Advertisement
Not a member of Pastebin yet?
Sign Up,
it unlocks many cool features!
- /**
- copy from
- https://softwarerecs.stackexchange.com/questions/11009/c11-thread-pool-implementation
- -> https://github.com/progschj/ThreadPool
- */
- #include <vector>
- #include <queue>
- #include <memory>
- #include <thread>
- #include <mutex>
- #include <condition_variable>
- #include <future>
- #include <functional>
- #include <stdexcept>
- #include <iostream>
- class ThreadPool {
- public:
- ThreadPool(size_t);
- template<class F, class... Args>
- auto enqueue(F&& f, Args&&... args)
- -> std::future<typename std::result_of<F(Args...)>::type>;
- ~ThreadPool();
- private:
- // need to keep track of threads so we can join them
- std::vector< std::thread > workers;
- // the task queue
- std::queue< std::function<void()> > tasks;
- // synchronization
- std::mutex queue_mutex;
- std::condition_variable condition;
- bool stop;
- };
- // the constructor just launches some amount of workers
- inline ThreadPool::ThreadPool(size_t threads)
- : stop(false)
- {
- for(size_t i = 0;i<threads;++i)
- workers.emplace_back(
- [this]
- {
- for(;;)
- {
- std::function<void()> task;
- {
- std::unique_lock<std::mutex> lock(this->queue_mutex);
- this->condition.wait(lock,
- [this]{ return this->stop || !this->tasks.empty(); });
- if(this->stop && this->tasks.empty())
- return;
- task = std::move(this->tasks.front());
- this->tasks.pop();
- }
- task();
- }
- }
- );
- }
- // add new work item to the pool
- template<class F, class... Args>
- auto ThreadPool::enqueue(F&& f, Args&&... args)
- -> std::future<typename std::result_of<F(Args...)>::type>
- {
- using return_type = typename std::result_of<F(Args...)>::type;
- 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(queue_mutex);
- // don't allow enqueueing after stopping the pool
- if(stop)
- throw std::runtime_error("enqueue on stopped ThreadPool");
- tasks.emplace([task](){ (*task)(); });
- }
- condition.notify_one();
- return res;
- }
- // the destructor joins all threads
- inline ThreadPool::~ThreadPool()
- {
- {
- std::unique_lock<std::mutex> lock(queue_mutex);
- stop = true;
- }
- condition.notify_all();
- for(std::thread &worker: workers)
- worker.join();
- }
- //-------------user here
- ThreadPool pool(4);
- class C{
- public: int d=35;
- };
- class B{
- public: C* c;
- public: void test(){
- std::vector<std::future<void>> cac;
- for(int n=0;n<5;n++){
- cac.push_back(
- pool.enqueue([&](){
- test2();
- })
- );
- }
- for(auto& ele : cac){
- ele.get();
- }
- };
- public: void test2(){
- std::vector<std::future<void>> cac;
- for(int n=0;n<5;n++){
- cac.push_back(
- pool.enqueue([&](){
- int accu=0;
- for(int i=0;i<10000;i++){
- accu+=i;
- }
- std::cout<<accu<<" access c="<<c->d<<std::endl;
- })
- );
- }
- for(auto& ele : cac){
- ele.get();
- }
- }
- };
- int main(){
- C c;
- B b; b.c=&c;
- b.test();
- std::cout<<"end"<<std::endl;
- }
Advertisement
Add Comment
Please, Sign In to add comment
Advertisement