Question

我正在尝试将std :: pair添加到共享内存队列中。这不会编译。

将std :: pair添加到共享内存队列的正确方法是什么？

#include <boost/lockfree/spsc_queue.hpp> // ring buffer

#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/allocators/allocator.hpp>
#include <boost/interprocess/containers/string.hpp>


namespace bip = boost::interprocess;
namespace shm
{
typedef bip::allocator<char, bip::managed_shared_memory::segment_manager> char_alloc;
typedef bip::basic_string<char, std::char_traits<char>, char_alloc >      shared_string;

typedef boost::lockfree::spsc_queue<
    shared_string,
    boost::lockfree::capacity<200>
> ring_buffer;
}

#include <unistd.h>

// Ringbuffer fully constructed in shared memory. The element std::pair are
// also allocated from the same shared memory segment. 
shm::ring_buffer *queue;

int main()
{
    // create segment and corresponding allocator
    bip::managed_shared_memory segment(bip::open_or_create, "MySharedMemory", 65536);

    typedef std::pair<float, float> ValueType;

    typedef bip::allocator<ValueType, bip::managed_shared_memory::segment_manager>
        ShmemAllocator;

    //Initialize the shared memory STL-compatible allocator
    ShmemAllocator pair_alloc (segment.get_segment_manager());

    queue = segment.find_or_construct<shm::ring_buffer>("queue")();

    for (int i = 0; i < 3; i++)
    {
        //Do I really need a pointer to shared memory?
        ValueType *reading = segment.construct<ValueType>
           ("Sensor Pacific")     //name of the object
           (57.3, 57.8);    //ctor first argument

        queue->push(reading); // THIS_FAILS_TO_COMPILE
    }
}

我也试过

ValueType t = std::make_pair<float, float>(57.3, 57.8);
queue->push(ShmemAllocator(t, pair_alloc));

如果我改变了队列的类型，它也不起作用：

shm::ring_buffer<ValueType> *queue;

我知道我需要修改下面这部分代码，以便queue的类型为shared_std_pair，而不是shared_string，但不知道该怎么做。得到我的部分是typedef bip::basic_string<char, std::char_traits<char>, char_alloc > shared_string

我需要shared_std_pair

namespace shm
{
typedef bip::allocator<char, bip::managed_shared_memory::segment_manager> char_alloc;
typedef bip::basic_string<char, std::char_traits<char>, char_alloc >      shared_string;


typedef boost::lockfree::spsc_queue<
    shared_string,
    boost::lockfree::capacity<200>
> ring_buffer;
}

感觉我必须使用std::uses_allocator<std::tuple>这样的内容，但我不会看到std::pair的内容。

如何将std :: pair添加到共享内存队列

0 个答案: