data_creator_writer_shm.cpp

#include "shared_data.h"
#include <boost/interprocess/mapped_region.hpp>
#include <boost/interprocess/shared_memory_object.hpp>
#include <boost/interprocess/sync/scoped_lock.hpp>
#include <algorithm>
#include <cstdio>
#include <iostream>
#include <thread>

using namespace boost::interprocess;

int main()
{
    // Remove shared memory on construction and destruction
    struct shm_remove
    {
        shm_remove()
        {
            shared_memory_object::remove("MySharedMemory");
        }
        ~shm_remove()
        {
            shared_memory_object::remove("MySharedMemory");
        }
    } remover;

    // Create a shared memory object.
    shared_memory_object shm(create_only, "MySharedMemory", read_write);
    // Set size
    shm.truncate(sizeof(Image));
    // Map the whole shared memory in this process
    mapped_region region(shm, read_write);
    // Get the address of the mapped region
    void* addr = region.get_address();

    // Construct the shared structure in memory
    Image* image = new (addr) Image;

    // Write some pixels
    {
        scoped_lock<interprocess_mutex> lock(image->mutex);
        image->data.fill(10);
    }

    // Wait until the other process ends
    while (1)
    {
        scoped_lock<interprocess_mutex> lock(image->mutex);
        if (std::all_of(image->data.begin(),
                        image->data.end(),
                        [](auto pixel) { return pixel == 11; }))
        {
            break;
        }
        else
        {
            lock.unlock();
            std::this_thread::sleep_for(std::chrono::seconds{1});
        }
    }
    return 0;
}