std::package_task bind.lambda,thread,future

#include <atomic>
#include <chrono>
#include <cmath>
#include <condition_variable>
#include <cstddef>
#include <forward_list>
#include <fstream>
#include <functional>
#include <future>
#include <iomanip>
#include <iostream>
#include <latch>
#include <list>
#include <map>
#include <memory>
#include <mutex>
#include <optional>
#include <queue>
#include <random>
#include <stack>
#include <string>
#include <thread>
#include <utility>
#include <uuid/uuid.h>
#include <vector>

char *uuid_value = (char *)malloc(40);
char *get_uuid_value()
{
    uuid_t new_uuid;
    uuid_generate(new_uuid);
    uuid_unparse(new_uuid, uuid_value);
    return uuid_value;
}

std::string get_time_now(bool is_exact = false)
{
    std::stringstream ss;
    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);
    ss << std::put_time(&tm_info, "%Y%m%d%H%M%S");
    if (is_exact)
    {
        std::chrono::seconds seconds = std::chrono::duration_cast<std::chrono::seconds>(now.time_since_epoch());
        std::chrono::milliseconds mills = std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch());
        std::chrono::microseconds micros = std::chrono::duration_cast<std::chrono::microseconds>(now.time_since_epoch());
        std::chrono::nanoseconds nanos = std::chrono::duration_cast<std::chrono::nanoseconds>(now.time_since_epoch());
        ss << "_" << std::setw(3) << std::setfill('0') << (mills.count() - seconds.count() * 1000)
           << std::setw(3) << std::setfill('0') << (micros.count() - mills.count() * 1000)
           << std::setw(3) << std::setfill('0') << (nanos.count() - micros.count() * 1000);
    }
    return ss.str();
}

std::string get_uuid_for_len(const int &len)
{
    std::stringstream ss;
    for (int i = 0; i < len; i++)
    {
        ss << i + 1 << "," << get_uuid_value() << std::endl;
    }
    return ss.str();
}

void package_task_lambda(const int &len)
{
    std::packaged_task<std::string(const int &)> task([](const int &len)
                                                      {
        std::stringstream ss;
        for(int i=0;i<len;i++)
        {
          ss<<i+1<<","<<get_uuid_value()<<std::endl;  
        }
        std::cout << get_time_now() << ",thread id: " << std::this_thread::get_id() << ",finished in " << __FUNCTION__ << std::endl;
        return ss.str(); });

    std::future<std::string> fut = task.get_future();
    task(std::cref(len));
    std::cout << "Task lambda:" << fut.get() << std::endl;
    std::cout << get_time_now() << ",thread id: " << std::this_thread::get_id() << ",finished in " << __FUNCTION__ << std::endl;
}

void package_task_thread_move(const int &len)
{
    std::packaged_task<std::string(const int &len)> task(get_uuid_for_len);
    std::future<std::string> fut = task.get_future();
    std::thread t1(std::move(task), std::cref(len));
    t1.join();
    std::cout << fut.get() << std::endl;
    std::cout << get_time_now() << ",thread id: " << std::this_thread::get_id() << ",finished in " << __FUNCTION__ << std::endl;
}

void packaged_task_bind(const int &len)
{
    std::packaged_task<std::string()> task(std::bind(get_uuid_for_len, std::cref(len)));
    std::future<std::string> fut = task.get_future();
    task();
    std::cout << fut.get() << std::endl;
    std::cout << get_time_now() << ",thread id: " << std::this_thread::get_id() << ",finished in " << __FUNCTION__ << std::endl;
}

int main(int agrs, char **argv)
{
    packaged_task_bind(atoi(argv[1]));
    std::cout << get_time_now() << ",thread id:" << std::this_thread::get_id() << ",finished in " << __FUNCTION__ << std::endl;
}

g++-12 -std=c++2a -I. *.cpp -o h1 -luuid -lpthread

./h1 10