80 lines
2.3 KiB
C
80 lines
2.3 KiB
C
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#pragma once
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#include <vector>
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#include <queue>
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#include <thread>
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#include <mutex>
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#include <condition_variable>
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#include <functional>
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#include <atomic>
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#include <future>
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class ThreadPool {
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private:
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std::vector<std::thread> workers_;
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std::queue<std::function<void()>> tasks_;
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std::mutex queue_mutex_;
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std::condition_variable condition_;
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std::atomic<bool> stop_{false};
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public:
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explicit ThreadPool(size_t num_threads = std::thread::hardware_concurrency()) {
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for (size_t i = 0; i < num_threads; ++i) {
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workers_.emplace_back([this] {
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for (;;) {
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std::function<void()> task;
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{
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std::unique_lock<std::mutex> lock(queue_mutex_);
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condition_.wait(lock, [this] { return stop_ || !tasks_.empty(); });
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if (stop_ && tasks_.empty()) return;
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task = std::move(tasks_.front());
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tasks_.pop();
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}
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task();
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}
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});
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}
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}
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template<class F, class... Args>
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auto enqueue(F&& f, Args&&... args) -> std::future<typename std::invoke_result<F, Args...>::type> {
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using return_type = typename std::invoke_result<F, Args...>::type;
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auto task = std::make_shared<std::packaged_task<return_type()>>(
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std::bind(std::forward<F>(f), std::forward<Args>(args)...)
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);
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std::future<return_type> res = task->get_future();
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{
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std::unique_lock<std::mutex> lock(queue_mutex_);
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if (stop_) {
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throw std::runtime_error("enqueue on stopped ThreadPool");
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}
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tasks_.emplace([task](){ (*task)(); });
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}
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condition_.notify_one();
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return res;
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}
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size_t pending_tasks() const {
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std::lock_guard<std::mutex> lock(const_cast<std::mutex&>(queue_mutex_));
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return tasks_.size();
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}
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~ThreadPool() {
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stop_ = true;
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condition_.notify_all();
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for (std::thread& worker : workers_) {
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worker.join();
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}
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}
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};
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