ZeroMQ C++ 上的简单 FlatBuffer 示例 - 通过 zmq 将结构复制到 flatbuffer 并再次返回结构

Question

我参考了一些 and I'm modeling my system off of the server and client 示例，我觉得我已经很接近了。

StarBuffer.fbs:
table StarBuffer { radius: double; mass: double; volume: double; } root_type StarBuffer;

subscriber.cpp:

//    
//  Durable subscriber
//
// Olivier Chamoux <olivier.chamoux@fr.thalesgroup.com>

#include "zhelpers.hpp"
#include <zmq.hpp>
#include "StarBuffer.h" // generated flat file from StarBuffer.fbs

struct Star {
    double radius ;
    double mass;
    double volume;
};

int main (int argc, char *argv[])
{ 
    zmq::context_t context = zmq::context_t(1);

    //  Connect our subscriber socket
    zmq::socket_t subSocket = zmq::socket_t(context, ZMQ_SUB);
    subSocket.setsockopt(ZMQ_IDENTITY, "Hello", 5);
    subSocket.setsockopt(ZMQ_SUBSCRIBE, "", 0);
    subSocket.connect("tcp://localhost:5565");

    //  Get updates, expect random Ctrl-C death
    while (1) {
        zmq::message_t receiveMessage;
        subSocket.recv(&receiveMessage);

        flatbuffers::FlatBufferBuilder fbb;
        StarBufferBuilder builder(fbb);

        auto star = GetStarBuffer(receiveMessage.data());

        std::cout << "Received Star" << std::endl;
        std::cout << "radius: " << star->radius() << std::endl;
        std::cout << "mass: " << star->mass() << std::endl;
        std::cout << "volume: " << star->volume() << std::endl;
    }
    return 0;
}

publisher.cpp:

//
//  Publisher for durable subscriber
//
// Olivier Chamoux <olivier.chamoux@fr.thalesgroup.com>

#include "zhelpers.hpp"
#include <zmq.hpp>
#include <random>
#include "StarBuffer.h" // generated flat file from StarBuffer.fbs

struct Star {
    double radius ;
    double mass;
    double volume;
};

template<typename Numeric, typename Generator = std::mt19937>
Numeric random(Numeric from, Numeric to)
{
    thread_local static Generator gen(std::random_device{}());

    using dist_type = typename std::conditional
    <
        std::is_integral<Numeric>::value
        , std::uniform_int_distribution<Numeric>
        , std::uniform_real_distribution<Numeric>
    >::type;

    thread_local static dist_type dist;

    return dist(gen, typename dist_type::param_type{from, to});
}


Star getRandomStar() {
    double lower_bound = 0;
    double upper_bound = std::numeric_limits<double>::max();
    double randomRadius = random(lower_bound, upper_bound);
    double randomMass = random(lower_bound, upper_bound);
    double randomVolume = random(lower_bound, upper_bound);

    Star s = Star();
    s.radius = randomRadius;
    s.mass = randomMass;
    s.volume = randomVolume;

   return s;
}

int main () {

    zmq::context_t context = zmq::context_t(1);

    //  We send updates via this socket
    zmq::socket_t publishSocket = zmq::socket_t(context, ZMQ_PUB);
    publishSocket.bind("tcp://*:5565");

    //  Now broadcast exactly 10 updates with pause
    int update_nbr;
    for (update_nbr = 0; update_nbr < 100; update_nbr++) {

        Star randomStar = getRandomStar();

        flatbuffers::FlatBufferBuilder fbb;
        StarBufferBuilder builder(fbb);

        builder.add_radius(randomStar.radius);
        builder.add_mass(randomStar.mass);
        builder.add_volume(randomStar.volume);

        auto response = builder.Finish();
        fbb.Finish(response);

        std::cout << "Sending Star " << update_nbr << "…" << std::endl;
        int buffersize = fbb.GetSize();
        zmq::message_t request(buffersize);
        memcpy((void *)request.data(), fbb.GetBufferPointer(), buffersize);
        publishSocket.send(request);
        std::cout << "Star sent!" << std::endl;

        sleep(1);
    }
    return 0;
}

编辑：代码编译并运行！我在这里更新了代码，以反映我在本地机器上的工作代码，供人们继续使用，因为这花了我很多时间才完成。

因为我也花了一段时间才弄明白这些东西，所以这里是构建过程：

flatc --cpp StarBuffer.fbs mv StarBuffer_generated.h StarBuffer.h g++ -std=c++11 publisher.cpp -lzmq -o ./bin/zmq_pub g++ -std=c++11 subscriber.cpp -lzmq -o ./bin/zmq_sub

您的本地目录中需要 'zhelpers.cpp' 和 'flatbuffers/flatbuffers.h'。

Answer 1

尝试auto star = GetRootAsStarBuffer(request.data());。您使用的 Create 函数是创建缓冲区，而不是读取现有缓冲区。

无关，但在写作方面，您应该看看是否可以创建 message_t 而不必使用 memcpy，这样效率会更高。

ZeroMQ C++ 上的简单 FlatBuffer 示例 - 通过 zmq 将结构复制到 flatbuffer 并再次返回结构

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