C++如何实现线程池_C++11手动实现一个简单的固定大小线程池

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

class ThreadPool {
public:
    explicit ThreadPool(size_t numThreads) : stop(false) {
        for (size_t i = 0; i < numThreads; ++i) {
            workers.emplace_back([this] {
                while (true) {
                    std::function task;
                    {
                        std::unique_lock lock(queue_mutex);
                        condition.wait(lock, [this] { return stop || !tasks.empty(); });
                        if (stop && tasks.empty()) return;
                        task = std::move(tasks.front());
                        tasks.pop();
                    }
                    task();
                }
            });
        }
    }

    template
    auto enqueue(F&& f) -> std::future::type> {
        using return_type = typename std::result_of::type;

        auto task = std::make_shared>(
            std::forward(f)
        );

        std::future res = task->get_future();
        {
            std::unique_lock 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 lock(queue_mutex);
            stop = true;
        }
        condition.notify_all();
        for (std::thread &worker : workers) {
            worker.join();
        }
    }

private:
    std::vector workers;
    std::queue> tasks;

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

int main() {
    ThreadPool pool(4);

    // 提交任务并获取 future
    auto result1 = pool.enqueue([]() {
        std::cout << "Task 1 running on thread " << std::this_thread::get_id() << std::endl;
        return 42;
    });

    auto result2 = pool.enqueue([]() {
        std::cout << "Task 2 running on thread " << std::this_thread::get_id() << std::endl;
        return 84;
    });

    // 等待结果
    std::cout << "Result1: " << result1.get() << std::endl;
    std::cout << "Result2: " << result2.get() << std::endl;

    return 0;
}