libs/interprocess/example/doc_node_allocator.cpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2006-2012. Distributed under the Boost
   4 // Software License, Version 1.0. (See accompanying file
   5 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // See http://www.boost.org/libs/interprocess for documentation.
   8 //
   9 //////////////////////////////////////////////////////////////////////////////
  10 #include <boost/interprocess/detail/config_begin.hpp>
  11 #include <boost/interprocess/detail/workaround.hpp>
  12 //[doc_node_allocator
  13 #include <boost/interprocess/managed_shared_memory.hpp>
  14 #include <boost/interprocess/allocators/node_allocator.hpp>
  15 #include <cassert>
  16 //<-
  17 #include "../test/get_process_id_name.hpp"
  18 //->
  19
  20 using namespace boost::interprocess;
  21
  22 int main ()
  23 {
  24    //Remove shared memory on construction and destruction
  25    struct shm_remove
  26    {
  27    //<-
  28    #if 1
  29       shm_remove() { shared_memory_object::remove(test::get_process_id_name()); }
  30       ~shm_remove(){ shared_memory_object::remove(test::get_process_id_name()); }
  31    #else
  32    //->
  33       shm_remove() { shared_memory_object::remove("MySharedMemory"); }
  34       ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
  35    //<-
  36    #endif
  37    //->
  38    } remover;
  39    //<-
  40    (void)remover;
  41    //->
  42
  43    //Create shared memory
  44    //<-
  45    #if 1
  46    managed_shared_memory segment(create_only,
  47                                  test::get_process_id_name(),  //segment name
  48                                  65536);
  49    #else
  50    //->
  51    managed_shared_memory segment(create_only,
  52                                  "MySharedMemory",  //segment name
  53                                  65536);
  54    //<-
  55    #endif
  56    //->
  57
  58    //Create a node_allocator that allocates ints from the managed segment
  59    //The number of chunks per segment is the default value
  60    typedef node_allocator<int, managed_shared_memory::segment_manager>
  61       node_allocator_t;
  62    node_allocator_t allocator_instance(segment.get_segment_manager());
  63
  64    //Create another node_allocator. Since the segment manager address
  65    //is the same, this node_allocator will be
  66    //attached to the same pool so "allocator_instance2" can deallocate
  67    //nodes allocated by "allocator_instance"
  68    node_allocator_t allocator_instance2(segment.get_segment_manager());
  69
  70    //Create another node_allocator using copy-constructor. This
  71    //node_allocator will also be attached to the same pool
  72    node_allocator_t allocator_instance3(allocator_instance2);
  73
  74    //All allocators are equal
  75    assert(allocator_instance == allocator_instance2);
  76    assert(allocator_instance2 == allocator_instance3);
  77
  78    //So memory allocated with one can be deallocated with another
  79    allocator_instance2.deallocate(allocator_instance.allocate(1), 1);
  80    allocator_instance3.deallocate(allocator_instance2.allocate(1), 1);
  81
  82    //The common pool will be destroyed here, since no allocator is
  83    //attached to the pool
  84    return 0;
  85 }
  86 //]
  87 #include <boost/interprocess/detail/config_end.hpp>