#include <iostream>
#include <thread>
#include <vector>
#include <queue>
#include <mutex>
#include <condition_variable>

class ThreadPool {
public:
    ThreadPool(size_t numThreads) : m_stop(false) {
        for (size_t i = 0; i < numThreads; i++) {
            m_threads.emplace_back([this] {
                while (true) {
                    std::function<void()> task;
                    {
                        std::unique_lock<std::mutex> lock(m_queueMutex);
                        m_condition.wait(lock, [this] { return m_stop || !m_tasks.empty(); });
                        if (m_stop && m_tasks.empty()) {
                            return;
                        }
                        task = std::move(m_tasks.front());
                        m_tasks.pop();
                    }
                    task();
                }
            });
        }
    }

    template<typename Func>
    void enqueue(Func func) {
        {
            std::unique_lock<std::mutex> lock(m_queueMutex);
            m_tasks.emplace(func);
        }
        m_condition.notify_one();
    }

    ~ThreadPool() {
        {
            std::unique_lock<std::mutex> lock(m_queueMutex);
            m_stop = true;
        }
        m_condition.notify_all();
        for (std::thread &thread : m_threads) {
            thread.join();
        }
    }

private:
    std::vector<std::thread> m_threads;
    std::queue<std::function<void()>> m_tasks;
    std::mutex m_queueMutex;
    std::condition_variable m_condition;
    bool m_stop;
};

int main() {
    ThreadPool pool(4);  // 4개의 스레드로 이루어진 스레드 풀 생성

    // 작업 등록
    for (int i = 0; i < 8; i++) {
        pool.enqueue([i] {
            std::cout << "Task " << i << " executed by thread " << std::this_thread::get_id() << std::endl;
        });
    }
    
    std::this_thread::sleep_for(std::chrono::seconds(2));  // 모든 작업이 완료될 때까지 대기
}

#include <iostream>
#include <fstream>
#include <string>
#include <future>

std::string readFromFile(const std::string& filename) {
    std::ifstream file(filename);
    if (file.is_open()) {
        std::string content((std::istreambuf_iterator<char>(file)), std::istreambuf_iterator<char>());
        return content;
    } else {
        return "File not found";
    }
}

int main() {
    std::future<std::string> result = std::async(std::launch::async, readFromFile, "example.txt");
    // 다른 작업 수행
    std::cout << "Do something else while file reading..." << std::endl;

    std::string content = result.get();  // 파일 읽기가 완료될 때까지 대기
    std::cout << "File content: " << content << std::endl;
}