libs/interprocess/example/doc_shared_memory.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_shared_memory
  12 #include <boost/interprocess/shared_memory_object.hpp>
  13 #include <boost/interprocess/mapped_region.hpp>
  14 #include <cstring>
  15 #include <cstdlib>
  16 #include <string>
  17 //<-
  18 #include "../test/get_process_id_name.hpp"
  19 //->
  20
  21 int main(int argc, char *argv[])
  22 {
  23    using namespace boost::interprocess;
  24
  25    if(argc == 1){  //Parent process
  26       //Remove shared memory on construction and destruction
  27       struct shm_remove
  28       {
  29       //<-
  30       #if 1
  31          shm_remove() { shared_memory_object::remove(test::get_process_id_name()); }
  32          ~shm_remove(){ shared_memory_object::remove(test::get_process_id_name()); }
  33       #else
  34       //->
  35          shm_remove() { shared_memory_object::remove("MySharedMemory"); }
  36          ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
  37       //<-
  38       #endif
  39       //->
  40       } remover;
  41
  42       //Create a shared memory object.
  43       //<-
  44       #if 1
  45       shared_memory_object shm (create_only, test::get_process_id_name(), read_write);
  46       #else
  47       //->
  48       shared_memory_object shm (create_only, "MySharedMemory", read_write);
  49       //<-
  50       #endif
  51       //->
  52
  53       //Set size
  54       shm.truncate(1000);
  55
  56       //Map the whole shared memory in this process
  57       mapped_region region(shm, read_write);
  58
  59       //Write all the memory to 1
  60       std::memset(region.get_address(), 1, region.get_size());
  61
  62       //Launch child process
  63       std::string s(argv[0]); s += " child ";
  64       //<-
  65       s += test::get_process_id_name();
  66       //->
  67       if(0 != std::system(s.c_str()))
  68          return 1;
  69    }
  70    else{
  71       //Open already created shared memory object.
  72       //<-
  73       #if 1
  74       shared_memory_object shm (open_only, argv[2], read_only);
  75       #else
  76       //->
  77       shared_memory_object shm (open_only, "MySharedMemory", read_only);
  78       //<-
  79       #endif
  80       //->
  81
  82       //Map the whole shared memory in this process
  83       mapped_region region(shm, read_only);
  84
  85       //Check that memory was initialized to 1
  86       char *mem = static_cast<char*>(region.get_address());
  87       for(std::size_t i = 0; i < region.get_size(); ++i)
  88          if(*mem++ != 1)
  89             return 1;   //Error checking memory
  90    }
  91    return 0;
  92 }
  93 //]
  94 #include <boost/interprocess/detail/config_end.hpp>