libs/interprocess/example/comp_doc_anonymous_upgradable_mutexB.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
  12 //[doc_anonymous_upgradable_mutexB
  13 #include <boost/interprocess/shared_memory_object.hpp>
  14 #include <boost/interprocess/mapped_region.hpp>
  15 #include <boost/interprocess/sync/scoped_lock.hpp>
  16 #include "doc_upgradable_mutex_shared_data.hpp"
  17 #include <iostream>
  18 #include <cstdio>
  19
  20 using namespace boost::interprocess;
  21
  22 int main ()
  23 {
  24    //Remove shared memory on destruction
  25    struct shm_remove
  26    {
  27       ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
  28    } remover;
  29
  30    //Open the shared memory object.
  31    shared_memory_object shm
  32       (open_only                    //only create
  33       ,"MySharedMemory"              //name
  34       ,read_write  //read-write mode
  35       );
  36
  37    //Map the whole shared memory in this process
  38    mapped_region region
  39       (shm                       //What to map
  40       ,read_write //Map it as read-write
  41       );
  42
  43    //Get the address of the mapped region
  44    void * addr       = region.get_address();
  45
  46    //Construct the shared structure in memory
  47    shared_data * data = static_cast<shared_data*>(addr);
  48
  49    //Write some logs
  50    for(int i = 0; i < 100; ++i){
  51       //Lock the upgradable_mutex
  52       scoped_lock<interprocess_upgradable_mutex> lock(data->upgradable_mutex);
  53       std::sprintf(data->items[(data->current_line++) % shared_data::NumItems]
  54                ,"%s_%d", "process_a", i);
  55       if(i == (shared_data::NumItems-1))
  56          data->end_b = true;
  57       //Mutex is released here
  58    }
  59
  60    //Wait until the other process ends
  61    while(1){
  62       scoped_lock<interprocess_upgradable_mutex> lock(data->upgradable_mutex);
  63       if(data->end_a)
  64          break;
  65    }
  66    return 0;
  67 }
  68 //]
  69
  70 #include <boost/interprocess/detail/config_end.hpp>