Re: [Boost-users] How to Read the stored memory map in C++

Subject: Re: [Boost-users] How to Read the stored memory map in C++
From: manish4gupta (manish_at_[hidden])
Date: 2009-09-24 20:59:46

Hi Ion,
How can i solve my pblm? I tried many things but nothing seems to be
working. 

Regards
Manish

manish4gupta wrote:
> 
> I am loading the map into memory with one program and retrieving the map
> values by another program.
> 
> Process1.
> #include <boost/interprocess/managed_shared_memory.hpp>
> #include <boost/interprocess/allocators/allocator.hpp>
> #include <boost/interprocess/containers/map.hpp>
> #include <boost/interprocess/containers/vector.hpp>
> #include <boost/interprocess/containers/string.hpp>
> #include <iostream>
> 
> using namespace boost::interprocess;
> 
> //Typedefs of allocators and containers
> typedef managed_shared_memory::segment_manager                      
> segment_manager_t;
> typedef allocator<void, segment_manager_t>                          
> void_allocator;
> typedef allocator<int, segment_manager_t>                           
> int_allocator;
> typedef vector<int, int_allocator>                                  
> int_vector;
> typedef allocator<int_vector, segment_manager_t>                    
> int_vector_allocator;
> typedef vector<int_vector, int_vector_allocator>                    
> int_vector_vector;
> typedef allocator<char, segment_manager_t>                          
> char_allocator;
> typedef basic_string<char, std::char_traits<char>, char_allocator>  
> char_string;
> 
> class complex_data
> {
>    int               id_;
>    char_string       char_string_;
>    int_vector_vector int_vector_vector_;
> 
>    public:
>    //Since void_allocator is convertible to any other allocator<T>, we can
> simplify
>    //the initialization taking just one allocator for all inner
> containers.
>    complex_data(int id, const char *name, const void_allocator
> &void_alloc)
>       : id_(id), char_string_(name, void_alloc),
> int_vector_vector_(void_alloc)
>    {}
>    //Other members...
> };
> 
> //Definition of the map holding a string as key and complex_data as mapped
> type
> typedef std::pair<const char_string, int>                     
> map_value_type;
> typedef std::pair<char_string, int>                           
> movable_to_map_value_type;
> typedef allocator<map_value_type, segment_manager_t>                   
> map_value_type_allocator;
> typedef map< char_string, int
>            , std::less<char_string>, map_value_type_allocator>         
> complex_map_type;
> 
> int main ()
> {
>    //Remove shared memory on construction and destruction
>    struct shm_remove
>    {
>       shm_remove() { shared_memory_object::remove("MySharedMemory"); }
>       ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
>    } remover;
> 
>    //Create shared memory
>    managed_shared_memory segment(create_only,"MySharedMemory", 65536);
> 
>    //An allocator convertible to any allocator<T, segment_manager_t> type
>    void_allocator alloc_inst (segment.get_segment_manager());
> 
>    //Construct the shared memory map and fill it
>    complex_map_type *mymap = segment.construct<complex_map_type>
>       //(object name), (first ctor parameter, second ctor parameter)
>          ("MyMap")(std::less<char_string>(), alloc_inst);
> std::string s = "test";
> char_string cs(s.c_str(), alloc_inst);
> //string y (cs.c_str());
> //std::cout << y <<"\n";
> 
> // = (char_string)s;
>  
>    for(int i = 0; i < 100; ++i)
>    {
>        mymap->insert(std::pair<char_string, int>(cs , i));
>       //char_string  key_object(alloc_inst);
>       //map_value_type value(key_object, i);
>      // mymap->insert(value);
>    }
>    return 0;
> }
> 
> Process2.
> #include <boost/interprocess/managed_shared_memory.hpp>
> #include <boost/interprocess/allocators/allocator.hpp>
> #include <boost/interprocess/containers/map.hpp>
> #include <boost/interprocess/containers/vector.hpp>
> #include <boost/interprocess/containers/string.hpp>
> #include <iostream>
> #include <boost/interprocess/containers/vector.hpp>
> #include <algorithm>
> using namespace boost::interprocess;
> typedef managed_shared_memory::segment_manager                      
> segment_manager_t;
> typedef allocator<void, segment_manager_t>                          
> void_allocator;
> typedef allocator<int, segment_manager_t>                           
> int_allocator;
> typedef vector<int, int_allocator>                                  
> int_vector;
> typedef allocator<int_vector, segment_manager_t>                    
> int_vector_allocator;
> typedef vector<int_vector, int_vector_allocator>                    
> int_vector_vector;
> typedef allocator<char, segment_manager_t>                          
> char_allocator;
> typedef basic_string<char, std::char_traits<char>, char_allocator>  
> char_string;
> 
> class complex_data
> {
>    int id_;
>    char_string char_string_;
>    int_vector_vector int_vector_vector_;
>    public:
>    complex_data(int id, const char *name, const void_allocator
> &void_alloc): id_(id), char_string_(name, void_alloc),
> int_vector_vector_(void_alloc)
>    {}
> };
> 
> typedef std::pair<const char_string, int> map_value_type;
> typedef std::pair<char_string, int> movable_to_map_value_type;
> typedef allocator<map_value_type, segment_manager_t> 
> map_value_type_allocator;
> typedef map< char_string, int,std::less<char_string>,
> map_value_type_allocator> complex_map_type;
> 
> int main ()
> {
>   using namespace boost::interprocess;
>   try
>   {
>       managed_shared_memory segment(open_only  ,"MySharedMemory");  
>       typedef map< char_string, int, std::less<char_string>,
> map_value_type_allocator> complex_map_type;
>       complex_map_type *MyMap =
> segment.find<complex_map_type>("MyMap").first;       
>       for (complex_map_type::iterator it = MyMap->begin(); it !=
> MyMap->end(); it++)
>       {
>          std::cout << it->first << "\n";
>       }
>       segment.destroy<complex_map_type>("MyMap");
>    }
>    catch(...)
>    {
>       shared_memory_object::remove("MySharedMemory");
>       throw;
>    }
>    shared_memory_object::remove("MySharedMemory");
>    return 0;
> }
> 
> 
> But i am getting the following error message 
> 
> terminate called after throwing an instance of
> 'boost::interprocess::interprocess_exception'
>   what():  No such file or directory
> Aborted
>  
> What is the reason for this? Thanks in advance.
> 
> 

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