混合编程python与C++

Posted on by hackdl

上个版本: 只是用到ctypes进行传输, 这次将python服务端更改为C++服务端,方便后续维护.
本文实现功能: python传输图片给C++, C++接受图片后对图片进行处理,并将结果返回给python客户端, pass image from python to C++

C++ 服务端

.h文件

注意文中的model

// .h
#pragma once
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;
using namespace cv;

class ModelManager;

class ServerManager
{
private:
	int m_port;
	char *m_addr;
	cv::VideoCapture m_cap;
	int m_server;
	int m_accept; // client conn
public:
	bool initialization(const int &port, const cv::VideoCapture &cap, char *addr = nullptr);
	bool initialization(const int &port, char *addr = nullptr);
	bool build_connect();
	bool acceptClient();
	void error_print(const char *ptr);
	bool free_connect();

	bool send_data_frame(ModelManager& model);
	bool receive_data_frame(cv::Mat &frame, ModelManager& model);
};

.cpp文件

#include "ServerManager.h"
#include "ModelManager.h"
#define BUFFER_SIZE 65538

void ServerManager::error_print(const char * ptr) {
        perror(ptr);
        exit(EXIT_FAILURE);
}

bool ServerManager::initialization(const int& port, const cv::VideoCapture& cap, char* addr){
    m_port = htons(port);
	m_addr = addr;
	m_cap = cap;
	return true;
}

bool ServerManager::initialization(const int& port, char* addr){
    m_port = htons(port);
    m_addr = addr;
	return true;
}

bool ServerManager::build_connect() {
	struct sockaddr_in server_addr;
    bzero(&server_addr,sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_addr.s_addr = m_addr?inet_addr(m_addr):INADDR_ANY;  
	server_addr.sin_port = m_port;
	// create socket 
	m_server = socket(AF_INET, SOCK_STREAM, 0);
	if(m_server  decode;
	// int bytes_received = 0;
	// do
	// {
	// 	int nBytes = recv(m_accept, buf, data_size - bytes_received, 0);
	// 	for (int i = 0; i  decode(data_size, 0);
	int index = 0;
	int bytes_received = 0;
	int count = data_size;
	while (count > 0)// if count >= 0, dead loop
	{
		int iRet = recv(m_accept, recv_char, count, 0);
		if (index >= data_size) index = data_size;
		memcpy(&decode[index], recv_char , iRet);
		index += iRet;
		if (!iRet) { return -1; }
		count -= iRet;
	}
	// decode message
	frame = imdecode(decode, cv::IMREAD_COLOR);
	// push into Model's queueMat
	model.mtxQueueImg.lock();
	model.queueMat.push(frame);
	model.mtxQueueImg.unlock();
	return true;
}

bool ServerManager::free_connect() {
	m_cap.release();
	close(m_accept);
    close(m_server);
	return true;
}

C++ model部分代码

.h文件

#pragma once
#include "CV_Classify.h"
#include "CV_Detect.h"
#include "ServerManager.h"
#include 
#include 
#include 
#include  // usleep
#include 
#include "cJSON.h"
#include 

using namespace std;
using namespace cv;

class ModelManager{
public:
    Detect objdetect;
    Classify objclassify;
    std::mutex mtxQueueDet;  // mutex for detect queue
    std::mutex mtxQueueImg;  // mutex for image queue
    std::mutex mtxQueueCls;  // mutex for classify queue
    std::queue queueMat;
    std::queue queueDetOut;// Detect queue
    std::queue queueClsOut;// Classify queue
    
    bool DetectFlag = true;
    bool ClassifyFlag = true;
    bool empty_flag = false;
    friend class ServerManager;
public:
    void initDetectModel() ;
    void initClassifyModel() ;
    void DetectImg();
    void ClassifyImg();
    void getClsResult(ObjClassifyOutput &output);
    // ObjClassifyOutput getClsResult();
    char* createJson();
};

.cpp文件

部分有删减,createJson可参考使用,利用json来传递值

#include "ModelManager.h"

void ModelManager::initDetectModel() 
{
    std::string config_path = "DetectConfig.yaml";
    objdetect.Init(config_path, 1);
}
void ModelManager::initClassifyModel() 
{
    std::string config_path = "ClassiflyConfig.yaml";
    objclassify.Init(config_path, 1);
}

void ModelManager::DetectImg()
{
    DetectInput detect_input;
    DetectOutput detect_output;
    cv::Mat frame;
    size_t mm = 0;
    while(1)
    { 
        if (queueMat.empty()) 
        {
            if(!DetectFlag)
            {
                break;
            }
			usleep(2000);
            continue;
		}
        // get image from queueMat
        mtxQueueImg.lock();
        frame = queueMat.front();
        queueMat.pop();
        mtxQueueImg.unlock();
        // run model
        objdetect.Run(detect_input, detect_output);
        // push detect result into queueDetOut
        mtxQueueDet.lock();
        queueDetOut.push(detect_output);
        // cout

C++ 服务端运行

#include 
#include 
#include 
#define PORT 8080
void recvServer(ServerManager& s, ModelManager& model){
    int idx = 0;
    
    while (true){
        // auto start = std::chrono::steady_clock::now();
        cv::Mat frame;
        s.receive_data_frame(frame, model);
        // cal time cost
        // auto end = std::chrono::steady_clock::now();
        // std::chrono::duration elapsed = end - start;
        // std::cout

python客户端

import json
import socket
import struct
import time
from multiprocessing import JoinableQueue
from threading import Thread

import os
from natsort import ns, natsorted

host = '192.168.0.2'  # '192.168.0.2' 'localhost'
port = 8080


def img_encode(img_path):
    img = cv2.imread(img_path)
    # img = cv2.resize(img, (500, 500), interpolation=cv2.INTER_CUBIC)
    img_param = [95]  # 图片压缩率0-100
    _, img = cv2.imencode('.jpg', img, img_param)
    img = img.tobytes()
    return img


def img_product(img_queue, path, path_mode='image'):
    if path_mode == 'image':
        image = img_encode(path)
        img_queue.put(image)
    elif path_mode == 'dir':
        dir_list = os.listdir(path)
        files = natsorted(dir_list, alg=ns.PATH)  # 顺序读取文件名
        for filename in files:
            img_path = path + '/' + filename
            image = img_encode(img_path)
            img_queue.put(image)
        img_queue.put('E')
    img_queue.join()


def server_consumer(img_queue):
    while True:
        start = int(round(time.time() * 1000))
        # 1. get img from queue
        img_obj = img_queue.get()
        img_queue.task_done()
        # get end signal
        if img_obj[0] == 'E':
        client.close()
        break
        # 2. send package(img_bytes_size, img_bytes)
        pack_size = struct.pack("i", len(img_obj))
        client.send(pack_size + img_obj)
        end = int(round(time.time() * 1000))

        data = client.recv(65536)
        json_str = data.decode('utf8', 'ignore').strip(b'x00'.decode())
        results = json.loads(json_str)
        end = int(round(time.time() * 1000))
        end_time = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())
        print('send and recv cost time: ', (end - start))
        print(results)


        if __name__ == '__main__':
        client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        client.connect((host, port))
        img_dir = 'data'
        one_img = './data/image.jpg'
        mode = 'dir'

        img_jq = JoinableQueue()
        producer = Thread(target=img_product, args=(img_jq, img_dir, mode,))
        consumer = Thread(target=server_consumer, args=(img_jq,))
        producer.daemon = True  # set daemon but not set join()

        producer.start()
        consumer.start()

    # producer.join() // 让生产者先关闭,防止close错误
        consumer.join()

总结

  • 其实这个项目真正做完感觉还是挺简单, 就是对socket通信不太熟悉, 以及传图片没做过.
  • 实际上传图片只需要读取图片后,imencode,然后tobytes,最后发送size和data即可.而接受端只需要拼接数组,然后imdecode即可.
  • 另外传输结果的话利用json传输可以让结果可读性可高, 传输也比较方便, 当时copy别人的发送代码, 没有细看,导致使用memcpy让json格式乱码,导致无法解码json.
  • 如果你感觉接收端没问题,一定要看看发送端.
  • 之后的新任务就是视频传输利用rtsp流,敬请期待

参考博客

  • use memcpy in receive_frame function if you want,对应github地址
  • a pure client and server code to create a simple demo
  • 如果用ctrl+z中断,可能导致address in use,使用bg/fg

    • 用户可以使用fg/bg操作继续前台或后台的任务，fg命令重新启动前台被中断的任务，bg命令把被中断的任务放在后台执行
  • zmq send img
  • 优化imdecode速度,本代码未使用
  • 视频传输跟图片传输差不多
  • Linux c++获取本地毫秒级精确时间
  • 如果不想用json,可以试试struct
  • 利用json来传输分类结果

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