写一些std::string相关的操作

数据包装成string,注意,提前reserve下内存
主要考察sting::append(char*, size)把char*指向的数据保存到string内

void sendBufToRedis(sw::redis::Redis & redis, uint8_t * p_buf, uint64_t buf_size)
  {
          // prepare data  
          std::string str_data;
          str_data.reserve(buf_size);
          uint64_t str_capacity = str_data.capacity();
          printf("str_capacity: %d \n", str_capacity);
          str_data.append((char*)p_buf, buf_size);
          // set  
          redis.set("img", str_data);
  }

从string取数据

#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui_c.h>
#include <stdint.h>
#include <sw/redis++/redis++.h>
#include <unordered_map>
#include <unordered_set>
#include <iostream>

const uint64_t DATA_SIZE{1024*1024*3};
const uint64_t rows{1464};
const uint64_t cols{1936};
const std::string URL{R"(tcp://192.168.0.41:6379)"};

void ctr(cv::Mat& mat_in, std::string& str_data_in)
{
        if(mat_in.empty())      mat_in.create(rows, cols, CV_8UC1);
        else    mat_in.resize(rows, cols);

        memcpy(mat_in.data, str_data_in.c_str(), rows*cols);
}

int main()
{
        sw::redis::Redis redis(URL);

        // init str_data
        std::string str_data;
        str_data.reserve(DATA_SIZE);

        cv::Mat img;
        cv::namedWindow("Wnd", CV_WINDOW_NORMAL);

        // while in loop
        while(1)
        {
                // get from redis-server
                str_data = *redis.get("img");
                // convert raw data to mat
                ctr(img, str_data);

                // show it
                cv::imshow("Wnd", img);
                cv::waitKey(10);

        }

        return 0;
}