interprocess/example/doc_offset_ptr.cpp

//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2006-2007. 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_offset_ptr
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/offset_ptr.hpp>

using namespace boost::interprocess;

//Shared memory linked list node
struct list_node
{
   offset_ptr<list_node> next;
   int                   value;
};

int main ()
{
   //Remove shared memory on construction and destruction
   struct shm_destroy
   {
      shm_destroy() { shared_memory_object::remove("MySharedMemory"); }
      ~shm_destroy(){ shared_memory_object::remove("MySharedMemory"); }
   } remover;

   managed_shared_memory segment(
      create_only, 
      "MySharedMemory", //segment name
      65536);           //segment size in bytes

   //Create linked list with 10 nodes in shared memory
   offset_ptr<list_node> prev = 0, current, first;

   int i;
   for(i = 0; i < 10; ++i, prev = current){
      current = static_cast<list_node*>(segment.allocate(sizeof(list_node)));
      current->value = i;
      current->next  = 0;

      if(!prev)
         first = current;
      else
         prev->next = current;
   }

   //Communicate list to other processes
   //. . .
   //When done, destroy list
   for(current = first; current; /**/){
      prev = current;
      current = current->next;
      segment.deallocate(prev.get());
   }
   return 0;
}
//]
#include <boost/interprocess/detail/config_end.hpp>