C++ mutex,lock,unlock,lockguard

//model/util.h
#pragma once

#include <algorithm>
#include <chrono>
#include <ctime>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <map>
#include <mutex>
#include <sstream>
#include <thread>
#include <uuid/uuid.h>
#include <vector>

class util
{
public:
    util();
    ~util();
    util(util &ul) = delete;
    util operator=(util &ul) = delete;
    char *uuid_value;
    char *get_uuid();
    std::string get_uuid_str();
    std::string get_time_now();
    void print_log(const std::string &msg);
    std::mutex _mtx;
    std::map<int, std::string> _mtx_map;
    static void fill_mtx_map(util &ul, const int &len);
    void mt_thread_mutext(util &ul, const int &x, const int &y, const int &z);
    std::mutex _guard_mtx;
    std::map<int, std::string> _guard_mtx_map;
    static void fill_mtx_guard_map(util &ul, const int &len);
    void mt_thread_mtx_guard(util &ul, const int &x, const int &y, const int &z);
};





//model/util.cpp
#include "model/util.h"

void util::fill_mtx_guard_map(util &ul, const int &len)
{
    std::lock_guard<std::mutex> guard(ul._guard_mtx);
    ul.print_log("Started in " + std::string(__FILE__) + "," + std::string(__FUNCTION__) + "," + std::to_string(__LINE__));
    std::cout << "std::this_thread::get_id()= " << std::this_thread::get_id() << std::endl;
    static int num = 0;
    for (int i = 0; i < len; i++)
    {
        ul._guard_mtx_map.insert(std::pair<int, std::string>(++num, ul.get_uuid()));
    }
    ul.print_log("Finished in " + std::string(__FILE__) + "," + std::string(__FUNCTION__) + "," + std::to_string(__LINE__));
}

void util::mt_thread_mtx_guard(util &ul, const int &x, const int &y, const int &z)
{
    print_log("Started in " + std::string(__FILE__) + "," + std::string(__FUNCTION__) + "," + std::to_string(__LINE__));
    std::cout << "std::this_thread::get_id()= " << std::this_thread::get_id() << std::endl;

    std::thread t1(fill_mtx_guard_map, std::ref(ul), std::cref(x));
    std::thread t2(fill_mtx_guard_map, std::ref(ul), std::cref(y));
    std::thread t3(fill_mtx_guard_map, std::ref(ul), std::cref(z));
    t1.join();
    t2.join();
    t3.join();

    std::cout << "_guard_mtx_map's size =" << _guard_mtx_map.size() << std::endl;
    auto itr = _guard_mtx_map.begin();
    while (itr != _guard_mtx_map.end())
    {
        std::cout << "Key=" << itr->first << "," << itr->second << std::endl;
        itr = std::next(itr, 5000000);
    }
    print_log("Finished in " + std::string(__FILE__) + "," + std::string(__FUNCTION__) + "," + std::to_string(__LINE__));
}

void util::mt_thread_mutext(util &ul, const int &x, const int &y, const int &z)
{
    print_log("Started in " + std::string(__FILE__) + "," + std::string(__FUNCTION__) + "," + std::to_string(__LINE__));

    std::thread t1(fill_mtx_map, std::ref(ul), std::cref(x));
    std::thread t2(fill_mtx_map, std::ref(ul), std::cref(y));
    std::thread t3(fill_mtx_map, std::ref(ul), std::cref(z));

    t1.join();
    t2.join();
    t3.join();

    std::cout << "Map size= " << _mtx_map.size() << std::endl;
    auto itr = _mtx_map.begin();
    while (itr != _mtx_map.end())
    {
        std::cout << "Key=" << itr->first << "," << itr->second << std::endl;
        itr = std::next(itr, 5000000);
    }

    print_log("Finished in " + std::string(__FILE__) + "," + std::string(__FUNCTION__) + "," + std::to_string(__LINE__));
}

void util::fill_mtx_map(util &ul, const int &len)
{
    ul._mtx.lock();
    ul.print_log("Started in " + std::string(__FILE__) + "," + std::string(__FUNCTION__) + "," + std::to_string(__LINE__));
    static int num = 0;
    try
    {
        for (int i = 0; i < len; i++)
        {
            ul._mtx_map.insert(std::pair<int, std::string>(++num, ul.get_uuid()));
        }
    }
    catch (const std::exception &e)
    {
        ul._mtx.unlock();
        std::cerr << e.what() << 'n';
    }
    ul.print_log("Finished in " + std::string(__FILE__) + "," + std::string(__FUNCTION__) + "," + std::to_string(__LINE__));
    ul._mtx.unlock();
}

void util::print_log(const std::string &msg)
{
    std::cout << get_time_now() << "," << msg << std::endl;
}

std::string util::get_time_now()
{
    std::chrono::time_point<std::chrono::high_resolution_clock> now = std::chrono::high_resolution_clock::now();
    time_t raw_time = std::chrono::high_resolution_clock::to_time_t(now);
    struct tm tm_info = *localtime(&raw_time);
    std::chrono::milliseconds mills = std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch());
    std::chrono::seconds seconds = std::chrono::duration_cast<std::chrono::seconds>(now.time_since_epoch());
    std::stringstream ss;
    ss << std::put_time(&tm_info, "%Y%m%d%H%M%S") << std::setw(3) << std::setfill('0') << (mills.count() - seconds.count() * 1000);
    return ss.str();
}

util::util()
{
    uuid_value = (char *)malloc(40);
    std::cout << get_time_now() << " in constructor!" << std::endl;
}

util::~util()
{
    std::cout << get_time_now() << " in deconstructor!" << std::endl;
}

char *util::get_uuid()
{
    uuid_t new_uuid;
    uuid_generate(new_uuid);
    uuid_unparse(new_uuid, uuid_value);
    return uuid_value;
}

std::string util::get_uuid_str()
{
    uuid_t new_uuid;
    uuid_generate(new_uuid);
    uuid_unparse(new_uuid, uuid_value);
    std::string uuid_str(uuid_value);
    return uuid_str;
}



//main.cpp
#include "model/util.h"

void mt_thread_mutex_lock_unlock(const int &x, const int &y, const int &z)
{
    util ul;
    ul.print_log("Started in "+std::string(__FILE__)+","+std::string(__FUNCTION__)+","+std::to_string(__LINE__));
    ul.mt_thread_mutext(std::ref(ul),std::cref(x),std::cref(y),std::cref(z));
    ul.print_log("Finished in "+std::string(__FILE__)+","+std::string(__FUNCTION__)+","+std::to_string(__LINE__));
}

void mt_thread_mutex_lock_guard(const int &x,const int &y,const int&z)
{
    util ul;
    ul.print_log("Started in "+std::string(__FILE__)+","+std::string(__FUNCTION__)+","+std::to_string(__LINE__));
    ul.mt_thread_mtx_guard(std::ref(ul),std::cref(x),std::cref(y),std::cref(z));
    ul.print_log("Finished in "+std::string(__FILE__)+","+std::string(__FUNCTION__)+","+std::to_string(__LINE__));
}

int main(int args,char **argv)
{
    try
    {
        mt_thread_mutex_lock_guard(std::atoi(argv[1]),std::atoi(argv[2]),std::atoi(argv[3]));
    }
    catch(const std::exception& e)
    {
        std::cerr << e.what() << 'n';
    }  

}

g++ -g -std=c++2a -I. *.cpp ./model/*.cpp -o h1 -luuid -lpthread