141 lines
2.9 KiB
C++
141 lines
2.9 KiB
C++
#pragma once
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#include <vector>
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#include <queue>
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#include <memory>
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#include <thread>
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#include <mutex>
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#include <condition_variable>
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#include <future>
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#include <functional>
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#include <stdexcept>
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#include <map>
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#include <type_traits>
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#include <iostream>
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class ThreadPool
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{
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public:
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ThreadPool(size_t);
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template<class F, class... Args>
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auto enqueue(F&& f, Args&&... args)
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-> std::future<typename std::invoke_result<F, Args...>::type>;
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~ThreadPool();
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int thread_number(std::thread::id id)
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{
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if(id_map.find(id) != id_map.end())
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return (int)id_map[id];
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return -1;
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}
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size_t num_threads()
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{
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return num_threads_;
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}
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static ThreadPool* get()
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{
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return instance(0);
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}
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static ThreadPool* instance(uint32_t numthreads)
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{
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std::unique_lock<std::mutex> lock(singleton_mutex);
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if(!singleton) {
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singleton = new ThreadPool(numthreads ? numthreads : hardware_concurrency());
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}
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return singleton;
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}
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static void release()
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{
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std::unique_lock<std::mutex> lock(singleton_mutex);
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delete singleton;
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singleton = nullptr;
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}
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static uint32_t hardware_concurrency()
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{
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return std::thread::hardware_concurrency();
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}
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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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bool stop;
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std::map<std::thread::id, size_t> id_map;
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size_t num_threads_;
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static ThreadPool* singleton;
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static std::mutex singleton_mutex;
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};
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inline ThreadPool::ThreadPool(size_t threads) : stop(false), num_threads_(threads)
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{
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if(threads == 1)
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return;
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for(size_t i = 0; i < threads; ++i)
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workers.emplace_back([this] {
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for(;;)
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{
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std::function<void()> task;
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{
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std::unique_lock<std::mutex> lock(this->queue_mutex);
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this->condition.wait(lock,
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[this] { return this->stop || !this->tasks.empty(); });
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if(this->stop && this->tasks.empty())
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return;
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task = std::move(this->tasks.front());
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this->tasks.pop();
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}
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task();
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}
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});
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size_t thread_count = 0;
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for(std::thread& worker : workers)
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{
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id_map[worker.get_id()] = thread_count;
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thread_count++;
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}
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}
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// add new work item to the pool
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template<class F, class... Args>
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auto ThreadPool::enqueue(F&& f, Args&&... args)
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-> std::future<typename std::invoke_result<F, Args...>::type>
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{
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assert(num_threads_ > 1);
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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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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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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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inline ThreadPool::~ThreadPool()
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{
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{
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std::unique_lock<std::mutex> lock(queue_mutex);
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stop = true;
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}
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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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