doc_cached_node_allocator.cpp

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//////////////////////////////////////////////////////////////////////////////
//
// (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_cached_node_allocator
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/allocators/cached_node_allocator.hpp>
#include <cassert>

using namespace boost::interprocess;

int main ()
{
   shared_memory_object::remove("MySharedMemory");
   try{
      //Create shared memory
      managed_shared_memory segment(create_only, 
                                    "MySharedMemory",  //segment name
                                    65536);

      //Create a cached_node_allocator that allocates ints from the managed segment
      //The number of chunks per segment is the default value
      typedef cached_node_allocator<int, managed_shared_memory::segment_manager>
         cached_node_allocator_t;
      cached_node_allocator_t allocator_instance(segment.get_segment_manager());

      //The max cached nodes are configurable per instance
      allocator_instance.set_max_cached_nodes(3);

      //Create another cached_node_allocator. Since the segment manager address
      //is the same, this cached_node_allocator will be
      //attached to the same pool so "allocator_instance2" can deallocate
      //nodes allocated by "allocator_instance"
      cached_node_allocator_t allocator_instance2(segment.get_segment_manager());

      //The max cached nodes are configurable per instance
      allocator_instance2.set_max_cached_nodes(5);

      //Create another cached_node_allocator using copy-constructor. This
      //cached_node_allocator will also be attached to the same pool
      cached_node_allocator_t allocator_instance3(allocator_instance2);

      //We can clear the cache
      allocator_instance3.deallocate_cache();

      //All allocators are equal
      assert(allocator_instance == allocator_instance2);
      assert(allocator_instance2 == allocator_instance3);

      //So memory allocated with one can be deallocated with another
      allocator_instance2.deallocate(allocator_instance.allocate(1), 1);
      allocator_instance3.deallocate(allocator_instance2.allocate(1), 1);

      //The common pool will be destroyed here, since no allocator is
      //attached to the pool
   }
   catch(...){
      shared_memory_object::remove("MySharedMemory");
      throw;
   }
   shared_memory_object::remove("MySharedMemory");
   return 0;
}
//]
#include <boost/interprocess/detail/config_end.hpp>