boost_1_45_0/libs/interprocess/example/doc_unordered_map.cpp

//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2006-2009. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/interprocess for documentation.
//
//////////////////////////////////////////////////////////////////////////////
#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>
//[doc_unordered_map
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/allocators/allocator.hpp>

#include <boost/unordered_map.hpp>     //boost::unordered_map
#include <functional>                  //std::equal_to
#include <boost/functional/hash.hpp>   //boost::hash
//<-
#include "../test/get_process_id_name.hpp"
//->

int main ()
{
   using namespace boost::interprocess;
   //Remove shared memory on construction and destruction
   struct shm_remove
   {
   //<-
   #if 1
      shm_remove() { shared_memory_object::remove(test::get_process_id_name()); }
      ~shm_remove(){ shared_memory_object::remove(test::get_process_id_name()); }
   #else
   //->
      shm_remove() { shared_memory_object::remove("MySharedMemory"); }
      ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
   //<-
   #endif
   //->
   } remover;

   //Create shared memory
   //<-
   #if 1
   managed_shared_memory segment(create_only, test::get_process_id_name(), 65536);
   #else
   //->
   managed_shared_memory segment(create_only, "MySharedMemory", 65536);
   //<-
   #endif
   //->

   //Note that unordered_map<Key, MappedType>'s value_type is std::pair<const Key, MappedType>,
   //so the allocator must allocate that pair.
   typedef int    KeyType;
   typedef float  MappedType;
   typedef std::pair<const int, float> ValueType;

   //Typedef the allocator
   typedef allocator<ValueType, managed_shared_memory::segment_manager> ShmemAllocator;

   //Alias an unordered_map of ints that uses the previous STL-like allocator.
   typedef boost::unordered_map
      < KeyType               , MappedType
      , boost::hash<KeyType>  ,std::equal_to<KeyType>
      , ShmemAllocator>
   MyHashMap;

   //Construct a shared memory hash map.
   //Note that the first parameter is the initial bucket count and
   //after that, the hash function, the equality function and the allocator
   MyHashMap *myhashmap = segment.construct<MyHashMap>("MyHashMap")  //object name
      ( 3, boost::hash<int>(), std::equal_to<int>()                  //
      , segment.get_allocator<ValueType>());                         //allocator instance

   //Insert data in the hash map
   for(int i = 0; i < 100; ++i){
      myhashmap->insert(ValueType(i, (float)i));
   }
   return 0;
}
//]
#include <boost/interprocess/detail/config_end.hpp>