ｃ＋＋单例模式线程池源码示例

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

class ThreadPool {
public:
    static ThreadPool& getInstance(size_t threads = 4) {
        static ThreadPool instance(threads);
        return instance;
    }

    // 禁用拷贝构造和赋值操作符，确保单例
    ThreadPool(const ThreadPool&) = delete;
    ThreadPool& operator=(const ThreadPool&) = delete;

    // 提交任务到线程池
    template<class F, class... Args>
    auto submit(F&& f, Args&&... args) -> std::future<decltype(f(args...))> {
        using return_type = decltype(f(args...));

        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(m_queue_mutex);
            m_tasks.emplace([task]() { (*task)(); });
        }
        m_condition.notify_one();
        return res;
    }

    // 关闭线程池并等待所有线程完成任务
    void shutdown() {
        {
            std::unique_lock<std::mutex> lock(m_queue_mutex);
            m_stop = true;
        }
        m_condition.notify_all();
        for (std::thread &worker : m_workers) {
            worker.join();
        }
    }

private:
    // 构造函数私有化，单例模式
    ThreadPool(size_t threads) : m_stop(false) {
        for (size_t i = 0; i < threads; ++i) {
            m_workers.emplace_back([this] {
                for (;;) {
                    std::function<void()> task;

                    {
                        std::unique_lock<std::mutex> lock(m_queue_mutex);
                        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();
                }
            });
        }
    }

    ~ThreadPool() {
        shutdown();
    }

    // 线程池中的线程和任务队列
    std::vector<std::thread> m_workers;
    std::queue<std::function<void()>> m_tasks;

    // 同步机制
    std::mutex m_queue_mutex;
    std::condition_variable m_condition;
    bool m_stop;
};

// 模拟的任务类
class TaskManager {
public:
    void performTask() {
        std::cout << "Task is running on thread: " << std::this_thread::get_id() << std::endl;
    }

    void run() {
        ThreadPool& pool = ThreadPool::getInstance();
        auto result = pool.submit(&TaskManager::performTask, this);
        result.get();  // 等待任务完成
    }
};

int main() {
    TaskManager task1;
    TaskManager task2;

    task1.run();
    task2.run();

    ThreadPool::getInstance().shutdown(); // 关闭线程池

    return 0;
}