libs/interprocess/example/comp_doc_anonymous_upgradable_mutexA.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_anonymous_upgradable_mutexA
  12 #include <boost/interprocess/shared_memory_object.hpp>
  13 #include <boost/interprocess/mapped_region.hpp>
  14 #include <boost/interprocess/sync/scoped_lock.hpp>
  15 #include "doc_upgradable_mutex_shared_data.hpp"
  16 #include <iostream>
  17 #include <cstdio>
  18
  19 using namespace boost::interprocess;
  20
  21 int main ()
  22 {
  23    //Remove shared memory on destruction
  24    struct shm_remove
  25    {
  26       ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
  27    } remover;
  28
  29    //Create a shared memory object.
  30    shared_memory_object shm
  31       (create_only               //only create
  32       ,"MySharedMemory"           //name
  33       ,read_write   //read-write mode
  34       );
  35
  36    //Set size
  37    shm.truncate(sizeof(shared_data));
  38
  39    //Map the whole shared memory in this process
  40    mapped_region region
  41       (shm                       //What to map
  42       ,read_write //Map it as read-write
  43       );
  44
  45    //Get the address of the mapped region
  46    void * addr       = region.get_address();
  47
  48    //Construct the shared structure in memory
  49    shared_data * data = new (addr) shared_data;
  50
  51    //Write some logs
  52    for(int i = 0; i < shared_data::NumItems; ++i){
  53       //Lock the upgradable_mutex
  54       scoped_lock<interprocess_upgradable_mutex> lock(data->upgradable_mutex);
  55       std::sprintf(data->items[(data->current_line++) % shared_data::NumItems]
  56                ,"%s_%d", "process_a", i);
  57       if(i == (shared_data::NumItems-1))
  58          data->end_a = true;
  59       //Mutex is released here
  60    }
  61
  62    //Wait until the other process ends
  63    while(1){
  64       scoped_lock<interprocess_upgradable_mutex> lock(data->upgradable_mutex);
  65       if(data->end_b)
  66          break;
  67    }
  68
  69    return 0;
  70 }
  71 //]
  72 #include <boost/interprocess/detail/config_end.hpp>