实战小项目之基于yolo的目标检测web api实现

　　上个月，对微服务及web service有了一些想法，看了一本app后台开发及运维的书，主要是一些概念性的东西，对service有了一些基本了解。互联网最开始的构架多是cs构架，浏览器兴起以后，变成了bs，最近几年，随着移动互联网的兴起，cs构架再次火了起来，有了一个新的概念，web service。

　　最近两天，想结合自己这段时间学的东西，实现一个cs构架的service接口。说一下大体流程，client上传图片到http服务器，http后台使用yolo进行图片的检测，之后将检测结果封装成json返回到client，client进行解析显示。

client

　　使用libcurl作为http请求工具，使用rapidjson进行结果json数据的解析

　　上传图片时，没有使用标准的http多媒体方式，而是使用post 二进制流的方式，比较笨，有待改进。

server

　　物体检测识别使用yolo c语言版本，修改原工程darknet的main，引入自己的main，实现直接检测的功能，main的流程：

导入yolo参数--必要初始化--fork子进程--安装信号--初始化fifo--sleep等待图片上传           接收信号唤醒--读取图像--预测-写入json文件--fifo写唤醒子进程

　　　　　　　　　　　　　|　　　　　　　　　　　　　　　　　　　　　　　　　　　　　|　　　　　　　　　　　　　　　　　　　|

　　　　　　　　　　　执行libevent实现的http server--eventloop监听--有文件上传结束--signal 父进程--阻塞在fifo读                         读取json，http返回

具体代码

client

extern "C"{
#include <unistd.h>
#include <sys/types.h>
#include <time.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <fcntl.h>

//iso
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//others
#include "curl/curl.h"
}

//c++
#include <iostream>
#include <string>
#include <fstream>
#include "rapidjson/document.h"
#include "rapidjson/stringbuffer.h"
#include "rapidjson/writer.h"

#define psln(x) std::cout << #x " = " << (x) << std::endl

using namespace std;

size_t WriteFunction(void *input, size_t uSize, size_t uCount, void *arg) {
    size_t uLen = uSize * uCount;
    string *pStr = (string*) (arg);
    pStr->append((char*) (input), uLen);
    return uLen;
}

int main(int argc,char **argv){
    if(argc<3){
        printf("usage:./a.out uri pic
");
        exit(-1);
    }
    CURL *pCurl = NULL;
    CURLcode code;
    code = curl_global_init(CURL_GLOBAL_DEFAULT);
    if (code != CURLE_OK) {
        cout << "curl global init err" << endl;
        return -1;
    }
    pCurl = curl_easy_init();
    if (pCurl == NULL) {
        cout << "curl easy init err" << endl;
        return -1;
    }

    curl_slist *pHeaders = NULL;
    string sBuffer;
    string header = "username:tla001";
    pHeaders = curl_slist_append(pHeaders, header.c_str());

    ifstream in;
    in.open(argv[2], ios::in | ios::binary);
    if (!in.is_open()) {
        printf("open err
");
        exit(-1);
    }
    in.seekg(0, ios_base::end);
    const size_t maxSize = in.tellg();
    in.seekg(0);
    char * picBin = new char[maxSize];
    in.read(picBin, maxSize);
    in.close();
    cout << maxSize << endl;

    size_t sendSize = maxSize + sizeof(size_t);
    char *sendBuff = new char[sendSize];
    //    sprintf(sendBuff, "%d", maxSize);
    memcpy(sendBuff, &maxSize, sizeof(size_t));
    //    size_t tmp = 0;
    //    memcpy(&tmp, sendBuff, sizeof(size_t));
    //    cout << "tmp=" << tmp << endl;
    memcpy(sendBuff + sizeof(size_t), picBin, maxSize);
    curl_easy_setopt(pCurl, CURLOPT_URL, argv[1]);
    curl_easy_setopt(pCurl, CURLOPT_HTTPHEADER, pHeaders);
    curl_easy_setopt(pCurl, CURLOPT_TIMEOUT, 20);
    //    curl_easy_setopt(pCurl, CURLOPT_HEADER, 1);
    curl_easy_setopt(pCurl, CURLOPT_POST, 1L);
    curl_easy_setopt(pCurl, CURLOPT_POSTFIELDS, sendBuff);
    curl_easy_setopt(pCurl, CURLOPT_POSTFIELDSIZE, sendSize);
    curl_easy_setopt(pCurl, CURLOPT_WRITEFUNCTION, &WriteFunction);
    curl_easy_setopt(pCurl, CURLOPT_WRITEDATA, &sBuffer);

    code = curl_easy_perform(pCurl);
    if (code != CURLE_OK) {
        cout << "curl perform err,retcode="<<code << endl;
        return -1;
    }
    long retcode = 0;
    code = curl_easy_getinfo(pCurl, CURLINFO_RESPONSE_CODE, &retcode);
    if (code != CURLE_OK) {
        cout << "curl perform err" << endl;
        return -1;
    }
    //cout << "[http return code]: " << retcode << endl;
    //cout << "[http context]: " << endl << sBuffer << endl;
    using rapidjson::Document;
    Document doc;
    doc.Parse<0>(sBuffer.c_str());
    if (doc.HasParseError()) {
        rapidjson::ParseErrorCode code = doc.GetParseError();
        psln(code);
        return -1;
    }
    using rapidjson::Value;
    Value &content = doc["content"];
    if (content.IsArray()) {
        for (int i = 0; i < content.Size(); i++) {
            Value &v = content[i];
            assert(v.IsObject());
            cout<<"object "<<"["<<i+1<<"]"<<endl;
            if (v.HasMember("class") && v["class"].IsString()) {
                cout <<"	[class]:"<<v["class"].GetString()<<endl;
            }
            if (v.HasMember("prob") && v["prob"].IsDouble()) {
                cout <<"	[prob]:"<<v["prob"].GetDouble()<<endl;
            }
            cout<<"	***************************"<<endl;
            if (v.HasMember("left") && v["left"].IsInt()) {
                cout <<"	[left]:"<<v["left"].GetInt()<<endl;
            }
            if (v.HasMember("right") && v["right"].IsInt()) {
                cout <<"	[right]:"<<v["right"].GetInt()<<endl;
            }
            if (v.HasMember("top") && v["top"].IsInt()) {
                cout <<"	[top]:"<<v["top"].GetInt()<<endl;
            }
            if (v.HasMember("bot") && v["bot"].IsInt()) {
                cout <<"	[bot]:"<<v["bot"].GetInt()<<endl;
            }
            cout<<endl;

        }
    }

    delete[] picBin;
    delete[] sendBuff;
    curl_easy_cleanup(pCurl);

    curl_global_cleanup();
    return 0;
}

server

main.c

#include <time.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "parser.h"
#include "utils.h"
#include "cuda.h"
#include "blas.h"
#include "connected_layer.h"

extern void predict_classifier(char *datacfg, char *cfgfile, char *weightfile, char *filename, int top);
extern void test_detector(char *datacfg, char *cfgfile, char *weightfile, char *filename, float thresh, float hier_thresh, char *outfile, int fullscreen);
extern void run_voxel(int argc, char **argv);
extern void run_yolo(int argc, char **argv);
extern void run_detector(int argc, char **argv);
extern void run_coco(int argc, char **argv);
extern void run_writing(int argc, char **argv);
extern void run_captcha(int argc, char **argv);
extern void run_nightmare(int argc, char **argv);
extern void run_dice(int argc, char **argv);
extern void run_compare(int argc, char **argv);
extern void run_classifier(int argc, char **argv);
extern void run_regressor(int argc, char **argv);
extern void run_char_rnn(int argc, char **argv);
extern void run_vid_rnn(int argc, char **argv);
extern void run_tag(int argc, char **argv);
extern void run_cifar(int argc, char **argv);
extern void run_go(int argc, char **argv);
extern void run_art(int argc, char **argv);
extern void run_super(int argc, char **argv);
extern void run_lsd(int argc, char **argv);

void average(int argc, char *argv[])
{
    char *cfgfile = argv[2];
    char *outfile = argv[3];
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    network sum = parse_network_cfg(cfgfile);

    char *weightfile = argv[4];   
    load_weights(&sum, weightfile);

    int i, j;
    int n = argc - 5;
    for(i = 0; i < n; ++i){
        weightfile = argv[i+5];   
        load_weights(&net, weightfile);
        for(j = 0; j < net.n; ++j){
            layer l = net.layers[j];
            layer out = sum.layers[j];
            if(l.type == CONVOLUTIONAL){
                int num = l.n*l.c*l.size*l.size;
                axpy_cpu(l.n, 1, l.biases, 1, out.biases, 1);
                axpy_cpu(num, 1, l.weights, 1, out.weights, 1);
                if(l.batch_normalize){
                    axpy_cpu(l.n, 1, l.scales, 1, out.scales, 1);
                    axpy_cpu(l.n, 1, l.rolling_mean, 1, out.rolling_mean, 1);
                    axpy_cpu(l.n, 1, l.rolling_variance, 1, out.rolling_variance, 1);
                }
            }
            if(l.type == CONNECTED){
                axpy_cpu(l.outputs, 1, l.biases, 1, out.biases, 1);
                axpy_cpu(l.outputs*l.inputs, 1, l.weights, 1, out.weights, 1);
            }
        }
    }
    n = n+1;
    for(j = 0; j < net.n; ++j){
        layer l = sum.layers[j];
        if(l.type == CONVOLUTIONAL){
            int num = l.n*l.c*l.size*l.size;
            scal_cpu(l.n, 1./n, l.biases, 1);
            scal_cpu(num, 1./n, l.weights, 1);
                if(l.batch_normalize){
                    scal_cpu(l.n, 1./n, l.scales, 1);
                    scal_cpu(l.n, 1./n, l.rolling_mean, 1);
                    scal_cpu(l.n, 1./n, l.rolling_variance, 1);
                }
        }
        if(l.type == CONNECTED){
            scal_cpu(l.outputs, 1./n, l.biases, 1);
            scal_cpu(l.outputs*l.inputs, 1./n, l.weights, 1);
        }
    }
    save_weights(sum, outfile);
}

void speed(char *cfgfile, int tics)
{
    if (tics == 0) tics = 1000;
    network net = parse_network_cfg(cfgfile);
    set_batch_network(&net, 1);
    int i;
    time_t start = time(0);
    image im = make_image(net.w, net.h, net.c*net.batch);
    for(i = 0; i < tics; ++i){
        network_predict(net, im.data);
    }
    double t = difftime(time(0), start);
    printf("
%d evals, %f Seconds
", tics, t);
    printf("Speed: %f sec/eval
", t/tics);
    printf("Speed: %f Hz
", tics/t);
}

void operations(char *cfgfile)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    int i;
    long ops = 0;
    for(i = 0; i < net.n; ++i){
        layer l = net.layers[i];
        if(l.type == CONVOLUTIONAL){
            ops += 2l * l.n * l.size*l.size*l.c * l.out_h*l.out_w;
        } else if(l.type == CONNECTED){
            ops += 2l * l.inputs * l.outputs;
        }
    }
    printf("Floating Point Operations: %ld
", ops);
    printf("Floating Point Operations: %.2f Bn
", (float)ops/1000000000.);
}

void oneoff(char *cfgfile, char *weightfile, char *outfile)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    int oldn = net.layers[net.n - 2].n;
    int c = net.layers[net.n - 2].c;
    scal_cpu(oldn*c, .1, net.layers[net.n - 2].weights, 1);
    scal_cpu(oldn, 0, net.layers[net.n - 2].biases, 1);
    net.layers[net.n - 2].n = 9418;
    net.layers[net.n - 2].biases += 5;
    net.layers[net.n - 2].weights += 5*c;
    if(weightfile){
        load_weights(&net, weightfile);
    }
    net.layers[net.n - 2].biases -= 5;
    net.layers[net.n - 2].weights -= 5*c;
    net.layers[net.n - 2].n = oldn;
    printf("%d
", oldn);
    layer l = net.layers[net.n - 2];
    copy_cpu(l.n/3, l.biases, 1, l.biases +   l.n/3, 1);
    copy_cpu(l.n/3, l.biases, 1, l.biases + 2*l.n/3, 1);
    copy_cpu(l.n/3*l.c, l.weights, 1, l.weights +   l.n/3*l.c, 1);
    copy_cpu(l.n/3*l.c, l.weights, 1, l.weights + 2*l.n/3*l.c, 1);
    *net.seen = 0;
    save_weights(net, outfile);
}

void oneoff2(char *cfgfile, char *weightfile, char *outfile, int l)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    if(weightfile){
        load_weights_upto(&net, weightfile, 0, net.n);
        load_weights_upto(&net, weightfile, l, net.n);
    }
    *net.seen = 0;
    save_weights_upto(net, outfile, net.n);
}

void partial(char *cfgfile, char *weightfile, char *outfile, int max)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    if(weightfile){
        load_weights_upto(&net, weightfile, 0, max);
    }
    *net.seen = 0;
    save_weights_upto(net, outfile, max);
}

#include "convolutional_layer.h"
void rescale_net(char *cfgfile, char *weightfile, char *outfile)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    if(weightfile){
        load_weights(&net, weightfile);
    }
    int i;
    for(i = 0; i < net.n; ++i){
        layer l = net.layers[i];
        if(l.type == CONVOLUTIONAL){
            rescale_weights(l, 2, -.5);
            break;
        }
    }
    save_weights(net, outfile);
}

void rgbgr_net(char *cfgfile, char *weightfile, char *outfile)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    if(weightfile){
        load_weights(&net, weightfile);
    }
    int i;
    for(i = 0; i < net.n; ++i){
        layer l = net.layers[i];
        if(l.type == CONVOLUTIONAL){
            rgbgr_weights(l);
            break;
        }
    }
    save_weights(net, outfile);
}

void reset_normalize_net(char *cfgfile, char *weightfile, char *outfile)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    if (weightfile) {
        load_weights(&net, weightfile);
    }
    int i;
    for (i = 0; i < net.n; ++i) {
        layer l = net.layers[i];
        if (l.type == CONVOLUTIONAL && l.batch_normalize) {
            denormalize_convolutional_layer(l);
        }
        if (l.type == CONNECTED && l.batch_normalize) {
            denormalize_connected_layer(l);
        }
        if (l.type == GRU && l.batch_normalize) {
            denormalize_connected_layer(*l.input_z_layer);
            denormalize_connected_layer(*l.input_r_layer);
            denormalize_connected_layer(*l.input_h_layer);
            denormalize_connected_layer(*l.state_z_layer);
            denormalize_connected_layer(*l.state_r_layer);
            denormalize_connected_layer(*l.state_h_layer);
        }
    }
    save_weights(net, outfile);
}

layer normalize_layer(layer l, int n)
{
    int j;
    l.batch_normalize=1;
    l.scales = calloc(n, sizeof(float));
    for(j = 0; j < n; ++j){
        l.scales[j] = 1;
    }
    l.rolling_mean = calloc(n, sizeof(float));
    l.rolling_variance = calloc(n, sizeof(float));
    return l;
}

void normalize_net(char *cfgfile, char *weightfile, char *outfile)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    if(weightfile){
        load_weights(&net, weightfile);
    }
    int i;
    for(i = 0; i < net.n; ++i){
        layer l = net.layers[i];
        if(l.type == CONVOLUTIONAL && !l.batch_normalize){
            net.layers[i] = normalize_layer(l, l.n);
        }
        if (l.type == CONNECTED && !l.batch_normalize) {
            net.layers[i] = normalize_layer(l, l.outputs);
        }
        if (l.type == GRU && l.batch_normalize) {
            *l.input_z_layer = normalize_layer(*l.input_z_layer, l.input_z_layer->outputs);
            *l.input_r_layer = normalize_layer(*l.input_r_layer, l.input_r_layer->outputs);
            *l.input_h_layer = normalize_layer(*l.input_h_layer, l.input_h_layer->outputs);
            *l.state_z_layer = normalize_layer(*l.state_z_layer, l.state_z_layer->outputs);
            *l.state_r_layer = normalize_layer(*l.state_r_layer, l.state_r_layer->outputs);
            *l.state_h_layer = normalize_layer(*l.state_h_layer, l.state_h_layer->outputs);
            net.layers[i].batch_normalize=1;
        }
    }
    save_weights(net, outfile);
}

void statistics_net(char *cfgfile, char *weightfile)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    if (weightfile) {
        load_weights(&net, weightfile);
    }
    int i;
    for (i = 0; i < net.n; ++i) {
        layer l = net.layers[i];
        if (l.type == CONNECTED && l.batch_normalize) {
            printf("Connected Layer %d
", i);
            statistics_connected_layer(l);
        }
        if (l.type == GRU && l.batch_normalize) {
            printf("GRU Layer %d
", i);
            printf("Input Z
");
            statistics_connected_layer(*l.input_z_layer);
            printf("Input R
");
            statistics_connected_layer(*l.input_r_layer);
            printf("Input H
");
            statistics_connected_layer(*l.input_h_layer);
            printf("State Z
");
            statistics_connected_layer(*l.state_z_layer);
            printf("State R
");
            statistics_connected_layer(*l.state_r_layer);
            printf("State H
");
            statistics_connected_layer(*l.state_h_layer);
        }
        printf("
");
    }
}

void denormalize_net(char *cfgfile, char *weightfile, char *outfile)
{
    gpu_index = -1;
    network net = parse_network_cfg(cfgfile);
    if (weightfile) {
        load_weights(&net, weightfile);
    }
    int i;
    for (i = 0; i < net.n; ++i) {
        layer l = net.layers[i];
        if (l.type == CONVOLUTIONAL && l.batch_normalize) {
            denormalize_convolutional_layer(l);
            net.layers[i].batch_normalize=0;
        }
        if (l.type == CONNECTED && l.batch_normalize) {
            denormalize_connected_layer(l);
            net.layers[i].batch_normalize=0;
        }
        if (l.type == GRU && l.batch_normalize) {
            denormalize_connected_layer(*l.input_z_layer);
            denormalize_connected_layer(*l.input_r_layer);
            denormalize_connected_layer(*l.input_h_layer);
            denormalize_connected_layer(*l.state_z_layer);
            denormalize_connected_layer(*l.state_r_layer);
            denormalize_connected_layer(*l.state_h_layer);
            l.input_z_layer->batch_normalize = 0;
            l.input_r_layer->batch_normalize = 0;
            l.input_h_layer->batch_normalize = 0;
            l.state_z_layer->batch_normalize = 0;
            l.state_r_layer->batch_normalize = 0;
            l.state_h_layer->batch_normalize = 0;
            net.layers[i].batch_normalize=0;
        }
    }
    save_weights(net, outfile);
}

void mkimg(char *cfgfile, char *weightfile, int h, int w, int num, char *prefix)
{
    network net = load_network(cfgfile, weightfile, 0);
    image *ims = get_weights(net.layers[0]);
    int n = net.layers[0].n;
    int z;
    for(z = 0; z < num; ++z){
        image im = make_image(h, w, 3);
        fill_image(im, .5);
        int i;
        for(i = 0; i < 100; ++i){
            image r = copy_image(ims[rand()%n]);
            rotate_image_cw(r, rand()%4);
            random_distort_image(r, 1, 1.5, 1.5);
            int dx = rand()%(w-r.w);
            int dy = rand()%(h-r.h);
            ghost_image(r, im, dx, dy);
            free_image(r);
        }
        char buff[256];
        sprintf(buff, "%s/gen_%d", prefix, z);
        save_image(im, buff);
        free_image(im);
    }
}

void visualize(char *cfgfile, char *weightfile)
{
    network net = parse_network_cfg(cfgfile);
    if(weightfile){
        load_weights(&net, weightfile);
    }
    visualize_network(net);
#ifdef OPENCV
    cvWaitKey(0);
#endif
}

int running=0;
int exitFlag=0;
void sigHandle(int signal){
    if(signal==SIGUSR1){
        printf("rec SIGUSR1
");
        running=1;
    }
     if(signal==SIGINT){
        printf("rec SIGINT
");
        exitFlag=1;
    }
}
int main(int argc, char **argv)
{
    gpu_index = find_int_arg(argc, argv, "-i", 0);
    if(find_arg(argc, argv, "-nogpu")) {
        gpu_index = -1;
    }

#ifndef GPU
    gpu_index = -1;
#else
    if(gpu_index >= 0){
        cuda_set_device(gpu_index);
    }
#endif

    float thresh = find_float_arg(argc, argv, "-thresh", .24);
    char *filename ="test.jpg";
    char *outfile = find_char_arg(argc, argv, "-out", 0);
    int fullscreen = find_arg(argc, argv, "-fullscreen");
    char *cfgfile="cfg/yolo.cfg";
    char *weightfile="yolo.weights";
    char *datacfg="cfg/coco.data";
    float hier_thresh=0.5;
     list *options = read_data_cfg(datacfg);
    char *name_list = option_find_str(options, "names", "data/names.list");
    char **names = get_labels(name_list);

    image **alphabet = load_alphabet();
    network net = parse_network_cfg(cfgfile);
    if(weightfile){
        load_weights(&net, weightfile);
    }
    set_batch_network(&net, 1);
    srand(2222222);
    clock_t time;
    char buff[256];
    char *input = buff;
    int j;
    float nms=.4;
    int ret;
    int childPid=0;
    if((ret=fork())<0)
        exit(-1);
    else if(ret==0){
        printf("child pid :%d
",childPid=getpid());
        printf("parent pid:%d
",getppid());
        ServerRun();
    }

    if(signal(SIGUSR1,sigHandle)==SIG_ERR){
        perror("set signal err");
    }
     if(signal(SIGINT,sigHandle)==SIG_ERR){
        perror("set signal err");
    }

    const char * FIFO_NAME="/tmp/myfifo";
    if(access(FIFO_NAME,F_OK)==-1){
        int res=mkfifo(FIFO_NAME,0777);
        if(res!=0){
            printf("could not create fifo
");
            exit(-1);
        }
    }
    int fifo_fd=open(FIFO_NAME,O_WRONLY);
    

    layer l = net.layers[net.n-1];

    box *boxes = calloc(l.w*l.h*l.n, sizeof(box));
    float **probs = calloc(l.w*l.h*l.n, sizeof(float *));
    for(j = 0; j < l.w*l.h*l.n; ++j) probs[j] = calloc(l.classes + 1, sizeof(float *));

    while(!exitFlag){
        while(!running){
            if(exitFlag)
                break;
            sleep(1);
        }
        if(exitFlag)
            break;
        if(filename){
            strncpy(input, filename, 256);
        } 
        image im = load_image_color(input,0,0);
        image sized = letterbox_image(im, net.w, net.h);
        //image sized = resize_image(im, net.w, net.h);
        //image sized2 = resize_max(im, net.w);
        //image sized = crop_image(sized2, -((net.w - sized2.w)/2), -((net.h - sized2.h)/2), net.w, net.h);
        //resize_network(&net, sized.w, sized.h);
       

        float *X = sized.data;
        time=clock();
        network_predict(net, X);
        printf("%s: Predicted in %f seconds.
", input, sec(clock()-time));
        get_region_boxes(l, im.w, im.h, net.w, net.h, thresh, probs, boxes, 0, 0, hier_thresh, 1);
        if (nms) do_nms_obj(boxes, probs, l.w*l.h*l.n, l.classes, nms);
        //else if (nms) do_nms_sort(boxes, probs, l.w*l.h*l.n, l.classes, nms);
        draw_detections(im, l.w*l.h*l.n, thresh, boxes, probs, names, alphabet, l.classes);
        if(outfile){
            save_image(im, outfile);
        }
        else{
            save_image(im, "predictions");
#ifdef OPENCV
            cvNamedWindow("predictions", CV_WINDOW_NORMAL); 
            if(fullscreen){
                cvSetWindowProperty("predictions", CV_WND_PROP_FULLSCREEN, CV_WINDOW_FULLSCREEN);
            }
            show_image(im, "predictions");
            cvWaitKey(2000);
            cvDestroyAllWindows();
#endif
        }

        free_image(im);
        free_image(sized);
       
        // if (filename) break;
        running=0;
        int res=write(fifo_fd,"1",1);
        if(res==-1){
            printf("write fifo err
");
            // exit(-1);
        }
    }
    if(kill(childPid,9)==0){
        waitpid(childPid,NULL,0);
    }

    close(fifo_fd);
    free(boxes);
    free_ptrs((void **)probs, l.w*l.h*l.n);

    return 0;
}

eventserver.c

/*
 * eventserver.c
 *
 *  Created on: Jun 13, 2017
 *      Author: tla001
 */
#include <unistd.h>
#include <sys/types.h>
#include <time.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <arpa/inet.h>

//iso
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//others
#include <event2/event-config.h>
#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>
#include <event2/event.h>
#include <event2/http.h>
#include <event2/keyvalq_struct.h>
#include <event2/http_struct.h>
#include <event2/buffer_compat.h>

#include "cJSON.h"

void test_request_cb(struct evhttp_request *req, void *arg) {
    int ppid=getppid();
    int type = evhttp_request_get_command(req);
    const char *requestUri = evhttp_request_get_uri(req);
    if (EVHTTP_REQ_GET == type) {
        printf("method:GET uri:%s
", requestUri);
    } else if (EVHTTP_REQ_POST == type) {
        printf("method:POST uri:%s
", requestUri);
    }

    char *post_data = (char *) EVBUFFER_DATA(req->input_buffer);
//    printf("post data: %s", post_data);
    size_t maxSize = 0;
    memcpy(&maxSize, post_data, sizeof(size_t));


    FILE *fp = fopen("test.jpg", "wb");
    fwrite(post_data + sizeof(size_t), 1, maxSize, fp);
    fclose(fp);
    kill(ppid,SIGUSR1);
    const char *FIFO_NAME="/tmp/myfifo";
    int fifo_fd=open(FIFO_NAME,O_RDONLY);
    char tmp=0;
    int res=read(fifo_fd,&tmp,1);
    if(res==-1){
        printf("read err
");
        goto THISEXIT;
    }
    close(fifo_fd);
    printf("fifo tmp=%c
", tmp);
    char *resData="rec";
    if(tmp=='1'){
        FILE *fp=fopen("res.json","rb");
        if(fp==NULL)
            goto THISEXIT;
        fseek(fp,0,SEEK_END);
        size_t size=ftell(fp);
        rewind(fp);
        resData=NULL;
        resData=(char*)malloc(sizeof(char)*size+1);
        int readSize=fread(resData,1,size,fp);
        if(readSize!=size){
            printf("read err
");
        }
        resData[sizeof(char)*size]='';
        printf("%s
", resData);
        fclose(fp);
    }
    


    printf("rec data len:%d
", strlen(resData));
    struct evbuffer *buf1 = evbuffer_new();
    evbuffer_add_printf(buf1, resData);
    evhttp_send_reply(req, 200, "OK", buf1);
    if(resData&&tmp=='1')
        free(resData);
    return ;
THISEXIT:
    kill(ppid,SIGINT);
        
    exit(-1);
}
void ServerRun() {
    int port = 5555;

    struct event_base *base;
    struct evhttp *http;
    struct evhttp_bound_socket *handle;

    if (signal(SIGPIPE, SIG_IGN) == SIG_ERR) {
        printf("signal error,error[%d],error[%s]", errno, strerror(errno));
        exit(-1);
    }
    base = event_base_new();
    if (!base) {
        printf("create an event_base err
");
        exit(-1);
    }
    http = evhttp_new(base);
    if (!http) {
        printf("create evhttp err
");
        exit(-1);
    }
    evhttp_set_cb(http, "/test", test_request_cb, NULL);

    handle = evhttp_bind_socket_with_handle(http, "0.0.0.0", port);
    if (!handle) {
        printf("bind to port[%d] err
", port);
        exit(-1);
    }

    {
        struct sockaddr_storage ss;
        evutil_socket_t fd;
        ev_socklen_t socklen = sizeof(ss);
        char addrbuf[128];
        void *inaddr;
        const char *addr;
        int got_port = -1;
        fd = evhttp_bound_socket_get_fd(handle);
        memset(&ss, 0, sizeof(ss));
        if (getsockname(fd, (struct sockaddr*) &ss, &socklen)) {
            perror("getsockname failed");
            exit(-1);
        }
        if (ss.ss_family == AF_INET) {
            got_port = ntohs(((struct sockaddr_in*) &ss)->sin_port);
            inaddr = &((struct sockaddr_in*) &ss)->sin_addr;
        } else if (ss.ss_family == AF_INET6) {
            got_port = ntohs(((struct sockaddr_in6*) &ss)->sin6_port);
            inaddr = &((struct sockaddr_in6*) &ss)->sin6_addr;
        } else {
            printf("Weird address family
");
            exit(1);
        }

        addr = evutil_inet_ntop(ss.ss_family, inaddr, addrbuf, sizeof(addrbuf));
        if (addr) {
            printf("Listening on %s:%d
", addr, got_port);
        } else {
            printf("evutil_inet_ntop failed
");
            exit(-1);
        }
    }
    event_base_dispatch(base);
}

image.c修改一下函数

void draw_detections(image im, int num, float thresh, box *boxes, float **probs, char **names, image **alphabet, int classes)
{

    int i;
    cJSON *res=cJSON_CreateObject();
    cJSON *content,*rec;
    cJSON_AddItemToObject(res,"content",content=cJSON_CreateArray());
    for(i = 0; i < num; ++i){
        int class = max_index(probs[i], classes);
        float prob = probs[i][class];
        if(prob > thresh){

            int width = im.h * .012;

            if(0){
                width = pow(prob, 1./2.)*10+1;
                alphabet = 0;
            }

            //printf("%d %s: %.0f%%
", i, names[class], prob*100);
            // printf("%s: %.0f%%
", names[class], prob*100);
            int offset = class*123457 % classes;
            float red = get_color(2,offset,classes);
            float green = get_color(1,offset,classes);
            float blue = get_color(0,offset,classes);
            float rgb[3];

            //width = prob*20+2;

            rgb[0] = red;
            rgb[1] = green;
            rgb[2] = blue;
            box b = boxes[i];

            int left  = (b.x-b.w/2.)*im.w;
            int right = (b.x+b.w/2.)*im.w;
            int top   = (b.y-b.h/2.)*im.h;
            int bot   = (b.y+b.h/2.)*im.h;

            if(left < 0) left = 0;
            if(right > im.w-1) right = im.w-1;
            if(top < 0) top = 0;
            if(bot > im.h-1) bot = im.h-1;

            cJSON_AddItemToObject(content,"rec",rec=cJSON_CreateObject());
            cJSON_AddStringToObject(rec,"class",names[class]);
            cJSON_AddNumberToObject(rec,"prob",prob*100);
            cJSON_AddNumberToObject(rec,"left",left);
            cJSON_AddNumberToObject(rec,"right",right);
            cJSON_AddNumberToObject(rec,"top",top);
            cJSON_AddNumberToObject(rec,"bot",bot);

            draw_box_width(im, left, top, right, bot, width, red, green, blue);
            if (alphabet) {
                image label = get_label(alphabet, names[class], (im.h*.03)/10);
                draw_label(im, top + width, left, label, rgb);
                free_image(label);
            }
        }
    }
    char *resStr=cJSON_Print(res);
    cJSON_Delete(res);
    // printf("%s
", resStr);
    FILE *fp=fopen("res.json","wb");
    fwrite(resStr,1,strlen(resStr),fp);
    fclose(fp);
}

Makefile做了必要的修改

GPU=1
CUDNN=1
OPENCV=1
DEBUG=0

ARCH= -gencode arch=compute_20,code=[sm_20,sm_21] 
      -gencode arch=compute_30,code=sm_30 
      -gencode arch=compute_35,code=sm_35 
      -gencode arch=compute_50,code=[sm_50,compute_50] 
      -gencode arch=compute_52,code=[sm_52,compute_52]

# This is what I use, uncomment if you know your arch and want to specify
# ARCH=  -gencode arch=compute_52,code=compute_52

VPATH=./src/
EXEC=myapp
OBJDIR=./obj/

CC=gcc
NVCC=nvcc 
OPTS=-Ofast
LDFLAGS= -lm -pthread -L/usr/local/libevent/lib -levent
COMMON=-I/usr/local/libevent/include 
CFLAGS=-Wall -Wfatal-errors 

ifeq ($(DEBUG), 1) 
OPTS=-O0 -g
endif

CFLAGS+=$(OPTS)

ifeq ($(OPENCV), 1) 
COMMON+= -DOPENCV
CFLAGS+= -DOPENCV
LDFLAGS+= `pkg-config --libs opencv` 
COMMON+= `pkg-config --cflags opencv` 
endif

ifeq ($(GPU), 1) 
COMMON+= -DGPU -I/usr/local/cuda/include/
CFLAGS+= -DGPU
LDFLAGS+= -L/usr/local/cuda/lib64 -lcuda -lcudart -lcublas -lcurand
endif

ifeq ($(CUDNN), 1) 
COMMON+= -DCUDNN 
CFLAGS+= -DCUDNN
LDFLAGS+= -lcudnn
endif

OBJ=main.o eventserver.o cJSON.o gemm.o utils.o cuda.o deconvolutional_layer.o convolutional_layer.o list.o image.o activations.o im2col.o col2im.o blas.o crop_layer.o dropout_layer.o maxpool_layer.o softmax_layer.o data.o matrix.o network.o connected_layer.o cost_layer.o parser.o option_list.o detection_layer.o captcha.o route_layer.o writing.o box.o nightmare.o normalization_layer.o avgpool_layer.o coco.o dice.o yolo.o detector.o layer.o compare.o regressor.o classifier.o local_layer.o swag.o shortcut_layer.o activation_layer.o rnn_layer.o gru_layer.o rnn.o rnn_vid.o crnn_layer.o demo.o tag.o cifar.o go.o batchnorm_layer.o art.o region_layer.o reorg_layer.o lsd.o super.o voxel.o tree.o
ifeq ($(GPU), 1) 
LDFLAGS+= -lstdc++ 
OBJ+=convolutional_kernels.o deconvolutional_kernels.o activation_kernels.o im2col_kernels.o col2im_kernels.o blas_kernels.o crop_layer_kernels.o dropout_layer_kernels.o maxpool_layer_kernels.o network_kernels.o avgpool_layer_kernels.o
endif

OBJS = $(addprefix $(OBJDIR), $(OBJ))
DEPS = $(wildcard src/*.h) Makefile

all: obj backup results $(EXEC)

$(EXEC): $(OBJS)
	$(CC) $(COMMON) $(CFLAGS) $^ -o $@ $(LDFLAGS)

$(OBJDIR)%.o: %.c $(DEPS)
	$(CC) $(COMMON) $(CFLAGS) -c $< -o $@

$(OBJDIR)%.o: %.cu $(DEPS)
	$(NVCC) $(ARCH) $(COMMON) --compiler-options "$(CFLAGS)" -c $< -o $@

obj:
	mkdir -p obj
backup:
	mkdir -p backup
results:
	mkdir -p results

.PHONY: clean

clean:
	rm -rf $(OBJS) $(EXEC)

　　

　　在使用进程控制的时候，有一些防止出错的机制。

本项目涉及的技术yolo检测  --libevent http server --libcurl http client --http json