ceph/src/boost/libs/interprocess/example/comp_doc_anonymous_upgradable_mutexB.cpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2006-2012. 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    (void)remover;
  31    //->
  32
  33    //Open the shared memory object.
  34    shared_memory_object shm
  35       (open_only                    //only create
  36       ,"MySharedMemory"              //name
  37       ,read_write  //read-write mode
  38       );
  39
  40    //Map the whole shared memory in this process
  41    mapped_region region
  42       (shm                       //What to map
  43       ,read_write //Map it as read-write
  44       );
  45
  46    //Get the address of the mapped region
  47    void * addr       = region.get_address();
  48
  49    //Construct the shared structure in memory
  50    shared_data * data = static_cast<shared_data*>(addr);
  51
  52    //Write some logs
  53    for(int i = 0; i < 100; ++i){
  54       //Lock the upgradable_mutex
  55       scoped_lock<interprocess_upgradable_mutex> lock(data->upgradable_mutex);
  56       std::sprintf(data->items[(data->current_line++) % shared_data::NumItems]
  57                ,"%s_%d", "process_a", i);
  58       if(i == (shared_data::NumItems-1))
  59          data->end_b = true;
  60       //Mutex is released here
  61    }
  62
  63    //Wait until the other process ends
  64    while(1){
  65       scoped_lock<interprocess_upgradable_mutex> lock(data->upgradable_mutex);
  66       if(data->end_a)
  67          break;
  68    }
  69    return 0;
  70 }
  71 //]
  72
  73 #include <boost/interprocess/detail/config_end.hpp>