class GlobalProp_h{

private:
	/// Access to globalPropertiest items through the iterator
	globalPropIt _gpit;

public:
	/// Default Constructor
	GlobalProp_h(){}
	/// Constructor with Parameters: for lookup of Nodes
	GlobalProp_h (const globalPropIt &it) : _gpit(it){}
	/// Copy Constructor
	GlobalProp_h (const GlobalProp_h &gph) : _gpit(gph._gpit){}

	/// Access to key of globalPropeties items
	string key(){ return _gpit->_key;}
	/// Access to value of globalPropeties items
	string value(){return _gpit->_value;}

	propertystream_h propertyStreamHandler(){
		return _gpit->_props;
	}
};

/// Iterator for the data structure of the global properties index
typedef grobalProperties::iterator globalPropIt;

class GlobalPropIterator{

private:
	/// _propRangeIt: for keeping a range in order to iterate over the graphs
	pair<globalPropIt,globalPropIt> _globalPropRangeIt;
	/// _noMatches: true if there are no matches during the lookup function
	bool _noMatches;

public:
	/// Default Constructor
	GlobalPropIterator(){}
	/// Constructor with parameters for local lookup
	GlobalPropIterator(pair<globalPropIt,globalPropIt> rangeIt, bool noMatches) :
		_globalPropRangeIt(rangeIt), _noMatches(noMatches){}
	/// Default Constructor
	GlobalPropIterator(const GlobalPropIterator &gpi) :
		_globalPropRangeIt(gpi._globalPropRangeIt), _noMatches(gpi._noMatches){}

	// returns null_h on end of stream ...
	GlobalProp_h next(){
		return GlobalProp_h(_globalPropRangeIt.first++);
	}

	/// This function returns true whenever is the end of the stream
	bool end(){
		return (_globalPropRangeIt.first == _globalPropRangeIt.second);
	}

	/// Overload operator!: shows if a creation was unsuccessful
	bool operator!(){ return _noMatches; }
};

class Graph {

private:

	propIndex _localPropRep;
	/// Repository for the properties of the global properties related to the graph;
	grobalProperties _globalPropRep;

public:

	// TODO: Really constructors
	/// Default Constructor
	Graph() {}
	/// Copy constructors
	Graph(const Graph &g) : _localPropRep(g._localPropRep),
		_globalPropRep(g._globalPropRep){}

	bool addProperty(string key, string value);

	GlobalPropIterator properties(string pattern) const;

	/// Function to lookup Local Properties
	propertystream_h lookupLocalProp(string pattern);

	friend class Graph_h;
};

/// GraphMap: Data Structure for setting an index in the uniqueGraphName and retrieving handler Graph_h
struct graphMap {
	string _name;
	Graph _graph;

	/// Default Constructor
	graphMap(){}
	/// Constructor with parameters: initialize the name and graph
	graphMap(string uniqueGraphName, Graph graph) :
		_name(uniqueGraphName),	_graph (graph) {}
	/// Constructor with parameters: initialize the name and graph
	graphMap(const graphMap &gm) : _name(gm._name), _graph (gm._graph) {}
};

///ordered_unique Index in the data structure graph_hm
typedef multi_index_container<
	graphMap,
	indexed_by<
		ordered_unique<
			BOOST_MULTI_INDEX_MEMBER(graphMap,string,_name)
		>
	>
...
graphIndex;
/// Defing an iterator for the graphMapIndex
typedef graphIndex::iterator graphIt;

class Graph_h {

private:
	/// \brief GraphIterator: Iterator pointing to the Graph
	graphIt _git;

	Graph _localGraph;

	bool _createSuccess;

public:
	/// Default Constructor
	Graph_h() : _createSuccess(false) {}
	/// Constructor with Parameters: for creation of Graphs
	Graph_h ( pair<graphIt,bool> creation) :
		_git(creation.first), _createSuccess(creation.second){
		_localGraph = creation.first->_graph;
	}
	/// Constructor with Parameters: for lookup of Graphs
	Graph_h (const graphIt &it) :
		_git(it), _createSuccess(false){
		_localGraph = it->_graph;
	}

	/// Constructor with Parameters: for lookup of Graphs
	Graph_h (const Graph_h &h) :
		_git(h._git),  _localGraph(h._localGraph), _createSuccess(h._createSuccess){}

	bool operator!(){
		return !_createSuccess;
	}

	/// Operator-> overloading: allows access to graph members
	Graph* operator->() {return &_localGraph;}
};

propertystream_h Graph::lookupLocalProp(string pattern){
	pair<propIt,propIt> rangeIt;
	propIt rangeItfirst = _localPropRep.find(pattern);
	rangeIt.first = rangeItfirst;
	rangeIt.second = _localPropRep.end();
	if (rangeIt.first != _localPropRep.end())
		// second parameter means that the variable noMatches, so false in case that found the key
		return propertystream_h(rangeIt, false);
	else
		//No matches
		return propertystream_h(rangeIt, true);
}

GlobalPropIterator Graph::properties(string pattern) const{

	pair<globalPropIt,globalPropIt> globalRangePropIt;
	bool noMatchesTmp=false;
	//Whole range
	if (!pattern.compare("*")){
		globalRangePropIt.first = _globalPropRep.begin();
		globalRangePropIt.second = _globalPropRep.end();
	}
	if (globalRangePropIt.first == globalRangePropIt.second)
		noMatchesTmp = true;

	return GlobalPropIterator(globalRangePropIt, noMatchesTmp);
}

bool Graph::addProperty(string key, string value){

	bool boolLocal, boolGlobal;
	pair <propIt,propIt> rangePropIt;
	string globalKey = "graph:";
	globalKey.append(key); // "graph:namePorperty"

	boolLocal = _localPropRep.insert(property(key,value)).second;

	//Defining the whole range for iterate over the local properties
	rangePropIt.first = _localPropRep.begin();
	rangePropIt.second = _localPropRep.end();

	//Debug
	propIt it = rangePropIt.first;
	cout << "How it should be showed when accessing the iterator..."<<endl;
	while (rangePropIt.first != rangePropIt.second){
		cout << "DEBUG@addProperty: " << *(rangePropIt.first++);
	}
	cout << endl;
	rangePropIt.first = it;
	//Debug

	boolGlobal = _globalPropRep.insert(
			globalPropSchema( globalKey, value, propertystream_h(rangePropIt, false) )
	).second;

	return (boolLocal && boolGlobal);
}

class DynamicGraphs {
public:
	/// Data member to represent the graph repository (using ordered_unique index)
	static graphIndex _graphRep;

	Graph_h createGraph(string uniqueGraphName);
};

graphIndex DynamicGraphs::_graphRep;

/// Creation of Graph in DynamicGraphs
Graph_h DynamicGraphs::createGraph(string uniqueGraphName){
	Graph g;
	g.addProperty("name", uniqueGraphName);
	//Test
	g.addProperty("age", "Unknown");
	g.addProperty("color", "blue");
	return Graph_h(
			_graphRep.insert(
					graphMap( uniqueGraphName, g )
							)
				);
}

int main(){
	DynamicGraphs dg;
	Graph_h graph_h;
	propertystream_h propS;
	property_h prop_h;
	GlobalPropIterator gpit;
	GlobalProp_h gp_h;
	propertystream_h ps_h;
	property_h p_h;

	graph_h = dg.createGraph("COI:0351-123-4555");
	if (!graph_h)
		cout << "Unsuccessful creation!"<<endl;
	else
		cout << "Successful creation!" <<endl;

	//It works, because it takes from the _localPropRep, and it passes it as value!!!
	ps_h = graph_h->lookupLocalProp("name");
	while(!ps_h.end()){
		cout << "LocalProperties: ";
		p_h=ps_h.next();
		cout << "Key: " << p_h.key() << " Value: " << p_h.value() <<endl;
	}

	// It does not work, because is accessing the propertystream_h from
	// the _globalPropRep (index of the tuple
	// {string globalkey, string value, propertystream_h props}
	// the propertystream_h it has as member a pair of iterators for another index.
	// -> after a lot of debugging (about 16h) OI found out that
	// it seems that during the creation of a graph,
	// when it passes the graph to graph_h, and goes out of scope, it keep the
	// iterator reference to the first element, but just that... the next
	// gives me segmentation fault. Anyone knows how to pass the graph and the its members
	// the indexes-repositories as value, so it would not depend on the pointing to
	// the graph that was freed from the memory?
	gpit = graph_h->properties("*");
	if (!gpit)
		cout << "Not found any property in the globalProperties Repository."<<endl;
	else{
		int i=0;
		while (!gpit.end())
		{
			gp_h = gpit.next();
			cout << "While_1::Iteration_" << ++i << endl;
			cout << "GlobalProperty key: " << gp_h.key() << endl;
			cout << "GlobalProperty value: " << gp_h.value() << endl;
			ps_h = gp_h.propertyStreamHandler();
			int j = 0;
			while (!ps_h.end()){
				p_h = ps_h.next();
				cout << "While_2::Iteration" << ++j << endl;
				cout << "GlobalProperty::PropertyStream: key " << p_h.key() << endl;
				cout << "GlobalProperty::PropertyStream: value " << p_h.value() << endl;
			}
		}
	}
}

-- 
*************************************************
Rodrigo Dias Ferreira

Master Student of Computational Engineering
Technische Universität Dresden - Germany
Mobile Phone:+49 171 3158797
E-mail: rodrigodias@gmx.de

*************************************************

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