libs/interprocess/example/doc_managed_grow.cpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2006-2009. 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 //[doc_managed_grow
  12 #include <boost/interprocess/managed_shared_memory.hpp>
  13 #include <boost/interprocess/managed_mapped_file.hpp>
  14 #include <cassert>
  15 //<-
  16 #include "../test/get_process_id_name.hpp"
  17 //->
  18
  19 class MyClass
  20 {
  21    //...
  22 };
  23
  24 int main()
  25 {
  26    using namespace boost::interprocess;
  27    //Remove shared memory on construction and destruction
  28    struct shm_remove
  29    {
  30    //<-
  31    #if 1
  32       shm_remove() { shared_memory_object::remove(test::get_process_id_name()); }
  33       ~shm_remove(){ shared_memory_object::remove(test::get_process_id_name()); }
  34    #else
  35    //->
  36       shm_remove() { shared_memory_object::remove("MySharedMemory"); }
  37       ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
  38    //<-
  39    #endif
  40    //->
  41    } remover;
  42
  43    {
  44       //Create a managed shared memory
  45       //<-
  46       #if 1
  47       managed_shared_memory shm(create_only, test::get_process_id_name(), 1000);
  48       #else
  49       //->
  50       managed_shared_memory shm(create_only, "MySharedMemory", 1000);
  51       //<-
  52       #endif
  53       //->
  54
  55       //Check size
  56       assert(shm.get_size() == 1000);
  57       //Construct a named object
  58       MyClass *myclass = shm.construct<MyClass>("MyClass")();
  59       //The managed segment is unmapped here
  60       //<-
  61       (void)myclass;
  62       //->
  63    }
  64    {
  65       //Now that the segment is not mapped grow it adding extra 500 bytes
  66       //<-
  67       #if 1
  68       managed_shared_memory::grow(test::get_process_id_name(), 500);
  69       #else
  70       //->
  71       managed_shared_memory::grow("MySharedMemory", 500);
  72       //<-
  73       #endif
  74       //->
  75
  76       //Map it again
  77       //<-
  78       #if 1
  79       managed_shared_memory shm(open_only, test::get_process_id_name());
  80       #else
  81       //->
  82       managed_shared_memory shm(open_only, "MySharedMemory");
  83       //<-
  84       #endif
  85       //->
  86       //Check size
  87       assert(shm.get_size() == 1500);
  88       //Check "MyClass" is still there
  89       MyClass *myclass = shm.find<MyClass>("MyClass").first;
  90       assert(myclass != 0);
  91       //The managed segment is unmapped here
  92    }
  93    {
  94       //Now minimize the size of the segment
  95       //<-
  96       #if 1
  97       managed_shared_memory::shrink_to_fit(test::get_process_id_name());
  98       #else
  99       //->
 100       managed_shared_memory::shrink_to_fit("MySharedMemory");
 101       //<-
 102       #endif
 103       //->
 104
 105       //Map it again
 106       //<-
 107       #if 1
 108       managed_shared_memory shm(open_only, test::get_process_id_name());
 109       #else
 110       //->
 111       managed_shared_memory shm(open_only, "MySharedMemory");
 112       //<-
 113       #endif
 114       //->
 115       //Check size
 116       assert(shm.get_size() < 1000);
 117       //Check "MyClass" is still there
 118       MyClass *myclass = shm.find<MyClass>("MyClass").first;
 119       assert(myclass != 0);
 120       //The managed segment is unmapped here
 121    }
 122    return 0;
 123 }
 124 //]
 125 #include <boost/interprocess/detail/config_end.hpp>