The creator of the asynchronous operation can then use a variety of methods to query, wait for, or extract a value from thestd::future. These methods may block if the asynchronous operation has not yet provided
future_status Page Discussion std::future_status C++ Concurrency support library Defined in header<future> enumclassfuture_status{ ready, timeout, deferred }; (since C++11) Specifies state of a future as returned bywait_forandwait_untilfunctions ofstd::futureandstd::shared_future....
上面的最后一段话,中文含义是:注意std::future所引用的共享状态是不和任何其他异步操作所返回的future对象所共享的(与之对应的是std::shared_future) 并且异步操作创建方只能调用一次future::get来获取异步调用的结果信息,这是因为future::get函数内部,会断开future对象与关联状态对象之间的链接,如下代码行5 future对象...
()<<" launching thread\n";std::future<int>f=std::async(std::launch::async,[]{std::this_thread::sleep_for(1s);returntrue?throwstd::runtime_error("7"):7;});std::cout<<time()<<" waiting for the future, f.valid() = "<<f.valid()<<'\n';try{intn=f.get();std::cout<<...
future::valid future::wait future::wait_for future::wait_untilfuture() noexcept; (1) (since C++11) future( future&& other ) noexcept; (2) (since C++11) future( const future& other ) = delete; (3) (since C++11) Constructs a std::future object. 1...
std::future 可以理解为一个轻型Thread std::future 相对于QtConcurrent ,std::future不要求传入函数必须为static声明,这大大提高了灵活性。 参考链接:std::future<T>::wait_for - cppreference.com 代码实现: QProgressDialog *m_pProgressDialog = new QProgressDialog(tr("Checking..."),tr("Cancel"),0,0...
std::future是一种简易方便的线程间同步手段中的一环,与std::promise或者std::packaged_task配合实现简单的线程同步,由于是共享关联之中被动的一方,所以始终存在是否有效的问题,对于共享状态值的获取也需要在其标志为ready的条件下进行。 (参考网站:CSDN、cppreference.com、cplusplus.com等) ...
main.cpp #include<iostream>#include<future>#include<thread>intmain(){// future from a packaged_taskstd::packaged_task<int()>task([]{return7;});// wrap the functionstd::future<int>f1=task.get_future();// get a futurestd::threadt(std::move(task));// launch on a thread// future...
std::promise - cppreference.com std::future - cppreference.com std::shared_future - cppreference.com 请注意,上述示例代码仅用于演示std::promise和std::future的基本用法,并未涉及std::shared_future。在实际应用中,你可以根据需要使用std::shared_future来共享异步操作的结果。
C++ 11 std::future_error https://en.cppreference.com/w/cpp/thread/future_error https://en.cppreference.com/w/cpp/thread