C++写一个线程池

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

class ThreadPool {
    
    
public:
    ThreadPool(size_t num_threads) {
    
    
        for (size_t i = 0; i < num_threads; ++i) {
    
    
            threads_.emplace_back([this]() {
    
    
                while (true) {
    
    
                    std::function<void()> task;
                    {
    
    
                        std::unique_lock<std::mutex> lock(mutex_);
                        cond_.wait(lock, [this]() {
    
     return stop_ || !tasks_.empty(); });
                        if (stop_ && tasks_.empty()) {
    
    
                            return;
                        }
                        task = std::move(tasks_.front());
                        tasks_.pop();
                    }
                    task();
                }
            });
        }
    }

    ~ThreadPool() {
    
    
        {
    
    
            std::unique_lock<std::mutex> lock(mutex_);
            stop_ = true;
        }
        cond_.notify_all();
        for (auto& thread : threads_) {
    
    
            thread.join();
        }
    }

    template <class F, class... Args>
    void enqueue(F&& f, Args&&... args) {
    
    
        auto task = std::bind(std::forward<F>(f), std::forward<Args>(args)...);
        {
    
    
            std::unique_lock<std::mutex> lock(mutex_);
            tasks_.emplace(task);
        }
        cond_.notify_one();
    }

private:
    std::vector<std::thread> threads_;
    std::queue<std::function<void()>> tasks_;
    std::mutex mutex_;
    std::condition_variable cond_;
    bool stop_ = false;
};

#include <iostream>
#include "thread_pool.h"

void task(int x) {
    
    
    std::cout << "Task " << x << " is running on thread " << std::this_thread::get_id() << std::endl;
    std::this_thread::sleep_for(std::chrono::seconds(1));
    std::cout << "Task " << x << " is done" << std::endl;
}

int main() {
    
    
    ThreadPool pool(4);
    for (int i = 0; i < 10; ++i) {
    
    
        pool.enqueue(task, i);
    }
    return 0;
}