共享内存向量的提升

问题描述

我有以下代码.尝试使用结构包含字符串和数组的共享内存向量.但是当我编译代码时，我得到了错误:

I have the following code. Trying to have a shared memory vector with structure having string and arrays. But when i compile the code I am getting error:

 usr/local/include/boost/container/vector.hpp:1819:4: error: no matching function for call to ‘InData::InData(InData* const&)’

关于如何解决此问题的任何建议.我是Boost的新手.

Any suggestion how to fix this. I am new to Boost.

#include <iostream>
#include <string>
#include <cstdlib>
#include <boost/interprocess/ipc/message_queue.hpp>
#include <boost/scoped_ptr.hpp>
#include <boost/interprocess/shared_memory_object.hpp>
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/mapped_region.hpp>
#include <boost/interprocess/allocators/allocator.hpp>
#include <boost/interprocess/containers/string.hpp>
#include <boost/interprocess/containers/vector.hpp>

using namespace boost::interprocess;

typedef boost::interprocess::basic_string<char> shared_string;

    struct InData
    {
        int X,Y,H,W;
        shared_string Label;
    };

    int main()
    {

        shared_memory_object::remove("MySharedMemory");
        managed_shared_memory managed_shm(create_only, "MySharedMemory", 10000);

        InData tData;// = managed_shm.construct<InData>("InDataStructure")();

        tData.Label = "Hello World";
        tData.H = 1;
        tData.W = 1;
        tData.Y = 1;
        tData.X = 1;

        typedef allocator<InData,managed_shared_memory::segment_manager> tStructData;
        typedef vector<InData,tStructData>  MyVector;

        //Initialize shared memory STL-compatible allocator
         tStructData alloc_inst (managed_shm.get_segment_manager());

         //Construct a vector named "MyVector" in shared memory with argument alloc_inst
          MyVector *myvector = managed_shm.construct<MyVector>("MyVector")(alloc_inst);

          //InData data;
          myvector->push_back(&tData);

        return 0;
    }

如果只是myvector->push_back(tData)

/usr/local/include/boost/container/detail/advanced_insert_int.hpp:166:10: error: no match for ‘operator=’ (operand types are ‘InData’ and ‘const value_type {aka const InData}’)

推荐答案

我已经对我的评论进行了现场编码: 录制的会话

I've live-coded my review: recorded session

固定的代码如下.一些注意事项(不过请观看流媒体会话):

The fixed up code is below. Some of the notes (please watch the streaming session, though):

1. 您未能为共享"字符串分配分配器.这意味着它使用std::allocator，并且分配是从程序堆完成的. OOOPS.如果幸运的话，您的程序将终止.

1. you failed to give the "shared" string an allocator. That means it uses std::allocator and the allocations are done from the program heap. OOOPS. Your program will die, if you're lucky.

一旦给shared_string适当的分配器，就会发现涟漪效应.您需要在构造shared_string时传递分配器实例，因为进程间分配器实例默认不是可构造的.

once you give the shared_string the proper allocator, you'll find ripple effects. You need to pass in allocator instances at construction of shared_string because interprocess allocator instances are not default constructible.

命名很重要:

naming is important:

typedef allocator<InData, managed_shared_memory::segment_manager> tStructData;

为什么命名您的分配器类型为tStructData?您最好将其称为XXX.因此，将其更改为

why name your allocator type tStructData? You might as well call it XXX. So, change it to

typedef allocator<InData, managed_shared_memory::segment_manager> salloc;

考虑使用从segment_manager

行

myvector->push_back(&tData);

尝试将 pointer 推入类对象的向量中.不管您的分配器是什么，它永远都行不通

tries to push a pointer into a vector of class objects. That can never work, regardless of your allocator(s)

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

using namespace boost::interprocess;

struct InData;
typedef allocator<InData, managed_shared_memory::segment_manager> salloc;

typedef boost::interprocess::basic_string<char, std::char_traits<char>, salloc::rebind<char>::other> shared_string;

struct InData {
    int X, Y, H, W;

    InData(salloc alloc) : Label(alloc) {}

    shared_string Label;
};

int main() {

    shared_memory_object::remove("MySharedMemory");
    managed_shared_memory managed_shm(create_only, "MySharedMemory", 10000);

    // Initialize shared memory STL-compatible allocator
    salloc alloc_inst(managed_shm.get_segment_manager());

    InData tData(alloc_inst); // = managed_shm.construct<InData>("InDataStructure")();

    tData.Label = "Hello World";
    tData.H = 1;
    tData.W = 1;
    tData.Y = 1;
    tData.X = 1;

    // Construct a vector named "MyVector" in shared memory with argument alloc_inst
    typedef vector<InData, salloc> MyVector;
    MyVector *myvector = managed_shm.construct<MyVector>("MyVector")(alloc_inst);

    // InData data;
    myvector->push_back(tData);
}

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