マルチスレッドな進捗バー

progress_bar.cpp

#include <iostream>
#include <string>
#include <thread>
#include <atomic>
#include <unistd.h>
#include <mutex>

std::atomic<bool> end_flag = false;
std::atomic<bool> out_flag = false;
std::atomic<double> current_time = 0;
std::mutex mtx;
std::string bar;
double max = 10;

void output() {
  std::unique_lock<std::mutex> lock(mtx);
  if (current_time != 0) {
    double pers = (current_time / max) * 100;
    bar += "====";
    std::cout << pers << "% [" << bar << ">\r" << std::flush;
  }
}

void thread1() {
    for (int i = 0; i < max; ++i) {
        sleep(1);
        current_time = current_time + 1.0;
        out_flag = true;
    }
    end_flag = true;
}

void thread2() {
  while (!end_flag) {
    if (out_flag) {
      out_flag = false;
      output();
    }
  }
}

int main() {
    std::thread t1(thread1);
    std::thread t2(thread2);
    t1.join();
    t2.join();
}