threadpool.cpp

std::vector<std::thread> threads;
int num_threads = std::thread::hardware_concurrency();
for (int i = 0; i < num_threads; ++i) {
    threads.emplace_back([&](){
        while (true) {
            // Wait for a task to be added to the queue
            std::unique_lock<std::mutex> lock(queue_mutex);
            while (task_queue.empty()) {
                condition.wait(lock);
            }

            // Get the next task from the queue
            std::function<void()> task = task_queue.front();
            task_queue.pop();

            // Unlock the mutex before executing the task
            lock.unlock();

            // Execute the task
            task();
        }
    });
}


int listener_fd = socket(AF_INET, SOCK_STREAM, 0);
if (listener_fd == -1) {
    // Error handling
}

int opt = 1;
setsockopt(listener_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

struct sockaddr_in server_addr;
memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(8080);
server_addr.sin_addr.s_addr = htonl(INADDR_ANY);

int bind_status = bind(listener_fd, (struct sockaddr*)&server_addr, sizeof(server_addr));
if (bind_status == -1) {
    // Error handling
}

int listen_status = listen(listener_fd, SOMAXCONN);
if (listen_status == -1) {
    // Error handling
}


while (true) {
    int client_fd = accept(listener_fd, NULL, NULL);
    if (client_fd == -1) {
        // Error handling
    }

    // Add a task to the thread pool to handle the connection
    std::lock_guard<std::mutex> lock(queue_mutex);
    task_queue.emplace([&](){
        handle_connection(client_fd);
        close(client_fd);
    });
    condition.notify_one();
}


void handle_connection(int client_fd) {
    char buffer[1024];
    int num_bytes = read(client_fd, buffer, sizeof(buffer));
    if (num_bytes == -1) {
        // Error handling
    }

    // Parse the HTTP request
    std::string request(buffer, num_bytes);
    // ...

    // Send the HTTP response
    std::string response = "HTTP/1.1 200 OK\r\nContent-Length: 5\r\n\r\nHello";
    int bytes_sent = send(client_fd, response.c_str(), response.length(), 0);
    if (bytes_sent == -1) {
        // Error handling
    }
}


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

class ThreadPool {
public:
    ThreadPool(size_t num_threads) : stop(false) {
        for (size_t i = 0; i < num_threads; ++i) {
            threads.emplace_back(
                [this] {
                    for (;;) {
                        std::function<void()> task;
                        {
                            std::unique_lock<std::mutex> lock(this->queue_mutex);
                            this->condition.wait(lock,
                                [this] { return this->stop || !this->tasks.empty(); });
                            if (this->stop && this->tasks.empty())
                                return;
                            task = std::move(this->tasks.front());
                            this->tasks.pop();
                        }
                        task();
                    }
                }
            );
        }
    }

    template<class F, class... Args>
    auto enqueue(F&& f, Args&&... args)
        -> std::future<typename std::result_of<F(Args...)>::type> {
        using return_type = typename std::result_of<F(Args...)>::type;

        auto task = std::make_shared<std::packaged_task<return_type()>>
            (std::bind(std::forward<F>(f), std::forward<Args>(args)...));

        std::future<return_type> res = task->get_future();
        {
            std::unique_lock<std::mutex> lock(queue_mutex);

            if (stop)
                throw std::runtime_error("enqueue on stopped ThreadPool");

            tasks.emplace([task]() { (*task)(); });
        }
        condition.notify_one();
        return res;
    }

    ~ThreadPool() {
        {
            std::unique_lock<std::mutex> lock(queue_mutex);
            stop = true;
        }
        condition.notify_all();
        for (std::thread& thread : threads)
            thread.join();
    }

private:
    std::vector<std::thread> threads;
    std::queue<std::function<void()>> tasks;

    std::mutex queue_mutex;
    std::condition_variable condition;
    bool stop;
};