libs/interprocess/example/doc_ipc_message.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 #include <boost/interprocess/detail/workaround.hpp>
  12 //[doc_ipc_message
  13 #include <boost/interprocess/managed_shared_memory.hpp>
  14 #include <cstdlib> //std::system
  15 #include <sstream>
  16 //<-
  17 #include "../test/get_process_id_name.hpp"
  18 //->
  19
  20 int main (int argc, char *argv[])
  21 {
  22    using namespace boost::interprocess;
  23    if(argc == 1){  //Parent process
  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       //Create a managed shared memory segment
  41       //<-
  42       #if 1
  43       managed_shared_memory segment(create_only, test::get_process_id_name(), 65536);
  44       #else
  45       //->
  46       managed_shared_memory segment(create_only, "MySharedMemory", 65536);
  47       //<-
  48       #endif
  49       //->
  50
  51       //Allocate a portion of the segment (raw memory)
  52       std::size_t free_memory = segment.get_free_memory();
  53       void * shptr = segment.allocate(1024/*bytes to allocate*/);
  54
  55       //Check invariant
  56       if(free_memory <= segment.get_free_memory())
  57          return 1;
  58
  59       //An handle from the base address can identify any byte of the shared
  60       //memory segment even if it is mapped in different base addresses
  61       managed_shared_memory::handle_t handle = segment.get_handle_from_address(shptr);
  62       std::stringstream s;
  63       s << argv[0] << " " << handle;
  64       //<-
  65       s << " " << test::get_process_id_name();
  66       //->
  67       s << std::ends;
  68       //Launch child process
  69       if(0 != std::system(s.str().c_str()))
  70          return 1;
  71       //Check memory has been freed
  72       if(free_memory != segment.get_free_memory())
  73          return 1;
  74    }
  75    else{
  76       //Open managed segment
  77       //<-
  78       #if 1
  79       managed_shared_memory segment(open_only, argv[2]);
  80       #else
  81       //->
  82       managed_shared_memory segment(open_only, "MySharedMemory");
  83       //<-
  84       #endif
  85       //->
  86
  87       //An handle from the base address can identify any byte of the shared
  88       //memory segment even if it is mapped in different base addresses
  89       managed_shared_memory::handle_t handle = 0;
  90
  91       //Obtain handle value
  92       std::stringstream s; s << argv[1]; s >> handle;
  93
  94       //Get buffer local address from handle
  95       void *msg = segment.get_address_from_handle(handle);
  96
  97       //Deallocate previously allocated memory
  98       segment.deallocate(msg);
  99    }
 100    return 0;
 101 }
 102 //]
 103 #include <boost/interprocess/detail/config_end.hpp>